diff --git a/clients/ds-app/.gitignore b/clients/ds-app/.gitignore
new file mode 100644
index 0000000..405c589
--- /dev/null
+++ b/clients/ds-app/.gitignore
@@ -0,0 +1,28 @@
+# macOS
+.DS_Store
+
+# Swift / SwiftPM
+.build/
+.swiftpm/
+Package.resolved
+
+# Xcode
+DerivedData/
+build/
+# A-6: generated by `xcodegen generate` from project.yml (the source of truth). Regenerate, don't commit.
+*.xcodeproj/
+Support/Info.plist
+Support/DSApp.entitlements
+*.xcodeproj/project.xcworkspace/xcuserdata/
+*.xcodeproj/xcuserdata/
+*.xcworkspace/xcuserdata/
+*.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
+xcuserdata/
+*.moved-aside
+*.hmap
+*.ipa
+*.dSYM.zip
+*.dSYM
+
+# Misc
+*.swp
diff --git a/clients/ds-app/App/DSApp.swift b/clients/ds-app/App/DSApp.swift
new file mode 100644
index 0000000..fbba2c8
--- /dev/null
+++ b/clients/ds-app/App/DSApp.swift
@@ -0,0 +1,24 @@
+import SwiftUI
+import AppFeature
+
+/// Thin @main entry: window + DI only. Injects AppModel (FixtureDSClient + AIRouter(MockAIProvider))
+/// so the whole pipeline renders with zero real backend / zero real LLM. Feature logic lives in
+/// AppFeature, keeping the seam to a future Xcode/iPhone target trivial.
+@main
+struct DSApp: App {
+    @State private var model: AppModel
+
+    @MainActor
+    init() {
+        _model = State(initialValue: AppModel.preview)
+    }
+
+    var body: some Scene {
+        WindowGroup {
+            RootView()
+                .environment(model)
+                .frame(minWidth: 980, minHeight: 640)
+        }
+        .windowStyle(.automatic)
+    }
+}
diff --git a/clients/ds-app/Package.swift b/clients/ds-app/Package.swift
new file mode 100644
index 0000000..f73f6cd
--- /dev/null
+++ b/clients/ds-app/Package.swift
@@ -0,0 +1,57 @@
+// swift-tools-version: 6.2
+//
+// DS multidevice app — unified package (S2 AIFabric + S3 app), one repo / one manifest.
+//
+// AIFabric (Sources/AI, S2-owned) is compiled exactly once as a single target here, so the
+// "소비모델 b" duplicate-symbol concern (two packages each compiling Sources/AI) does not arise.
+// It is also exposed as a library product so a future separate app package could depend on it.
+//
+// Ownership boundary unchanged: S2 owns Sources/AI/** + Tests/AITests/**; S3 owns DSKit / AppFeature
+// / Tests/DSKitTests. S3 consumes AIFabric read-only.
+//
+// A-6 (Xcode .app target via xcodegen): the runnable macOS app shell lives in App/DSApp.swift, owned
+// by the xcodegen "DSApp" application target (project.yml), NOT by SPM. SPM here builds only the
+// libraries + tests, so `swift build` / `swift test` stay backend-free and the executable lives in
+// the real .app bundle (Info.plist + entitlements) where Cmd+R actually opens a window. The App
+// target depends on the AppFeature library product below.
+import PackageDescription
+
+let package = Package(
+    name: "DSApp",
+    platforms: [
+        .macOS(.v26), // FoundationModels (OnDeviceProvider) + 3-column NavigationSplitView
+    ],
+    products: [
+        .library(name: "AIFabric", targets: ["AIFabric"]),
+        // Consumed by the xcodegen "DSApp" .app target (App/DSApp.swift).
+        .library(name: "AppFeature", targets: ["AppFeature"]),
+    ],
+    targets: [
+        .target(
+            name: "AIFabric",
+            path: "Sources/AI",
+            swiftSettings: [.swiftLanguageMode(.v6)]
+        ),
+        .target(
+            name: "DSKit",
+            resources: [.process("Resources")],
+            swiftSettings: [.swiftLanguageMode(.v6)]
+        ),
+        .target(
+            name: "AppFeature",
+            dependencies: ["DSKit", "AIFabric"],
+            swiftSettings: [.swiftLanguageMode(.v6)]
+        ),
+        .testTarget(
+            name: "DSKitTests",
+            dependencies: ["DSKit", "AIFabric"],
+            swiftSettings: [.swiftLanguageMode(.v6)]
+        ),
+        .testTarget(
+            name: "AITests",
+            dependencies: ["AIFabric"],
+            path: "Tests/AITests",
+            swiftSettings: [.swiftLanguageMode(.v6)]
+        ),
+    ]
+)
diff --git a/clients/ds-app/Sources/AI/AIProvider.swift b/clients/ds-app/Sources/AI/AIProvider.swift
new file mode 100644
index 0000000..c99db10
--- /dev/null
+++ b/clients/ds-app/Sources/AI/AIProvider.swift
@@ -0,0 +1,143 @@
+// AIProvider.swift — S2 인터페이스 동결 (멀티디바이스 LLM 라우팅 패브릭)
+//
+// 이 파일이 앱(S3)이 코딩하는 "AI 호출 모양"을 동결한다.
+// S3 는 이 프로토콜 + MockAIProvider 로 빌드하고, S2 가 실제 provider
+// (OnDevice / LocalMLX / RemoteDS / Specialized)를 그 뒤에서 채운다.
+//
+// Foundation 외 의존 0 → 표준 출발선. 실제 구현(FoundationModels / MLX / URLSession)은
+// Providers/ 의 각 스켈레톤에서 S2 가 결선.
+
+import Foundation
+
+// MARK: - Provider 식별 (디바이스 역할 = 인프라 패브릭과 1:1)
+
+public enum AIProviderID: String, Codable, Sendable, CaseIterable {
+    /// 맥북·아이폰 온디바이스 (Apple Foundation Models). 즉답·오프라인·프라이버시.
+    case onDevice
+    /// 맥미니 메인 로컬 LLM 허브 (Gemma 4 26B, MLX :8801 / llm-router :8890). 무거운 생성.
+    case localMLX
+    /// 원격 DS 코퍼스 RAG (`GET /search/ask`). 전체 지식베이스 질의 — 온디바이스 불가 영역.
+    case remoteDS
+    /// GPU 특화 통로 (rerank / embed / vision / OCR). 온디맨드.
+    case specialized
+}
+
+// MARK: - 태스크 분류 (앱이 AI 에 요청하는 일의 종류 → 라우팅 기준)
+
+public enum AITask: String, Codable, Sendable {
+    /// 선택 텍스트/문서 빠른 요약.
+    case quickSummarize
+    /// 메모 정리·제목 생성·태그 제안.
+    case memoAssist
+    /// 현재 문서/선택에 대한 질문 (로컬 컨텍스트, 코퍼스 불필요).
+    case askSelection
+    /// 전체 지식베이스 RAG 질의 (코퍼스 필요 → 원격 DS).
+    case corpusAsk
+    /// 문서 분류 (도메인/카테고리 제안).
+    case classify
+    /// 이미지/스캔 PDF 이해 (비전).
+    case vision
+}
+
+public enum AIConfidence: String, Codable, Sendable {
+    case high, medium, low
+}
+
+public enum AIFinishReason: String, Codable, Sendable {
+    case completed      // 정상 완료
+    case refused        // 모델이 답변 거부 (근거 부족 등)
+    case timeout        // 생성 지연으로 생략
+    case unavailable    // provider 사용 불가 (503 계열)
+    case noEvidence     // (corpusAsk) 관련 근거 없음
+}
+
+// MARK: - 요청 / 응답
+
+public struct AICompletionRequest: Sendable {
+    public var task: AITask
+    public var prompt: String
+    /// 선택 텍스트·문서 본문 등 로컬 컨텍스트 (corpusAsk 는 보통 nil — 코퍼스가 컨텍스트).
+    public var context: String?
+    public var systemPrompt: String?
+    public var maxTokens: Int?
+    /// 사용자가 명시적으로 고른 provider. 지정 시 **자동 fallback 금지**(명시 opt-in).
+    public var explicitProvider: AIProviderID?
+
+    public init(
+        task: AITask,
+        prompt: String,
+        context: String? = nil,
+        systemPrompt: String? = nil,
+        maxTokens: Int? = nil,
+        explicitProvider: AIProviderID? = nil
+    ) {
+        self.task = task
+        self.prompt = prompt
+        self.context = context
+        self.systemPrompt = systemPrompt
+        self.maxTokens = maxTokens
+        self.explicitProvider = explicitProvider
+    }
+}
+
+/// corpusAsk 응답의 근거 — DS `Citation`(CONTRACT.md §4)에서 매핑.
+public struct AICitation: Codable, Sendable, Identifiable {
+    public var id: Int { n }
+    public var n: Int
+    public var docId: Int
+    public var title: String?
+    public var sectionTitle: String?
+    public var spanText: String
+
+    public init(n: Int, docId: Int, title: String?, sectionTitle: String?, spanText: String) {
+        self.n = n
+        self.docId = docId
+        self.title = title
+        self.sectionTitle = sectionTitle
+        self.spanText = spanText
+    }
+}
+
+public struct AICompletionResponse: Sendable {
+    public var text: String
+    public var providerUsed: AIProviderID
+    public var finishReason: AIFinishReason
+    public var citations: [AICitation]
+    public var confidence: AIConfidence?
+    public var latencyMs: Double?
+    /// 라우팅 가시성 — rule-based fallback 으로 1차 선택이 빗나갔을 때 채워짐(silent 금지).
+    public var routingNote: String?
+
+    public init(
+        text: String,
+        providerUsed: AIProviderID,
+        finishReason: AIFinishReason = .completed,
+        citations: [AICitation] = [],
+        confidence: AIConfidence? = nil,
+        latencyMs: Double? = nil,
+        routingNote: String? = nil
+    ) {
+        self.text = text
+        self.providerUsed = providerUsed
+        self.finishReason = finishReason
+        self.citations = citations
+        self.confidence = confidence
+        self.latencyMs = latencyMs
+        self.routingNote = routingNote
+    }
+}
+
+// MARK: - 프로토콜 (S2 가 구현, S3 가 소비)
+
+public protocol AIProvider: Sendable {
+    var id: AIProviderID { get }
+    /// 능력 프로브 (온디바이스 Apple Intelligence 가용? 맥미니 도달 가능? 등).
+    var isAvailable: Bool { get async }
+    func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse
+}
+
+public enum AIProviderError: Error, Sendable {
+    case notImplemented(AIProviderID)
+    case unavailable(AIProviderID)
+    case backendError(AIProviderID, status: Int, reason: String?)
+}
diff --git a/clients/ds-app/Sources/AI/AIRouter.swift b/clients/ds-app/Sources/AI/AIRouter.swift
new file mode 100644
index 0000000..75a5688
--- /dev/null
+++ b/clients/ds-app/Sources/AI/AIRouter.swift
@@ -0,0 +1,99 @@
+// AIRouter.swift — 태스크 → provider 라우팅 정책 (3단 fallback: explicit > rule > error)
+//
+// 정책 = feedback_task_routing_hybrid + feedback_no_silent_fallback_explicit_opt_in:
+//   1) 명시 provider 지정 → 그것만, 불가 시 **에러**(자동 fallback 금지).
+//   2) 미지정 → 태스크별 선호 체인(rule), 정의된 fallback 은 routingNote 로 가시화.
+//   3) 전부 불가 → noProviderAvailable.
+
+import Foundation
+
+public struct AIRoutingPolicy: Sendable {
+    /// 태스크별 provider 선호 순서. 앞쪽 우선, 불가/실패 시 다음으로(가시 fallback).
+    public var preference: [AITask: [AIProviderID]]
+
+    public init(preference: [AITask: [AIProviderID]]) {
+        self.preference = preference
+    }
+
+    public func chain(for task: AITask) -> [AIProviderID] {
+        preference[task] ?? [.onDevice, .localMLX, .remoteDS]
+    }
+
+    /// 기본 정책 — 디바이스 역할 표와 일치.
+    /// 빠른/사적 = 온디바이스 우선, 무거운 생성 = 맥미니, 코퍼스 = 원격 DS, 비전 = GPU 특화.
+    public static let `default` = AIRoutingPolicy(preference: [
+        .quickSummarize: [.onDevice, .localMLX],
+        .memoAssist:     [.onDevice, .localMLX],
+        .askSelection:   [.onDevice, .localMLX, .remoteDS],
+        .corpusAsk:      [.remoteDS],                 // 코퍼스는 원격만 — 온디바이스로 폴백 불가
+        .classify:       [.localMLX, .remoteDS, .onDevice],
+        .vision:         [.specialized, .onDevice],
+    ])
+}
+
+public enum AIRoutingError: Error, Sendable {
+    case providerNotConfigured(AIProviderID)
+    case explicitProviderUnavailable(AIProviderID)   // 명시 지정인데 불가 → 자동 fallback 안 함
+    case noProviderAvailable(AITask)
+}
+
+public struct AIRouter: Sendable {
+    public let providers: [AIProviderID: any AIProvider]
+    public let policy: AIRoutingPolicy
+    /// 라우팅 로그 훅 (silent skip 방지 — 가시 fallback). 기본은 무시.
+    public let log: @Sendable (String) -> Void
+
+    public init(
+        providers: [AIProviderID: any AIProvider],
+        policy: AIRoutingPolicy = .default,
+        log: @escaping @Sendable (String) -> Void = { _ in }
+    ) {
+        self.providers = providers
+        self.policy = policy
+        self.log = log
+    }
+
+    public func route(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        // 1) 명시 opt-in — 자동 fallback 금지.
+        if let explicit = request.explicitProvider {
+            guard let provider = providers[explicit] else {
+                throw AIRoutingError.providerNotConfigured(explicit)
+            }
+            guard await provider.isAvailable else {
+                log("explicit provider \(explicit.rawValue) unavailable — no fallback (opt-in)")
+                throw AIRoutingError.explicitProviderUnavailable(explicit)
+            }
+            return try await provider.complete(request)
+        }
+
+        // 2) rule-based 선호 체인 — 정의된 fallback 은 routingNote 로 가시화.
+        let chain = policy.chain(for: request.task)
+        var attempted: [AIProviderID] = []
+        var lastError: Error?
+
+        for id in chain {
+            guard let provider = providers[id] else { continue }
+            guard await provider.isAvailable else {
+                log("provider \(id.rawValue) unavailable for \(request.task.rawValue) — trying next")
+                attempted.append(id)
+                continue
+            }
+            do {
+                var response = try await provider.complete(request)
+                if !attempted.isEmpty {
+                    response.routingNote = "fallback from \(attempted.map(\.rawValue).joined(separator: ",")) → \(id.rawValue)"
+                }
+                return response
+            } catch {
+                log("provider \(id.rawValue) failed for \(request.task.rawValue): \(error) — trying next")
+                attempted.append(id)
+                lastError = error
+                continue
+            }
+        }
+
+        // 3) 전부 불가.
+        if let lastError { throw lastError }
+        throw AIRoutingError.noProviderAvailable(request.task)
+    }
+}
diff --git a/clients/ds-app/Sources/AI/Composition.swift b/clients/ds-app/Sources/AI/Composition.swift
new file mode 100644
index 0000000..7296206
--- /dev/null
+++ b/clients/ds-app/Sources/AI/Composition.swift
@@ -0,0 +1,82 @@
+// Composition.swift — S2 → S3 통합 진입점 (소비모델 b) + 엔드포인트 단일소스 config.
+//
+// INTEGRATION (소비모델 b): 앱(S3)은 이 패키지의 `AIFabric` product 에 **로컬 SwiftPM 의존**으로 붙고,
+//   Sources/AI 를 앱 타깃에 직접 포함하지 않는다(소스 이중소유/중복심볼 방지). S3 는 makeDefaultRouter(...)
+//   하나로 실 라우터를 와이어링하고 MockAIProvider 를 대체한다. 구체 DSAskClient(HTTP) = S3 소유.
+//
+// 엔드포인트 단일소스(S2-Fa): raw URL 산재 금지 — 부주의한 편집의 침묵 엔드포인트 swap 방지
+// (2026-05-17 Hermes incident 선례). env override → 검증된 기본값. ([[feedback_hermes_config_single_source_envvar]])
+import Foundation
+import os
+
+public struct AIProviderConfiguration: Sendable {
+    /// 맥미니 llm-router base (trailing slash 없는 base; 경로는 provider 가 append).
+    public var localMLXBaseURL: URL
+    /// llm-router 모델 별칭(라이브 확정 2026-06-05: 'mac-mini-default' → gemma-4-26b resolve).
+    public var localMLXModel: String
+    /// DS API base — S3 의 DSAskClient 가 사용. 공인 https://document.hyungi.net/api · 내부 http://100.110.63.63:8000/api.
+    /// 주의: DS `/search/ask` 는 **trailing slash 필수**(경로 결합 시 S3 client 가 보장).
+    public var dsBaseURL: URL
+    public var requestTimeout: TimeInterval
+    public var probeTimeout: TimeInterval
+
+    public init(
+        localMLXBaseURL: URL,
+        localMLXModel: String = "mac-mini-default",
+        dsBaseURL: URL,
+        requestTimeout: TimeInterval = 60,
+        probeTimeout: TimeInterval = 2
+    ) {
+        self.localMLXBaseURL = localMLXBaseURL
+        self.localMLXModel = localMLXModel
+        self.dsBaseURL = dsBaseURL
+        self.requestTimeout = requestTimeout
+        self.probeTimeout = probeTimeout
+    }
+
+    /// 환경변수 override → 검증된 기본값(단일 source). 키 부재 시 기본값.
+    public static func resolved(
+        environment: [String: String] = ProcessInfo.processInfo.environment
+    ) -> AIProviderConfiguration {
+        let localMLX = environment["AIFABRIC_LOCALMLX_URL"].flatMap(URL.init(string:))
+            ?? URL(string: "http://100.76.254.116:8890")!
+        let model = environment["AIFABRIC_LOCALMLX_MODEL"] ?? "mac-mini-default"
+        let ds = environment["AIFABRIC_DS_URL"].flatMap(URL.init(string:))
+            ?? URL(string: "https://document.hyungi.net/api")!
+        return AIProviderConfiguration(localMLXBaseURL: localMLX, localMLXModel: model, dsBaseURL: ds)
+    }
+}
+
+/// 기본 OSLog 라우팅 훅 — 폴백/스킵을 가시화(silent 금지). S3 도 참조 가능(public).
+public enum AIFabricLog {
+    static let router = Logger(subsystem: "ds-app.AIFabric", category: "AIRouter")
+    public static let routerHook: @Sendable (String) -> Void = { msg in
+        router.info("\(msg, privacy: .public)")
+    }
+}
+
+/// S3 → S2 단일 진입점. 4 provider 전부 등록(vision 체인 가시 폴백 보장) + 기본 정책 + log 훅.
+/// - client: S3 가 주입하는 구체 DS ask client(HTTP).
+/// - config: 엔드포인트 단일소스(기본 = env override → 검증 기본값).
+/// - session: LocalMLX URLSession(기본 .shared; 테스트는 mock 주입).
+public func makeDefaultRouter(
+    client: DSAskClient,
+    config: AIProviderConfiguration = .resolved(),
+    session: URLSession = .shared,
+    policy: AIRoutingPolicy = .default,
+    log: @escaping @Sendable (String) -> Void = AIFabricLog.routerHook
+) -> AIRouter {
+    let providers: [AIProviderID: any AIProvider] = [
+        .remoteDS: RemoteDSProvider(client: client),
+        .localMLX: LocalMLXProvider(
+            baseURL: config.localMLXBaseURL,
+            model: config.localMLXModel,
+            session: session,
+            requestTimeout: config.requestTimeout,
+            probeTimeout: config.probeTimeout
+        ),
+        .onDevice: OnDeviceProvider(),
+        .specialized: SpecializedProvider(),   // scaffold(불가) — vision 폴백 가시화
+    ]
+    return AIRouter(providers: providers, policy: policy, log: log)
+}
diff --git a/clients/ds-app/Sources/AI/MockAIProvider.swift b/clients/ds-app/Sources/AI/MockAIProvider.swift
new file mode 100644
index 0000000..69459a7
--- /dev/null
+++ b/clients/ds-app/Sources/AI/MockAIProvider.swift
@@ -0,0 +1,67 @@
+// MockAIProvider.swift — S3 가 실 LLM 없이 빌드/프리뷰하기 위한 mock.
+//
+// 어떤 AIProviderID 로도 가장해 태스크별 canned 응답을 반환한다.
+// S3 SwiftUI 프리뷰 / UI 테스트가 이걸 주입해 AI 흐름을 끝까지 그릴 수 있다.
+
+import Foundation
+
+public struct MockAIProvider: AIProvider {
+    public let id: AIProviderID
+    public let available: Bool
+    /// 인위적 지연(ms) — 로딩 UI 확인용.
+    public let simulatedLatencyMs: Double
+
+    public init(id: AIProviderID = .onDevice, available: Bool = true, simulatedLatencyMs: Double = 120) {
+        self.id = id
+        self.available = available
+        self.simulatedLatencyMs = simulatedLatencyMs
+    }
+
+    public var isAvailable: Bool {
+        get async { available }
+    }
+
+    public func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        guard available else { throw AIProviderError.unavailable(id) }
+
+        switch request.task {
+        case .quickSummarize:
+            return AICompletionResponse(
+                text: "요약(mock): 엘보 내경 가공 시 공차 +0.1/-0.0 관리와 최종 치수 검사 기록이 핵심.",
+                providerUsed: id, confidence: .high, latencyMs: simulatedLatencyMs
+            )
+        case .memoAssist:
+            return AICompletionResponse(
+                text: "제목 제안(mock): 엘보 발주 확인 / 태그: 발주, 엘보, 업무",
+                providerUsed: id, confidence: .medium, latencyMs: simulatedLatencyMs
+            )
+        case .askSelection:
+            return AICompletionResponse(
+                text: "선택 구간 답변(mock): UCS-66 면제 곡선은 재료군과 두께로 MDMT 면제를 판정합니다.",
+                providerUsed: id, confidence: .high, latencyMs: simulatedLatencyMs
+            )
+        case .corpusAsk:
+            return AICompletionResponse(
+                text: "충격시험 면제는 UCS-66 면제 곡선으로 판정합니다 [1]. 설계 응력비가 낮으면 UCS-66.1로 MDMT를 더 낮출 수 있습니다 [1].",
+                providerUsed: .remoteDS,
+                citations: [
+                    AICitation(n: 1, docId: 4912,
+                               title: "ASME Section VIII Div 1 — Impact Test 요건",
+                               sectionTitle: "2. UCS-66 면제 곡선",
+                               spanText: "재료군과 두께에 따라 MDMT에서의 충격시험 면제 여부를 결정한다.")
+                ],
+                confidence: .high, latencyMs: 2840
+            )
+        case .classify:
+            return AICompletionResponse(
+                text: "분류 제안(mock): Engineering / 압력용기",
+                providerUsed: id, confidence: .medium, latencyMs: simulatedLatencyMs
+            )
+        case .vision:
+            return AICompletionResponse(
+                text: "비전(mock): 스캔 도면에서 표제란·치수선·용접기호가 식별됨.",
+                providerUsed: .specialized, confidence: .medium, latencyMs: 900
+            )
+        }
+    }
+}
diff --git a/clients/ds-app/Sources/AI/Providers/LocalMLXProvider.swift b/clients/ds-app/Sources/AI/Providers/LocalMLXProvider.swift
new file mode 100644
index 0000000..91c7e91
--- /dev/null
+++ b/clients/ds-app/Sources/AI/Providers/LocalMLXProvider.swift
@@ -0,0 +1,161 @@
+// LocalMLXProvider.swift — S2 구현 (맥미니 메인 로컬 LLM 허브).
+//
+// 맥미니 Gemma 4 26B, llm-router :8890 (OpenAI 호환, wake-on-call). 결정 #4: raw MLX :8801 폐기.
+//   - isAvailable = GET /v1/models 경량 probe(짧은 timeout, wake 미트리거 → '가용인데 콜드' 정상)
+//   - complete   = POST /v1/chat/completions, messages system/user 분리(call-shape 고정)
+//
+// fixture(llm-router-chat.*.json) = CAPTURED_LIVE (2026-06-05, Tailscale 100.76.254.116:8890 실측).
+//    요청 model='mac-mini-default'(별칭) → 응답 model='mlx-community/gemma-4-26b-a4b-it-8bit'.
+import Foundation
+
+public struct LocalMLXProvider: AIProvider {
+    public let id: AIProviderID = .localMLX
+
+    /// 맥미니 허브 베이스 URL (S2-Fa config 에서 주입). trailing slash 없는 base, 경로는 appendingPathComponent.
+    public let baseURL: URL
+    let model: String
+    let session: URLSession
+    let requestTimeout: TimeInterval
+    let probeTimeout: TimeInterval
+
+    public init(
+        baseURL: URL,
+        model: String = "mac-mini-default",   // llm-router 별칭(라이브 /v1/models 확인) → gemma-4-26b resolve
+        session: URLSession = .shared,
+        requestTimeout: TimeInterval = 60,
+        probeTimeout: TimeInterval = 2
+    ) {
+        self.baseURL = baseURL
+        self.model = model
+        self.session = session
+        self.requestTimeout = requestTimeout
+        self.probeTimeout = probeTimeout
+    }
+
+    // MARK: isAvailable — 경량 health probe (wake 미트리거)
+
+    public var isAvailable: Bool {
+        get async {
+            var req = URLRequest(url: baseURL.appendingPathComponent("v1/models"))
+            req.httpMethod = "GET"
+            req.timeoutInterval = probeTimeout
+            do {
+                let (_, resp) = try await session.data(for: req)
+                guard let http = resp as? HTTPURLResponse else { return false }
+                return (200..<300).contains(http.statusCode)
+            } catch {
+                // timeout/연결오류 → false(throw 아님). probe 는 wake/모델로드 유발 X.
+                // '가용=응답가능 ≠ 즉답' — 콜드 모델은 첫 complete() 가 로드지연 흡수.
+                return false
+            }
+        }
+    }
+
+    // MARK: complete — OpenAI 호환 chat/completions
+
+    public func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        try Task.checkCancellation()
+
+        var req = URLRequest(url: baseURL.appendingPathComponent("v1/chat/completions"))
+        req.httpMethod = "POST"
+        req.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        req.timeoutInterval = requestTimeout          // S2-Fe: 행 걸린 생성 무한정지 방지
+        req.httpBody = try Self.encodeRequest(request, model: model)
+
+        let started = Date()
+        let data: Data
+        let resp: URLResponse
+        do {
+            // URLSession async 는 Task 취소를 자동 honor → CancellationError 전파(S2-Fe).
+            (data, resp) = try await session.data(for: req)
+        } catch let e as URLError where e.code == .timedOut {
+            throw AIProviderError.backendError(id, status: -1, reason: "request timed out after \(Int(requestTimeout))s")
+        }
+
+        guard let http = resp as? HTTPURLResponse else {
+            throw AIProviderError.backendError(id, status: -1, reason: "non-HTTP response")
+        }
+        guard (200..<300).contains(http.statusCode) else {
+            // non-200 → backendError (빈 text 침묵 금지).
+            let reason = String(data: data, encoding: .utf8).map { String($0.prefix(300)) }
+            throw AIProviderError.backendError(id, status: http.statusCode, reason: reason)
+        }
+
+        let decoded = try JSONDecoder().decode(OpenAIChatResponse.self, from: data)
+        guard let choice = decoded.choices.first else {
+            throw AIProviderError.backendError(id, status: http.statusCode, reason: "no choices in response")
+        }
+        return AICompletionResponse(
+            text: choice.message.content,
+            providerUsed: .localMLX,
+            finishReason: Self.finishReason(choice.finishReason),
+            citations: [],                                  // 로컬 생성 — 코퍼스 인용 없음
+            confidence: nil,
+            latencyMs: Date().timeIntervalSince(started) * 1000,
+            routingNote: nil                                // fallback note 는 라우터가 채움
+        )
+    }
+
+    // MARK: 매핑
+
+    static func finishReason(_ openAI: String?) -> AIFinishReason {
+        switch openAI {
+        case "stop":   return .completed
+        case "length": return .completed   // max_tokens 절단 — 정상 완료로 취급
+        default:       return .completed
+        }
+    }
+
+    /// AICompletionRequest → OpenAI chat/completions body. messages system/user 분리(fixture 와 단일 source-of-truth).
+    /// system.content = systemPrompt ?? "" (plan S2-2c). temperature 는 AICompletionRequest 에 없음(동결) → 미설정(서버 기본).
+    static func encodeRequest(_ request: AICompletionRequest, model: String) throws -> Data {
+        let body = OpenAIChatRequest(
+            model: model,
+            messages: [
+                OpenAIChatRequest.Message(role: "system", content: request.systemPrompt ?? ""),
+                OpenAIChatRequest.Message(role: "user", content: request.prompt),
+            ],
+            maxTokens: request.maxTokens,
+            stream: false
+        )
+        let enc = JSONEncoder()
+        enc.outputFormatting = [.sortedKeys]
+        return try enc.encode(body)
+    }
+}
+
+// MARK: - OpenAI 호환 wire 타입 (내부)
+
+struct OpenAIChatRequest: Encodable, Sendable {
+    struct Message: Encodable, Sendable {
+        let role: String
+        let content: String
+    }
+    let model: String
+    let messages: [Message]
+    let maxTokens: Int?
+    let stream: Bool
+
+    enum CodingKeys: String, CodingKey {
+        case model, messages, stream
+        case maxTokens = "max_tokens"
+    }
+}
+
+struct OpenAIChatResponse: Decodable, Sendable {
+    struct Choice: Decodable, Sendable {
+        struct Message: Decodable, Sendable {
+            let role: String
+            let content: String
+        }
+        let index: Int?
+        let message: Message
+        let finishReason: String?
+
+        enum CodingKeys: String, CodingKey {
+            case index, message
+            case finishReason = "finish_reason"
+        }
+    }
+    let choices: [Choice]
+}
diff --git a/clients/ds-app/Sources/AI/Providers/OnDeviceProvider.swift b/clients/ds-app/Sources/AI/Providers/OnDeviceProvider.swift
new file mode 100644
index 0000000..5b21885
--- /dev/null
+++ b/clients/ds-app/Sources/AI/Providers/OnDeviceProvider.swift
@@ -0,0 +1,196 @@
+// OnDeviceProvider.swift — S2 구현 (맥북·아이폰 온디바이스, Apple FoundationModels).
+//
+// 라이브 경로(결정 #3): SystemLanguageModel.default.availability(동기) + LanguageModelSession.respond().
+// 모델 ~3B/2-bit QAT → quickSummarize/classify 적합, corpusAsk 무리(라우팅이 corpusAsk 를 RemoteDS 로만 보냄).
+//
+// 테스트 가능성: 모델 backend 를 seam(OnDeviceModelBackend)으로 주입 → CI/비-AI Mac 은 mock 으로
+// 에러매핑/라우팅 단위테스트, M5 Max 는 라이브 통합테스트(아래 default = FoundationModels).
+//
+// 실측 동결(S2-3a, M5 Max 2026-06-04): availability=available · respond()→Response<String>.content ·
+// GenerationError 9 case · 컨텍스트 오버플로→exceededContextWindowSize · 취소=COOPERATIVE(respond() 가
+// mid-flight Task.cancel 협조 → checkCancellation 은 belt-and-suspenders, streamResponse 불필요).
+import Foundation
+import os
+
+// MARK: - 중립 타입 (FoundationModels 비의존 — 매핑 로직을 HW 없이 단위테스트)
+
+public enum OnDeviceAvailability: Sendable, Equatable {
+    case available
+    case unavailable(reason: String)
+}
+
+/// FoundationModels.LanguageModelSession.GenerationError 의 중립 미러(9 case + unknown).
+/// 라이브 backend 가 SDK 에러를 이걸로 번역 → provider 가 finishReason/throw 로 매핑(순수·테스트 가능).
+public enum OnDeviceGenerationError: Error, Sendable, Equatable {
+    case guardrailViolation
+    case refusal
+    case exceededContextWindowSize
+    case rateLimited
+    case concurrentRequests
+    case unsupportedLanguageOrLocale
+    case unsupportedGuide
+    case decodingFailure
+    case assetsUnavailable
+    case unknown(String)
+}
+
+/// 온디바이스 모델 backend seam. 라이브 = FoundationModelsBackend, 테스트 = mock.
+protocol OnDeviceModelBackend: Sendable {
+    var availability: OnDeviceAvailability { get }
+    /// 실패는 OnDeviceGenerationError 또는 CancellationError 로 throw.
+    func generate(prompt: String, systemPrompt: String?, maxTokens: Int?) async throws -> String
+}
+
+// MARK: - Provider
+
+public struct OnDeviceProvider: AIProvider {
+    public let id: AIProviderID = .onDevice
+    private let backend: OnDeviceModelBackend
+    private let log: @Sendable (String) -> Void
+
+    public init() {
+        self.backend = Self.makeLiveBackend()
+        let logger = Logger(subsystem: "ds-app.AIFabric", category: "OnDeviceProvider")
+        self.log = { msg in logger.warning("\(msg, privacy: .public)") }
+    }
+
+    /// 테스트 seam — backend/log 주입(HW 비의존 단위테스트).
+    init(backend: OnDeviceModelBackend, log: @escaping @Sendable (String) -> Void = { _ in }) {
+        self.backend = backend
+        self.log = log
+    }
+
+    public var isAvailable: Bool {
+        get async { backend.availability == .available }
+    }
+
+    public func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        // belt-and-suspenders: 실제 mid-flight 취소는 respond() 내부가 협조(S2-3a 실측).
+        try Task.checkCancellation()
+        let started = Date()
+        do {
+            let text = try await backend.generate(
+                prompt: request.prompt,
+                systemPrompt: request.systemPrompt,
+                maxTokens: request.maxTokens
+            )
+            return AICompletionResponse(
+                text: text,
+                providerUsed: .onDevice,
+                finishReason: .completed,
+                latencyMs: Date().timeIntervalSince(started) * 1000
+            )
+        } catch let e as OnDeviceGenerationError {
+            return try mapError(e)
+        }
+        // CancellationError 등은 자연 전파.
+    }
+
+    /// GenerationError 매핑(S2-3c). 거부 = 답변의 일종 → 반환(폴백 X). 그 외 = provider 불가 → throw(라우터가 가시 폴백).
+    private func mapError(_ e: OnDeviceGenerationError) throws -> AICompletionResponse {
+        switch e {
+        case .guardrailViolation, .refusal:
+            return AICompletionResponse(
+                text: "",
+                providerUsed: .onDevice,
+                finishReason: .refused,
+                routingNote: "on-device refused (guardrail/refusal)"
+            )
+        case .rateLimited:
+            // stateless-per-request 인데 발생 = 세션 재사용 버그 신호(가림 금지 → loud + 불가).
+            log("UNEXPECTED onDevice rateLimited on stateless session — 세션 재사용 버그 의심")
+            throw AIProviderError.unavailable(id)
+        case .concurrentRequests:
+            log("UNEXPECTED onDevice concurrentRequests on stateless session — 세션 재사용 버그 의심")
+            throw AIProviderError.unavailable(id)
+        case .exceededContextWindowSize:
+            log("onDevice context window(4096) exceeded — 라우터가 localMLX 로 폴백")
+            throw AIProviderError.unavailable(id)
+        case .unsupportedLanguageOrLocale:
+            log("onDevice unsupported language/locale — 폴백")
+            throw AIProviderError.unavailable(id)
+        case .unsupportedGuide, .decodingFailure, .assetsUnavailable:
+            throw AIProviderError.unavailable(id)
+        case .unknown(let detail):
+            log("onDevice unknown generation error: \(detail)")
+            throw AIProviderError.unavailable(id)
+        }
+    }
+
+    static func makeLiveBackend() -> OnDeviceModelBackend {
+        #if canImport(FoundationModels)
+        return FoundationModelsBackend()
+        #else
+        return UnavailableBackend(reason: "FoundationModels not importable on this platform")
+        #endif
+    }
+}
+
+/// FoundationModels 미가용 플랫폼/SDK 폴백.
+struct UnavailableBackend: OnDeviceModelBackend {
+    let reason: String
+    var availability: OnDeviceAvailability { .unavailable(reason: reason) }
+    func generate(prompt: String, systemPrompt: String?, maxTokens: Int?) async throws -> String {
+        throw OnDeviceGenerationError.unknown("backend unavailable: \(reason)")
+    }
+}
+
+// MARK: - 라이브 FoundationModels backend (M5 Max / Apple Intelligence)
+
+#if canImport(FoundationModels)
+import FoundationModels
+
+struct FoundationModelsBackend: OnDeviceModelBackend {
+
+    var availability: OnDeviceAvailability {
+        switch SystemLanguageModel.default.availability {
+        case .available:
+            return .available
+        case .unavailable(let reason):
+            switch reason {
+            case .deviceNotEligible:           return .unavailable(reason: "deviceNotEligible")
+            case .appleIntelligenceNotEnabled: return .unavailable(reason: "appleIntelligenceNotEnabled")
+            case .modelNotReady:               return .unavailable(reason: "modelNotReady")
+            @unknown default:                  return .unavailable(reason: "unknownReason")
+            }
+        @unknown default:
+            return .unavailable(reason: "unknown")
+        }
+    }
+
+    func generate(prompt: String, systemPrompt: String?, maxTokens: Int?) async throws -> String {
+        // instructions = init 시점. systemPrompt nil 이면 생략(빈 문자열 금지 — S2-3c, LocalMLX 의 ?? '' 와 구분).
+        let session: LanguageModelSession
+        if let systemPrompt {
+            session = LanguageModelSession(model: .default, instructions: systemPrompt)
+        } else {
+            session = LanguageModelSession(model: .default)
+        }
+        session.prewarm()   // 동기 반환(~1.3ms), 백그라운드 워밍(S2-3a)
+        // temperature 는 AICompletionRequest 에 없음(동결) → 미설정(모델 기본). LocalMLX 와 동일 정책.
+        let options = GenerationOptions(maximumResponseTokens: maxTokens)
+        do {
+            let response = try await session.respond(to: prompt, options: options)
+            return response.content   // Response<String>.content : String
+        } catch let g as LanguageModelSession.GenerationError {
+            throw Self.translate(g)
+        }
+    }
+
+    /// SDK GenerationError(9 case) → 중립 OnDeviceGenerationError. exhaustive + @unknown default.
+    static func translate(_ g: LanguageModelSession.GenerationError) -> OnDeviceGenerationError {
+        switch g {
+        case .guardrailViolation:          return .guardrailViolation
+        case .refusal:                     return .refusal
+        case .exceededContextWindowSize:   return .exceededContextWindowSize
+        case .rateLimited:                 return .rateLimited
+        case .concurrentRequests:          return .concurrentRequests
+        case .unsupportedLanguageOrLocale: return .unsupportedLanguageOrLocale
+        case .unsupportedGuide:            return .unsupportedGuide
+        case .decodingFailure:             return .decodingFailure
+        case .assetsUnavailable:           return .assetsUnavailable
+        @unknown default:                  return .unknown("\(g)")
+        }
+    }
+}
+#endif
diff --git a/clients/ds-app/Sources/AI/Providers/RemoteDSProvider.swift b/clients/ds-app/Sources/AI/Providers/RemoteDSProvider.swift
new file mode 100644
index 0000000..1744e8d
--- /dev/null
+++ b/clients/ds-app/Sources/AI/Providers/RemoteDSProvider.swift
@@ -0,0 +1,155 @@
+// RemoteDSProvider.swift — S2 구현 (원격 DS 코퍼스 RAG).
+//
+// S1 계약과 만나는 다리 (CONTRACT.md §4 / AI-ROUTING.md §4):
+//   complete(corpusAsk) → DSAskClient.ask(query:backend:) → AskResponse → AICompletionResponse
+//   AskResponse.ai_answer        → text
+//   AskResponse.citations[]      → [AICitation]
+//   AskResponse.synthesis_status → AIFinishReason
+//   AskResponse.confidence       → AIConfidence
+//   AskResponse.backend_used     → routingNote (어느 LLM 이 응답했는지)
+//
+// HTTP 는 S3 의 구체 client(LiveDSClient)가 소유 — S2 는 DSAskClient 프로토콜 seam + 매핑만.
+// 인터페이스 동결: AIProvider 프로토콜은 불변. RemoteDSProvider.init(client:) 은 S2 가 채우는 구현부.
+import Foundation
+
+// MARK: - S2 가 소유하는 DS ask seam (구체 impl = S3)
+
+/// DS `GET /search/ask?q=&backend=` 호출 추상화. S3 의 LiveDSClient 가 conform,
+/// S2 는 mock 으로 단위테스트(라이브 네트워크 0). HTTP 실패는 conformer 가 throw
+/// (권장: `AIProviderError.backendError(.remoteDS, status:, reason:)`) — 침묵 폴백 금지.
+public protocol DSAskClient: Sendable {
+    func ask(query: String, backend: String) async throws -> AskResponse
+}
+
+// MARK: - DS /search/ask 응답 (부분 미러, 디코딩 전용)
+//
+// 명시 CodingKeys — convertFromSnakeCase 금지(S3 모델 규약과 일관). fixture: contract/fixtures/ask.json.
+
+public struct AskResponse: Decodable, Sendable {
+    public let aiAnswer: String
+    public let citations: [AskCitation]
+    public let synthesisStatus: String
+    public let synthesisMs: Double?
+    public let confidence: String?
+    public let backendUsed: String?
+    public let refused: Bool?
+
+    enum CodingKeys: String, CodingKey {
+        case aiAnswer = "ai_answer"
+        case citations
+        case synthesisStatus = "synthesis_status"
+        case synthesisMs = "synthesis_ms"
+        case confidence
+        case backendUsed = "backend_used"
+        case refused
+    }
+
+    public init(aiAnswer: String, citations: [AskCitation], synthesisStatus: String,
+                synthesisMs: Double? = nil, confidence: String? = nil,
+                backendUsed: String? = nil, refused: Bool? = nil) {
+        self.aiAnswer = aiAnswer
+        self.citations = citations
+        self.synthesisStatus = synthesisStatus
+        self.synthesisMs = synthesisMs
+        self.confidence = confidence
+        self.backendUsed = backendUsed
+        self.refused = refused
+    }
+}
+
+public struct AskCitation: Decodable, Sendable {
+    public let n: Int
+    public let docId: Int
+    public let title: String?
+    public let sectionTitle: String?
+    public let spanText: String
+
+    enum CodingKeys: String, CodingKey {
+        case n
+        case docId = "doc_id"
+        case title
+        case sectionTitle = "section_title"
+        case spanText = "span_text"
+    }
+
+    public init(n: Int, docId: Int, title: String?, sectionTitle: String?, spanText: String) {
+        self.n = n
+        self.docId = docId
+        self.title = title
+        self.sectionTitle = sectionTitle
+        self.spanText = spanText
+    }
+}
+
+// MARK: - Provider
+
+public struct RemoteDSProvider: AIProvider {
+    public let id: AIProviderID = .remoteDS
+    private let client: DSAskClient
+
+    public init(client: DSAskClient) {
+        self.client = client
+    }
+
+    /// 원격 코퍼스는 항상 후보(라우팅 시맨틱). 실제 도달 실패는 complete 에서 표면화.
+    public var isAvailable: Bool {
+        get async { true }
+    }
+
+    public func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        // corpusAsk 외 태스크는 이 provider 의 책임 아님(라우터가 거름).
+        guard request.task == .corpusAsk else {
+            throw AIProviderError.notImplemented(id)
+        }
+        try Task.checkCancellation()
+        let backend = Self.dsBackend(for: request.explicitProvider)
+        // HTTP 실패(503 등)는 client 가 throw → 그대로 전파(자동 로컬 폴백 금지).
+        let response = try await client.ask(query: request.prompt, backend: backend)
+        return Self.map(response)
+    }
+
+    // MARK: 매핑 (AI-ROUTING.md §4, 고정)
+
+    static func map(_ r: AskResponse) -> AICompletionResponse {
+        let citations = r.citations.map {
+            AICitation(n: $0.n, docId: $0.docId, title: $0.title,
+                       sectionTitle: $0.sectionTitle, spanText: $0.spanText)
+        }
+        return AICompletionResponse(
+            text: r.aiAnswer,
+            providerUsed: .remoteDS,
+            finishReason: finishReason(fromSynthesisStatus: r.synthesisStatus),
+            citations: citations,
+            confidence: r.confidence.flatMap(AIConfidence.init(rawValue:)),
+            latencyMs: r.synthesisMs,            // latency 는 synthesis_ms 만 기록(하드 게이트 없음)
+            routingNote: r.backendUsed           // 어느 LLM 이 응답했는지
+        )
+    }
+
+    static func finishReason(fromSynthesisStatus status: String) -> AIFinishReason {
+        switch status {
+        case "completed": return .completed
+        case "timeout": return .timeout
+        case "no_evidence", "skipped": return .noEvidence
+        case "backend_unavailable": return .unavailable
+        default: return .refused
+        }
+    }
+
+    /// explicitProvider → DS 합성 backend (AI-ROUTING.md §4, 고정).
+    /// **dict 아닌 exhaustive switch** — 미래 AIProviderID 추가 시 컴파일러가 backend 결정을 강제
+    /// (미매핑 provider → nil → 미정의 backend → 404 침묵실패를 컴파일 타임에 차단).
+    static func dsBackend(for explicit: AIProviderID?) -> String {
+        guard let explicit else { return "mac-mini-default" }   // 미지정 → DS 기본
+        switch explicit {
+        case .localMLX:    return "gemma-macmini"
+        case .remoteDS:    return "mac-mini-default"   // 명시 remoteDS = DS 기본 합성
+        case .onDevice:    return "mac-mini-default"   // onDevice 는 코퍼스 합성 불가 → DS 기본
+        case .specialized: return "mac-mini-default"   // specialized 코퍼스 backend 없음 → DS 기본
+        }
+        // TODO(qwen-macbook): 현재 어떤 AIProviderID 도 'qwen-macbook'(M5 Max Qwen VLM) 로 매핑 안 됨.
+        //   해당 provider case 가 생기면 위 exhaustive switch 가 컴파일 실패 → backend 결정 강제(S2-1b 게이트 b).
+        // TODO(claude-cloud): cloud backend = 'claude-cloud' 는 DS 가 503(scaffold, S2-4b). 매핑하는 case 없음.
+        //   503 은 client 가 backendError(.remoteDS, status:503, …) 로 표면화 — 절대 로컬 침묵 폴백 X(과금 버킷 분리).
+    }
+}
diff --git a/clients/ds-app/Sources/AI/Providers/SpecializedProvider.swift b/clients/ds-app/Sources/AI/Providers/SpecializedProvider.swift
new file mode 100644
index 0000000..0d11025
--- /dev/null
+++ b/clients/ds-app/Sources/AI/Providers/SpecializedProvider.swift
@@ -0,0 +1,27 @@
+// SpecializedProvider.swift — S2 scaffold (GPU 특화 통로: rerank / embed / vision / OCR).
+//
+// 이번 PR = **scaffold-only**: isAvailable=false, complete→notImplemented(.specialized). HTTP client/API key/cost = 0.
+// 목적: 라우터 .vision 체인 [.specialized, .onDevice] 에서 specialized 가 **dict 에 부재 → 침묵 continue** 하던 것을,
+//       등록된 명시-불가 provider 로 바꿔 폴백을 **가시화**(라우터가 'specialized unavailable → onDevice' log).
+//
+// 실 vision 통합 = backend 확정 + fixture 캡처 후 **별 PR**(결정 #1):
+//   후보 = MacBook M5 Max Qwen VLM  http://100.118.112.84:8810 (OpenAI 호환, wake-on-call) — 패브릭 내 유일 생성형 VLM.
+//   GPU Ollama 는 embedding(bge-m3) 전용이라 생성형 vision 아님.
+import Foundation
+
+public struct SpecializedProvider: AIProvider {
+    public let id: AIProviderID = .specialized
+
+    public init() {}
+
+    /// scaffold — 미구현. 라우터가 가시 폴백하도록 정직하게 false.
+    public var isAvailable: Bool {
+        get async { false }
+    }
+
+    public func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        // 침묵 nil-skip 금지 — 명시 notImplemented 로 vision-chain 폴백을 가시화.
+        // TODO(vision): .specialized → M5 Max Qwen VLM(:8810, wake-on-call) 실 call-shape + fixture 후 별 PR.
+        throw AIProviderError.notImplemented(id)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/AI/AICompletionView.swift b/clients/ds-app/Sources/AppFeature/AI/AICompletionView.swift
new file mode 100644
index 0000000..733e722
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/AI/AICompletionView.swift
@@ -0,0 +1,87 @@
+import SwiftUI
+import AIFabric
+
+public extension AIProviderID {
+    var displayName: String {
+        switch self {
+        case .onDevice: return "온디바이스"
+        case .localMLX: return "맥미니"
+        case .remoteDS: return "원격 DS"
+        case .specialized: return "GPU 특화"
+        }
+    }
+}
+
+/// Reusable renderer for any AICompletionResponse: answer text, numbered citations (deep-link to doc),
+/// an ALWAYS-visible provider/routing badge (the no-silent-fallback visibility rule), and confidence.
+public struct AICompletionView: View {
+    public let response: AICompletionResponse
+    public var onOpenDoc: (Int) -> Void
+
+    public init(response: AICompletionResponse, onOpenDoc: @escaping (Int) -> Void) {
+        self.response = response
+        self.onOpenDoc = onOpenDoc
+    }
+
+    public var body: some View {
+        VStack(alignment: .leading, spacing: 12) {
+            // Routing badges (mandatory, always shown)
+            HStack(spacing: 8) {
+                Chip(response.providerUsed.displayName, Sage.brand)
+                if let note = response.routingNote {
+                    Chip(note, Sage.amber)
+                }
+                if response.finishReason != .completed {
+                    Chip(finishLabel(response.finishReason), Sage.danger)
+                }
+                if let c = response.confidence {
+                    Chip("신뢰도 \(confidenceLabel(c))", Sage.muted)
+                }
+                if let ms = response.latencyMs {
+                    Text("\(Int(ms)) ms").font(.caption2).foregroundStyle(Sage.muted)
+                }
+            }
+
+            // Answer
+            Text(response.text)
+                .font(.body)
+                .foregroundStyle(Sage.ink)
+                .textSelection(.enabled)
+
+            // Citations
+            if !response.citations.isEmpty {
+                VStack(alignment: .leading, spacing: 6) {
+                    Text("출처").font(.caption.weight(.bold)).foregroundStyle(Sage.muted)
+                    ForEach(response.citations) { c in
+                        Button { onOpenDoc(c.docId) } label: {
+                            HStack(alignment: .top, spacing: 8) {
+                                Text("[\(c.n)]").font(.caption.weight(.bold)).foregroundStyle(Sage.brand)
+                                VStack(alignment: .leading, spacing: 2) {
+                                    Text(c.title ?? c.sectionTitle ?? "문서 \(c.docId)")
+                                        .font(.callout.weight(.medium)).foregroundStyle(Sage.ink)
+                                    Text(c.spanText).font(.caption).foregroundStyle(Sage.muted).lineLimit(2)
+                                }
+                            }
+                        }
+                        .buttonStyle(.plain)
+                    }
+                }
+                .padding(10)
+                .background(Sage.surface, in: RoundedRectangle(cornerRadius: 10))
+            }
+        }
+    }
+
+    private func finishLabel(_ r: AIFinishReason) -> String {
+        switch r {
+        case .completed: return "완료"
+        case .refused: return "거부"
+        case .timeout: return "시간 초과"
+        case .unavailable: return "사용 불가"
+        case .noEvidence: return "근거 없음"
+        }
+    }
+    private func confidenceLabel(_ c: AIConfidence) -> String {
+        switch c { case .high: return "높음"; case .medium: return "중간"; case .low: return "낮음" }
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/AI/AIService.swift b/clients/ds-app/Sources/AppFeature/AI/AIService.swift
new file mode 100644
index 0000000..cca6c7f
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/AI/AIService.swift
@@ -0,0 +1,59 @@
+import Foundation
+import AIFabric
+
+/// Renderable failure (the UI never sees a raw AIRoutingError — that would break the
+/// "visible error, not silent fallback" contract).
+public enum AIServiceError: Error, Sendable {
+    case explicitUnavailable(AIProviderID)
+    case notConfigured(AIProviderID)
+    case noneAvailable(AITask)
+    case providerFailed(String)
+    case unknown(String)
+}
+
+public enum AIResult: Sendable {
+    case success(AICompletionResponse)
+    case failure(AIServiceError)
+}
+
+/// The single app-facing facade over the S2 fabric. Views call intent methods; AIService is the ONLY
+/// place AICompletionRequest is built. An actor (not @Observable): routing is async work that should
+/// serialize and not hop to MainActor.
+public actor AIService {
+    private let router: AIRouter
+
+    public init(router: AIRouter) { self.router = router }
+
+    private func run(_ request: AICompletionRequest) async -> AIResult {
+        do {
+            return .success(try await router.route(request))
+        } catch let e as AIRoutingError {
+            switch e {
+            case .explicitProviderUnavailable(let id): return .failure(.explicitUnavailable(id))
+            case .providerNotConfigured(let id): return .failure(.notConfigured(id))
+            case .noProviderAvailable(let t): return .failure(.noneAvailable(t))
+            }
+        } catch let e as AIProviderError {
+            return .failure(.providerFailed("\(e)"))
+        } catch {
+            return .failure(.unknown("\(error)"))
+        }
+    }
+
+    // Intent methods — UI gesture -> AITask. (vision is deferred: the frozen request is text-only.)
+    public func summarize(text: String) async -> AIResult {
+        await run(AICompletionRequest(task: .quickSummarize, prompt: "다음 문서를 요약", context: text))
+    }
+    public func memoAssist(content: String) async -> AIResult {
+        await run(AICompletionRequest(task: .memoAssist, prompt: "제목과 태그 제안", context: content))
+    }
+    public func askSelection(selection: String, question: String) async -> AIResult {
+        await run(AICompletionRequest(task: .askSelection, prompt: question, context: selection))
+    }
+    public func corpusAsk(question: String, explicit: AIProviderID? = nil) async -> AIResult {
+        await run(AICompletionRequest(task: .corpusAsk, prompt: question, context: nil, explicitProvider: explicit))
+    }
+    public func classify(documentText: String) async -> AIResult {
+        await run(AICompletionRequest(task: .classify, prompt: "도메인/카테고리 분류 제안", context: documentText))
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/AI/AppAIComposition.swift b/clients/ds-app/Sources/AppFeature/AI/AppAIComposition.swift
new file mode 100644
index 0000000..b957a7d
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/AI/AppAIComposition.swift
@@ -0,0 +1,37 @@
+import Foundation
+import AIFabric
+import DSKit
+
+/// The ONE composition touch-point that names MockAIProvider. When S2 ships real providers,
+/// only this file changes (mockProviders -> realProviders) — AIService, views, and intents stay put.
+public enum AppAIComposition {
+    public static func mockProviders(unavailable: Set<AIProviderID> = []) -> [AIProviderID: any AIProvider] {
+        var providers: [AIProviderID: any AIProvider] = [:]
+        for id in AIProviderID.allCases {
+            providers[id] = MockAIProvider(id: id, available: !unavailable.contains(id))
+        }
+        return providers
+    }
+
+    public static func mockRouter(unavailable: Set<AIProviderID> = []) -> AIRouter {
+        AIRouter(
+            providers: mockProviders(unavailable: unavailable),
+            policy: .default,
+            log: { msg in
+                #if DEBUG
+                print("[route]", msg)
+                #endif
+            }
+        )
+    }
+
+    /// FU-B seam: the real S2 fabric (RemoteDS/LocalMLX/OnDevice/Specialized) via `makeDefaultRouter`,
+    /// fed S3's concrete `LiveDSAskClient`. The app default stays `mockRouter` (offline scaffold);
+    /// switching to live is THIS one call — AIService, views, and intents are unchanged.
+    public static func realRouter(
+        base: DSBaseURL = .publicTLS,
+        token: @escaping @Sendable () async -> String? = { nil }
+    ) -> AIRouter {
+        makeDefaultRouter(client: LiveDSAskClient(base: base, token: token))
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/AI/LiveDSAskClient.swift b/clients/ds-app/Sources/AppFeature/AI/LiveDSAskClient.swift
new file mode 100644
index 0000000..f18ae9b
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/AI/LiveDSAskClient.swift
@@ -0,0 +1,50 @@
+import Foundation
+import AIFabric
+import DSKit
+
+/// S3-owned concrete `DSAskClient` (the HTTP seam S2's `RemoteDSProvider` calls). Hits DS
+/// `GET /search/ask?q=&backend=` and decodes **AIFabric.AskResponse** (a decode-only type that
+/// RemoteDSProvider maps to AICompletionResponse). This is the piece S2's plan assigns to S3
+/// ("구체 DSAskClient(HTTP) = S3 소유"). FU-A: exercised only when the real router is wired.
+public struct LiveDSAskClient: DSAskClient {
+    private let base: DSBaseURL
+    private let session: URLSession
+    private let decoder: JSONDecoder
+    private let token: @Sendable () async -> String?
+
+    public init(
+        base: DSBaseURL = .publicTLS,
+        session: URLSession = .shared,
+        token: @escaping @Sendable () async -> String? = { nil }
+    ) {
+        self.base = base
+        self.session = session
+        self.decoder = DSDecoder.make()
+        self.token = token
+    }
+
+    public func ask(query: String, backend: String) async throws -> AIFabric.AskResponse {
+        let raw = base.url.absoluteString + "/search/ask"
+        guard var comps = URLComponents(string: raw) else {
+            throw DSError.transport(underlying: "bad ask URL")
+        }
+        comps.queryItems = [
+            URLQueryItem(name: "q", value: query),
+            URLQueryItem(name: "backend", value: backend),
+        ]
+        guard let url = comps.url else { throw DSError.transport(underlying: "bad ask URL components") }
+
+        var request = URLRequest(url: url)
+        if let token = await token() {
+            request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
+        }
+        let (data, response) = try await session.data(for: request)
+        guard let http = response as? HTTPURLResponse else {
+            throw DSError.transport(underlying: "no HTTP response")
+        }
+        guard (200..<300).contains(http.statusCode) else {
+            throw DSError.from(status: http.statusCode, data: data)
+        }
+        return try decoder.decode(AIFabric.AskResponse.self, from: data)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Markdown/MarkdownView.swift b/clients/ds-app/Sources/AppFeature/Markdown/MarkdownView.swift
new file mode 100644
index 0000000..dcf1a56
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Markdown/MarkdownView.swift
@@ -0,0 +1,187 @@
+import SwiftUI
+
+/// Lightweight block-aware Markdown renderer. SwiftUI's `AttributedString(markdown:)` is INLINE-only —
+/// it silently drops block structure including GFM TABLES (the completed fixture's UCS-66 table would
+/// vanish). This splits blocks by hand (headings, lists, pipe tables, fenced code, blockquote,
+/// paragraphs) and renders each natively; inline emphasis/links use AttributedString per line.
+/// Full CommonMark fidelity is a deferred dependency swap (swift-markdown / MarkdownUI).
+public struct MarkdownView: View {
+    let markdown: String
+    public init(_ markdown: String) { self.markdown = markdown }
+
+    public var body: some View {
+        VStack(alignment: .leading, spacing: 10) {
+            ForEach(Array(MarkdownBlock.parse(markdown).enumerated()), id: \.offset) { _, block in
+                view(for: block)
+            }
+        }
+    }
+
+    @ViewBuilder
+    private func view(for block: MarkdownBlock) -> some View {
+        switch block {
+        case .heading(let level, let text):
+            inline(text)
+                .font(headingFont(level))
+                .foregroundStyle(Sage.ink)
+                .padding(.top, level <= 2 ? 6 : 2)
+        case .paragraph(let text):
+            inline(text).font(.body).foregroundStyle(Sage.ink)
+        case .listItem(let text):
+            HStack(alignment: .top, spacing: 8) {
+                Text("•").foregroundStyle(Sage.brand)
+                inline(text).font(.body).foregroundStyle(Sage.ink)
+            }
+        case .quote(let text):
+            inline(text)
+                .font(.body).foregroundStyle(Sage.muted)
+                .padding(.leading, 10)
+                .overlay(Rectangle().fill(Sage.brand).frame(width: 3), alignment: .leading)
+        case .code(let text):
+            Text(text)
+                .font(.system(.callout, design: .monospaced))
+                .foregroundStyle(Sage.ink)
+                .padding(10)
+                .frame(maxWidth: .infinity, alignment: .leading)
+                .background(Sage.surface, in: RoundedRectangle(cornerRadius: 8))
+        case .table(let header, let rows):
+            tableView(header: header, rows: rows)
+        }
+    }
+
+    private func tableView(header: [String], rows: [[String]]) -> some View {
+        let columns = max(header.count, rows.map(\.count).max() ?? 0)
+        return VStack(spacing: 0) {
+            tableRow(cells: header, columns: columns, isHeader: true)
+            ForEach(Array(rows.enumerated()), id: \.offset) { _, row in
+                tableRow(cells: row, columns: columns, isHeader: false)
+            }
+        }
+        .background(Sage.card, in: RoundedRectangle(cornerRadius: 8))
+        .overlay(RoundedRectangle(cornerRadius: 8).stroke(Sage.line))
+    }
+
+    private func tableRow(cells: [String], columns: Int, isHeader: Bool) -> some View {
+        HStack(spacing: 0) {
+            ForEach(0..<columns, id: \.self) { i in
+                inline(i < cells.count ? cells[i] : "")
+                    .font(isHeader ? .callout.weight(.semibold) : .callout)
+                    .foregroundStyle(isHeader ? Sage.ink : Sage.muted)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .padding(.horizontal, 8).padding(.vertical, 6)
+            }
+        }
+        .background(isHeader ? Sage.surface : Sage.card)
+        .overlay(Rectangle().fill(Sage.line).frame(height: 1), alignment: .bottom)
+    }
+
+    private func inline(_ s: String) -> Text {
+        if let attr = try? AttributedString(markdown: s, options: .init(interpretedSyntax: .inlineOnlyPreservingWhitespace)) {
+            return Text(attr)
+        }
+        return Text(s)
+    }
+
+    private func headingFont(_ level: Int) -> Font {
+        switch level {
+        case 1: return .title2.weight(.bold)
+        case 2: return .title3.weight(.semibold)
+        case 3: return .headline
+        default: return .subheadline.weight(.semibold)
+        }
+    }
+}
+
+enum MarkdownBlock {
+    case heading(Int, String)
+    case paragraph(String)
+    case listItem(String)
+    case quote(String)
+    case code(String)
+    case table([String], [[String]])
+
+    static func parse(_ md: String) -> [MarkdownBlock] {
+        var blocks: [MarkdownBlock] = []
+        let lines = md.components(separatedBy: "\n")
+        var i = 0
+        var para: [String] = []
+
+        func flushPara() {
+            if !para.isEmpty {
+                blocks.append(.paragraph(para.joined(separator: " ")))
+                para.removeAll()
+            }
+        }
+
+        while i < lines.count {
+            let raw = lines[i]
+            let line = raw.trimmingCharacters(in: .whitespaces)
+
+            // fenced code
+            if line.hasPrefix("```") {
+                flushPara()
+                var code: [String] = []
+                i += 1
+                while i < lines.count, !lines[i].trimmingCharacters(in: .whitespaces).hasPrefix("```") {
+                    code.append(lines[i]); i += 1
+                }
+                blocks.append(.code(code.joined(separator: "\n")))
+                i += 1
+                continue
+            }
+
+            // GFM pipe table: a header row followed by an alignment separator row (| --- | :--: |)
+            if line.contains("|"), i + 1 < lines.count, isTableSeparator(lines[i + 1]) {
+                flushPara()
+                let header = splitRow(line)
+                var rows: [[String]] = []
+                i += 2 // skip header + separator (the separator is NOT data)
+                while i < lines.count, lines[i].trimmingCharacters(in: .whitespaces).contains("|"),
+                      !lines[i].trimmingCharacters(in: .whitespaces).isEmpty {
+                    rows.append(splitRow(lines[i])); i += 1
+                }
+                blocks.append(.table(header, rows))
+                continue
+            }
+
+            if line.isEmpty { flushPara(); i += 1; continue }
+
+            if line.hasPrefix("#") {
+                flushPara()
+                let level = line.prefix(while: { $0 == "#" }).count
+                let text = line.drop(while: { $0 == "#" }).trimmingCharacters(in: .whitespaces)
+                blocks.append(.heading(min(level, 6), text))
+                i += 1; continue
+            }
+            if line.hasPrefix("> ") {
+                flushPara()
+                blocks.append(.quote(String(line.dropFirst(2))))
+                i += 1; continue
+            }
+            if line.hasPrefix("- ") || line.hasPrefix("* ") || line.hasPrefix("+ ") {
+                flushPara()
+                blocks.append(.listItem(String(line.dropFirst(2))))
+                i += 1; continue
+            }
+
+            para.append(line)
+            i += 1
+        }
+        flushPara()
+        return blocks
+    }
+
+    /// A separator row is all dashes/colons/pipes/spaces, e.g. `| --- | :--: |`.
+    private static func isTableSeparator(_ line: String) -> Bool {
+        let t = line.trimmingCharacters(in: .whitespaces)
+        guard t.contains("-"), t.contains("|") else { return false }
+        return t.allSatisfy { $0 == "-" || $0 == ":" || $0 == "|" || $0 == " " }
+    }
+
+    private static func splitRow(_ line: String) -> [String] {
+        var t = line.trimmingCharacters(in: .whitespaces)
+        if t.hasPrefix("|") { t.removeFirst() }
+        if t.hasSuffix("|") { t.removeLast() }
+        return t.components(separatedBy: "|").map { $0.trimmingCharacters(in: .whitespaces) }
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Pages/AskView.swift b/clients/ds-app/Sources/AppFeature/Pages/AskView.swift
new file mode 100644
index 0000000..b9d4acf
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Pages/AskView.swift
@@ -0,0 +1,85 @@
+import SwiftUI
+import AIFabric
+
+/// RAG proof page: routes corpusAsk through AIService (-> AIRouter -> MockAIProvider). Explicit backend
+/// pick sets explicitProvider; an explicit-unavailable result renders a visible, non-retrying error.
+struct AskView: View {
+    @Environment(AppModel.self) private var model
+    @State private var backend: BackendChoice = .auto
+
+    var body: some View {
+        @Bindable var model = model
+        ScrollView {
+            VStack(alignment: .leading, spacing: 14) {
+                Picker("백엔드", selection: $backend) {
+                    ForEach(BackendChoice.allCases) { Text($0.label).tag($0) }
+                }
+                .pickerStyle(.segmented)
+
+                HStack(spacing: 8) {
+                    TextField("코퍼스 전체에 질문", text: $model.askQuery)
+                        .textFieldStyle(.roundedBorder)
+                        .onSubmit { Task { await model.runAsk(backend: backend.provider) } }
+                    Button("질문") { Task { await model.runAsk(backend: backend.provider) } }
+                        .buttonStyle(.borderedProminent)
+                }
+
+                if let result = model.askResult {
+                    switch result {
+                    case .success(let response):
+                        AICompletionView(response: response) { docID in
+                            model.section = .documents
+                            Task { await model.openDocument(docID) }
+                        }
+                        if let meta = model.askMeta {
+                            HStack(spacing: 6) {
+                                Chip("완성도 \(meta.completeness)", Sage.muted)
+                                if let aspects = meta.coveredAspects {
+                                    ForEach(aspects, id: \.self) { Chip($0, Sage.brand) }
+                                }
+                            }
+                        }
+                    case .failure(let err):
+                        ErrorBanner(text: message(for: err))
+                    }
+                } else {
+                    EmptyState(text: "질문을 입력하세요").frame(minHeight: 160)
+                }
+            }
+            .padding(16)
+        }
+        .background(Sage.surface)
+    }
+
+    private func message(for error: AIServiceError) -> String {
+        switch error {
+        case .explicitUnavailable(let id):
+            return "\(id.displayName) 백엔드를 쓸 수 없습니다 — 다른 백엔드로 자동 전환하지 않았습니다. 다른 백엔드를 고르세요."
+        case .notConfigured(let id): return "\(id.displayName) 백엔드 미구성"
+        case .noneAvailable: return "응답 가능한 백엔드가 없습니다."
+        case .providerFailed(let s): return "응답 실패: \(s)"
+        case .unknown(let s): return "오류: \(s)"
+        }
+    }
+}
+
+enum BackendChoice: String, CaseIterable, Identifiable {
+    case auto, onDevice, localMLX, remoteDS
+    var id: String { rawValue }
+    var label: String {
+        switch self {
+        case .auto: return "자동"
+        case .onDevice: return "온디바이스"
+        case .localMLX: return "맥미니"
+        case .remoteDS: return "원격 DS"
+        }
+    }
+    var provider: AIProviderID? {
+        switch self {
+        case .auto: return nil
+        case .onDevice: return .onDevice
+        case .localMLX: return .localMLX
+        case .remoteDS: return .remoteDS
+        }
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Pages/DashboardView.swift b/clients/ds-app/Sources/AppFeature/Pages/DashboardView.swift
new file mode 100644
index 0000000..93901e9
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Pages/DashboardView.swift
@@ -0,0 +1,38 @@
+import SwiftUI
+
+/// Corpus-health overview (not a dumped table). Stat hero + domain distribution bars; tapping a
+/// domain jumps to Documents (cross-page nav proof).
+struct DashboardView: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        ScrollView {
+            VStack(alignment: .leading, spacing: 18) {
+                if let s = model.stats {
+                    LazyVGrid(columns: [GridItem(.adaptive(minimum: 150), spacing: 12)], spacing: 12) {
+                        StatCard(title: "전체", value: s.total, color: Sage.brand)
+                        StatCard(title: "문서", value: s.documents, color: Sage.brand)
+                        StatCard(title: "검토 대기", value: s.reviewPending, color: Sage.amber)
+                        StatCard(title: "파이프라인 실패", value: s.pipelineFailed, color: Sage.danger)
+                    }
+
+                    VStack(alignment: .leading, spacing: 10) {
+                        Text("도메인 분포").font(.headline).foregroundStyle(Sage.ink)
+                        ForEach(s.byDomain.sorted { $0.value > $1.value }, id: \.key) { key, value in
+                            DomainBar(name: key, count: value, max: s.byDomain.values.max() ?? 1)
+                                .contentShape(Rectangle())
+                                .onTapGesture { model.section = .documents }
+                        }
+                    }
+                    .padding(16)
+                    .background(Sage.card, in: RoundedRectangle(cornerRadius: 14))
+                    .overlay(RoundedRectangle(cornerRadius: 14).stroke(Sage.line))
+                } else {
+                    ProgressView().frame(maxWidth: .infinity, minHeight: 200)
+                }
+            }
+            .padding(20)
+        }
+        .background(Sage.surface)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Pages/DigestView.swift b/clients/ds-app/Sources/AppFeature/Pages/DigestView.swift
new file mode 100644
index 0000000..2c73bf1
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Pages/DigestView.swift
@@ -0,0 +1,52 @@
+import SwiftUI
+
+/// News-brief reading layout (its own treatment): per-country sections of rank-ordered topic cards.
+/// date-only displayed from the raw string (no Date conversion → no timezone off-by-one).
+struct DigestView: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        ScrollView {
+            VStack(alignment: .leading, spacing: 16) {
+                if let digest = model.digest {
+                    VStack(alignment: .leading, spacing: 2) {
+                        Text("뉴스 다이제스트").font(.title2.weight(.bold)).foregroundStyle(Sage.ink)
+                        Text("\(digest.digestDateDisplay) · 기사 \(digest.totalArticles ?? 0)건 · \(digest.totalTopics ?? 0)개 주제")
+                            .font(.caption).foregroundStyle(Sage.muted)
+                    }
+
+                    ForEach(digest.countries) { country in
+                        VStack(alignment: .leading, spacing: 8) {
+                            Chip(country.country, Sage.brand)
+                            ForEach(country.topics) { topic in
+                                VStack(alignment: .leading, spacing: 5) {
+                                    Text(topic.topicLabel).font(.headline).foregroundStyle(Sage.ink)
+                                    Text(topic.summary).font(.callout).foregroundStyle(Sage.muted)
+                                    HStack(spacing: 8) {
+                                        Text("기사 \(topic.articleCount ?? topic.articles.count)건")
+                                            .font(.caption2).foregroundStyle(Sage.muted)
+                                        if topic.llmFallbackUsed == true {
+                                            Text("fallback").font(.caption2).foregroundStyle(Sage.amber)
+                                        }
+                                    }
+                                    ForEach(topic.articles) { article in
+                                        Text("· \(article.title ?? "기사 \(article.id)")")
+                                            .font(.caption).foregroundStyle(Sage.ink)
+                                    }
+                                }
+                                .padding(12)
+                                .frame(maxWidth: .infinity, alignment: .leading)
+                                .background(Sage.card, in: RoundedRectangle(cornerRadius: 10))
+                                .overlay(RoundedRectangle(cornerRadius: 10).stroke(Sage.line))
+                            }
+                        }
+                    }
+                } else {
+                    ProgressView().frame(maxWidth: .infinity, minHeight: 200)
+                }
+            }
+            .padding(20)
+        }
+        .background(Sage.surface)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Pages/DocumentsView.swift b/clients/ds-app/Sources/AppFeature/Pages/DocumentsView.swift
new file mode 100644
index 0000000..20eb96e
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Pages/DocumentsView.swift
@@ -0,0 +1,91 @@
+import SwiftUI
+import DSKit
+
+struct DocumentListView: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        let selection = Binding<Int?>(
+            get: { model.selectedDocumentID },
+            set: { if let id = $0 { Task { await model.openDocument(id) } } }
+        )
+        List(model.documentList, selection: selection) { doc in
+            DocumentRow(doc: doc)
+        }
+        .listStyle(.inset)
+        .background(Sage.surface)
+    }
+}
+
+struct DocumentRow: View {
+    let doc: DocumentResponse
+    var body: some View {
+        VStack(alignment: .leading, spacing: 4) {
+            HStack(spacing: 6) {
+                Chip(doc.displayFormat.uppercased(), Sage.formatColor(doc.displayFormat))
+                Text(doc.title ?? doc.downloadLabel)
+                    .font(.callout.weight(.medium)).foregroundStyle(Sage.ink).lineLimit(1)
+                Spacer()
+                if doc.pinned == true { Text("고정").font(.caption2).foregroundStyle(Sage.amber) }
+            }
+            HStack(spacing: 6) {
+                if let d = doc.aiDomain { Chip(d, Sage.domainColor(d)) }
+                if let r = doc.reviewStatus {
+                    Text(r).font(.caption2).foregroundStyle(Sage.reviewStatusColor(r))
+                }
+                Spacer()
+                Text(doc.updatedAtRaw.prefix(10)).font(.caption2.monospacedDigit()).foregroundStyle(Sage.muted)
+            }
+        }
+        .padding(.vertical, 4)
+    }
+}
+
+/// MD-first detail: render md_content when renderable, else extracted_text fallback + 'MD 변환 대기'
+/// badge + emphasized original-download button. (Download builds a real-shaped ?token= URL.)
+struct DocumentDetailView: View {
+    @Environment(AppModel.self) private var model
+    let detail: DocumentDetailResponse
+
+    var body: some View {
+        ScrollView {
+            VStack(alignment: .leading, spacing: 14) {
+                Text(detail.base.title ?? detail.base.downloadLabel)
+                    .font(.title2.weight(.bold)).foregroundStyle(Sage.ink)
+
+                HStack(spacing: 8) {
+                    if let d = detail.base.aiDomain { Chip(d, Sage.domainColor(d)) }
+                    Chip(detail.base.displayFormat.uppercased(), Sage.formatColor(detail.base.displayFormat))
+                    if let conf = detail.base.aiConfidence {
+                        Chip("AI \(String(format: "%.0f%%", conf * 100))", Sage.muted)
+                    }
+                    Spacer()
+                    if let url = model.downloadURL(for: detail.base) {
+                        Link(detail.base.downloadLabel, destination: url).font(.callout.weight(.semibold))
+                    }
+                }
+
+                if let tags = detail.base.aiTags, !tags.isEmpty {
+                    HStack(spacing: 6) { ForEach(tags, id: \.self) { Chip($0, Sage.brand) } }
+                }
+
+                Divider()
+
+                if detail.mdIsRenderable, let md = detail.mdContent {
+                    MarkdownView(md)
+                } else {
+                    HStack { Chip("MD 변환 대기", Sage.amber); Spacer() }
+                    Text(detail.extractedText ?? "본문 없음")
+                        .font(.body).foregroundStyle(Sage.muted)
+                        .frame(maxWidth: .infinity, alignment: .leading)
+                    if let url = model.downloadURL(for: detail.base) {
+                        Link("원본 다운로드 — \(detail.base.downloadLabel)", destination: url)
+                            .font(.callout.weight(.semibold))
+                    }
+                }
+            }
+            .padding(20)
+        }
+        .background(Sage.surface)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Pages/MemosView.swift b/clients/ds-app/Sources/AppFeature/Pages/MemosView.swift
new file mode 100644
index 0000000..0c5bc04
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Pages/MemosView.swift
@@ -0,0 +1,76 @@
+import SwiftUI
+import DSKit
+
+/// Capture-first treatment: quick-capture box + list distinguishing note vs audio.
+struct MemoListView: View {
+    @Environment(AppModel.self) private var model
+    @State private var draft: String = ""
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0) {
+            HStack(spacing: 8) {
+                TextField("빠른 메모 캡처", text: $draft)
+                    .textFieldStyle(.roundedBorder)
+                Button("저장") {
+                    let content = draft
+                    draft = ""
+                    Task { _ = try? await model.client.createMemo(MemoCreate(content: content)) }
+                }
+                .buttonStyle(.bordered)
+                .disabled(draft.isEmpty)
+            }
+            .padding(12)
+
+            let selection = Binding<Int?>(
+                get: { model.selectedMemoID },
+                set: { if let id = $0 { Task { await model.openMemo(id) } } }
+            )
+            List(model.memoList, selection: selection) { memo in
+                VStack(alignment: .leading, spacing: 3) {
+                    HStack(spacing: 6) {
+                        if memo.isAudio { Chip("음성", Sage.formatColor("audio")) }
+                        if memo.aiEventKind == "task" { Chip("할 일", Sage.amber) }
+                        Text(memo.title ?? "메모 \(memo.id)")
+                            .font(.callout.weight(.medium)).foregroundStyle(Sage.ink).lineLimit(1)
+                        Spacer()
+                        if memo.isPinned { Text("고정").font(.caption2).foregroundStyle(Sage.amber) }
+                    }
+                    Text(memo.content ?? "").font(.caption).foregroundStyle(Sage.muted).lineLimit(2)
+                }
+                .padding(.vertical, 3)
+            }
+            .listStyle(.inset)
+        }
+        .background(Sage.surface)
+    }
+}
+
+struct MemoDetailView: View {
+    let memo: MemoResponse
+
+    var body: some View {
+        ScrollView {
+            VStack(alignment: .leading, spacing: 12) {
+                Text(memo.title ?? "메모").font(.title2.weight(.bold)).foregroundStyle(Sage.ink)
+
+                if memo.isAudio {
+                    HStack(spacing: 8) {
+                        Image(systemName: "waveform")
+                        Text("원본 재생 (스캐폴드에서는 비활성)").foregroundStyle(Sage.muted)
+                    }
+                    .padding(10)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .background(Sage.surface, in: RoundedRectangle(cornerRadius: 8))
+                }
+
+                if let tags = memo.aiTags, !tags.isEmpty {
+                    HStack(spacing: 6) { ForEach(tags, id: \.self) { Chip($0, Sage.brand) } }
+                }
+
+                MarkdownView(memo.content ?? "")
+            }
+            .padding(20)
+        }
+        .background(Sage.surface)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Pages/SearchView.swift b/clients/ds-app/Sources/AppFeature/Pages/SearchView.swift
new file mode 100644
index 0000000..59fc7d0
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Pages/SearchView.swift
@@ -0,0 +1,50 @@
+import SwiftUI
+import DSKit
+
+/// Distinct from the Documents table: relevance-forward result cards (score bar + match_reason).
+struct SearchView: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        @Bindable var model = model
+        VStack(alignment: .leading, spacing: 0) {
+            HStack(spacing: 8) {
+                TextField("검색어를 입력하세요", text: $model.searchQuery)
+                    .textFieldStyle(.roundedBorder)
+                    .onSubmit { Task { await model.runSearch() } }
+                Button("검색") { Task { await model.runSearch() } }
+                    .buttonStyle(.borderedProminent)
+            }
+            .padding(12)
+
+            if let response = model.searchResponse {
+                List(response.results) { result in
+                    VStack(alignment: .leading, spacing: 5) {
+                        HStack(spacing: 6) {
+                            if let d = result.aiDomain { Chip(d, Sage.domainColor(d)) }
+                            Text(result.title ?? "문서 \(result.id)")
+                                .font(.callout.weight(.medium)).foregroundStyle(Sage.ink).lineLimit(1)
+                            Spacer()
+                            if let m = result.matchReason {
+                                Text(m).font(.caption2).foregroundStyle(Sage.muted)
+                            }
+                        }
+                        Text(result.snippet ?? result.aiSummary ?? "")
+                            .font(.caption).foregroundStyle(Sage.muted).lineLimit(2)
+                        if let score = result.score { ScoreBar(score: score) }
+                    }
+                    .padding(.vertical, 4)
+                    .contentShape(Rectangle())
+                    .onTapGesture {
+                        model.section = .documents
+                        Task { await model.openDocument(result.id) }
+                    }
+                }
+                .listStyle(.inset)
+            } else {
+                EmptyState(text: "검색어를 입력하세요")
+            }
+        }
+        .background(Sage.surface)
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Shell/Components.swift b/clients/ds-app/Sources/AppFeature/Shell/Components.swift
new file mode 100644
index 0000000..df30ed4
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Shell/Components.swift
@@ -0,0 +1,71 @@
+import SwiftUI
+
+struct StatCard: View {
+    let title: String
+    let value: Int
+    let color: Color
+    var body: some View {
+        VStack(alignment: .leading, spacing: 4) {
+            Text(title).font(.caption).foregroundStyle(Sage.muted)
+            Text("\(value)").font(.title.weight(.bold)).foregroundStyle(color)
+        }
+        .frame(maxWidth: .infinity, alignment: .leading)
+        .padding(14)
+        .background(Sage.card, in: RoundedRectangle(cornerRadius: 12))
+        .overlay(RoundedRectangle(cornerRadius: 12).stroke(Sage.line))
+    }
+}
+
+struct DomainBar: View {
+    let name: String
+    let count: Int
+    let max: Int
+    var body: some View {
+        HStack(spacing: 10) {
+            Text(name).font(.caption).foregroundStyle(Sage.ink)
+                .frame(width: 120, alignment: .leading).lineLimit(1)
+            GeometryReader { geo in
+                ZStack(alignment: .leading) {
+                    RoundedRectangle(cornerRadius: 4).fill(Sage.surface)
+                    RoundedRectangle(cornerRadius: 4)
+                        .fill(Sage.domainColor(name))
+                        .frame(width: geo.size.width * fraction)
+                }
+            }
+            .frame(height: 10)
+            Text("\(count)").font(.caption.monospacedDigit()).foregroundStyle(Sage.muted)
+                .frame(width: 44, alignment: .trailing)
+        }
+    }
+    private var fraction: CGFloat { max > 0 ? CGFloat(count) / CGFloat(max) : 0 }
+}
+
+struct ScoreBar: View {
+    let score: Double
+    var body: some View {
+        HStack(spacing: 6) {
+            GeometryReader { geo in
+                ZStack(alignment: .leading) {
+                    RoundedRectangle(cornerRadius: 3).fill(Sage.surface)
+                    RoundedRectangle(cornerRadius: 3).fill(Sage.brand)
+                        .frame(width: geo.size.width * CGFloat(min(max(score, 0), 1)))
+                }
+            }
+            .frame(height: 6)
+            Text(String(format: "%.2f", score)).font(.caption2.monospacedDigit()).foregroundStyle(Sage.muted)
+        }
+    }
+}
+
+struct ErrorBanner: View {
+    let text: String
+    var body: some View {
+        Text(text)
+            .font(.callout)
+            .foregroundStyle(Sage.danger)
+            .frame(maxWidth: .infinity, alignment: .leading)
+            .padding(12)
+            .background(Sage.danger.opacity(0.08), in: RoundedRectangle(cornerRadius: 10))
+            .overlay(RoundedRectangle(cornerRadius: 10).stroke(Sage.danger.opacity(0.3)))
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Shell/RootView.swift b/clients/ds-app/Sources/AppFeature/Shell/RootView.swift
new file mode 100644
index 0000000..cecc501
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Shell/RootView.swift
@@ -0,0 +1,126 @@
+import SwiftUI
+import DSKit
+
+/// DEVONthink-style 3-column shell. RootView only ROUTES; each page owns its own interior treatment
+/// (no shell-level auto-inherit). macOS-only target.
+public struct RootView: View {
+    @Environment(AppModel.self) private var model
+    @State private var columnVisibility: NavigationSplitViewVisibility = .all
+
+    public init() {}
+
+    public var body: some View {
+        NavigationSplitView(columnVisibility: $columnVisibility) {
+            Sidebar()
+                .navigationSplitViewColumnWidth(min: 220, ideal: 250)
+        } content: {
+            ContentColumn()
+                .navigationSplitViewColumnWidth(min: 300, ideal: 380)
+        } detail: {
+            DetailColumn()
+        }
+        .navigationSplitViewStyle(.balanced)
+        .tint(Sage.brand)
+        .task { await model.loadInitial() }
+    }
+}
+
+struct Sidebar: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        let selection = Binding<AppModel.Section?>(
+            get: { model.section },
+            set: { if let v = $0 { model.section = v } }
+        )
+        List(selection: selection) {
+            Section {
+                ForEach(AppModel.Section.allCases) { s in
+                    Text(s.title).tag(s)
+                }
+            }
+            if model.section == .documents, !model.tree.isEmpty {
+                Section("도메인") {
+                    ForEach(model.tree) { node in
+                        DomainRow(node: node)
+                    }
+                }
+            }
+        }
+        .listStyle(.sidebar)
+        .background(Sage.sidebar)
+    }
+}
+
+struct DomainRow: View {
+    @Environment(AppModel.self) private var model
+    let node: DomainTreeNode
+
+    var body: some View {
+        HStack(spacing: 8) {
+            Circle().fill(Sage.domainColor(node.name)).frame(width: 8, height: 8)
+            Text(node.name).font(.callout).foregroundStyle(Sage.ink)
+            Spacer()
+            Text("\(node.count)").font(.caption).foregroundStyle(Sage.muted)
+        }
+        .contentShape(Rectangle())
+        .onTapGesture { model.section = .documents }
+    }
+}
+
+struct ContentColumn: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        Group {
+            switch model.section {
+            case .dashboard: DashboardView()
+            case .documents: DocumentListView()
+            case .search: SearchView()
+            case .ask: AskView()
+            case .memos: MemoListView()
+            case .digest: DigestView()
+            }
+        }
+        .navigationTitle(model.section.title)
+    }
+}
+
+struct DetailColumn: View {
+    @Environment(AppModel.self) private var model
+
+    var body: some View {
+        Group {
+            switch model.section {
+            case .documents:
+                if let d = model.documentDetail { DocumentDetailView(detail: d) }
+                else { EmptyState(text: "문서를 선택하세요") }
+            case .memos:
+                if let m = model.memoDetail { MemoDetailView(memo: m) }
+                else { EmptyState(text: "메모를 선택하세요") }
+            default:
+                EmptyState(text: model.section.title)
+            }
+        }
+    }
+}
+
+struct EmptyState: View {
+    let text: String
+    var body: some View {
+        Text(text)
+            .foregroundStyle(Sage.muted)
+            .frame(maxWidth: .infinity, maxHeight: .infinity)
+            .background(Sage.surface)
+    }
+}
+
+#if DEBUG
+#Preview("DS App — full shell") {
+    @Previewable @State var model = AppModel.preview
+    RootView()
+        .environment(model)
+        .task { await model.loadInitial() }
+        .frame(minWidth: 1000, minHeight: 660)
+}
+#endif
diff --git a/clients/ds-app/Sources/AppFeature/State/AppModel.swift b/clients/ds-app/Sources/AppFeature/State/AppModel.swift
new file mode 100644
index 0000000..41d2242
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/State/AppModel.swift
@@ -0,0 +1,98 @@
+import SwiftUI
+import Observation
+import DSKit
+import AIFabric
+
+/// The single app-state store driving the 3-pane shell. @MainActor @Observable: mutations are
+/// main-isolated; the DSClient returns Sendable models; AIService is an actor.
+@MainActor
+@Observable
+public final class AppModel {
+    public enum Section: String, CaseIterable, Identifiable, Hashable {
+        case dashboard, documents, search, ask, memos, digest
+        public var id: String { rawValue }
+        public var title: String {
+            switch self {
+            case .dashboard: return "대시보드"
+            case .documents: return "문서"
+            case .search: return "검색"
+            case .ask: return "질문"
+            case .memos: return "메모"
+            case .digest: return "뉴스"
+            }
+        }
+    }
+
+    public var section: Section = .dashboard
+    public var selectedDocumentID: Int?
+    public var selectedMemoID: Int?
+
+    public var tree: [DomainTreeNode] = []
+    public var stats: CategoryCounts?
+    public var documentList: [DocumentResponse] = []
+    public var documentDetail: DocumentDetailResponse?
+    public var searchQuery: String = ""
+    public var searchResponse: SearchResponse?
+    public var askQuery: String = ""
+    public var askResult: AIResult?
+    public var askMeta: DSKit.AskResponse? // qualified: AIFabric also defines an AskResponse
+    public var memoList: [MemoResponse] = []
+    public var memoDetail: MemoResponse?
+    public var digest: DigestResponse?
+    public var errorText: String?
+
+    let client: any DSClient
+    let ai: AIService
+    /// Placeholder token from the auth fixture — builds a real-SHAPED download URL with no expectation it resolves offline.
+    public private(set) var accessToken: String = ""
+
+    public init(client: any DSClient, ai: AIService) {
+        self.client = client
+        self.ai = ai
+    }
+
+    @MainActor
+    public static var preview: AppModel {
+        AppModel(client: FixtureDSClient(), ai: AIService(router: AppAIComposition.mockRouter()))
+    }
+
+    public func loadInitial() async {
+        await guarded { self.accessToken = (try? await self.client.login(username: "hyungi", password: "x", totpCode: nil).accessToken) ?? "" }
+        await guarded { self.tree = try await self.client.documentTree() }
+        await guarded { self.stats = try await self.client.categoryCounts() }
+        await guarded { self.documentList = try await self.client.documents(DocumentListQuery()).items }
+        await guarded { self.memoList = try await self.client.memos(MemoListQuery()).items }
+        await guarded { self.digest = try await self.client.digest(date: nil, country: nil) }
+    }
+
+    public func openDocument(_ id: Int) async {
+        selectedDocumentID = id
+        await guarded { self.documentDetail = try await self.client.document(id: id) }
+    }
+
+    public func runSearch() async {
+        guard !searchQuery.isEmpty else { return }
+        await guarded { self.searchResponse = try await self.client.search(q: self.searchQuery, mode: .hybrid, page: 1, debug: false) }
+    }
+
+    public func runAsk(backend: AIProviderID?) async {
+        guard !askQuery.isEmpty else { return }
+        askResult = await ai.corpusAsk(question: askQuery, explicit: backend)
+        await guarded { self.askMeta = try await self.client.ask(q: self.askQuery, limit: nil, backend: nil, debug: false) }
+    }
+
+    public func openMemo(_ id: Int) async {
+        selectedMemoID = id
+        await guarded { self.memoDetail = try await self.client.memo(id: id) }
+    }
+
+    public func downloadURL(for doc: DocumentResponse) -> URL? {
+        guard doc.hasDownloadableOriginal, !accessToken.isEmpty else { return nil }
+        return DSDownload.fileURL(base: .publicTLS, documentID: doc.id, accessToken: accessToken)
+    }
+
+    private func guarded(_ work: () async throws -> Void) async {
+        do { try await work() }
+        catch { errorText = (error as? LocalizedError)?.errorDescription ?? "\(error)" }
+    }
+}
diff --git a/clients/ds-app/Sources/AppFeature/Theme/SageTheme.swift b/clients/ds-app/Sources/AppFeature/Theme/SageTheme.swift
new file mode 100644
index 0000000..b2277fb
--- /dev/null
+++ b/clients/ds-app/Sources/AppFeature/Theme/SageTheme.swift
@@ -0,0 +1,85 @@
+import SwiftUI
+
+/// Single sage token source (web F1 @theme parity). The shell/tokens are fixed; each page's magnetic
+/// treatment layers on top. No emoji — status/format are color chips + short text. Status helpers are
+/// per-vocabulary (md/review) so a value from one vocabulary never mis-colors another.
+public enum Sage {
+    public static let brand = Color(hex: 0x4f8a6b)
+    public static let brandDark = Color(hex: 0x3d7256)
+    public static let surface = Color(hex: 0xf1f4ee)
+    public static let card = Color.white
+    public static let sidebar = Color(hex: 0xf4f7f1)
+    public static let ink = Color(hex: 0x23291f)
+    public static let muted = Color(hex: 0x697061)
+    public static let line = Color(hex: 0xdde3d6)
+    public static let amber = Color(hex: 0xb5840a)
+    public static let danger = Color(hex: 0xc0564a)
+
+    public static func domainColor(_ d: String?) -> Color {
+        switch d {
+        case "Engineering": return Color(hex: 0x2f7d8f)
+        case "Industrial_Safety": return Color(hex: 0xb5840a)
+        case "General": return Color(hex: 0x7a8b3f)
+        case "Programming": return Color(hex: 0x3d7256)
+        case "법령": return Color(hex: 0x8a6a3f)
+        case "Philosophy": return Color(hex: 0x7a6a9b)
+        default: return muted
+        }
+    }
+
+    public static func formatColor(_ f: String?) -> Color {
+        switch f?.lowercased() {
+        case "md": return Color(hex: 0x5a8f7a)
+        case "pdf": return Color(hex: 0xc0564a)
+        case "m4a", "mp3", "wav", "audio": return Color(hex: 0x8a6aa5)
+        case "html": return Color(hex: 0xc2911f)
+        case "docx", "xlsx", "txt": return Color(hex: 0x6f7c8a)
+        default: return muted
+        }
+    }
+
+    public static func mdStatusColor(_ s: String?) -> Color {
+        switch s {
+        case "completed": return brand
+        case "partial": return Color(hex: 0x7a9f86)
+        case "processing", "pending": return amber
+        case "failed": return danger
+        default: return muted
+        }
+    }
+
+    public static func reviewStatusColor(_ s: String?) -> Color {
+        switch s {
+        case "approved": return brand
+        case "pending": return amber
+        case "rejected": return danger
+        default: return muted
+        }
+    }
+}
+
+public extension Color {
+    init(hex: UInt) {
+        self.init(
+            .sRGB,
+            red: Double((hex >> 16) & 0xff) / 255.0,
+            green: Double((hex >> 8) & 0xff) / 255.0,
+            blue: Double(hex & 0xff) / 255.0,
+            opacity: 1.0
+        )
+    }
+}
+
+/// A small color chip + short label (no emoji icons).
+public struct Chip: View {
+    let text: String
+    let color: Color
+    public init(_ text: String, _ color: Color) { self.text = text; self.color = color }
+    public var body: some View {
+        Text(text)
+            .font(.caption2.weight(.semibold))
+            .foregroundStyle(color)
+            .padding(.horizontal, 7).padding(.vertical, 2)
+            .background(color.opacity(0.13), in: Capsule())
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Auth/KeychainStore.swift b/clients/ds-app/Sources/DSKit/Auth/KeychainStore.swift
new file mode 100644
index 0000000..45754e6
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Auth/KeychainStore.swift
@@ -0,0 +1,71 @@
+import Foundation
+import Security
+
+/// Access-token persistence. The scaffold/preview/unsigned-build path uses InMemoryTokenStore
+/// (Keychain on an unsigned binary can prompt or return errSecMissingEntitlement); the signed app
+/// uses KeychainStore. Only the ACCESS token is stored — refresh rides the HttpOnly cookie.
+public protocol TokenPersistence: Sendable {
+    func read() -> String?
+    func save(_ token: String) throws
+    func delete() throws
+}
+
+public final class InMemoryTokenStore: TokenPersistence, @unchecked Sendable {
+    private let lock = NSLock()
+    private var token: String?
+    public init() {}
+    public func read() -> String? { lock.withLock { token } }
+    public func save(_ token: String) throws { lock.withLock { self.token = token } }
+    public func delete() throws { lock.withLock { token = nil } }
+}
+
+public struct KeychainStore: TokenPersistence, Sendable {
+    private let service: String
+    private let account: String
+
+    public init(service: String = "net.hyungi.ds-app", account: String = "access_token") {
+        self.service = service
+        self.account = account
+    }
+
+    public func read() -> String? {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: service,
+            kSecAttrAccount as String: account,
+            kSecReturnData as String: true,
+            kSecMatchLimit as String: kSecMatchLimitOne,
+        ]
+        var item: CFTypeRef?
+        guard SecItemCopyMatching(query as CFDictionary, &item) == errSecSuccess,
+              let data = item as? Data,
+              let token = String(data: data, encoding: .utf8)
+        else { return nil }
+        return token
+    }
+
+    public func save(_ token: String) throws {
+        let base: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: service,
+            kSecAttrAccount as String: account,
+        ]
+        SecItemDelete(base as CFDictionary) // upsert
+        var add = base
+        add[kSecValueData as String] = Data(token.utf8)
+        add[kSecAttrAccessible as String] = kSecAttrAccessibleAfterFirstUnlock
+        let status = SecItemAdd(add as CFDictionary, nil)
+        guard status == errSecSuccess else {
+            throw DSError.transport(underlying: "keychain save failed (\(status))")
+        }
+    }
+
+    public func delete() throws {
+        let base: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: service,
+            kSecAttrAccount as String: account,
+        ]
+        SecItemDelete(base as CFDictionary)
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Auth/TokenProvider.swift b/clients/ds-app/Sources/DSKit/Auth/TokenProvider.swift
new file mode 100644
index 0000000..63fdeb1
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Auth/TokenProvider.swift
@@ -0,0 +1,43 @@
+import Foundation
+
+/// Concurrency-safe access-token holder with SINGLE-FLIGHT refresh: concurrent 401s must not each
+/// fire `/auth/refresh`. The coalescing is via a stored `Task` handle (not a bool) — entrants await
+/// the same in-flight task; it's cleared (success OR failure) when complete. Clearing too early lets a
+/// follower re-refresh; never clearing means the next expiry won't refresh.
+public actor TokenProvider {
+    private var cached: String?
+    private let persistence: TokenPersistence
+    private let refresh: @Sendable () async throws -> String
+    private var inFlightRefresh: Task<String, Error>?
+
+    public init(persistence: TokenPersistence, refresh: @escaping @Sendable () async throws -> String) {
+        self.persistence = persistence
+        self.refresh = refresh
+        self.cached = persistence.read()
+    }
+
+    public func current() -> String? { cached ?? persistence.read() }
+
+    public func set(_ token: String) {
+        cached = token
+        try? persistence.save(token)
+    }
+
+    public func clear() {
+        cached = nil
+        try? persistence.delete()
+    }
+
+    public func refreshOnce() async throws -> String {
+        if let task = inFlightRefresh {
+            return try await task.value
+        }
+        let task = Task { try await self.refresh() }
+        inFlightRefresh = task
+        defer { inFlightRefresh = nil }
+        let token = try await task.value
+        cached = token
+        try? persistence.save(token)
+        return token
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/DSClient.swift b/clients/ds-app/Sources/DSKit/DSClient.swift
new file mode 100644
index 0000000..6082ad8
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/DSClient.swift
@@ -0,0 +1,43 @@
+import Foundation
+
+/// The single networking seam the whole app codes against. The app builds entirely on
+/// `FixtureDSClient` (zero backend); `LiveDSClient` (FU-A) drops in later unchanged.
+///
+/// `ask(backend:)` keeps `backend` as `String?` (raw AI-ROUTING §4 values) — S2 maps AIProviderID
+/// to that string. This shape is locked by AI-ROUTING.md §4 (a documented contract), verified at
+/// integration by the FU-B call-shape regression.
+public protocol DSClient: Sendable {
+    // Auth
+    func login(username: String, password: String, totpCode: String?) async throws -> AccessTokenResponse
+    func me() async throws -> UserResponse
+    func refresh() async throws -> AccessTokenResponse
+    func logout() async throws
+
+    // Documents
+    func documents(_ query: DocumentListQuery) async throws -> DocumentListResponse
+    func document(id: Int) async throws -> DocumentDetailResponse
+    func documentContent(id: Int) async throws -> DocumentContentResponse
+    func documentTree() async throws -> [DomainTreeNode]
+    func categoryCounts() async throws -> CategoryCounts
+    func duplicates() async throws -> DuplicatesResponse
+    func patchDocument(id: Int, _ update: DocumentUpdate) async throws -> DocumentResponse
+    func putContent(id: Int, content: String) async throws
+    func deleteDocument(id: Int) async throws
+
+    // Search / Ask
+    func search(q: String, mode: SearchMode?, page: Int?, debug: Bool?) async throws -> SearchResponse
+    func ask(q: String, limit: Int?, backend: String?, debug: Bool?) async throws -> AskResponse
+
+    // Memos
+    func memos(_ query: MemoListQuery) async throws -> MemoListResponse
+    func memo(id: Int) async throws -> MemoResponse
+    func createMemo(_ create: MemoCreate) async throws -> MemoResponse
+    func patchMemo(id: Int, _ update: MemoUpdate) async throws -> MemoResponse
+    func pinMemo(id: Int, pinned: Bool) async throws -> MemoResponse
+    func archiveMemo(id: Int, archived: Bool) async throws -> MemoResponse
+    func toggleMemoTask(id: Int, taskIndex: Int, checked: Bool) async throws -> MemoResponse
+    func deleteMemo(id: Int) async throws
+
+    // Digest
+    func digest(date: String?, country: String?) async throws -> DigestResponse
+}
diff --git a/clients/ds-app/Sources/DSKit/DSCoding.swift b/clients/ds-app/Sources/DSKit/DSCoding.swift
new file mode 100644
index 0000000..44199ec
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/DSCoding.swift
@@ -0,0 +1,18 @@
+import Foundation
+
+/// Single decoder/encoder factory shared by every fixture load and both DS clients
+/// (call-shape single source of truth). NO `.convertFromSnakeCase` (every model has explicit
+/// CodingKeys) and NO global date strategy (dates are String-raw + DSDate accessors).
+public enum DSDecoder {
+    public static func make() -> JSONDecoder {
+        JSONDecoder()
+    }
+}
+
+public enum DSEncoder {
+    public static func make() -> JSONEncoder {
+        let e = JSONEncoder()
+        e.outputFormatting = [.sortedKeys]
+        return e
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/DSConfig.swift b/clients/ds-app/Sources/DSKit/DSConfig.swift
new file mode 100644
index 0000000..d699242
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/DSConfig.swift
@@ -0,0 +1,18 @@
+import Foundation
+
+/// Injectable base URL. Public TLS by default; Tailscale alternative uses a MagicDNS hostname
+/// (NOT a hardcoded 100.x IP, which changes on node re-registration). Scaffold never makes a live
+/// call, so the Tailscale host is a placeholder until FU-A.
+public enum DSBaseURL: Sendable {
+    case publicTLS
+    case tailscale
+    case custom(URL)
+
+    public var url: URL {
+        switch self {
+        case .publicTLS: return URL(string: "https://document.hyungi.net/api")!
+        case .tailscale: return URL(string: "http://ds-gpu.tailnet-name.ts.net:8000/api")!
+        case .custom(let u): return u
+        }
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/DSDate.swift b/clients/ds-app/Sources/DSKit/DSDate.swift
new file mode 100644
index 0000000..1834452
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/DSDate.swift
@@ -0,0 +1,33 @@
+import Foundation
+
+/// Date parsing for the contract's mixed shapes. Two ISO-8601 datetime shapes (with / without
+/// fractional seconds) coexist with date-only strings in the SAME response (digest), so a single
+/// JSONDecoder.dateDecodingStrategy is impossible. Dates are decoded as `String?` raw and parsed here.
+///
+/// Concurrency (B-1 review): uses value-type `Date.ISO8601FormatStyle` (Sendable) as static lets —
+/// no shared reference formatter, so no `nonisolated(unsafe)`.
+///
+/// Date-only (B-1 r2 review): `digest_date` should be DISPLAYED from its raw string (no Date conversion)
+/// to avoid KST off-by-one; `parse` here fixes date-only to UTC and is for sort/window math only.
+public enum DSDate {
+    private static let isoFractional = Date.ISO8601FormatStyle(includingFractionalSeconds: true)
+    private static let isoPlain = Date.ISO8601FormatStyle(includingFractionalSeconds: false)
+
+    public static func parse(_ s: String?) -> Date? {
+        guard let s, !s.isEmpty else { return nil }
+        if let d = try? isoFractional.parse(s) { return d }
+        if let d = try? isoPlain.parse(s) { return d }
+        return parseDateOnly(s)
+    }
+
+    /// Date-only "YYYY-MM-DD" fixed to UTC (avoids timezone off-by-one). Value-type Calendar, Sendable-safe.
+    private static func parseDateOnly(_ s: String) -> Date? {
+        let p = s.split(separator: "-")
+        guard p.count == 3, let y = Int(p[0]), let m = Int(p[1]), let d = Int(p[2]) else { return nil }
+        var comps = DateComponents()
+        comps.year = y; comps.month = m; comps.day = d
+        var cal = Calendar(identifier: .gregorian)
+        cal.timeZone = TimeZone(identifier: "UTC")!
+        return cal.date(from: comps)
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/DSError.swift b/clients/ds-app/Sources/DSKit/DSError.swift
new file mode 100644
index 0000000..26633ba
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/DSError.swift
@@ -0,0 +1,62 @@
+import Foundation
+
+/// Typed error decoded from the contract's two error body shapes ({detail: String} OR
+/// {detail: {error_code, message}}) and keyed by HTTP status.
+///
+/// Boundary note: an in-body synthesis failure (AskResponse.synthesis_status == "backend_unavailable")
+/// is an HTTP success and is NOT a DSError — only a true HTTP 503 maps to .serviceUnavailable.
+public enum DSError: Error, Sendable {
+    case unauthorized(message: String?)
+    case notFound(message: String?)
+    case validation(message: String?, errorCode: String?)
+    case serviceUnavailable(message: String?)
+    case server(status: Int, message: String?, errorCode: String?)
+    case transport(underlying: String)
+    case decoding(String)
+
+    public var isAuthExpired: Bool {
+        if case .unauthorized = self { return true }
+        return false
+    }
+
+    public static func from(status: Int, data: Data) -> DSError {
+        let body = DSErrorBody.parse(data)
+        switch status {
+        case 401: return .unauthorized(message: body?.message)
+        case 404: return .notFound(message: body?.message)
+        case 422: return .validation(message: body?.message, errorCode: body?.errorCode)
+        case 503: return .serviceUnavailable(message: body?.message)
+        default: return .server(status: status, message: body?.message, errorCode: body?.errorCode)
+        }
+    }
+}
+
+struct DSErrorBody {
+    let message: String?
+    let errorCode: String?
+
+    static func parse(_ data: Data) -> DSErrorBody? {
+        guard let obj = try? JSONSerialization.jsonObject(with: data) as? [String: Any] else { return nil }
+        if let s = obj["detail"] as? String {
+            return DSErrorBody(message: s, errorCode: nil)
+        }
+        if let d = obj["detail"] as? [String: Any] {
+            return DSErrorBody(message: d["message"] as? String, errorCode: d["error_code"] as? String)
+        }
+        return nil
+    }
+}
+
+extension DSError: LocalizedError {
+    public var errorDescription: String? {
+        switch self {
+        case .unauthorized(let m): return m ?? "인증이 만료되었습니다. 다시 로그인하세요."
+        case .notFound(let m): return m ?? "찾을 수 없습니다."
+        case .validation(let m, _): return m ?? "요청이 올바르지 않습니다."
+        case .serviceUnavailable(let m): return m ?? "서비스를 일시적으로 사용할 수 없습니다."
+        case .server(let s, let m, _): return m ?? "서버 오류 (\(s))"
+        case .transport(let u): return "네트워크 오류: \(u)"
+        case .decoding(let d): return "응답 해석 실패: \(d)"
+        }
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/DownloadURL.swift b/clients/ds-app/Sources/DSKit/DownloadURL.swift
new file mode 100644
index 0000000..0c7c0be
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/DownloadURL.swift
@@ -0,0 +1,21 @@
+import Foundation
+
+/// Original-file download URL builder. CRITICAL: this endpoint authenticates via the `?token=` QUERY
+/// parameter, NOT an Authorization header (iframe/download compatibility). The token must live only in
+/// the query. Callers must redact the token when logging the URL.
+public enum DSDownload {
+    public static func fileURL(
+        base: DSBaseURL,
+        documentID id: Int,
+        accessToken: String,
+        download: Bool = true
+    ) -> URL? {
+        let endpoint = base.url.appendingPathComponent("documents/\(id)/file")
+        var comps = URLComponents(url: endpoint, resolvingAgainstBaseURL: false)
+        comps?.queryItems = [
+            URLQueryItem(name: "token", value: accessToken),
+            URLQueryItem(name: "download", value: download ? "true" : "false"),
+        ]
+        return comps?.url
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Endpoint.swift b/clients/ds-app/Sources/DSKit/Endpoint.swift
new file mode 100644
index 0000000..f2c895b
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Endpoint.swift
@@ -0,0 +1,135 @@
+import Foundation
+
+/// Single source of truth mapping each DSClient call to HTTP method + path + query + body.
+/// Trailing slashes are significant (e.g. `documents/`, `search/`) and are preserved by building the
+/// URL from the base string rather than appendingPathComponent (which strips them).
+enum DSEndpoint {
+    case login(String, String, String?)
+    case me
+    case refresh
+    case logout
+    case documents(DocumentListQuery)
+    case document(Int)
+    case documentContent(Int)
+    case documentTree
+    case categoryCounts
+    case duplicates
+    case patchDocument(Int, DocumentUpdate)
+    case putContent(Int, String)
+    case deleteDocument(Int)
+    case search(String, SearchMode?, Int?, Bool?)
+    case ask(String, Int?, String?, Bool?)
+    case memos(MemoListQuery)
+    case memo(Int)
+    case createMemo(MemoCreate)
+    case patchMemo(Int, MemoUpdate)
+    case pinMemo(Int, Bool)
+    case archiveMemo(Int, Bool)
+    case toggleMemoTask(Int, Int, Bool)
+    case deleteMemo(Int)
+    case digest(String?, String?)
+
+    var method: String {
+        switch self {
+        case .login, .refresh, .logout, .createMemo: return "POST"
+        case .patchDocument, .patchMemo, .pinMemo, .archiveMemo, .toggleMemoTask: return "PATCH"
+        case .putContent: return "PUT"
+        case .deleteDocument, .deleteMemo: return "DELETE"
+        default: return "GET"
+        }
+    }
+
+    var path: String {
+        switch self {
+        case .login: return "auth/login"
+        case .me: return "auth/me"
+        case .refresh: return "auth/refresh"
+        case .logout: return "auth/logout"
+        case .documents: return "documents/"
+        case .document(let id): return "documents/\(id)"
+        case .documentContent(let id): return "documents/\(id)/content"
+        case .documentTree: return "documents/tree"
+        case .categoryCounts: return "documents/stats/category-counts"
+        case .duplicates: return "documents/duplicates"
+        case .patchDocument(let id, _): return "documents/\(id)"
+        case .putContent(let id, _): return "documents/\(id)/content"
+        case .deleteDocument(let id): return "documents/\(id)"
+        case .search: return "search/"
+        case .ask: return "search/ask"
+        case .memos: return "memos/"
+        case .memo(let id): return "memos/\(id)"
+        case .createMemo: return "memos/"
+        case .patchMemo(let id, _): return "memos/\(id)"
+        case .pinMemo(let id, _): return "memos/\(id)/pin"
+        case .archiveMemo(let id, _): return "memos/\(id)/archive"
+        case .toggleMemoTask(let id, let idx, _): return "memos/\(id)/tasks/\(idx)"
+        case .deleteMemo(let id): return "memos/\(id)"
+        case .digest: return "digest"
+        }
+    }
+
+    /// Bearer header applies to everything except login/refresh (refresh rides the HttpOnly cookie).
+    var requiresBearer: Bool {
+        switch self {
+        case .login, .refresh: return false
+        default: return true
+        }
+    }
+
+    var queryItems: [URLQueryItem] {
+        var items: [URLQueryItem] = []
+        func add(_ name: String, _ value: String?) { if let value { items.append(URLQueryItem(name: name, value: value)) } }
+        switch self {
+        case .documents(let q):
+            add("page", String(q.page)); add("page_size", String(q.pageSize))
+            add("domain", q.domain); add("sub_group", q.subGroup); add("source", q.source)
+            add("format", q.format); add("review_status", q.reviewStatus); add("category", q.category)
+        case .search(let qq, let mode, let page, let debug):
+            add("q", qq); add("mode", mode?.rawValue); add("page", page.map(String.init)); add("debug", debug.map(String.init))
+        case .ask(let qq, let limit, let backend, let debug):
+            add("q", qq); add("limit", limit.map(String.init)); add("backend", backend); add("debug", debug.map(String.init))
+        case .memos(let q):
+            add("page", String(q.page)); add("page_size", String(q.pageSize))
+            add("pinned", q.pinned.map(String.init)); add("archived", q.archived.map(String.init))
+        case .digest(let date, let country):
+            add("date", date); add("country", country)
+        default:
+            break
+        }
+        return items
+    }
+
+    func httpBody(_ encoder: JSONEncoder) throws -> Data? {
+        switch self {
+        case .login(let u, let p, let totp):
+            return try encoder.encode(LoginBody(username: u, password: p, totpCode: totp))
+        case .patchDocument(_, let update):
+            return try encoder.encode(update)
+        case .putContent(_, let content):
+            return try encoder.encode(ContentBody(content: content))
+        case .createMemo(let create):
+            return try encoder.encode(create)
+        case .patchMemo(_, let update):
+            return try encoder.encode(update)
+        case .pinMemo(_, let pinned):
+            return try encoder.encode(PinnedBody(pinned: pinned))
+        case .archiveMemo(_, let archived):
+            return try encoder.encode(ArchivedBody(archived: archived))
+        case .toggleMemoTask(_, _, let checked):
+            return try encoder.encode(CheckedBody(checked: checked))
+        default:
+            return nil
+        }
+    }
+}
+
+private struct LoginBody: Encodable {
+    let username: String
+    let password: String
+    let totpCode: String?
+    enum CodingKeys: String, CodingKey { case username, password; case totpCode = "totp_code" }
+}
+private struct ContentBody: Encodable { let content: String }
+private struct PinnedBody: Encodable { let pinned: Bool }
+private struct ArchivedBody: Encodable { let archived: Bool }
+private struct CheckedBody: Encodable { let checked: Bool }
diff --git a/clients/ds-app/Sources/DSKit/FixtureDSClient.swift b/clients/ds-app/Sources/DSKit/FixtureDSClient.swift
new file mode 100644
index 0000000..4cf9f23
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/FixtureDSClient.swift
@@ -0,0 +1,81 @@
+import Foundation
+
+/// Zero-backend DSClient: loads the 14 bundled fixtures (Bundle.module) with the SAME decoder the
+/// live client will use, so "it previews" == "the DTOs decode the real shapes". Powers SwiftUI
+/// previews and the contract acceptance test. Write-side methods return a plausible echo.
+///
+/// Holds no non-Sendable stored state (uses Bundle.module locally) → Sendable.
+public struct FixtureDSClient: DSClient {
+    public init() {}
+
+    private func load<T: Decodable>(_ name: String, as type: T.Type) throws -> T {
+        guard let url = Bundle.module.url(forResource: name, withExtension: "json") else {
+            throw DSError.notFound(message: "fixture \(name).json")
+        }
+        let data = try Data(contentsOf: url)
+        do {
+            return try DSDecoder.make().decode(T.self, from: data)
+        } catch {
+            throw DSError.decoding("\(name): \(error)")
+        }
+    }
+
+    // Auth
+    public func login(username: String, password: String, totpCode: String?) async throws -> AccessTokenResponse {
+        try load("auth_login", as: AccessTokenResponse.self)
+    }
+    public func me() async throws -> UserResponse { try load("auth_me", as: UserResponse.self) }
+    public func refresh() async throws -> AccessTokenResponse { try load("auth_login", as: AccessTokenResponse.self) }
+    public func logout() async throws {}
+
+    // Documents
+    public func documents(_ query: DocumentListQuery) async throws -> DocumentListResponse {
+        try load("documents_list", as: DocumentListResponse.self)
+    }
+    public func document(id: Int) async throws -> DocumentDetailResponse {
+        // id 5301 = the pending-MD fixture (extracted_text fallback); otherwise the completed MD-first fixture.
+        try load(id == 5301 ? "document_detail_pending_md" : "document_detail", as: DocumentDetailResponse.self)
+    }
+    public func documentContent(id: Int) async throws -> DocumentContentResponse {
+        try load("document_content", as: DocumentContentResponse.self)
+    }
+    public func documentTree() async throws -> [DomainTreeNode] {
+        try load("documents_tree", as: [DomainTreeNode].self)
+    }
+    public func categoryCounts() async throws -> CategoryCounts {
+        try load("documents_stats", as: CategoryCounts.self)
+    }
+    public func duplicates() async throws -> DuplicatesResponse {
+        try load("documents_duplicates", as: DuplicatesResponse.self)
+    }
+    public func patchDocument(id: Int, _ update: DocumentUpdate) async throws -> DocumentResponse {
+        try load("document_detail", as: DocumentDetailResponse.self).base
+    }
+    public func putContent(id: Int, content: String) async throws {}
+    public func deleteDocument(id: Int) async throws {}
+
+    // Search / Ask
+    public func search(q: String, mode: SearchMode?, page: Int?, debug: Bool?) async throws -> SearchResponse {
+        try load("search", as: SearchResponse.self)
+    }
+    public func ask(q: String, limit: Int?, backend: String?, debug: Bool?) async throws -> AskResponse {
+        try load("ask", as: AskResponse.self)
+    }
+
+    // Memos
+    public func memos(_ query: MemoListQuery) async throws -> MemoListResponse {
+        try load("memos_list", as: MemoListResponse.self)
+    }
+    public func memo(id: Int) async throws -> MemoResponse { try load("memo_detail", as: MemoResponse.self) }
+    public func createMemo(_ create: MemoCreate) async throws -> MemoResponse { try load("memo_detail", as: MemoResponse.self) }
+    public func patchMemo(id: Int, _ update: MemoUpdate) async throws -> MemoResponse { try load("memo_detail", as: MemoResponse.self) }
+    public func pinMemo(id: Int, pinned: Bool) async throws -> MemoResponse { try load("memo_detail", as: MemoResponse.self) }
+    public func archiveMemo(id: Int, archived: Bool) async throws -> MemoResponse { try load("memo_detail", as: MemoResponse.self) }
+    public func toggleMemoTask(id: Int, taskIndex: Int, checked: Bool) async throws -> MemoResponse { try load("memo_detail", as: MemoResponse.self) }
+    public func deleteMemo(id: Int) async throws {}
+
+    // Digest
+    public func digest(date: String?, country: String?) async throws -> DigestResponse {
+        try load("digest", as: DigestResponse.self)
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/JSONValue.swift b/clients/ds-app/Sources/DSKit/JSONValue.swift
new file mode 100644
index 0000000..4ea67b7
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/JSONValue.swift
@@ -0,0 +1,71 @@
+import Foundation
+
+/// A Sendable, fully-Codable representation of arbitrary JSON, for the contract's open-shape
+/// `[String: Any]?` fields (ai_suggestion, md_frontmatter, md_extraction_quality, memo_task_state,
+/// source_metadata, freshness_debug, debug). Plain Codable cannot decode those; this can.
+///
+/// Numeric note (B-1 review): on Foundation's JSONDecoder, a JSON boolean fails `Int` decode
+/// (no silent 1/0 coercion), so Bool ordering is harmless. The real disambiguation is Int-before-Double
+/// so integral numbers stay `.int`. BUT whole-valued floats like `1.0` can land as `.int` depending on
+/// toolchain — so numeric meaning MUST be read through `doubleValue`/`intValue` (which cross-convert),
+/// never by pattern-matching the raw case.
+public enum JSONValue: Codable, Sendable, Hashable {
+    case string(String)
+    case int(Int)
+    case double(Double)
+    case bool(Bool)
+    case object([String: JSONValue])
+    case array([JSONValue])
+    case null
+
+    public init(from decoder: Decoder) throws {
+        let c = try decoder.singleValueContainer()
+        if c.decodeNil() { self = .null; return }
+        if let b = try? c.decode(Bool.self) { self = .bool(b); return }
+        if let i = try? c.decode(Int.self) { self = .int(i); return }
+        if let d = try? c.decode(Double.self) { self = .double(d); return }
+        if let s = try? c.decode(String.self) { self = .string(s); return }
+        if let o = try? c.decode([String: JSONValue].self) { self = .object(o); return }
+        if let a = try? c.decode([JSONValue].self) { self = .array(a); return }
+        throw DecodingError.dataCorruptedError(in: c, debugDescription: "Unsupported JSON value")
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var c = encoder.singleValueContainer()
+        switch self {
+        case .string(let s): try c.encode(s)
+        case .int(let i): try c.encode(i)
+        case .double(let d): try c.encode(d)
+        case .bool(let b): try c.encode(b)
+        case .object(let o): try c.encode(o)
+        case .array(let a): try c.encode(a)
+        case .null: try c.encodeNil()
+        }
+    }
+
+    // Accessors cross-convert so numeric reads are robust regardless of int/double storage.
+    public var stringValue: String? { if case .string(let s) = self { return s }; return nil }
+    public var intValue: Int? {
+        switch self {
+        case .int(let i): return i
+        case .double(let d): return Int(d)
+        default: return nil
+        }
+    }
+    public var doubleValue: Double? {
+        switch self {
+        case .double(let d): return d
+        case .int(let i): return Double(i)
+        default: return nil
+        }
+    }
+    public var boolValue: Bool? { if case .bool(let b) = self { return b }; return nil }
+    public var objectValue: [String: JSONValue]? { if case .object(let o) = self { return o }; return nil }
+    public var arrayValue: [JSONValue]? { if case .array(let a) = self { return a }; return nil }
+
+    public subscript(key: String) -> JSONValue? { objectValue?[key] }
+    public subscript(index: Int) -> JSONValue? {
+        guard let a = arrayValue, index >= 0, index < a.count else { return nil }
+        return a[index]
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/LiveDSClient.swift b/clients/ds-app/Sources/DSKit/LiveDSClient.swift
new file mode 100644
index 0000000..9af4531
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/LiveDSClient.swift
@@ -0,0 +1,135 @@
+import Foundation
+
+/// Real-network DSClient (FU-A). Same DTOs/decoder as FixtureDSClient, so swapping it in is
+/// behavior-identical except for I/O. URLSession with shared cookie storage so the HttpOnly refresh
+/// cookie is replayed on `/auth/refresh`. A 401 on a bearer request triggers a single-flight refresh
+/// + ONE retry (never on login/refresh/logout, to avoid loops).
+///
+/// Immutable stored props (URLSession/decoder shared but never mutated) → @unchecked Sendable.
+public final class LiveDSClient: DSClient, @unchecked Sendable {
+    private let base: DSBaseURL
+    private let session: URLSession
+    private let decoder: JSONDecoder
+    private let encoder: JSONEncoder
+    private let tokens: TokenProvider
+
+    public init(base: DSBaseURL = .publicTLS, persistence: TokenPersistence = InMemoryTokenStore()) {
+        let baseURL = base
+        let config = URLSessionConfiguration.default
+        config.httpCookieStorage = .shared
+        config.httpShouldSetCookies = true
+        let session = URLSession(configuration: config)
+        let decoder = DSDecoder.make()
+
+        self.base = baseURL
+        self.session = session
+        self.decoder = decoder
+        self.encoder = DSEncoder.make()
+        // Refresh closure captures only Sendable values (no self): raw POST /auth/refresh via cookie.
+        self.tokens = TokenProvider(persistence: persistence) {
+            var request = URLRequest(url: baseURL.url.appendingPathComponent("auth/refresh"))
+            request.httpMethod = "POST"
+            let (data, response) = try await session.data(for: request)
+            guard let http = response as? HTTPURLResponse, http.statusCode == 200 else {
+                throw DSError.unauthorized(message: "refresh failed")
+            }
+            return try decoder.decode(AccessTokenResponse.self, from: data).accessToken
+        }
+    }
+
+    public func setAccessToken(_ token: String) async { await tokens.set(token) }
+
+    // MARK: - Request building / sending
+
+    private func makeRequest(_ endpoint: DSEndpoint, token: String?) throws -> URLRequest {
+        // Build URL from the base string to preserve trailing slashes; URLComponents percent-encodes.
+        let raw = base.url.absoluteString + "/" + endpoint.path
+        guard var comps = URLComponents(string: raw) else {
+            throw DSError.transport(underlying: "bad URL \(raw)")
+        }
+        if !endpoint.queryItems.isEmpty { comps.queryItems = endpoint.queryItems }
+        guard let url = comps.url else { throw DSError.transport(underlying: "bad URL components") }
+
+        var request = URLRequest(url: url)
+        request.httpMethod = endpoint.method
+        if endpoint.requiresBearer, let token { request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization") }
+        if let body = try endpoint.httpBody(encoder) {
+            request.httpBody = body
+            request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        }
+        return request
+    }
+
+    private func perform(_ endpoint: DSEndpoint) async throws -> Data {
+        let request = try makeRequest(endpoint, token: await tokens.current())
+        let (data, response) = try await dataOrTransport(request)
+        guard let http = response as? HTTPURLResponse else {
+            throw DSError.transport(underlying: "no HTTP response")
+        }
+        if http.statusCode == 401, endpoint.requiresBearer {
+            // Single-flight refresh + one retry.
+            let newToken = try await tokens.refreshOnce()
+            let retry = try makeRequest(endpoint, token: newToken)
+            let (data2, response2) = try await dataOrTransport(retry)
+            guard let http2 = response2 as? HTTPURLResponse else {
+                throw DSError.transport(underlying: "no HTTP response")
+            }
+            guard (200..<300).contains(http2.statusCode) else { throw DSError.from(status: http2.statusCode, data: data2) }
+            return data2
+        }
+        guard (200..<300).contains(http.statusCode) else { throw DSError.from(status: http.statusCode, data: data) }
+        return data
+    }
+
+    private func dataOrTransport(_ request: URLRequest) async throws -> (Data, URLResponse) {
+        do { return try await session.data(for: request) }
+        catch { throw DSError.transport(underlying: "\(error)") }
+    }
+
+    private func send<T: Decodable>(_ endpoint: DSEndpoint, as type: T.Type) async throws -> T {
+        let data = try await perform(endpoint)
+        do { return try decoder.decode(T.self, from: data) }
+        catch { throw DSError.decoding("\(endpoint.path): \(error)") }
+    }
+
+    private func sendVoid(_ endpoint: DSEndpoint) async throws { _ = try await perform(endpoint) }
+
+    // MARK: - DSClient
+
+    public func login(username: String, password: String, totpCode: String?) async throws -> AccessTokenResponse {
+        let token: AccessTokenResponse = try await send(.login(username, password, totpCode), as: AccessTokenResponse.self)
+        await tokens.set(token.accessToken)
+        return token
+    }
+    public func me() async throws -> UserResponse { try await send(.me, as: UserResponse.self) }
+    public func refresh() async throws -> AccessTokenResponse {
+        let token: AccessTokenResponse = try await send(.refresh, as: AccessTokenResponse.self)
+        await tokens.set(token.accessToken)
+        return token
+    }
+    public func logout() async throws { try await sendVoid(.logout); await tokens.clear() }
+
+    public func documents(_ query: DocumentListQuery) async throws -> DocumentListResponse { try await send(.documents(query), as: DocumentListResponse.self) }
+    public func document(id: Int) async throws -> DocumentDetailResponse { try await send(.document(id), as: DocumentDetailResponse.self) }
+    public func documentContent(id: Int) async throws -> DocumentContentResponse { try await send(.documentContent(id), as: DocumentContentResponse.self) }
+    public func documentTree() async throws -> [DomainTreeNode] { try await send(.documentTree, as: [DomainTreeNode].self) }
+    public func categoryCounts() async throws -> CategoryCounts { try await send(.categoryCounts, as: CategoryCounts.self) }
+    public func duplicates() async throws -> DuplicatesResponse { try await send(.duplicates, as: DuplicatesResponse.self) }
+    public func patchDocument(id: Int, _ update: DocumentUpdate) async throws -> DocumentResponse { try await send(.patchDocument(id, update), as: DocumentResponse.self) }
+    public func putContent(id: Int, content: String) async throws { try await sendVoid(.putContent(id, content)) }
+    public func deleteDocument(id: Int) async throws { try await sendVoid(.deleteDocument(id)) }
+
+    public func search(q: String, mode: SearchMode?, page: Int?, debug: Bool?) async throws -> SearchResponse { try await send(.search(q, mode, page, debug), as: SearchResponse.self) }
+    public func ask(q: String, limit: Int?, backend: String?, debug: Bool?) async throws -> AskResponse { try await send(.ask(q, limit, backend, debug), as: AskResponse.self) }
+
+    public func memos(_ query: MemoListQuery) async throws -> MemoListResponse { try await send(.memos(query), as: MemoListResponse.self) }
+    public func memo(id: Int) async throws -> MemoResponse { try await send(.memo(id), as: MemoResponse.self) }
+    public func createMemo(_ create: MemoCreate) async throws -> MemoResponse { try await send(.createMemo(create), as: MemoResponse.self) }
+    public func patchMemo(id: Int, _ update: MemoUpdate) async throws -> MemoResponse { try await send(.patchMemo(id, update), as: MemoResponse.self) }
+    public func pinMemo(id: Int, pinned: Bool) async throws -> MemoResponse { try await send(.pinMemo(id, pinned), as: MemoResponse.self) }
+    public func archiveMemo(id: Int, archived: Bool) async throws -> MemoResponse { try await send(.archiveMemo(id, archived), as: MemoResponse.self) }
+    public func toggleMemoTask(id: Int, taskIndex: Int, checked: Bool) async throws -> MemoResponse { try await send(.toggleMemoTask(id, taskIndex, checked), as: MemoResponse.self) }
+    public func deleteMemo(id: Int) async throws { try await sendVoid(.deleteMemo(id)) }
+
+    public func digest(date: String?, country: String?) async throws -> DigestResponse { try await send(.digest(date, country), as: DigestResponse.self) }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Auth.swift b/clients/ds-app/Sources/DSKit/Models/Auth.swift
new file mode 100644
index 0000000..70e7661
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Auth.swift
@@ -0,0 +1,28 @@
+import Foundation
+
+public struct AccessTokenResponse: Codable, Sendable, Equatable {
+    public let accessToken: String
+    public let tokenType: String
+
+    enum CodingKeys: String, CodingKey {
+        case accessToken = "access_token"
+        case tokenType = "token_type"
+    }
+}
+
+public struct UserResponse: Codable, Sendable, Equatable, Identifiable {
+    public let id: Int
+    public let username: String
+    public let isActive: Bool
+    public let totpEnabled: Bool
+    public let lastLoginAtRaw: String?
+
+    public var lastLoginAt: Date? { DSDate.parse(lastLoginAtRaw) }
+
+    enum CodingKeys: String, CodingKey {
+        case id, username
+        case isActive = "is_active"
+        case totpEnabled = "totp_enabled"
+        case lastLoginAtRaw = "last_login_at"
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Catalog.swift b/clients/ds-app/Sources/DSKit/Models/Catalog.swift
new file mode 100644
index 0000000..272a2d8
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Catalog.swift
@@ -0,0 +1,54 @@
+import Foundation
+
+/// Recursive domain tree (documents_tree.json is a top-level ARRAY). `children` is optional so
+/// SwiftUI OutlineGroup can treat leaves cleanly; `kids` is the non-optional accessor.
+public struct DomainTreeNode: Codable, Sendable, Identifiable {
+    public let name: String
+    public let path: String
+    public let count: Int
+    public let children: [DomainTreeNode]?
+
+    public var id: String { path }
+    public var kids: [DomainTreeNode] { children ?? [] }
+}
+
+public struct CategoryCounts: Codable, Sendable {
+    public let total: Int
+    public let documents: Int
+    public let byDomain: [String: Int]
+    public let reviewPending: Int
+    public let pipelineFailed: Int
+
+    enum CodingKeys: String, CodingKey {
+        case total, documents
+        case byDomain = "by_domain"
+        case reviewPending = "review_pending"
+        case pipelineFailed = "pipeline_failed"
+    }
+}
+
+public struct DuplicateGroup: Codable, Sendable, Identifiable {
+    public let canonicalId: Int
+    public let members: [Int]
+    public let reason: String
+    public let detail: String?
+
+    public var id: Int { canonicalId }
+
+    enum CodingKeys: String, CodingKey {
+        case members, reason, detail
+        case canonicalId = "canonical_id"
+    }
+}
+
+public struct DuplicatesResponse: Codable, Sendable {
+    public let groups: [DuplicateGroup]
+    public let totalGroups: Int
+    public let totalDuplicateDocs: Int
+
+    enum CodingKeys: String, CodingKey {
+        case groups
+        case totalGroups = "total_groups"
+        case totalDuplicateDocs = "total_duplicate_docs"
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Digest.swift b/clients/ds-app/Sources/DSKit/Models/Digest.swift
new file mode 100644
index 0000000..d4d5098
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Digest.swift
@@ -0,0 +1,88 @@
+import Foundation
+
+public struct ArticleRef: Codable, Sendable, Identifiable {
+    public let id: Int
+    public let title: String?
+}
+
+public struct TopicResponse: Codable, Sendable, Identifiable {
+    public let topicRank: Int
+    public let topicLabel: String
+    public let summary: String
+    public let articleIds: [Int]?
+    public let articles: [ArticleRef]
+    public let articleCount: Int?
+    public let importanceScore: Double?
+    public let rawWeightSum: Double?
+    public let llmFallbackUsed: Bool?
+
+    public var id: Int { topicRank }
+
+    enum CodingKeys: String, CodingKey {
+        case summary, articles
+        case topicRank = "topic_rank"
+        case topicLabel = "topic_label"
+        case articleIds = "article_ids"
+        case articleCount = "article_count"
+        case importanceScore = "importance_score"
+        case rawWeightSum = "raw_weight_sum"
+        case llmFallbackUsed = "llm_fallback_used"
+    }
+}
+
+public struct CountryGroup: Codable, Sendable, Identifiable {
+    public let country: String
+    public let topics: [TopicResponse]
+    public var id: String { country }
+}
+
+public struct DigestResponse: Codable, Sendable {
+    public let digestDateRaw: String?
+    public let windowStartRaw: String?
+    public let windowEndRaw: String?
+    public let decayLambda: Double?
+    public let totalArticles: Int?
+    public let totalCountries: Int?
+    public let totalTopics: Int?
+    public let generationMs: Int?
+    public let llmCalls: Int?
+    public let llmFailures: Int?
+    public let status: String?
+    public let countries: [CountryGroup]
+
+    /// date-only (B-1 r2): DISPLAY the raw string (no Date conversion → no KST off-by-one).
+    public var digestDateDisplay: String { digestDateRaw ?? "" }
+    /// Date conversions are for sort/window math only (UTC-fixed via DSDate).
+    public var windowStart: Date? { DSDate.parse(windowStartRaw) }
+    public var windowEnd: Date? { DSDate.parse(windowEndRaw) }
+
+    enum CodingKeys: String, CodingKey {
+        case status, countries
+        case digestDateRaw = "digest_date"
+        case windowStartRaw = "window_start"
+        case windowEndRaw = "window_end"
+        case decayLambda = "decay_lambda"
+        case totalArticles = "total_articles"
+        case totalCountries = "total_countries"
+        case totalTopics = "total_topics"
+        case generationMs = "generation_ms"
+        case llmCalls = "llm_calls"
+        case llmFailures = "llm_failures"
+    }
+}
+
+public struct DigestDateSummary: Codable, Sendable {
+    public let digestDateRaw: String?
+    public let totalTopics: Int?
+    public let totalCountries: Int?
+    public let totalArticles: Int?
+    public let status: String?
+
+    enum CodingKeys: String, CodingKey {
+        case status
+        case digestDateRaw = "digest_date"
+        case totalTopics = "total_topics"
+        case totalCountries = "total_countries"
+        case totalArticles = "total_articles"
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Document.swift b/clients/ds-app/Sources/DSKit/Models/Document.swift
new file mode 100644
index 0000000..d2cd79e
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Document.swift
@@ -0,0 +1,201 @@
+import Foundation
+
+/// Document list row. Non-optional set is intentional (B-2 review): only structural/envelope-grade
+/// fields whose absence is a contract violation are non-optional, so a malformed response throws
+/// loudly rather than silently nil-ing. `file_format` and `read_count` are OPTIONAL + fallback
+/// (a note has no format; a light projection may omit the counter — one production null must not
+/// kill the whole list decode). Everything else is optional (all-optional discipline).
+public struct DocumentResponse: Codable, Sendable, Identifiable, Equatable {
+    // Invariants (loud-throw on absence)
+    public let id: Int
+    public let fileType: String
+    public let createdAtRaw: String
+    public let updatedAtRaw: String
+    // Optional + fallback
+    public let fileFormat: String?
+    public let readCount: Int?
+    // Everything else optional
+    public let filePath: String?
+    public let fileSize: Int?
+    public let title: String?
+    public let aiDomain: String?
+    public let aiSubGroup: String?
+    public let aiTags: [String]?
+    public let aiSummary: String?
+    public let documentType: String?
+    public let importance: String?
+    public let aiConfidence: Double?
+    public let userNote: String?
+    public let userTags: [String]?
+    public let pinned: Bool?
+    public let askIncludable: Bool?
+    public let derivedPath: String?
+    public let originalFormat: String?
+    public let conversionStatus: String?
+    public let isRead: Bool?
+    public let reviewStatus: String?
+    public let editUrl: String?
+    public let previewStatus: String?
+    public let sourceChannel: String?
+    public let dataOrigin: String?
+    public let docPurpose: String?
+    public let facetCompany: String?
+    public let facetTopic: String?
+    public let facetYear: Int?
+    public let facetDoctype: String?
+    public let category: String?
+    public let aiSuggestion: JSONValue?
+    public let aiTldr: String?
+    public let aiBullets: [String]?
+    public let aiDetailSummary: String?
+    public let aiInconsistencies: [String]?
+    public let aiAnalysisTier: String?
+    public let extractedAtRaw: String?
+    public let aiProcessedAtRaw: String?
+    public let embeddedAtRaw: String?
+    public let lastReadAtRaw: String?
+    // [S1-ADD]
+    public let originalFilename: String?
+    public let duplicateOf: Int?
+    public let duplicateCount: Int?
+
+    public var createdAt: Date? { DSDate.parse(createdAtRaw) }
+    public var updatedAt: Date? { DSDate.parse(updatedAtRaw) }
+    public var lastReadAt: Date? { DSDate.parse(lastReadAtRaw) }
+    public var reads: Int { readCount ?? 0 }
+    public var displayFormat: String {
+        fileFormat ?? filePath.map { ($0 as NSString).pathExtension }.flatMap { $0.isEmpty ? nil : $0 } ?? "?"
+    }
+    public var downloadLabel: String {
+        originalFilename ?? filePath.map { ($0 as NSString).lastPathComponent } ?? "원본"
+    }
+    public var hasDownloadableOriginal: Bool { fileType != "note" }
+
+    enum CodingKeys: String, CodingKey {
+        case id, title, importance, pinned, category
+        case fileType = "file_type"
+        case createdAtRaw = "created_at"
+        case updatedAtRaw = "updated_at"
+        case fileFormat = "file_format"
+        case readCount = "read_count"
+        case filePath = "file_path"
+        case fileSize = "file_size"
+        case aiDomain = "ai_domain"
+        case aiSubGroup = "ai_sub_group"
+        case aiTags = "ai_tags"
+        case aiSummary = "ai_summary"
+        case documentType = "document_type"
+        case aiConfidence = "ai_confidence"
+        case userNote = "user_note"
+        case userTags = "user_tags"
+        case askIncludable = "ask_includable"
+        case derivedPath = "derived_path"
+        case originalFormat = "original_format"
+        case conversionStatus = "conversion_status"
+        case isRead = "is_read"
+        case reviewStatus = "review_status"
+        case editUrl = "edit_url"
+        case previewStatus = "preview_status"
+        case sourceChannel = "source_channel"
+        case dataOrigin = "data_origin"
+        case docPurpose = "doc_purpose"
+        case facetCompany = "facet_company"
+        case facetTopic = "facet_topic"
+        case facetYear = "facet_year"
+        case facetDoctype = "facet_doctype"
+        case aiSuggestion = "ai_suggestion"
+        case aiTldr = "ai_tldr"
+        case aiBullets = "ai_bullets"
+        case aiDetailSummary = "ai_detail_summary"
+        case aiInconsistencies = "ai_inconsistencies"
+        case aiAnalysisTier = "ai_analysis_tier"
+        case extractedAtRaw = "extracted_at"
+        case aiProcessedAtRaw = "ai_processed_at"
+        case embeddedAtRaw = "embedded_at"
+        case lastReadAtRaw = "last_read_at"
+        case originalFilename = "original_filename"
+        case duplicateOf = "duplicate_of"
+        case duplicateCount = "duplicate_count"
+    }
+}
+
+/// Single-document detail = the flat DocumentResponse fields + markdown/body fields, decoded from the
+/// same flat JSON object via composition (avoids duplicating ~45 field declarations). The pending-md
+/// fixture decodes through the SAME struct.
+public struct DocumentDetailResponse: Decodable, Sendable, Identifiable {
+    public let base: DocumentResponse
+    public let extractedText: String?
+    public let mdContent: String?
+    public let mdFrontmatter: JSONValue?
+    public let mdStatus: String?
+    public let mdExtractionQuality: JSONValue?
+    public let mdExtractionError: String?
+    public let mdExtractionEngine: String?
+    public let mdExtractionEngineVersion: String?
+    public let mdGeneratedAtRaw: String?
+
+    public var id: Int { base.id }
+    public var mdGeneratedAt: Date? { DSDate.parse(mdGeneratedAtRaw) }
+    /// MD-first render rule: render md_content when status is completed/partial, else fall back.
+    public var mdIsRenderable: Bool { mdStatus == "completed" || mdStatus == "partial" }
+
+    enum CodingKeys: String, CodingKey {
+        case extractedText = "extracted_text"
+        case mdContent = "md_content"
+        case mdFrontmatter = "md_frontmatter"
+        case mdStatus = "md_status"
+        case mdExtractionQuality = "md_extraction_quality"
+        case mdExtractionError = "md_extraction_error"
+        case mdExtractionEngine = "md_extraction_engine"
+        case mdExtractionEngineVersion = "md_extraction_engine_version"
+        case mdGeneratedAtRaw = "md_generated_at"
+    }
+
+    public init(from decoder: Decoder) throws {
+        self.base = try DocumentResponse(from: decoder)
+        let c = try decoder.container(keyedBy: CodingKeys.self)
+        self.extractedText = try c.decodeIfPresent(String.self, forKey: .extractedText)
+        self.mdContent = try c.decodeIfPresent(String.self, forKey: .mdContent)
+        self.mdFrontmatter = try c.decodeIfPresent(JSONValue.self, forKey: .mdFrontmatter)
+        self.mdStatus = try c.decodeIfPresent(String.self, forKey: .mdStatus)
+        self.mdExtractionQuality = try c.decodeIfPresent(JSONValue.self, forKey: .mdExtractionQuality)
+        self.mdExtractionError = try c.decodeIfPresent(String.self, forKey: .mdExtractionError)
+        self.mdExtractionEngine = try c.decodeIfPresent(String.self, forKey: .mdExtractionEngine)
+        self.mdExtractionEngineVersion = try c.decodeIfPresent(String.self, forKey: .mdExtractionEngineVersion)
+        self.mdGeneratedAtRaw = try c.decodeIfPresent(String.self, forKey: .mdGeneratedAtRaw)
+    }
+}
+
+public struct DocumentListResponse: Codable, Sendable {
+    public let items: [DocumentResponse]
+    public let total: Int
+    public let page: Int
+    public let pageSize: Int
+
+    enum CodingKeys: String, CodingKey {
+        case items, total, page
+        case pageSize = "page_size"
+    }
+}
+
+public struct DocumentContentResponse: Codable, Sendable {
+    public let id: Int
+    public let title: String?
+    public let domain: String?
+    public let subGroup: String?
+    public let documentType: String?
+    public let aiSummary: String?
+    public let aiTags: [String]?
+    public let content: String?
+    public let contentLength: Int?
+    public let truncated: Bool?
+
+    enum CodingKeys: String, CodingKey {
+        case id, title, domain, content, truncated
+        case subGroup = "sub_group"
+        case documentType = "document_type"
+        case aiSummary = "ai_summary"
+        case aiTags = "ai_tags"
+        case contentLength = "content_length"
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Memo.swift b/clients/ds-app/Sources/DSKit/Models/Memo.swift
new file mode 100644
index 0000000..a0c7d62
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Memo.swift
@@ -0,0 +1,71 @@
+import Foundation
+
+public struct MemoResponse: Codable, Sendable, Identifiable {
+    public let id: Int
+    public let title: String?
+    public let content: String?
+    public let fileFormat: String?
+    public let fileType: String?
+    public let filePath: String?
+    public let userTags: [String]?
+    public let aiTags: [String]?
+    public let aiDomain: String?
+    public let aiSubGroup: String?
+    public let aiSummary: String?
+    public let pinned: Bool?
+    public let archived: Bool?
+    public let askIncludable: Bool?
+    public let memoTaskState: JSONValue?
+    public let aiEventKind: String?
+    public let aiEventConfidence: Double?
+    public let sourceChannel: String?
+    public let sourceMetadata: JSONValue?
+    public let createdAtRaw: String?
+    public let updatedAtRaw: String?
+
+    public var createdAt: Date? { DSDate.parse(createdAtRaw) }
+    public var updatedAt: Date? { DSDate.parse(updatedAtRaw) }
+    public var isPinned: Bool { pinned ?? false }
+    public var isArchived: Bool { archived ?? false }
+    public var isAudio: Bool { fileType == "audio" }
+
+    /// Checked task indices derived from memo_task_state keys (index-keyed object).
+    public var checkedTaskIndices: Set<Int> {
+        guard let o = memoTaskState?.objectValue else { return [] }
+        var s = Set<Int>()
+        for k in o.keys { if let i = Int(k) { s.insert(i) } }
+        return s
+    }
+
+    enum CodingKeys: String, CodingKey {
+        case id, title, content, pinned, archived
+        case fileFormat = "file_format"
+        case fileType = "file_type"
+        case filePath = "file_path"
+        case userTags = "user_tags"
+        case aiTags = "ai_tags"
+        case aiDomain = "ai_domain"
+        case aiSubGroup = "ai_sub_group"
+        case aiSummary = "ai_summary"
+        case askIncludable = "ask_includable"
+        case memoTaskState = "memo_task_state"
+        case aiEventKind = "ai_event_kind"
+        case aiEventConfidence = "ai_event_confidence"
+        case sourceChannel = "source_channel"
+        case sourceMetadata = "source_metadata"
+        case createdAtRaw = "created_at"
+        case updatedAtRaw = "updated_at"
+    }
+}
+
+public struct MemoListResponse: Codable, Sendable {
+    public let items: [MemoResponse]
+    public let total: Int
+    public let page: Int
+    public let pageSize: Int
+
+    enum CodingKeys: String, CodingKey {
+        case items, total, page
+        case pageSize = "page_size"
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Requests.swift b/clients/ds-app/Sources/DSKit/Models/Requests.swift
new file mode 100644
index 0000000..9798499
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Requests.swift
@@ -0,0 +1,61 @@
+import Foundation
+
+public enum SearchMode: String, Sendable, CaseIterable {
+    case text, vector, hybrid
+}
+
+public struct DocumentListQuery: Sendable {
+    public var page: Int = 1
+    public var pageSize: Int = 20
+    public var domain: String?
+    public var subGroup: String?
+    public var source: String?
+    public var format: String?
+    public var reviewStatus: String?
+    public var category: String?
+    public init() {}
+}
+
+public struct MemoListQuery: Sendable {
+    public var page: Int = 1
+    public var pageSize: Int = 20
+    public var pinned: Bool?
+    public var archived: Bool?
+    public init() {}
+}
+
+public struct DocumentUpdate: Codable, Sendable {
+    public var title: String?
+    public var userNote: String?
+    public var pinned: Bool?
+    public var reviewStatus: String?
+    public init(title: String? = nil, userNote: String? = nil, pinned: Bool? = nil, reviewStatus: String? = nil) {
+        self.title = title; self.userNote = userNote; self.pinned = pinned; self.reviewStatus = reviewStatus
+    }
+    enum CodingKeys: String, CodingKey {
+        case title, pinned
+        case userNote = "user_note"
+        case reviewStatus = "review_status"
+    }
+}
+
+public struct MemoCreate: Codable, Sendable {
+    public var content: String
+    public var title: String?
+    public var askIncludable: Bool?
+    public var sourceChannel: String?
+    public init(content: String, title: String? = nil, askIncludable: Bool? = nil, sourceChannel: String? = nil) {
+        self.content = content; self.title = title; self.askIncludable = askIncludable; self.sourceChannel = sourceChannel
+    }
+    enum CodingKeys: String, CodingKey {
+        case content, title
+        case askIncludable = "ask_includable"
+        case sourceChannel = "source_channel"
+    }
+}
+
+public struct MemoUpdate: Codable, Sendable {
+    public var content: String
+    public var title: String?
+    public init(content: String, title: String? = nil) { self.content = content; self.title = title }
+}
diff --git a/clients/ds-app/Sources/DSKit/Models/Search.swift b/clients/ds-app/Sources/DSKit/Models/Search.swift
new file mode 100644
index 0000000..09222ad
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Models/Search.swift
@@ -0,0 +1,103 @@
+import Foundation
+
+public struct SearchResult: Codable, Sendable, Identifiable {
+    public let id: Int            // doc_id
+    public let title: String?
+    public let aiDomain: String?
+    public let aiSummary: String?
+    public let fileFormat: String?
+    public let score: Double?
+    public let snippet: String?
+    public let matchReason: String?
+    public let chunkId: Int?
+    public let chunkIndex: Int?
+    public let sectionTitle: String?
+    public let rerankScore: Double?
+    public let freshnessDebug: JSONValue?
+
+    enum CodingKeys: String, CodingKey {
+        case id, title, score, snippet
+        case aiDomain = "ai_domain"
+        case aiSummary = "ai_summary"
+        case fileFormat = "file_format"
+        case matchReason = "match_reason"
+        case chunkId = "chunk_id"
+        case chunkIndex = "chunk_index"
+        case sectionTitle = "section_title"
+        case rerankScore = "rerank_score"
+        case freshnessDebug = "freshness_debug"
+    }
+}
+
+public struct SearchResponse: Codable, Sendable {
+    public let results: [SearchResult]
+    public let total: Int
+    public let query: String
+    public let mode: String
+    public let debug: JSONValue?
+}
+
+/// Ask-response citation. DISTINCT from S2's `AICitation` (Sources/AI) — different field sets;
+/// RemoteDSProvider maps this -> AICitation itself. Do not reuse the S2 type here.
+public struct Citation: Codable, Sendable, Identifiable {
+    public let n: Int
+    public let chunkId: Int?
+    public let docId: Int
+    public let title: String?
+    public let sectionTitle: String?
+    public let spanText: String
+    public let fullSnippet: String
+    public let relevance: Double
+    public let rerankScore: Double
+
+    public var id: Int { n }
+
+    enum CodingKeys: String, CodingKey {
+        case n, title, relevance
+        case chunkId = "chunk_id"
+        case docId = "doc_id"
+        case sectionTitle = "section_title"
+        case spanText = "span_text"
+        case fullSnippet = "full_snippet"
+        case rerankScore = "rerank_score"
+    }
+}
+
+public struct ConfirmedItem: Codable, Sendable {
+    public let aspect: String
+    public let text: String
+    public let citations: [Int]
+}
+
+public struct AskResponse: Codable, Sendable {
+    public let results: [SearchResult]
+    public let aiAnswer: String?
+    public let citations: [Citation]
+    public let synthesisStatus: String
+    public let synthesisMs: Double
+    public let confidence: String?
+    public let refused: Bool
+    public let noResultsReason: String?
+    public let query: String
+    public let total: Int
+    public let completeness: String
+    public let coveredAspects: [String]?
+    public let missingAspects: [String]?
+    public let confirmedItems: [ConfirmedItem]?
+    public let backendRequested: String?
+    public let backendUsed: String?
+    public let debug: JSONValue?
+
+    enum CodingKeys: String, CodingKey {
+        case results, citations, confidence, refused, query, total, completeness, debug
+        case aiAnswer = "ai_answer"
+        case synthesisStatus = "synthesis_status"
+        case synthesisMs = "synthesis_ms"
+        case noResultsReason = "no_results_reason"
+        case coveredAspects = "covered_aspects"
+        case missingAspects = "missing_aspects"
+        case confirmedItems = "confirmed_items"
+        case backendRequested = "backend_requested"
+        case backendUsed = "backend_used"
+    }
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/ask.json b/clients/ds-app/Sources/DSKit/Resources/ask.json
new file mode 100644
index 0000000..a650751
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/ask.json
@@ -0,0 +1,47 @@
+{
+  "results": [
+    {
+      "id": 4912,
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "ai_domain": "Engineering",
+      "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+      "file_format": "pdf",
+      "score": 0.8714,
+      "snippet": "...UCS-66 면제 곡선과 MDMT 적용...",
+      "match_reason": "vector+rerank",
+      "chunk_id": 88213,
+      "chunk_index": 3,
+      "section_title": "2. UCS-66 면제 곡선",
+      "rerank_score": 0.913,
+      "freshness_debug": null
+    }
+  ],
+  "ai_answer": "충격시험 면제는 UCS-66 면제 곡선으로 판정합니다 [1]. 재료군(Curve A~D)과 거버닝 두께에 따라 최소설계금속온도(MDMT)에서 면제 여부가 정해지며, 설계 응력비가 낮으면 UCS-66.1에 따라 MDMT를 추가로 낮출 수 있습니다 [1].",
+  "citations": [
+    {
+      "n": 1,
+      "chunk_id": 88213,
+      "doc_id": 4912,
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "section_title": "2. UCS-66 면제 곡선",
+      "span_text": "재료군(Curve A~D)과 거버닝 두께에 따라 최소설계금속온도(MDMT)에서의 충격시험 면제 여부를 결정한다.",
+      "full_snippet": "재료군(Curve A~D)과 거버닝 두께에 따라 최소설계금속온도(MDMT)에서의 충격시험 면제 여부를 결정한다. 설계 응력비가 낮으면 UCS-66.1에 따라 MDMT를 추가로 낮출 수 있다. 면제되지 않는 경우 UG-84에 따라 Charpy V-notch 시험을 수행한다.",
+      "relevance": 0.91,
+      "rerank_score": 0.913
+    }
+  ],
+  "synthesis_status": "completed",
+  "synthesis_ms": 2841.5,
+  "confidence": "high",
+  "refused": false,
+  "no_results_reason": null,
+  "query": "충격시험은 언제 면제되나",
+  "total": 1,
+  "completeness": "full",
+  "covered_aspects": ["면제 곡선", "MDMT 적용"],
+  "missing_aspects": null,
+  "confirmed_items": null,
+  "backend_requested": "mac-mini-default",
+  "backend_used": "gemma-macmini",
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diff --git a/clients/ds-app/Sources/DSKit/Resources/auth_login.json b/clients/ds-app/Sources/DSKit/Resources/auth_login.json
new file mode 100644
index 0000000..cea80a3
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/auth_login.json
@@ -0,0 +1,4 @@
+{
+  "access_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJoeXVuZ2kiLCJ0eXBlIjoiYWNjZXNzIiwiZXhwIjoxNzQ5MDAwMDAwfQ.FIXTURE_SIGNATURE_NOT_REAL",
+  "token_type": "bearer"
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/auth_me.json b/clients/ds-app/Sources/DSKit/Resources/auth_me.json
new file mode 100644
index 0000000..c92ea4f
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/auth_me.json
@@ -0,0 +1,7 @@
+{
+  "id": 1,
+  "username": "hyungi",
+  "is_active": true,
+  "totp_enabled": false,
+  "last_login_at": "2026-06-04T07:55:12.330Z"
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/digest.json b/clients/ds-app/Sources/DSKit/Resources/digest.json
new file mode 100644
index 0000000..3c78d0e
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/digest.json
@@ -0,0 +1,54 @@
+{
+  "digest_date": "2026-06-03",
+  "window_start": "2026-05-27T00:00:00.000Z",
+  "window_end": "2026-06-03T00:00:00.000Z",
+  "decay_lambda": 0.18,
+  "total_articles": 312,
+  "total_countries": 4,
+  "total_topics": 9,
+  "generation_ms": 18420,
+  "llm_calls": 11,
+  "llm_failures": 0,
+  "status": "completed",
+  "countries": [
+    {
+      "country": "KR",
+      "topics": [
+        {
+          "topic_rank": 1,
+          "topic_label": "산업안전 규제 개정",
+          "summary": "중대재해처벌법 후속 시행령 개정 논의가 이어지며 제조업 현장 점검이 강화되는 흐름.",
+          "article_ids": [880123, 880140, 880155],
+          "articles": [
+            { "id": 880123, "title": "고용부, 중대재해 시행령 개정안 입법예고" },
+            { "id": 880140, "title": "제조 현장 안전점검 확대" },
+            { "id": 880155, "title": "압력설비 검사 주기 단축 검토" }
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+        }
+      ]
+    },
+    {
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+      "topics": [
+        {
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+          "topic_label": "ASME 코드 업데이트",
+          "summary": "ASME BPVC 2025 에디션 관련 산업계 적용 사례와 해설 자료가 늘어남.",
+          "article_ids": [880301, 880322],
+          "articles": [
+            { "id": 880301, "title": "ASME BPVC 2025 adoption notes" },
+            { "id": 880322, "title": "Impact test exemption clarifications" }
+          ],
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diff --git a/clients/ds-app/Sources/DSKit/Resources/document_content.json b/clients/ds-app/Sources/DSKit/Resources/document_content.json
new file mode 100644
index 0000000..b5430c3
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/document_content.json
@@ -0,0 +1,12 @@
+{
+  "id": 4912,
+  "title": "ASME Section VIII Div 1 — Impact Test 요건",
+  "domain": "Engineering",
+  "sub_group": "압력용기",
+  "document_type": "standard",
+  "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+  "ai_tags": ["ASME", "Section VIII", "충격시험", "UCS-66"],
+  "content": "ASME Section VIII Division 1 Impact Test Requirements\nUCS-66 면제 곡선과 MDMT 적용 ... (최대 15000자) ...",
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+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/document_detail.json b/clients/ds-app/Sources/DSKit/Resources/document_detail.json
new file mode 100644
index 0000000..e285003
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/document_detail.json
@@ -0,0 +1,63 @@
+{
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+  "file_type": "document",
+  "title": "ASME Section VIII Div 1 — Impact Test 요건",
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+  "ai_tags": ["ASME", "Section VIII", "충격시험", "UCS-66"],
+  "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+  "document_type": "standard",
+  "importance": "high",
+  "ai_confidence": 0.93,
+  "user_note": "MDMT 판정 시 자주 참조",
+  "user_tags": ["자주봄"],
+  "pinned": true,
+  "ask_includable": true,
+  "derived_path": "Engineering/ASME/ASME_SecVIII_Div1_Impact_Test.md",
+  "original_format": "pdf",
+  "conversion_status": "completed",
+  "is_read": true,
+  "review_status": "approved",
+  "edit_url": null,
+  "preview_status": "ready",
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+  "facet_company": "ASME",
+  "facet_topic": "압력용기",
+  "facet_year": 2023,
+  "facet_doctype": "standard",
+  "category": "library",
+  "ai_suggestion": null,
+  "ai_tldr": "충격시험 면제 곡선(UCS-66)과 MDMT 적용.",
+  "ai_bullets": ["UCS-66 면제 곡선", "UCS-66.1 감액", "UG-84 시험 요건"],
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+  "ai_inconsistencies": [],
+  "ai_analysis_tier": "deep",
+  "extracted_at": "2026-05-22T05:00:11.000Z",
+  "ai_processed_at": "2026-05-22T05:04:40.000Z",
+  "embedded_at": "2026-05-22T05:06:02.000Z",
+  "created_at": "2026-05-22T04:59:50.000Z",
+  "updated_at": "2026-06-01T09:21:33.000Z",
+  "read_count": 11,
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+  "original_filename": "ASME_SecVIII_Div1_Impact_Test.pdf",
+  "duplicate_of": null,
+  "duplicate_count": 1,
+  "extracted_text": "ASME Section VIII Division 1 Impact Test Requirements\nUCS-66 ... (원문 추출 텍스트, 폴백용) ...",
+  "md_content": "# ASME Section VIII Div 1 — 충격시험 요건\n\n## 1. 범위\n탄소강 및 저합금강 압력용기 재료의 노치 인성(충격시험) 요구를 규정한다.\n\n## 2. UCS-66 면제 곡선\n재료군(Curve A~D)과 거버닝 두께에 따라 **최소설계금속온도(MDMT)** 에서의 충격시험 면제 여부를 결정한다.\n\n| 곡선 | 대표 재료 | 비고 |\n|---|---|---|\n| A | SA-516 (비정규화) | 가장 보수적 |\n| B | SA-516 정규화 | |\n| C | SA-537 | |\n| D | 인성 우수 재료 | 가장 관대 |\n\n## 3. UCS-66.1 감액\n설계 응력비(stress ratio)가 낮으면 MDMT 를 추가로 낮출 수 있다.\n\n## 4. UG-84 시험 요건\n면제되지 않는 경우 Charpy V-notch 시험으로 흡수에너지/측면팽창 기준을 만족해야 한다.\n",
+  "md_frontmatter": {
+    "title": "ASME Section VIII Div 1 — 충격시험 요건",
+    "domain": "Engineering",
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+  "md_extraction_engine": "marker",
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+  "md_generated_at": "2026-05-22T05:03:30.000Z"
+}
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new file mode 100644
index 0000000..f664d71
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/document_detail_pending_md.json
@@ -0,0 +1,59 @@
+{
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+  "file_type": "document",
+  "title": "02 왕복압축기 운전 매뉴얼",
+  "ai_domain": "General",
+  "ai_sub_group": "설비매뉴얼",
+  "ai_tags": ["왕복압축기", "운전", "매뉴얼"],
+  "ai_summary": "왕복동식 압축기 기동/정지/점검 절차 매뉴얼.",
+  "document_type": "manual",
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+  "ai_analysis_tier": "triage",
+  "extracted_at": "2026-06-03T01:20:00.000Z",
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+  "embedded_at": null,
+  "created_at": "2026-06-03T01:19:55.000Z",
+  "updated_at": "2026-06-03T01:22:14.000Z",
+  "read_count": 0,
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+  "original_filename": "02_왕복압축기_운전매뉴얼.docx",
+  "duplicate_of": null,
+  "duplicate_count": 0,
+  "extracted_text": "왕복압축기 운전 매뉴얼\n1. 기동 전 점검\n - 윤활유 레벨 확인\n - 흡입/토출 밸브 상태 확인\n2. 기동 절차 ...",
+  "md_content": null,
+  "md_frontmatter": null,
+  "md_status": "pending",
+  "md_extraction_quality": null,
+  "md_extraction_error": null,
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+}
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new file mode 100644
index 0000000..0095e2c
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/documents_duplicates.json
@@ -0,0 +1,18 @@
+{
+  "groups": [
+    {
+      "canonical_id": 4912,
+      "members": [4912, 4977],
+      "reason": "content_hash",
+      "detail": "동일 본문 해시 (md_content normalized SHA-256 일치)"
+    },
+    {
+      "canonical_id": 5120,
+      "members": [5120, 5121, 5260],
+      "reason": "near_duplicate",
+      "detail": "제목/본문 유사도 0.97 (cross-format: pdf + docx 동일 문서)"
+    }
+  ],
+  "total_groups": 2,
+  "total_duplicate_docs": 3
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diff --git a/clients/ds-app/Sources/DSKit/Resources/documents_list.json b/clients/ds-app/Sources/DSKit/Resources/documents_list.json
new file mode 100644
index 0000000..2b892f5
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/documents_list.json
@@ -0,0 +1,157 @@
+{
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+      "document_type": "procedure",
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+      "pinned": false,
+      "ask_includable": true,
+      "derived_path": "Engineering/기계가공/엘보_내경가공_절차서.md",
+      "original_format": "pdf",
+      "conversion_status": "completed",
+      "is_read": true,
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+      "facet_doctype": "procedure",
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+      "ai_tldr": "엘보 내경 가공 공차·순서 절차.",
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+  "total": 783,
+  "page": 1,
+  "page_size": 20
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/documents_stats.json b/clients/ds-app/Sources/DSKit/Resources/documents_stats.json
new file mode 100644
index 0000000..f4e8edc
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/documents_stats.json
@@ -0,0 +1,14 @@
+{
+  "total": 1163,
+  "documents": 783,
+  "by_domain": {
+    "Industrial_Safety": 426,
+    "Engineering": 351,
+    "General": 189,
+    "Programming": 60,
+    "법령": 23,
+    "Philosophy": 12
+  },
+  "review_pending": 725,
+  "pipeline_failed": 19
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/documents_tree.json b/clients/ds-app/Sources/DSKit/Resources/documents_tree.json
new file mode 100644
index 0000000..d2fe617
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/documents_tree.json
@@ -0,0 +1,16 @@
+[
+  { "name": "Industrial_Safety", "path": "Industrial_Safety", "count": 426,
+    "children": [
+      { "name": "위험성평가", "path": "Industrial_Safety/위험성평가", "count": 118, "children": [] },
+      { "name": "KGS", "path": "Industrial_Safety/KGS", "count": 73, "children": [] }
+    ] },
+  { "name": "Engineering", "path": "Engineering", "count": 351,
+    "children": [
+      { "name": "압력용기", "path": "Engineering/압력용기", "count": 96, "children": [] },
+      { "name": "기계가공", "path": "Engineering/기계가공", "count": 54, "children": [] }
+    ] },
+  { "name": "General", "path": "General", "count": 189, "children": [] },
+  { "name": "Programming", "path": "Programming", "count": 60, "children": [] },
+  { "name": "법령", "path": "법령", "count": 23, "children": [] },
+  { "name": "Philosophy", "path": "Philosophy", "count": 12, "children": [] }
+]
diff --git a/clients/ds-app/Sources/DSKit/Resources/memo_detail.json b/clients/ds-app/Sources/DSKit/Resources/memo_detail.json
new file mode 100644
index 0000000..0495a0e
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/memo_detail.json
@@ -0,0 +1,23 @@
+{
+  "id": 20238,
+  "title": "엘보 발주 확인 건",
+  "content": "엘보 내경가공 발주서 금요일까지 확인.\n- [ ] 도면 rev C 기준 공차 재확인\n- [ ] 발주처에 납기 회신",
+  "file_format": "txt",
+  "user_tags": ["업무"],
+  "ai_tags": ["발주", "엘보"],
+  "ai_domain": "General",
+  "ai_sub_group": "업무메모",
+  "ai_summary": "엘보 발주서 금요일까지 확인, 도면 rev C 공차 재확인.",
+  "pinned": true,
+  "archived": false,
+  "ask_includable": true,
+  "memo_task_state": { "0": { "checked_at": "2026-06-03T10:02:00.000Z" } },
+  "ai_event_kind": "task",
+  "ai_event_confidence": 0.78,
+  "source_channel": "memo",
+  "source_metadata": {},
+  "file_type": "note",
+  "file_path": null,
+  "created_at": "2026-06-03T09:40:00.000Z",
+  "updated_at": "2026-06-03T10:02:00.000Z"
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/memos_list.json b/clients/ds-app/Sources/DSKit/Resources/memos_list.json
new file mode 100644
index 0000000..53ea0ea
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/memos_list.json
@@ -0,0 +1,53 @@
+{
+  "items": [
+    {
+      "id": 20238,
+      "title": "엘보 발주 확인 건",
+      "content": "엘보 내경가공 발주서 금요일까지 확인. 도면 rev C 기준으로 공차 재확인 필요.",
+      "file_format": "txt",
+      "user_tags": ["업무"],
+      "ai_tags": ["발주", "엘보"],
+      "ai_domain": "General",
+      "ai_sub_group": "업무메모",
+      "ai_summary": "엘보 발주서 금요일까지 확인, 도면 rev C 공차 재확인.",
+      "pinned": true,
+      "archived": false,
+      "ask_includable": true,
+      "memo_task_state": { "0": { "checked_at": "2026-06-03T10:02:00.000Z" } },
+      "ai_event_kind": "task",
+      "ai_event_confidence": 0.78,
+      "source_channel": "memo",
+      "source_metadata": {},
+      "file_type": "note",
+      "file_path": null,
+      "created_at": "2026-06-03T09:40:00.000Z",
+      "updated_at": "2026-06-03T10:02:00.000Z"
+    },
+    {
+      "id": 20251,
+      "title": "음성 메모 — 현장 점검",
+      "content": "3공장 압축기 베어링 소음. 다음 점검 때 진동 측정 추가하기로.",
+      "file_format": "m4a",
+      "user_tags": null,
+      "ai_tags": ["현장", "압축기", "점검"],
+      "ai_domain": "Industrial_Safety",
+      "ai_sub_group": "현장메모",
+      "ai_summary": "3공장 압축기 베어링 소음, 진동 측정 추가 예정.",
+      "pinned": false,
+      "archived": false,
+      "ask_includable": true,
+      "memo_task_state": {},
+      "ai_event_kind": "note",
+      "ai_event_confidence": 0.64,
+      "source_channel": "voice",
+      "source_metadata": { "duration_s": 23, "device": "iPhone" },
+      "file_type": "audio",
+      "file_path": "memos/voice/2026/06/test-voice-memo.m4a",
+      "created_at": "2026-06-02T17:11:00.000Z",
+      "updated_at": "2026-06-02T17:11:40.000Z"
+    }
+  ],
+  "total": 4807,
+  "page": 1,
+  "page_size": 20
+}
diff --git a/clients/ds-app/Sources/DSKit/Resources/search.json b/clients/ds-app/Sources/DSKit/Resources/search.json
new file mode 100644
index 0000000..f17e72e
--- /dev/null
+++ b/clients/ds-app/Sources/DSKit/Resources/search.json
@@ -0,0 +1,38 @@
+{
+  "results": [
+    {
+      "id": 4912,
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "ai_domain": "Engineering",
+      "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+      "file_format": "pdf",
+      "score": 0.8714,
+      "snippet": "...UCS-66 면제 곡선과 MDMT 적용. 충격시험 면제 여부는 재료군과 두께로 결정...",
+      "match_reason": "vector+rerank",
+      "chunk_id": 88213,
+      "chunk_index": 3,
+      "section_title": "2. UCS-66 면제 곡선",
+      "rerank_score": 0.913,
+      "freshness_debug": null
+    },
+    {
+      "id": 5044,
+      "title": "KGS FU211 §2.5 — 가스설비 충격 관련 요건",
+      "ai_domain": "Industrial_Safety",
+      "ai_summary": "KGS FU211 가스 사용시설 기준 중 충격/내압 관련 조항.",
+      "file_format": "pdf",
+      "score": 0.7321,
+      "snippet": "...§2.5 충격에 의한 손상 방지... §2.8 내압 시험...",
+      "match_reason": "vector",
+      "chunk_id": 90122,
+      "chunk_index": 1,
+      "section_title": "2.5",
+      "rerank_score": 0.742,
+      "freshness_debug": null
+    }
+  ],
+  "total": 2,
+  "query": "충격시험 면제",
+  "mode": "hybrid",
+  "debug": null
+}
diff --git a/clients/ds-app/Tests/AITests/AIRouterSmokeTests.swift b/clients/ds-app/Tests/AITests/AIRouterSmokeTests.swift
new file mode 100644
index 0000000..a65f6da
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/AIRouterSmokeTests.swift
@@ -0,0 +1,84 @@
+import XCTest
+@testable import AIFabric
+
+/// S2-Fc — AI-ROUTING.md §3 스모크 매트릭스를 mock provider(라이브 net 0)로 검증.
+/// 정성 게이트(올바른 라우팅 시맨틱 + 정확한 에러 enum + 폴백 가시성). latency 는 기록만.
+final class AIRouterSmokeTests: XCTestCase {
+
+    private func askFixture() throws -> AskResponse {
+        try Fixture.decode(AskResponse.self, from: "ask.json")
+    }
+
+    /// 모든 태스크가 1순위 성공하는 정상 패브릭.
+    private func healthyRouter(log: @escaping @Sendable (String) -> Void = { _ in }) throws -> AIRouter {
+        AIRouter(providers: [
+            .onDevice: EchoProvider(id: .onDevice),
+            .localMLX: EchoProvider(id: .localMLX),
+            .remoteDS: RemoteDSProvider(client: MockDSAskClient(response: try askFixture())),
+            .specialized: SpecializedProvider(),   // 불가 scaffold
+        ], log: log)
+    }
+
+    func testQuickSummarizeToOnDevice() async throws {
+        let resp = try await healthyRouter().route(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .onDevice)
+        XCTAssertNil(resp.routingNote)
+    }
+
+    func testCorpusAskToRemoteDSWithCitations() async throws {
+        let resp = try await healthyRouter().route(AICompletionRequest(task: .corpusAsk, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .remoteDS)
+        XCTAssertEqual(resp.citations.count, 1)
+    }
+
+    func testClassifyToLocalMLX() async throws {
+        let resp = try await healthyRouter().route(AICompletionRequest(task: .classify, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertNil(resp.routingNote)
+    }
+
+    func testVisionSpecializedUnavailableFallsToOnDeviceVisibly() async throws {
+        let sink = LogSink()
+        let resp = try await healthyRouter(log: { sink.append($0) })
+            .route(AICompletionRequest(task: .vision, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .onDevice)
+        XCTAssertEqual(resp.routingNote, "fallback from specialized → onDevice")
+        XCTAssertTrue(sink.lines.contains { $0.contains("specialized") && $0.contains("unavailable") })
+    }
+
+    func testExplicitOnDeviceUnavailableErrorsNoFallback() async throws {
+        let router = AIRouter(providers: [
+            .onDevice: EchoProvider(id: .onDevice, available: false),
+            .localMLX: EchoProvider(id: .localMLX, available: true),
+        ])
+        do {
+            _ = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "p", explicitProvider: .onDevice))
+            XCTFail("explicit onDevice 불가 → 에러(자동 fallback X)")
+        } catch let AIRoutingError.explicitProviderUnavailable(id) {
+            XCTAssertEqual(id, .onDevice)
+        }
+    }
+
+    func testRuleFallbackOnDeviceDownToLocalMLXWithNote() async throws {
+        let router = AIRouter(providers: [
+            .onDevice: EchoProvider(id: .onDevice, available: false),
+            .localMLX: EchoProvider(id: .localMLX, available: true),
+        ])
+        let resp = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertEqual(resp.routingNote, "fallback from onDevice → localMLX")
+    }
+
+    func testAllUnavailableYieldsNoProviderAvailable() async throws {
+        let router = AIRouter(providers: [
+            .onDevice: EchoProvider(id: .onDevice, available: false),
+            .localMLX: EchoProvider(id: .localMLX, available: false),
+        ])
+        do {
+            _ = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+            XCTFail("전부 불가 → noProviderAvailable")
+        } catch let AIRoutingError.noProviderAvailable(task) {
+            XCTAssertEqual(task, .quickSummarize)
+        }
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/CompositionTests.swift b/clients/ds-app/Tests/AITests/CompositionTests.swift
new file mode 100644
index 0000000..12928a9
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/CompositionTests.swift
@@ -0,0 +1,66 @@
+import XCTest
+@testable import AIFabric
+
+/// S2-Fa(config 단일소스) + S2-Fb(컴포지션 루트) + S2-Fe(타임아웃/취소 전파).
+final class CompositionTests: XCTestCase {
+
+    // MARK: S2-Fa — 엔드포인트 단일소스 config
+
+    func testConfigDefaults() {
+        let c = AIProviderConfiguration.resolved(environment: [:])
+        XCTAssertEqual(c.localMLXBaseURL.absoluteString, "http://100.76.254.116:8890")
+        XCTAssertEqual(c.localMLXModel, "mac-mini-default")
+        XCTAssertEqual(c.dsBaseURL.absoluteString, "https://document.hyungi.net/api")
+        XCTAssertEqual(c.probeTimeout, 2)
+    }
+
+    func testConfigEnvOverride() {
+        let c = AIProviderConfiguration.resolved(environment: [
+            "AIFABRIC_LOCALMLX_URL": "http://127.0.0.1:9999",
+            "AIFABRIC_LOCALMLX_MODEL": "test-model",
+            "AIFABRIC_DS_URL": "http://100.110.63.63:8000/api",
+        ])
+        XCTAssertEqual(c.localMLXBaseURL.absoluteString, "http://127.0.0.1:9999")
+        XCTAssertEqual(c.localMLXModel, "test-model")
+        XCTAssertEqual(c.dsBaseURL.absoluteString, "http://100.110.63.63:8000/api")
+    }
+
+    // MARK: S2-Fb — 컴포지션 루트 (4 provider 전부 등록)
+
+    func testMakeDefaultRouterRegistersAllFour() async throws {
+        let client = MockDSAskClient(response: try Fixture.decode(AskResponse.self, from: "ask.json"))
+        let router = makeDefaultRouter(client: client, session: MockURLProtocol.session(), log: { _ in })
+        XCTAssertEqual(Set(router.providers.keys), Set(AIProviderID.allCases))
+        // corpusAsk 는 와이어링된 RemoteDS 로 흘러 citations 매핑.
+        let resp = try await router.route(AICompletionRequest(task: .corpusAsk, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .remoteDS)
+        XCTAssertEqual(resp.citations.count, 1)
+    }
+
+    func testMakeDefaultRouterVisionFallbackVisible() async throws {
+        let client = MockDSAskClient(response: try Fixture.decode(AskResponse.self, from: "ask.json"))
+        let sink = LogSink()
+        let router = makeDefaultRouter(client: client, session: MockURLProtocol.session(), log: { sink.append($0) })
+        // specialized scaffold(불가) → onDevice. (onDevice 가용 여부는 머신 의존 — 최소한 specialized 불가 log 는 떠야)
+        _ = try? await router.route(AICompletionRequest(task: .vision, prompt: "p"))
+        XCTAssertTrue(sink.lines.contains { $0.contains("specialized") && $0.contains("unavailable") },
+                      "specialized 불가가 침묵 아닌 log 로 가시화")
+    }
+
+    // MARK: S2-Fe — 취소 전파 (URLSession 경로 아날로그)
+
+    func testCancellationPropagatesThroughRouter() async throws {
+        let router = AIRouter(providers: [.localMLX: SleepingProvider(id: .localMLX)])
+        let task = Task {
+            try await router.route(AICompletionRequest(task: .classify, prompt: "p"))
+        }
+        try? await Task.sleep(nanoseconds: 100_000_000)
+        task.cancel()
+        do {
+            _ = try await task.value
+            XCTFail("취소된 생성은 CancellationError 전파")
+        } catch is CancellationError {
+            // 기대: URLSession async/Task.sleep 둘 다 취소 자동 honor. OnDevice respond() 도 협조적(S2-3a).
+        }
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/FixtureSupport.swift b/clients/ds-app/Tests/AITests/FixtureSupport.swift
new file mode 100644
index 0000000..6bae563
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/FixtureSupport.swift
@@ -0,0 +1,26 @@
+// FixtureSupport.swift — canonical fixture 로더 (contract/fixtures/ 를 #filePath 기준으로 직접 읽음).
+//
+// 픽스처는 repo 루트의 `contract/fixtures/` 에 단일 소유(S1 ask.json 등 + S2 가 추가하는
+// foundationmodels-respond / llm-router-chat). 테스트 타깃 안에 복제하면 드리프트가 생기므로
+// 복제 대신 #filePath 에서 repo 루트를 계산해 canonical 파일을 직접 로드한다.
+import Foundation
+
+enum Fixture {
+    /// repo 루트(.../ds-app-s2) — 이 파일은 <root>/Tests/AITests/FixtureSupport.swift.
+    static let repoRoot: URL = URL(fileURLWithPath: #filePath)
+        .deletingLastPathComponent()   // Tests/AITests
+        .deletingLastPathComponent()   // Tests
+        .deletingLastPathComponent()   // <root>
+
+    static func url(_ name: String) -> URL {
+        repoRoot.appendingPathComponent("contract/fixtures").appendingPathComponent(name)
+    }
+
+    static func data(_ name: String) throws -> Data {
+        try Data(contentsOf: url(name))
+    }
+
+    static func decode<T: Decodable>(_ type: T.Type, from name: String, using decoder: JSONDecoder = JSONDecoder()) throws -> T {
+        try decoder.decode(type, from: data(name))
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/HarnessSmokeTests.swift b/clients/ds-app/Tests/AITests/HarnessSmokeTests.swift
new file mode 100644
index 0000000..d592970
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/HarnessSmokeTests.swift
@@ -0,0 +1,18 @@
+import XCTest
+@testable import AIFabric
+
+/// Phase 0 하니스 스모크 — Sources/AI 단독 빌드/테스트가 도는지, 동결 타입이 보이는지만 확인.
+final class HarnessSmokeTests: XCTestCase {
+
+    func testFrozenTypesVisible() {
+        // 동결 인터페이스 심볼이 AIFabric product 에서 보인다.
+        XCTAssertEqual(AIProviderID.allCases.count, 4)
+        XCTAssertEqual(AIRoutingPolicy.default.chain(for: .corpusAsk), [.remoteDS])
+    }
+
+    func testAskFixtureReadable() throws {
+        // canonical contract/fixtures/ask.json 이 로드된다 (FixtureSupport 경로 확인).
+        let data = try Fixture.data("ask.json")
+        XCTAssertGreaterThan(data.count, 0)
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/LocalMLXProviderTests.swift b/clients/ds-app/Tests/AITests/LocalMLXProviderTests.swift
new file mode 100644
index 0000000..d60a9ee
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/LocalMLXProviderTests.swift
@@ -0,0 +1,169 @@
+import XCTest
+@testable import AIFabric
+
+final class LocalMLXProviderTests: XCTestCase {
+
+    private let baseURL = URL(string: "http://100.76.254.116:8890")!
+
+    override func tearDown() {
+        MockURLProtocol.reset()
+        super.tearDown()
+    }
+
+    private func provider() -> LocalMLXProvider {
+        LocalMLXProvider(baseURL: baseURL, model: "mac-mini-default", session: MockURLProtocol.session())
+    }
+
+    // MARK: isAvailable probe (wake 미트리거)
+
+    func testProbeAvailable() async throws {
+        MockURLProtocol.handler = { req in
+            MockURLProtocol.ok(req.url!, json: Data(#"{"data":[{"id":"gemma-macmini"}]}"#.utf8))
+        }
+        let available = await provider().isAvailable
+        XCTAssertTrue(available)
+        // probe 는 GET /v1/models
+        XCTAssertEqual(MockURLProtocol.recorder.lastURL?.path, "/v1/models")
+        XCTAssertEqual(MockURLProtocol.recorder.lastMethod, "GET")
+    }
+
+    func testProbeUnavailableOnError() async throws {
+        MockURLProtocol.handler = { _ in throw URLError(.cannotConnectToHost) }
+        let available = await provider().isAvailable
+        XCTAssertFalse(available)   // 연결오류 → false(throw 아님)
+    }
+
+    func testProbeUnavailableOn500() async throws {
+        MockURLProtocol.handler = { req in MockURLProtocol.status(req.url!, 500) }
+        let available = await provider().isAvailable
+        XCTAssertFalse(available)
+    }
+
+    // MARK: complete — 응답 매핑 + 요청 call-shape 락
+
+    func testCompleteMapsResponseFixture() async throws {
+        let body = try Fixture.data("llm-router-chat.response.json")
+        MockURLProtocol.handler = { req in MockURLProtocol.ok(req.url!, json: body) }
+
+        let resp = try await provider().complete(
+            AICompletionRequest(task: .quickSummarize, prompt: "충격시험 면제 기준을 한 문장으로 요약해줘.",
+                                systemPrompt: "You are a concise technical assistant.", maxTokens: 512)
+        )
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertEqual(resp.finishReason, .completed)
+        XCTAssertTrue(resp.citations.isEmpty)
+        XCTAssertNotNil(resp.latencyMs)
+        XCTAssertTrue(resp.text.contains("면제"))   // 실측 응답 본문
+    }
+
+    func testCompleteRequestCallShape() async throws {
+        let body = try Fixture.data("llm-router-chat.response.json")
+        MockURLProtocol.handler = { req in MockURLProtocol.ok(req.url!, json: body) }
+
+        _ = try await provider().complete(
+            AICompletionRequest(task: .quickSummarize, prompt: "PROMPT_X",
+                                systemPrompt: "SYS_Y", maxTokens: 512)
+        )
+        // POST /v1/chat/completions
+        XCTAssertEqual(MockURLProtocol.recorder.lastURL?.path, "/v1/chat/completions")
+        XCTAssertEqual(MockURLProtocol.recorder.lastMethod, "POST")
+
+        // messages system/user 분리 call-shape (load-bearing)
+        let sent = try XCTUnwrap(MockURLProtocol.recorder.lastBody)
+        let decoded = try JSONDecoder().decode(SentRequest.self, from: sent)
+        XCTAssertEqual(decoded.model, "mac-mini-default")
+        XCTAssertEqual(decoded.maxTokens, 512)
+        XCTAssertEqual(decoded.stream, false)
+        XCTAssertEqual(decoded.messages.count, 2)
+        XCTAssertEqual(decoded.messages[0].role, "system")
+        XCTAssertEqual(decoded.messages[0].content, "SYS_Y")
+        XCTAssertEqual(decoded.messages[1].role, "user")
+        XCTAssertEqual(decoded.messages[1].content, "PROMPT_X")
+    }
+
+    func testNilSystemPromptSendsEmptySystemMessage() async throws {
+        let body = try Fixture.data("llm-router-chat.response.json")
+        MockURLProtocol.handler = { req in MockURLProtocol.ok(req.url!, json: body) }
+        _ = try await provider().complete(AICompletionRequest(task: .quickSummarize, prompt: "P"))
+        let sent = try XCTUnwrap(MockURLProtocol.recorder.lastBody)
+        let decoded = try JSONDecoder().decode(SentRequest.self, from: sent)
+        XCTAssertEqual(decoded.messages[0].role, "system")
+        XCTAssertEqual(decoded.messages[0].content, "")   // plan S2-2c: systemPrompt ?? ""
+    }
+
+    func testNon200BackendError() async throws {
+        MockURLProtocol.handler = { req in MockURLProtocol.status(req.url!, 503, body: "model loading") }
+        do {
+            _ = try await provider().complete(AICompletionRequest(task: .quickSummarize, prompt: "P"))
+            XCTFail("non-200 must throw backendError, not silent empty text")
+        } catch let AIProviderError.backendError(id, status, reason) {
+            XCTAssertEqual(id, .localMLX)
+            XCTAssertEqual(status, 503)
+            XCTAssertEqual(reason, "model loading")
+        }
+    }
+
+    func testRequestFixtureMatchesEncoder() throws {
+        // 동결 request fixture 의 call-shape 가 encodeRequest 산출과 일치(템플릿 placeholder 회귀 방지).
+        let fixtureData = try Fixture.data("llm-router-chat.request.json")
+        let fixture = try JSONDecoder().decode(SentRequest.self, from: fixtureData)
+        XCTAssertEqual(fixture.messages.count, 2)
+        XCTAssertEqual(fixture.messages[0].role, "system")
+        XCTAssertEqual(fixture.messages[1].role, "user")
+        XCTAssertEqual(fixture.stream, false)
+    }
+
+    // MARK: rule-fallback 라우팅 (S2-2d) — onDevice 불가 → localMLX
+
+    func testFallbackFromOnDeviceToLocalMLX() async throws {
+        let body = try Fixture.data("llm-router-chat.response.json")
+        MockURLProtocol.handler = { req in MockURLProtocol.ok(req.url!, json: body) }
+        let router = AIRouter(providers: [
+            .onDevice: MockAIProvider(id: .onDevice, available: false),   // 불가
+            .localMLX: provider(),
+        ])
+        let resp = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "P"))
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertEqual(resp.routingNote, "fallback from onDevice → localMLX")
+    }
+
+    func testNoFallbackNoteOnFirstChoiceSuccess() async throws {
+        let body = try Fixture.data("llm-router-chat.response.json")
+        MockURLProtocol.handler = { req in MockURLProtocol.ok(req.url!, json: body) }
+        // classify 체인 = [.localMLX, .remoteDS, .onDevice] → 1순위 localMLX 성공 → note nil
+        let router = AIRouter(providers: [.localMLX: provider()])
+        let resp = try await router.route(AICompletionRequest(task: .classify, prompt: "P"))
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertNil(resp.routingNote)
+    }
+
+    // MARK: 라이브 통합 (맥미니 llm-router :8890 — offline 시 skip)
+
+    func testLiveLocalMLXIfReachable() async throws {
+        let live = LocalMLXProvider(baseURL: URL(string: "http://100.76.254.116:8890")!)  // 실 URLSession, Tailscale
+        let reachable = await live.isAvailable
+        guard reachable else {
+            throw XCTSkip("llm-router :8890 도달 불가(맥미니 offline) — 라이브 테스트 skip")
+        }
+        let resp = try await live.complete(
+            AICompletionRequest(task: .quickSummarize,
+                                prompt: "엘보 내경 가공 핵심을 한 문장으로 요약해줘.",
+                                systemPrompt: "You are a concise technical assistant.",
+                                maxTokens: 200)
+        )
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertEqual(resp.finishReason, .completed)
+        XCTAssertFalse(resp.text.isEmpty, "라이브 응답은 비어있지 않아야")
+        XCTAssertNotNil(resp.latencyMs)
+    }
+
+    /// 나간 요청 디코딩용(테스트 전용 미러).
+    struct SentRequest: Decodable {
+        struct Message: Decodable { let role: String; let content: String }
+        let model: String
+        let messages: [Message]
+        let maxTokens: Int?
+        let stream: Bool
+        enum CodingKeys: String, CodingKey { case model, messages, stream; case maxTokens = "max_tokens" }
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/MockURLProtocol.swift b/clients/ds-app/Tests/AITests/MockURLProtocol.swift
new file mode 100644
index 0000000..7c3d08b
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/MockURLProtocol.swift
@@ -0,0 +1,86 @@
+import Foundation
+
+/// 테스트용 URLProtocol — URLSession 을 가로채 canned 응답/에러를 돌려주고, 나간 요청을 기록.
+/// 라이브 네트워크 0 으로 LocalMLX 의 probe/complete call-shape 를 검증.
+final class MockURLProtocol: URLProtocol {
+    /// (request) -> (response, body). throw 하면 URLSession 에러 경로.
+    nonisolated(unsafe) static var handler: (@Sendable (URLRequest) throws -> (HTTPURLResponse, Data))?
+    /// 마지막으로 가로챈 요청(body 포함) 기록.
+    nonisolated(unsafe) static var recorder = RequestRecorder()
+
+    static func reset() {
+        handler = nil
+        recorder = RequestRecorder()
+    }
+
+    override class func canInit(with request: URLRequest) -> Bool { true }
+    override class func canonicalRequest(for request: URLRequest) -> URLRequest { request }
+
+    override func startLoading() {
+        Self.recorder.record(request)
+        guard let handler = Self.handler else {
+            client?.urlProtocol(self, didFailWithError: URLError(.unsupportedURL))
+            return
+        }
+        do {
+            let (response, data) = try handler(request)
+            client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
+            client?.urlProtocol(self, didLoad: data)
+            client?.urlProtocolDidFinishLoading(self)
+        } catch {
+            client?.urlProtocol(self, didFailWithError: error)
+        }
+    }
+
+    override func stopLoading() {}
+
+    // MARK: helpers
+
+    static func session() -> URLSession {
+        let config = URLSessionConfiguration.ephemeral
+        config.protocolClasses = [MockURLProtocol.self]
+        return URLSession(configuration: config)
+    }
+
+    static func ok(_ url: URL, json: Data) -> (HTTPURLResponse, Data) {
+        (HTTPURLResponse(url: url, statusCode: 200, httpVersion: nil, headerFields: nil)!, json)
+    }
+
+    static func status(_ url: URL, _ code: Int, body: String = "") -> (HTTPURLResponse, Data) {
+        (HTTPURLResponse(url: url, statusCode: code, httpVersion: nil, headerFields: nil)!, Data(body.utf8))
+    }
+}
+
+/// 나간 요청 기록(body 는 httpBody 또는 httpBodyStream 에서 추출 — URLProtocol 은 보통 stream 으로 전달).
+final class RequestRecorder: @unchecked Sendable {
+    private(set) var lastURL: URL?
+    private(set) var lastMethod: String?
+    private(set) var lastBody: Data?
+    private(set) var callCount = 0
+
+    func record(_ request: URLRequest) {
+        callCount += 1
+        lastURL = request.url
+        lastMethod = request.httpMethod
+        lastBody = request.bodyData
+    }
+}
+
+extension URLRequest {
+    /// URLProtocol 단계에서 body 추출 — httpBody 가 nil 이면 httpBodyStream 에서 읽음.
+    var bodyData: Data? {
+        if let httpBody { return httpBody }
+        guard let stream = httpBodyStream else { return nil }
+        stream.open()
+        defer { stream.close() }
+        var data = Data()
+        let bufSize = 8192
+        var buffer = [UInt8](repeating: 0, count: bufSize)
+        while stream.hasBytesAvailable {
+            let read = stream.read(&buffer, maxLength: bufSize)
+            if read <= 0 { break }
+            data.append(buffer, count: read)
+        }
+        return data
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/OnDeviceProviderTests.swift b/clients/ds-app/Tests/AITests/OnDeviceProviderTests.swift
new file mode 100644
index 0000000..88676ce
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/OnDeviceProviderTests.swift
@@ -0,0 +1,201 @@
+import XCTest
+@testable import AIFabric
+#if canImport(FoundationModels)
+import FoundationModels
+#endif
+
+/// HW 비의존 mock backend — availability + generate 결과를 주입.
+struct MockOnDeviceBackend: OnDeviceModelBackend {
+    let avail: OnDeviceAvailability
+    let outcome: Result<String, OnDeviceGenerationError>
+
+    init(avail: OnDeviceAvailability = .available,
+         outcome: Result<String, OnDeviceGenerationError> = .success("on-device ok")) {
+        self.avail = avail
+        self.outcome = outcome
+    }
+    var availability: OnDeviceAvailability { avail }
+    func generate(prompt: String, systemPrompt: String?, maxTokens: Int?) async throws -> String {
+        switch outcome {
+        case .success(let s): return s
+        case .failure(let e): throw e
+        }
+    }
+}
+
+/// complete() 호출 횟수를 세는 provider — 무폴백 단언용.
+actor CountingProvider: AIProvider {
+    nonisolated let id: AIProviderID
+    let available: Bool
+    private(set) var completeCalls = 0
+
+    init(id: AIProviderID, available: Bool) {
+        self.id = id
+        self.available = available
+    }
+    var isAvailable: Bool { get async { available } }
+    func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        completeCalls += 1
+        return AICompletionResponse(text: "should-not-be-called", providerUsed: id)
+    }
+}
+
+final class LogSink: @unchecked Sendable {
+    private let lock = NSLock()
+    private var storage: [String] = []
+    func append(_ s: String) { lock.lock(); storage.append(s); lock.unlock() }
+    var lines: [String] { lock.lock(); defer { lock.unlock() }; return storage }
+}
+
+final class OnDeviceProviderTests: XCTestCase {
+
+    // MARK: 가용성 + happy path (주입 backend)
+
+    func testAvailableReturnsText() async throws {
+        let p = OnDeviceProvider(backend: MockOnDeviceBackend(avail: .available, outcome: .success("요약 결과")))
+        let available = await p.isAvailable
+        XCTAssertTrue(available)
+        let resp = try await p.complete(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .onDevice)
+        XCTAssertEqual(resp.finishReason, .completed)
+        XCTAssertEqual(resp.text, "요약 결과")
+        XCTAssertNotNil(resp.latencyMs)
+    }
+
+    func testUnavailableReportsFalse() async throws {
+        let p = OnDeviceProvider(backend: MockOnDeviceBackend(avail: .unavailable(reason: "appleIntelligenceNotEnabled")))
+        let available = await p.isAvailable
+        XCTAssertFalse(available)
+    }
+
+    // MARK: GenerationError 매핑 (S2-3c)
+
+    func testGuardrailAndRefusalReturnRefused() async throws {
+        for err in [OnDeviceGenerationError.guardrailViolation, .refusal] {
+            let p = OnDeviceProvider(backend: MockOnDeviceBackend(outcome: .failure(err)))
+            let resp = try await p.complete(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+            XCTAssertEqual(resp.finishReason, .refused, "\(err) → .refused (답변의 일종, 폴백 X)")
+            XCTAssertEqual(resp.providerUsed, .onDevice)
+        }
+    }
+
+    func testRateLimitedThrowsUnavailableAndLoudLogs() async throws {
+        let sink = LogSink()
+        let p = OnDeviceProvider(backend: MockOnDeviceBackend(outcome: .failure(.rateLimited)),
+                                 log: { sink.append($0) })
+        do {
+            _ = try await p.complete(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+            XCTFail("rateLimited → throw unavailable")
+        } catch let AIProviderError.unavailable(id) {
+            XCTAssertEqual(id, .onDevice)
+        }
+        XCTAssertTrue(sink.lines.contains { $0.contains("rateLimited") }, "stateless 위반은 loud log")
+    }
+
+    func testConcurrentRequestsThrowsUnavailableAndLoudLogs() async throws {
+        let sink = LogSink()
+        let p = OnDeviceProvider(backend: MockOnDeviceBackend(outcome: .failure(.concurrentRequests)),
+                                 log: { sink.append($0) })
+        do {
+            _ = try await p.complete(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+            XCTFail("concurrentRequests → throw unavailable")
+        } catch let AIProviderError.unavailable(id) {
+            XCTAssertEqual(id, .onDevice)
+        }
+        XCTAssertTrue(sink.lines.contains { $0.contains("concurrentRequests") })
+    }
+
+    func testContextOverflowThrowsUnavailable() async throws {
+        let p = OnDeviceProvider(backend: MockOnDeviceBackend(outcome: .failure(.exceededContextWindowSize)))
+        do {
+            _ = try await p.complete(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+            XCTFail("exceededContextWindowSize → throw unavailable (폴백 유도)")
+        } catch let AIProviderError.unavailable(id) {
+            XCTAssertEqual(id, .onDevice)
+        }
+    }
+
+    // MARK: 라우팅 (S2-3d)
+
+    func testRouterFallsBackOnDeviceOverflowToLocalMLX() async throws {
+        let router = AIRouter(providers: [
+            .onDevice: OnDeviceProvider(backend: MockOnDeviceBackend(outcome: .failure(.exceededContextWindowSize))),
+            .localMLX: MockAIProvider(id: .localMLX, available: true),
+        ])
+        let resp = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "p"))
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertEqual(resp.routingNote, "fallback from onDevice → localMLX")
+    }
+
+    func testExplicitOnDeviceUnavailableNoFallback() async throws {
+        let counting = CountingProvider(id: .localMLX, available: true)
+        let router = AIRouter(providers: [
+            .onDevice: OnDeviceProvider(backend: MockOnDeviceBackend(avail: .unavailable(reason: "deviceNotEligible"))),
+            .localMLX: counting,
+        ])
+        do {
+            _ = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "p", explicitProvider: .onDevice))
+            XCTFail("explicit onDevice unavailable → explicitProviderUnavailable, 자동 폴백 금지")
+        } catch let AIRoutingError.explicitProviderUnavailable(id) {
+            XCTAssertEqual(id, .onDevice)
+        }
+        let calls = await counting.completeCalls
+        XCTAssertEqual(calls, 0, "명시 불가 시 타 provider complete() 호출 0")
+    }
+
+    // MARK: SDK GenerationError → 중립 매핑 lock (구성 가능한 케이스)
+
+    #if canImport(FoundationModels)
+    func testTranslateGenerationErrorCases() {
+        let ctx = LanguageModelSession.GenerationError.Context(debugDescription: "test")
+        XCTAssertEqual(FoundationModelsBackend.translate(.exceededContextWindowSize(ctx)), .exceededContextWindowSize)
+        XCTAssertEqual(FoundationModelsBackend.translate(.guardrailViolation(ctx)), .guardrailViolation)
+        XCTAssertEqual(FoundationModelsBackend.translate(.rateLimited(ctx)), .rateLimited)
+        XCTAssertEqual(FoundationModelsBackend.translate(.concurrentRequests(ctx)), .concurrentRequests)
+        XCTAssertEqual(FoundationModelsBackend.translate(.unsupportedLanguageOrLocale(ctx)), .unsupportedLanguageOrLocale)
+        XCTAssertEqual(FoundationModelsBackend.translate(.assetsUnavailable(ctx)), .assetsUnavailable)
+    }
+    #endif
+
+    // MARK: 라이브 통합 (M5 Max — 비-AI Mac 은 skip)
+
+    func testLiveOnDeviceIntegration() async throws {
+        let p = OnDeviceProvider()   // 라이브 FoundationModels backend
+        guard await p.isAvailable else {
+            throw XCTSkip("FoundationModels not available on this machine — live test skipped")
+        }
+        let resp = try await p.complete(
+            AICompletionRequest(task: .quickSummarize,
+                                prompt: "엘보 내경 가공의 핵심 관리 포인트를 한 문장으로 요약해줘.",
+                                maxTokens: 120)
+        )
+        XCTAssertEqual(resp.providerUsed, .onDevice)
+        XCTAssertEqual(resp.finishReason, .completed)
+        XCTAssertFalse(resp.text.isEmpty, "라이브 응답은 비어있지 않아야")
+    }
+
+    func testLiveCancellationCooperative() async throws {
+        let p = OnDeviceProvider()
+        guard await p.isAvailable else {
+            throw XCTSkip("FoundationModels not available — cancellation live test skipped")
+        }
+        let started = Date()
+        let task = Task { () -> AIFinishReason in
+            let r = try await p.complete(
+                AICompletionRequest(task: .quickSummarize,
+                                    prompt: "대한민국 압력용기 산업과 ASME 표준 채택 역사를 아주 길고 자세하게 여러 단락으로 서술해줘.",
+                                    maxTokens: 4000)
+            )
+            return r.finishReason
+        }
+        try? await Task.sleep(nanoseconds: 500_000_000)
+        task.cancel()
+        do {
+            _ = try await task.value
+            // 협조적이지 않으면 완주 — 정보로만(테스트 실패시키지 않음, 환경 의존).
+        } catch is CancellationError {
+            let elapsed = Date().timeIntervalSince(started)
+            XCTAssertLessThan(elapsed, 8.0, "협조적 취소면 빠르게 중단(S2-3a: ~33ms 후)")
+        }
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/RemoteDSProviderTests.swift b/clients/ds-app/Tests/AITests/RemoteDSProviderTests.swift
new file mode 100644
index 0000000..992a51c
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/RemoteDSProviderTests.swift
@@ -0,0 +1,151 @@
+import XCTest
+@testable import AIFabric
+
+/// 테스트용 DS client — ask.json 등 fixture 를 반환하거나 에러를 던지고, 받은 call-shape 를 기록.
+actor MockDSAskClient: DSAskClient {
+    let response: AskResponse?
+    let error: Error?
+    private(set) var lastBackend: String?
+    private(set) var lastQuery: String?
+    private(set) var callCount = 0
+
+    init(response: AskResponse? = nil, error: Error? = nil) {
+        self.response = response
+        self.error = error
+    }
+
+    func ask(query: String, backend: String) async throws -> AskResponse {
+        callCount += 1
+        lastBackend = backend
+        lastQuery = query
+        if let error { throw error }
+        return response!
+    }
+}
+
+final class RemoteDSProviderTests: XCTestCase {
+
+    private func askFixture() throws -> AskResponse {
+        try Fixture.decode(AskResponse.self, from: "ask.json")
+    }
+
+    // MARK: ask.json 디코딩 + 매핑 (call-shape 회귀)
+
+    func testAskJsonDecodeAndMap() throws {
+        let r = try askFixture()
+        XCTAssertEqual(r.synthesisStatus, "completed")
+        XCTAssertEqual(r.confidence, "high")
+        XCTAssertEqual(r.backendUsed, "gemma-macmini")
+        XCTAssertEqual(r.citations.count, 1)
+        XCTAssertEqual(r.citations[0].docId, 4912)
+        XCTAssertEqual(r.citations[0].n, 1)
+        XCTAssertEqual(r.citations[0].sectionTitle, "2. UCS-66 면제 곡선")
+
+        let mapped = RemoteDSProvider.map(r)
+        XCTAssertEqual(mapped.providerUsed, .remoteDS)
+        XCTAssertEqual(mapped.finishReason, .completed)
+        XCTAssertEqual(mapped.citations.count, 1)
+        XCTAssertEqual(mapped.citations[0].docId, 4912)
+        XCTAssertEqual(mapped.confidence, .high)
+        XCTAssertEqual(mapped.routingNote, "gemma-macmini")
+        XCTAssertEqual(mapped.latencyMs, 2841.5)
+        XCTAssertEqual(mapped.text, r.aiAnswer)
+    }
+
+    func testCompleteMapsFixture() async throws {
+        let mock = MockDSAskClient(response: try askFixture())
+        let provider = RemoteDSProvider(client: mock)
+        let resp = try await provider.complete(
+            AICompletionRequest(task: .corpusAsk, prompt: "충격시험은 언제 면제되나")
+        )
+        XCTAssertEqual(resp.providerUsed, .remoteDS)
+        XCTAssertEqual(resp.citations.count, 1)
+        XCTAssertEqual(resp.finishReason, .completed)
+        XCTAssertEqual(resp.routingNote, "gemma-macmini")
+    }
+
+    // MARK: backend exhaustive switch call-shape (쿼리 파라미터 락)
+
+    func testBackendCallShape_nilExplicit() async throws {
+        let mock = MockDSAskClient(response: try askFixture())
+        let provider = RemoteDSProvider(client: mock)
+        _ = try await provider.complete(AICompletionRequest(task: .corpusAsk, prompt: "q"))
+        let backend = await mock.lastBackend
+        XCTAssertEqual(backend, "mac-mini-default")   // 미지정 → DS 기본
+    }
+
+    func testBackendCallShape_localMLXExplicit() async throws {
+        let mock = MockDSAskClient(response: try askFixture())
+        let provider = RemoteDSProvider(client: mock)
+        _ = try await provider.complete(
+            AICompletionRequest(task: .corpusAsk, prompt: "q", explicitProvider: .localMLX)
+        )
+        let backend = await mock.lastBackend
+        XCTAssertEqual(backend, "gemma-macmini")
+    }
+
+    func testBackendMapPure() {
+        XCTAssertEqual(RemoteDSProvider.dsBackend(for: nil), "mac-mini-default")
+        XCTAssertEqual(RemoteDSProvider.dsBackend(for: .localMLX), "gemma-macmini")
+        XCTAssertEqual(RemoteDSProvider.dsBackend(for: .remoteDS), "mac-mini-default")
+        XCTAssertEqual(RemoteDSProvider.dsBackend(for: .onDevice), "mac-mini-default")
+        XCTAssertEqual(RemoteDSProvider.dsBackend(for: .specialized), "mac-mini-default")
+    }
+
+    func testNonCorpusTaskNotImplemented() async throws {
+        let mock = MockDSAskClient(response: try askFixture())
+        let provider = RemoteDSProvider(client: mock)
+        do {
+            _ = try await provider.complete(AICompletionRequest(task: .quickSummarize, prompt: "q"))
+            XCTFail("non-corpus task should not be served by RemoteDS")
+        } catch let AIProviderError.notImplemented(id) {
+            XCTAssertEqual(id, .remoteDS)
+        }
+    }
+
+    // MARK: 라우팅 — corpusAsk 무폴백 (오프라인에서도 정답)
+
+    func testCorpusAskRoutesToRemoteDSOnly() async throws {
+        let router = AIRouter(providers: [
+            .remoteDS: RemoteDSProvider(client: MockDSAskClient(response: try askFixture())),
+            .onDevice: MockAIProvider(id: .onDevice, available: true),   // available 이어도 corpusAsk 폴백 금지
+        ])
+        let resp = try await router.route(AICompletionRequest(task: .corpusAsk, prompt: "q"))
+        XCTAssertEqual(resp.providerUsed, .remoteDS)
+        XCTAssertEqual(resp.citations.count, 1)
+    }
+
+    func testCorpusAskRemoteDSDown_NoLocalFallback() async throws {
+        // remoteDS 불가 → 엉뚱한 온디바이스 코퍼스 답변 대신 명확한 실패(무폴백).
+        struct Net: Error {}
+        let router = AIRouter(providers: [
+            .remoteDS: RemoteDSProvider(client: MockDSAskClient(error: Net())),
+            .onDevice: MockAIProvider(id: .onDevice, available: true),
+        ])
+        do {
+            _ = try await router.route(AICompletionRequest(task: .corpusAsk, prompt: "q"))
+            XCTFail("corpusAsk must not fall back to onDevice")
+        } catch is Net {
+            // 기대: remoteDS 의 실패가 전파(코퍼스 체인 = [.remoteDS] only)
+        }
+    }
+
+    // MARK: S2-4b — cloud 'claude-cloud' = 명시 503 (로컬 대체 응답 금지)
+
+    func testCloud503Surfaces_NoSilentFallback() async throws {
+        let err = AIProviderError.backendError(.remoteDS, status: 503, reason: "cloud backend pending activation")
+        let router = AIRouter(providers: [
+            .remoteDS: RemoteDSProvider(client: MockDSAskClient(error: err)),
+            .onDevice: MockAIProvider(id: .onDevice, available: true),
+        ])
+        do {
+            _ = try await router.route(
+                AICompletionRequest(task: .corpusAsk, prompt: "q", explicitProvider: .remoteDS)
+            )
+            XCTFail("503 must surface, not fall back")
+        } catch let AIProviderError.backendError(id, status, _) {
+            XCTAssertEqual(id, .remoteDS)
+            XCTAssertEqual(status, 503)
+        }
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/SpecializedProviderTests.swift b/clients/ds-app/Tests/AITests/SpecializedProviderTests.swift
new file mode 100644
index 0000000..7809f53
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/SpecializedProviderTests.swift
@@ -0,0 +1,39 @@
+import XCTest
+@testable import AIFabric
+
+final class SpecializedProviderTests: XCTestCase {
+
+    func testScaffoldUnavailableAndNotImplemented() async throws {
+        let p = SpecializedProvider()
+        let available = await p.isAvailable
+        XCTAssertFalse(available)
+        do {
+            _ = try await p.complete(AICompletionRequest(task: .vision, prompt: "p"))
+            XCTFail("scaffold must throw notImplemented")
+        } catch let AIProviderError.notImplemented(id) {
+            XCTAssertEqual(id, .specialized)
+        }
+    }
+
+    /// .vision 체인 [.specialized, .onDevice] — specialized 등록·불가 → onDevice 로 **가시** 폴백(라우터 log).
+    /// (onDevice 는 providerUsed=id 를 정직히 반환하는 CountingProvider 사용 — MockAIProvider 는 vision 케이스에서
+    ///  providerUsed 를 .specialized 로 하드코딩하므로 부적합.)
+    func testVisionFallsBackToOnDeviceVisibly() async throws {
+        let sink = LogSink()
+        let onDevice = CountingProvider(id: .onDevice, available: true)
+        let router = AIRouter(
+            providers: [
+                .specialized: SpecializedProvider(),
+                .onDevice: onDevice,
+            ],
+            log: { sink.append($0) }
+        )
+        let resp = try await router.route(AICompletionRequest(task: .vision, prompt: "도면 보기"))
+        XCTAssertEqual(resp.providerUsed, .onDevice)
+        XCTAssertEqual(resp.routingNote, "fallback from specialized → onDevice")
+        let calls = await onDevice.completeCalls
+        XCTAssertEqual(calls, 1)
+        XCTAssertTrue(sink.lines.contains { $0.contains("specialized") && $0.contains("unavailable") },
+                      "specialized 불가가 침묵 아닌 log 로 가시화")
+    }
+}
diff --git a/clients/ds-app/Tests/AITests/TestProviders.swift b/clients/ds-app/Tests/AITests/TestProviders.swift
new file mode 100644
index 0000000..ae512bc
--- /dev/null
+++ b/clients/ds-app/Tests/AITests/TestProviders.swift
@@ -0,0 +1,28 @@
+import Foundation
+@testable import AIFabric
+
+/// providerUsed=id 를 정직히 반환하는 테스트 provider(MockAIProvider 는 일부 태스크에서 providerUsed 를 하드코딩).
+struct EchoProvider: AIProvider {
+    let id: AIProviderID
+    let available: Bool
+    init(id: AIProviderID, available: Bool = true) {
+        self.id = id
+        self.available = available
+    }
+    var isAvailable: Bool { get async { available } }
+    func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        AICompletionResponse(text: "echo:\(id.rawValue)", providerUsed: id)
+    }
+}
+
+/// 취소 전파 테스트용 — sleep 중 Task 취소 시 CancellationError(S2-Fe URLSession 경로 아날로그).
+struct SleepingProvider: AIProvider {
+    let id: AIProviderID
+    init(id: AIProviderID = .localMLX) { self.id = id }
+    var isAvailable: Bool { get async { true } }
+    func complete(_ request: AICompletionRequest) async throws -> AICompletionResponse {
+        try await Task.sleep(nanoseconds: 5_000_000_000)   // 취소되면 CancellationError throw
+        try Task.checkCancellation()
+        return AICompletionResponse(text: "done", providerUsed: id)
+    }
+}
diff --git a/clients/ds-app/Tests/DSKitTests/ClientPlumbingTests.swift b/clients/ds-app/Tests/DSKitTests/ClientPlumbingTests.swift
new file mode 100644
index 0000000..61693a6
--- /dev/null
+++ b/clients/ds-app/Tests/DSKitTests/ClientPlumbingTests.swift
@@ -0,0 +1,82 @@
+import XCTest
+@testable import DSKit
+
+/// Offline tests for the live-client plumbing (the live HTTP path itself needs a real backend, FU-A).
+final class ClientPlumbingTests: XCTestCase {
+
+    func testEndpointPathsAndMethods() {
+        XCTAssertEqual(DSEndpoint.documents(DocumentListQuery()).path, "documents/")
+        XCTAssertEqual(DSEndpoint.documents(DocumentListQuery()).method, "GET")
+        XCTAssertEqual(DSEndpoint.document(4912).path, "documents/4912")
+        XCTAssertEqual(DSEndpoint.documentTree.path, "documents/tree")
+        XCTAssertEqual(DSEndpoint.ask("q", nil, nil, nil).path, "search/ask")
+        XCTAssertEqual(DSEndpoint.pinMemo(5, true).method, "PATCH")
+        XCTAssertEqual(DSEndpoint.pinMemo(5, true).path, "memos/5/pin")
+        XCTAssertEqual(DSEndpoint.toggleMemoTask(5, 2, true).path, "memos/5/tasks/2")
+        XCTAssertEqual(DSEndpoint.putContent(7, "x").method, "PUT")
+        XCTAssertEqual(DSEndpoint.deleteMemo(9).method, "DELETE")
+    }
+
+    func testEndpointBearerRule() {
+        XCTAssertFalse(DSEndpoint.login("u", "p", nil).requiresBearer)
+        XCTAssertFalse(DSEndpoint.refresh.requiresBearer)
+        XCTAssertTrue(DSEndpoint.me.requiresBearer)
+        XCTAssertTrue(DSEndpoint.documents(DocumentListQuery()).requiresBearer)
+    }
+
+    func testEndpointQueryItems() {
+        let items = DSEndpoint.ask("충격시험", 5, "gemma-macmini", nil).queryItems
+        let dict = Dictionary(uniqueKeysWithValues: items.map { ($0.name, $0.value) })
+        XCTAssertEqual(dict["q"], "충격시험")
+        XCTAssertEqual(dict["backend"], "gemma-macmini")
+        XCTAssertEqual(dict["limit"], "5")
+        XCTAssertNil(dict["debug"]) // nil params are skipped, not sent as "nil"
+    }
+
+    func testEndpointBodies() throws {
+        let encoder = DSEncoder.make()
+        let pinBody = try DSEndpoint.pinMemo(5, true).httpBody(encoder)
+        XCTAssertEqual(String(data: pinBody ?? Data(), encoding: .utf8), #"{"pinned":true}"#)
+        let loginBody = try XCTUnwrap(DSEndpoint.login("hyungi", "pw", nil).httpBody(encoder))
+        let s = String(data: loginBody, encoding: .utf8) ?? ""
+        XCTAssertTrue(s.contains("\"username\":\"hyungi\""))
+        XCTAssertFalse(s.contains("totp_code")) // nil optional omitted
+        XCTAssertNil(try DSEndpoint.me.httpBody(encoder)) // GET has no body
+    }
+
+    /// Single-flight refresh: N concurrent refreshOnce() calls must fire the refresh closure exactly once.
+    func testSingleFlightRefresh() async throws {
+        let counter = CallCounter()
+        let provider = TokenProvider(persistence: InMemoryTokenStore()) {
+            try? await Task.sleep(nanoseconds: 50_000_000)
+            let n = await counter.inc()
+            return "token-\(n)"
+        }
+        let results = await withTaskGroup(of: String.self) { group -> [String] in
+            for _ in 0..<8 { group.addTask { (try? await provider.refreshOnce()) ?? "ERR" } }
+            var collected: [String] = []
+            for await value in group { collected.append(value) }
+            return collected
+        }
+        let calls = await counter.value
+        XCTAssertEqual(calls, 1, "refresh closure must run exactly once under concurrency")
+        XCTAssertTrue(results.allSatisfy { $0 == "token-1" })
+    }
+
+    func testTokenProviderCacheAndPersistence() async {
+        let store = InMemoryTokenStore()
+        let provider = TokenProvider(persistence: store) { "x" }
+        await provider.set("abc")
+        let current = await provider.current()
+        XCTAssertEqual(current, "abc")
+        XCTAssertEqual(store.read(), "abc")
+        await provider.clear()
+        let cleared = await provider.current()
+        XCTAssertNil(cleared)
+    }
+}
+
+actor CallCounter {
+    var value = 0
+    func inc() -> Int { value += 1; return value }
+}
diff --git a/clients/ds-app/Tests/DSKitTests/FixtureDecodeTests.swift b/clients/ds-app/Tests/DSKitTests/FixtureDecodeTests.swift
new file mode 100644
index 0000000..7bf0cee
--- /dev/null
+++ b/clients/ds-app/Tests/DSKitTests/FixtureDecodeTests.swift
@@ -0,0 +1,137 @@
+import XCTest
+@testable import DSKit
+
+/// The contract's "1차 수용 테스트": every fixture must decode through the app's models via the
+/// shared decoder, with representative VALUE assertions (no-throw alone would miss a silently-missing
+/// CodingKey). Driven through FixtureDSClient so it exercises client + decoder + models together.
+final class FixtureDecodeTests: XCTestCase {
+    let client = FixtureDSClient()
+
+    func testAuthLogin() async throws {
+        let r = try await client.login(username: "x", password: "y", totpCode: nil)
+        XCTAssertEqual(r.tokenType, "bearer")
+        XCTAssertFalse(r.accessToken.isEmpty)
+    }
+
+    func testAuthMe() async throws {
+        let u = try await client.me()
+        XCTAssertEqual(u.id, 1)
+        XCTAssertEqual(u.username, "hyungi")
+        XCTAssertNotNil(u.lastLoginAt) // fractional-seconds ISO parse
+    }
+
+    func testDocumentsList() async throws {
+        let r = try await client.documents(DocumentListQuery())
+        XCTAssertEqual(r.total, 783)
+        XCTAssertEqual(r.items.count, 3)
+        XCTAssertEqual(r.items[2].conversionStatus, "pending")
+        XCTAssertEqual(r.items[0].aiTags?.count, 4)
+        XCTAssertEqual(r.items[1].duplicateCount, 1)
+        XCTAssertEqual(r.items[0].fileFormat, "pdf")
+        XCTAssertEqual(r.items[0].reads, 3) // read_count fallback accessor
+    }
+
+    func testDocumentDetailCompleted() async throws {
+        let d = try await client.document(id: 4912)
+        XCTAssertEqual(d.mdStatus, "completed")
+        XCTAssertNotNil(d.mdContent)
+        XCTAssertTrue(d.mdIsRenderable)
+        XCTAssertEqual(d.mdExtractionQuality?["page_count"]?.intValue, 14)
+        XCTAssertEqual(d.base.aiInconsistencies?.isEmpty, true)
+        XCTAssertEqual(d.base.title, "ASME Section VIII Div 1 — Impact Test 요건")
+    }
+
+    func testDocumentDetailPending() async throws {
+        let d = try await client.document(id: 5301)
+        XCTAssertEqual(d.mdStatus, "pending")
+        XCTAssertNil(d.mdContent)
+        XCTAssertFalse(d.mdIsRenderable)
+        XCTAssertNotNil(d.extractedText)
+        XCTAssertNil(d.mdFrontmatter)
+    }
+
+    func testDocumentContent() async throws {
+        let c = try await client.documentContent(id: 4912)
+        XCTAssertEqual(c.contentLength, 8421)
+        XCTAssertEqual(c.truncated, false)
+    }
+
+    func testDocumentTree() async throws {
+        let t = try await client.documentTree()
+        XCTAssertEqual(t.count, 6)
+        XCTAssertEqual(t[0].kids.count, 2)
+        XCTAssertEqual(t[0].kids[0].name, "위험성평가")
+    }
+
+    func testStats() async throws {
+        let s = try await client.categoryCounts()
+        XCTAssertEqual(s.documents, 783)
+        XCTAssertEqual(s.byDomain["법령"], 23) // non-ASCII dict key
+    }
+
+    func testDuplicates() async throws {
+        let d = try await client.duplicates()
+        XCTAssertEqual(d.totalGroups, 2)
+        XCTAssertEqual(d.groups[1].members.count, 3)
+        XCTAssertEqual(d.groups[0].reason, "content_hash")
+    }
+
+    func testSearch() async throws {
+        let s = try await client.search(q: "충격시험", mode: .hybrid, page: 1, debug: false)
+        XCTAssertEqual(s.results.count, 2)
+        XCTAssertEqual(s.results[0].rerankScore, 0.913)
+        XCTAssertEqual(s.mode, "hybrid")
+    }
+
+    func testAsk() async throws {
+        let a = try await client.ask(q: "충격시험은 언제 면제되나", limit: nil, backend: nil, debug: false)
+        XCTAssertEqual(a.citations.count, 1)
+        XCTAssertEqual(a.confidence, "high")
+        XCTAssertNil(a.confirmedItems)
+        XCTAssertEqual(a.coveredAspects?.count, 2)
+        XCTAssertEqual(a.backendUsed, "gemma-macmini")
+    }
+
+    func testMemosList() async throws {
+        let m = try await client.memos(MemoListQuery())
+        XCTAssertEqual(m.total, 4807)
+        XCTAssertEqual(m.items[0].checkedTaskIndices, [0])
+        XCTAssertEqual(m.items[1].fileType, "audio")
+        XCTAssertTrue(m.items[1].isAudio)
+    }
+
+    func testMemoDetail() async throws {
+        let m = try await client.memo(id: 20238)
+        XCTAssertTrue(m.isPinned)
+        XCTAssertNotNil(m.memoTaskState?["0"]?["checked_at"]?.stringValue)
+    }
+
+    func testDigest() async throws {
+        let d = try await client.digest(date: nil, country: nil)
+        XCTAssertEqual(d.digestDateDisplay, "2026-06-03") // date-only raw display
+        XCTAssertNotNil(d.windowStart)                    // fractional ISO parse
+        XCTAssertEqual(d.countries.count, 2)
+        XCTAssertEqual(d.countries[0].topics[0].articles.count, 3)
+    }
+
+    /// JSONValue numeric robustness (B-1 review): whole-valued floats and integers must read correctly
+    /// through the cross-converting accessors regardless of int/double storage.
+    func testJSONValueNumberTrap() throws {
+        let data = Data(#"{"a": 1.0, "b": 0.97, "c": 23, "d": true}"#.utf8)
+        let v = try DSDecoder.make().decode(JSONValue.self, from: data)
+        XCTAssertEqual(v["a"]?.doubleValue, 1.0)
+        XCTAssertEqual(v["b"]?.doubleValue, 0.97)
+        XCTAssertEqual(v["c"]?.intValue, 23)
+        XCTAssertEqual(v["d"]?.boolValue, true)
+    }
+
+    /// Light round-trip encode (call-shape regression guard): decode -> encode -> decode, compare values.
+    func testAskRoundTrip() async throws {
+        let a = try await client.ask(q: "q", limit: nil, backend: nil, debug: false)
+        let data = try DSEncoder.make().encode(a)
+        let a2 = try DSDecoder.make().decode(AskResponse.self, from: data)
+        XCTAssertEqual(a2.citations.count, a.citations.count)
+        XCTAssertEqual(a2.backendUsed, a.backendUsed)
+        XCTAssertEqual(a2.confidence, a.confidence)
+    }
+}
diff --git a/clients/ds-app/Tests/DSKitTests/RouterFallbackTests.swift b/clients/ds-app/Tests/DSKitTests/RouterFallbackTests.swift
new file mode 100644
index 0000000..97a5390
--- /dev/null
+++ b/clients/ds-app/Tests/DSKitTests/RouterFallbackTests.swift
@@ -0,0 +1,42 @@
+import XCTest
+import AIFabric
+
+/// Gate 4 (AI flow): proves the S2 AIRouter produces a VISIBLE routingNote on a rule-based fallback,
+/// and that an explicit-provider-unavailable pick throws (no silent fallback). Sources/AI is consumed
+/// read-only; these tests never modify it.
+final class RouterFallbackTests: XCTestCase {
+
+    func testRuleFallbackIsVisible() async throws {
+        let router = AIRouter(providers: [
+            .onDevice: MockAIProvider(id: .onDevice, available: false),
+            .localMLX: MockAIProvider(id: .localMLX, available: true),
+        ])
+        let resp = try await router.route(AICompletionRequest(task: .quickSummarize, prompt: "x"))
+        XCTAssertEqual(resp.providerUsed, .localMLX)
+        XCTAssertEqual(resp.routingNote, "fallback from onDevice → localMLX")
+    }
+
+    func testExplicitUnavailableThrowsNoFallback() async throws {
+        let router = AIRouter(providers: [
+            .onDevice: MockAIProvider(id: .onDevice, available: false),
+            .localMLX: MockAIProvider(id: .localMLX, available: true),
+        ])
+        do {
+            _ = try await router.route(
+                AICompletionRequest(task: .quickSummarize, prompt: "x", explicitProvider: .onDevice)
+            )
+            XCTFail("expected explicitProviderUnavailable")
+        } catch let error as AIRoutingError {
+            guard case .explicitProviderUnavailable = error else {
+                return XCTFail("wrong error: \(error)")
+            }
+        }
+    }
+
+    func testCorpusAskRoutesRemoteWithCitation() async throws {
+        let router = AIRouter(providers: [.remoteDS: MockAIProvider(id: .remoteDS)])
+        let resp = try await router.route(AICompletionRequest(task: .corpusAsk, prompt: "q"))
+        XCTAssertEqual(resp.providerUsed, .remoteDS)
+        XCTAssertEqual(resp.citations.count, 1)
+    }
+}
diff --git a/clients/ds-app/contract/AI-ROUTING.md b/clients/ds-app/contract/AI-ROUTING.md
new file mode 100644
index 0000000..60eb551
--- /dev/null
+++ b/clients/ds-app/contract/AI-ROUTING.md
@@ -0,0 +1,67 @@
+# DS App AI 라우팅 계약 (S2 인터페이스 동결) — v0.1
+
+S1(데이터 fixture)이 앱의 **데이터 모양**을 동결했듯, 이 문서 + `Sources/AI/`는 앱의 **AI 호출 모양**을 동결한다.
+S3 는 `AIProvider` 프로토콜 + `MockAIProvider` 로 AI 흐름을 끝까지 그리고, S2 가 실 provider 를 뒤에서 채운다.
+
+- **Frozen**: 2026-06-04 · **typecheck PASS** (swift 6 strict concurrency) · **router 스모크 PASS**
+- **위치**: `Sources/AI/{AIProvider,AIRouter,MockAIProvider}.swift` + `Sources/AI/Providers/*.swift`
+- **파일 경계**: 이 `AI/` 디렉토리 = **S2 소유**(앱 나머지 = S3). 같은 Xcode repo 디렉토리 단위 분담 → 충돌 0.
+
+## 1. Provider 티어 (= 디바이스 역할 표와 1:1)
+
+| `AIProviderID` | 노드 | 용도 | 구현 경로 |
+|---|---|---|---|
+| `.onDevice` | 맥북·아이폰 | 즉답·오프라인·프라이버시 | Apple **FoundationModels** (`SystemLanguageModel`/`LanguageModelSession`) |
+| `.localMLX` | 맥미니 허브 | 무거운 로컬 생성 | Gemma 4 26B — llm-router `:8890` / MLX `:8801` (OpenAI 호환) |
+| `.remoteDS` | GPU(원격) | **코퍼스 RAG** | `GET /search/ask?backend=` (CONTRACT.md §4) |
+| `.specialized` | GPU | rerank·embed·**vision**·OCR | 특화 모델 통로(온디맨드) |
+
+## 2. 태스크 → 티어 정책 (`AIRoutingPolicy.default`)
+
+| `AITask` | 선호 체인 | 근거 |
+|---|---|---|
+| `quickSummarize` | onDevice → localMLX | 빠르고 사적 |
+| `memoAssist` | onDevice → localMLX | 짧은 보조 |
+| `askSelection` | onDevice → localMLX → remoteDS | 로컬 컨텍스트, 부족 시 승급 |
+| `corpusAsk` | **remoteDS only** | 코퍼스 필요 — 온디바이스로 폴백 불가 |
+| `classify` | localMLX → remoteDS → onDevice | 분류 품질 우선 |
+| `vision` | specialized → onDevice | GPU VLM 우선 |
+
+## 3. 3단 fallback 규칙 (feedback_task_routing_hybrid + no_silent_fallback)
+
+1. **explicit > rule > error.**
+2. **명시 opt-in**(`request.explicitProvider`) → 그 provider 만. 불가 시 **에러**(`explicitProviderUnavailable`) — 자동 다른 티어 호출 **금지**.
+3. **미지정** → 태스크 선호 체인 순회. 불가/실패는 다음으로 넘기되 **`routingNote`로 가시화**(silent skip 금지) + `log` 훅.
+4. 전부 불가 → `noProviderAvailable`.
+
+스모크 검증:
+```
+quickSummarize → onDevice         corpusAsk → remoteDS (citations=1)
+vision → specialized              classify → localMLX
+explicit onDevice 불가 → 에러(자동 fallback X)
+rule fallback: onDevice 불가 → localMLX  note="fallback from onDevice → localMLX"
+```
+
+## 4. S1 계약과의 다리 (`RemoteDSProvider`)
+
+`corpusAsk` 만 `.remoteDS` 책임. 매핑(고정):
+```
+GET /search/ask?q=<prompt>&backend=<map(explicitProvider)>   → AskResponse (CONTRACT.md §4)
+AskResponse.ai_answer            → AICompletionResponse.text
+AskResponse.citations[]          → AICitation[]  (n, doc_id, title, section_title, span_text)
+AskResponse.synthesis_status     → AIFinishReason  (completed/timeout/no_evidence/backend_unavailable/…)
+AskResponse.confidence           → AIConfidence
+AskResponse.backend_used         → routingNote (어느 LLM 이 응답했는지)
+```
+`backend` 매핑: `nil`→`mac-mini-default` · `.localMLX`→`gemma-macmini` · (M5 Max Qwen 경로)→`qwen-macbook` · cloud→`claude-cloud`(503, 별 PR).
+
+## 5. S2 가 다음에 채울 것 (인터페이스는 고정)
+- `OnDeviceProvider`: `import FoundationModels` 가용성 프로브 + `LanguageModelSession` 호출.
+- `LocalMLXProvider`: 맥미니 OpenAI 호환 호출(messages system/user 분리 call-shape 고정).
+- `RemoteDSProvider`: S3 의 DS API client 주입 → 위 §4 매핑 결선.
+- `SpecializedProvider`: GPU 비전/특화 통로(필요 태스크만).
+
+## 동시 출발선 (S1 + S2 둘 다 동결 완료)
+- **S3** = `MockAIProvider` 주입 + S1 `fixtures/` 디코딩 → 실 백엔드·실 LLM 대기 0 으로 앱 전체 빌드.
+- **S1** = `[S1-ADD]` 구현 + 응답 shape 유지.
+- **S2** = 위 §5 provider 결선. 인터페이스(`AIProvider`/`AIRouter`) 변경 시만 합의.
diff --git a/clients/ds-app/contract/CONTRACT.md b/clients/ds-app/contract/CONTRACT.md
new file mode 100644
index 0000000..8d00920
--- /dev/null
+++ b/clients/ds-app/contract/CONTRACT.md
@@ -0,0 +1,224 @@
+# DS App ↔ Backend API 계약 (S1 인터페이스 동결)
+
+> **목적**: 멀티디바이스 DS 앱(S3)이 빌드/프리뷰 시 의존하는 **응답 shape를 동결**한다.
+> 백엔드 구현(S1)·LLM 라우팅(S2)과 무관하게 이 계약 + `fixtures/*.json`만 보고 앱을 만든다.
+> **이 계약이 곧 S1·S2·S3 동시 출발선이다.** 변경은 버전 bump + 합의로만.
+
+- **Contract version**: `v0.1` (frozen 2026-06-04)
+- **Base URL**: `https://document.hyungi.net/api` (TLS, 공인) · 대안 Tailscale `http://100.110.63.63:8000/api`
+- **출처**: 실제 GPU 백엔드 Pydantic 응답 모델에서 추출(지어내지 않음). 파일 = `app/api/{documents,search,memos,digest,auth}.py`.
+- **표기**: `[EXISTING]` = 현재 백엔드가 이미 반환. `[S1-ADD]` = 신규 요구(MD-first 전포맷·중복검사·다운로드 편의)로 **S1이 추가**할 필드/엔드포인트 — 앱은 옵셔널로 디코딩(`?`), 없으면 폴백.
+
+---
+
+## 0. 공통 규약
+
+- **datetime**: ISO-8601 문자열 (`"2026-06-03T08:12:44.120Z"`). Swift `Date` 디코딩 시 ISO8601 + fractional seconds.
+- **date**: `"2026-06-03"` (date-only).
+- **null**: 필드 부재 가능 → 앱 모델 전부 옵셔널(`String?`). 위 모델의 `| None` = 옵셔널.
+- **페이지네이션**: `{ items, total, page, page_size }`. 요청 `?page=1&page_size=20`.
+- **에러 shape**: `{ "detail": "<메시지>" }` 또는 `{ "detail": { "error_code": "...", "message": "..." } }`. HTTP status로 분기(401/404/422/503).
+- **인증**: 모든 `/api/*`(auth 제외)는 `Authorization: Bearer <access_token>` 헤더.
+
+### 인증 흐름 (네이티브)
+- `POST /api/auth/login {username, password, totp_code?}` → `AccessTokenResponse {access_token, token_type}`.
+- refresh는 **HttpOnly 쿠키**(`path=/api/auth`)로 내려옴 → `URLSession`의 `HTTPCookieStorage`가 자동 보관, `POST /api/auth/refresh`로 access 재발급 가능(네이티브에서도 동작).
+- **권장**: access_token은 **Keychain** 보관. 만료 시 refresh → 실패하면 재로그인. (장수명 365d 토큰 옵션도 가능하나 v1은 정식 로그인.)
+- 로그아웃 `POST /api/auth/logout`, 현재 사용자 `GET /api/auth/me` → `UserResponse`.
+
+---
+
+## 1. Auth
+
+| Method | Path | 요청 | 응답 | fixture |
+|---|---|---|---|---|
+| POST | `/auth/login` | `{username, password, totp_code?}` | `AccessTokenResponse` | `auth_login.json` |
+| POST | `/auth/refresh` | (쿠키) | `AccessTokenResponse` | `auth_login.json` |
+| GET | `/auth/me` | — | `UserResponse` | `auth_me.json` |
+| POST | `/auth/logout` | — | `{}` | — |
+
+```
+AccessTokenResponse { access_token: String, token_type: String("bearer") }   [EXISTING]
+UserResponse { id: Int, username: String, is_active: Bool, totp_enabled: Bool, last_login_at: Date? }   [EXISTING]
+```
+
+---
+
+## 2. Documents (MD-first 뷰 핵심)
+
+| Method | Path | 요청 | 응답 | fixture |
+|---|---|---|---|---|
+| GET | `/documents/` | `page, page_size, domain?, sub_group?, source?, format?, review_status?, category?, has_suggestion?, proposed_category?` | `DocumentListResponse` | `documents_list.json` |
+| GET | `/documents/{id}` | — | `DocumentDetailResponse` (**md_content 동봉**) | `document_detail.json` |
+| GET | `/documents/{id}/file` | `?token=<access>&download=true` | **바이너리 원본** (PDF/이미지/오디오/원본) | — |
+| GET | `/documents/{id}/content` | — | 경량 텍스트(`content` 15k cap) | `document_content.json` |
+| GET | `/documents/tree` | — | 도메인 트리(사이드바) | `documents_tree.json` |
+| GET | `/documents/stats/category-counts` | — | 카테고리 카운트 | `documents_stats.json` |
+| POST | `/documents/` (multipart) | 파일 업로드 | `DocumentResponse` (201) | `document_detail.json` |
+| PATCH | `/documents/{id}` | `DocumentUpdate` | `DocumentResponse` | — |
+| PUT | `/documents/{id}/content` | `{content}` (md 편집 저장) | `{}` | — |
+| POST | `/documents/{id}/accept-suggestion` | `{expected_source_updated_at}` | `DocumentResponse` | — |
+| DELETE | `/documents/{id}/suggestion` | — | 204 | — |
+| DELETE | `/documents/{id}` | — | 204 | — |
+
+### DocumentResponse (리스트 행 — 경량, md 본문 없음) `[EXISTING]`
+```
+id: Int
+file_path: String?          file_format: String      file_size: Int?     file_type: String
+title: String?
+ai_domain: String?  ai_sub_group: String?  ai_tags: [String]?  ai_summary: String?
+document_type: String?  importance: String?  ai_confidence: Double?
+user_note: String?  user_tags: [String]?  pinned: Bool?  ask_includable: Bool?
+derived_path: String?  original_format: String?  conversion_status: String?
+is_read: Bool?  review_status: String?  edit_url: String?  preview_status: String?
+source_channel: String?  data_origin: String?  doc_purpose: String?
+facet_company: String?  facet_topic: String?  facet_year: Int?  facet_doctype: String?
+category: String?  ai_suggestion: [String:Any]?
+ai_tldr: String?  ai_bullets: [String]?  ai_detail_summary: String?
+ai_inconsistencies: [String]?  ai_analysis_tier: String?   // 'triage' | 'deep' | null
+extracted_at: Date?  ai_processed_at: Date?  embedded_at: Date?
+created_at: Date  updated_at: Date
+read_count: Int(=0)  last_read_at: Date?
+```
+
+### DocumentDetailResponse (단건 — 위 전부 + 본문/canonical markdown) `[EXISTING]`
+```
+…DocumentResponse 전 필드…
+extracted_text: String?
+md_content: String?               // ← MD-first 뷰의 1차 렌더 소스 (canonical markdown)
+md_frontmatter: [String:Any]?
+md_status: String?                // pending|processing|completed|partial|failed|skipped (enum은 S1 동결)
+md_extraction_quality: [String:Any]?
+md_extraction_error: String?
+md_extraction_engine: String?     md_extraction_engine_version: String?
+md_generated_at: Date?
+```
+
+### `[S1-ADD]` (신규 요구 반영 — 앱은 옵셔널 디코딩, 없으면 폴백)
+```
+DocumentResponse / Detail 에 추가 예정:
+  original_filename: String?       // 다운로드 버튼 라벨용 (없으면 file_path basename)
+  duplicate_of: Int?               // 중복검사 개선 — canonical doc id (자기 자신이 canonical이면 null)
+  duplicate_count: Int(=0)         // 이 문서와 동일 판정된 사본 수
+신규 엔드포인트:
+  GET /documents/duplicates        // 중복 그룹 목록 { groups: [{ canonical_id, members:[id], reason }] }
+```
+
+### MD-first 렌더 규칙 (앱 측 계약)
+1. 본문 뷰 = **`md_content` 우선** (md_status ∈ {completed, partial}일 때). 일관성 = 모든 포맷을 markdown으로 본다.
+2. md 없음(md_status ∈ {pending, processing, failed, skipped, null}) → `extracted_text` 폴백 + "원본 다운로드" 강조 + "MD 변환 대기" 배지.
+3. **원본 접근 = 항상 다운로드 버튼** → `GET /documents/{id}/file?token=<access>&download=true`.
+   - 주의: 이 엔드포인트는 **Authorization 헤더가 아니라 `?token=` 쿼리 파라미터**로 인증(iframe/다운로드 호환). 앱은 access_token을 쿼리로 붙인다.
+   - `note`(메모)는 물리 파일 없음 → 404. 다운로드 버튼 숨김.
+4. 앱은 **절대 SMB를 보지 않는다.** 원본/스토리지 계층(맥미니 4TB ↔ NAS Docker)은 이 URL 뒤에서 S1이 추상화. 앱엔 단일 다운로드 URL만 노출.
+
+---
+
+## 3. Search
+
+| Method | Path | 요청 | 응답 | fixture |
+|---|---|---|---|---|
+| GET | `/search/` | `q, mode?(text|vector|hybrid), page?, debug?` | `SearchResponse` | `search.json` |
+
+```
+SearchResponse { results: [SearchResult], total: Int, query: String, mode: String, debug: SearchDebug? }   [EXISTING]
+SearchResult {
+  id: Int                 // doc_id
+  title: String?  ai_domain: String?  ai_summary: String?  file_format: String
+  score: Double  snippet: String?  match_reason: String?
+  chunk_id: Int?  chunk_index: Int?  section_title: String?
+  rerank_score: Double?  freshness_debug: [String:Any]?
+}
+```
+
+---
+
+## 4. Ask (RAG — 원격 DS, S2 LLM 라우팅과 연결)
+
+| Method | Path | 요청 | 응답 | fixture |
+|---|---|---|---|---|
+| GET | `/search/ask` | `q, limit?, backend?, debug?` | `AskResponse` | `ask.json` |
+| POST | `/search/ask/react` | `{...}` | `AskReactResponse` | — |
+
+```
+AskResponse {                                                   [EXISTING]
+  results: [SearchResult]
+  ai_answer: String?
+  citations: [Citation]
+  synthesis_status: "completed"|"timeout"|"skipped"|"no_evidence"|"parse_failed"|"llm_error"|"backend_unavailable"
+  synthesis_ms: Double
+  confidence: "high"|"medium"|"low" | null
+  refused: Bool   no_results_reason: String?   query: String   total: Int
+  completeness: "full"|"partial"|"insufficient"   // 기본 "full"
+  covered_aspects: [String]?   missing_aspects: [String]?
+  confirmed_items: [ConfirmedItem]?
+  backend_requested: String?   backend_used: String?   // S2 라우팅 메타
+  debug: AskDebug?
+}
+Citation { n: Int, chunk_id: Int?, doc_id: Int, title: String?, section_title: String?,
+           span_text: String, full_snippet: String, relevance: Double, rerank_score: Double }
+ConfirmedItem { aspect: String, text: String, citations: [Int] }
+```
+
+- **`backend` 쿼리** = S2 인터페이스 접점: `qwen-macbook | gemma-macmini | mac-mini-default | claude-cloud | auto`. 미지정 = `mac-mini-default`(맥미니 26B).
+- **앱 라우팅 규칙(S2 계약)**: 빠른 요약/선택문 ask/메모 보조 = **온디바이스(Apple FM)** 로컬 처리(이 엔드포인트 미호출). **전체 코퍼스 RAG** = 이 `/search/ask` 호출(backend로 맥미니/특화 선택). `[S1-ADD]` 없음 — backend 인자는 이미 존재.
+
+---
+
+## 5. Memos (캡처/쓰기)
+
+| Method | Path | 요청 | 응답 | fixture |
+|---|---|---|---|---|
+| GET | `/memos/` | `page, page_size, pinned?, archived?` | `MemoListResponse` | `memos_list.json` |
+| GET | `/memos/{id}` | — | `MemoResponse` | `memo_detail.json` |
+| POST | `/memos/` | `MemoCreate {content, title?, ask_includable?, source_channel?, source_metadata?}` | `MemoResponse` (201) | `memo_detail.json` |
+| PATCH | `/memos/{id}` | `MemoUpdate {content, title?}` | `MemoResponse` | — |
+| PATCH | `/memos/{id}/pin` · `/archive` · `/ask-includable` | `{...}` | `MemoResponse` | — |
+| PATCH | `/memos/{id}/tasks/{task_index}` | `{checked}` | `MemoResponse` | — |
+| POST | `/memos/{id}/promote-to-event` | — | 201 | — |
+| DELETE | `/memos/{id}` | — | 204 | — |
+
+```
+MemoResponse {                                                  [EXISTING]
+  id: Int  title: String?  content: String?   // = extracted_text
+  file_format: String  file_type: String?     // "audio"(음성) | "note"(텍스트)
+  file_path: String?                           // 음성 메모 오디오 경로(있으면 재생 가능)
+  user_tags: [String]?  ai_tags: [String]?
+  ai_domain: String?  ai_sub_group: String?  ai_summary: String?
+  pinned: Bool  archived: Bool  ask_includable: Bool
+  memo_task_state: [String:Any]                // {"0": {"checked_at": "ISO"}}
+  ai_event_kind: String?  ai_event_confidence: Double?
+  source_channel: String?  source_metadata: [String:Any]
+  created_at: Date  updated_at: Date
+}
+```
+
+---
+
+## 6. Digest (뉴스)
+
+| Method | Path | 요청 | 응답 | fixture |
+|---|---|---|---|---|
+| GET | `/digest` | `?date=YYYY-MM-DD&country?` | `DigestResponse` | `digest.json` |
+| GET | `/digest/dates` | — | `[DigestDateSummary]` | — |
+
+```
+DigestResponse {                                                [EXISTING]
+  digest_date: Date(date-only)  window_start: Date  window_end: Date
+  decay_lambda: Double  total_articles: Int  total_countries: Int  total_topics: Int
+  generation_ms: Int?  llm_calls: Int  llm_failures: Int  status: String
+  countries: [CountryGroup]
+}
+CountryGroup { country: String, topics: [TopicResponse] }
+TopicResponse { topic_rank: Int, topic_label: String, summary: String,
+                article_ids: [Int], articles: [ArticleRef], article_count: Int,
+                importance_score: Double, raw_weight_sum: Double, llm_fallback_used: Bool }
+ArticleRef { id: Int, title: String? }
+DigestDateSummary { digest_date: Date, total_topics: Int, total_countries: Int, total_articles: Int, status: String }
+```
+
+---
+
+## 변경 관리
+- 이 계약을 깨는 변경(필드 제거/타입 변경) = `version` bump + S1/S2/S3 합의. `[S1-ADD]`는 옵셔널이라 non-breaking.
+- 통합 결선 시 fixture와 실 응답 **call-shape regression test**로 대조([[feedback_fixture_first_call_shape]]).
diff --git a/clients/ds-app/contract/README.md b/clients/ds-app/contract/README.md
new file mode 100644
index 0000000..cca56a2
--- /dev/null
+++ b/clients/ds-app/contract/README.md
@@ -0,0 +1,38 @@
+# DS App Contract (S1 인터페이스 동결) — v0.1
+
+S1·S2·S3 **동시 출발선**. 앱(S3)은 실 백엔드/실 LLM 없이 **이 디렉토리만 보고** 빌드한다.
+
+```
+contract/
+  CONTRACT.md            ← 엔드포인트 + 요청/응답 shape 동결 스펙 (읽기 시작점)
+  fixtures/              ← 응답 JSON 박제 (앱 프리뷰/디코딩 테스트가 로드)
+    auth_login.json            POST /auth/login
+    auth_me.json               GET  /auth/me
+    documents_list.json        GET  /documents/         (DocumentListResponse)
+    document_detail.json       GET  /documents/{id}     (md_status=completed — MD-first 렌더)
+    document_detail_pending_md.json  GET /documents/{id} (md_status=pending — extracted_text 폴백 케이스)
+    document_content.json      GET  /documents/{id}/content
+    documents_tree.json        GET  /documents/tree
+    documents_stats.json       GET  /documents/stats/category-counts
+    documents_duplicates.json  GET  /documents/duplicates   [S1-ADD] 중복검사
+    search.json                GET  /search/
+    ask.json                   GET  /search/ask
+    memos_list.json            GET  /memos/
+    memo_detail.json           GET  /memos/{id}
+    digest.json                GET  /digest
+```
+
+## 동결 원칙
+- 모든 shape는 **실제 GPU 백엔드 Pydantic 모델에서 추출**(지어내지 않음). `[S1-ADD]` 필드만 신규.
+- 앱 모델(Swift Codable)은 위 fixtures를 그대로 디코딩할 수 있어야 한다 = 1차 수용 테스트.
+- 통합 시 fixture ↔ 실 응답 **call-shape regression**으로 대조.
+
+## `[S1-ADD]` (S1이 추가할 신규 — 앱은 옵셔널 디코딩)
+- `original_filename`, `duplicate_of`, `duplicate_count` (DocumentResponse/Detail)
+- `GET /documents/duplicates` (중복검사 개선 트랙)
+- Word/Excel/이미지/오디오 → `md_content` 채우기 (MD-first 전포맷 — marker는 현재 PDF 전용)
+
+## 다음
+- S3: 이 fixtures를 디코딩하는 Swift `Codable` 모델 + API client(프로토콜) → macOS 앱.
+- S1: `[S1-ADD]` 구현 + 위 shape 유지(깨면 version bump).
+- S2: `/search/ask?backend=` + 온디바이스 provider 추상화(`AIProvider`).
diff --git a/clients/ds-app/contract/contract-check.sh b/clients/ds-app/contract/contract-check.sh
new file mode 100755
index 0000000..cd9b808
--- /dev/null
+++ b/clients/ds-app/contract/contract-check.sh
@@ -0,0 +1,80 @@
+#!/usr/bin/env bash
+# contract-check.sh — S2-Ff: 라이브 엔드포인트 ↔ 동결 fixture *모양* 드리프트 감지 (비차단 runbook).
+#
+#   라이브 재호출 → 키/타입 diff(LLM 값은 무시) → 드리프트면 비0 exit + fixture-update 안내.
+#   PR 게이트 아님 — 수동/Tailscale-CI 트리거([[feedback_pr_gate_vs_runbook_separation]]).
+#   fixture 는 동결·불변이며, 이 도구가 감지한 드리프트가 **재캡처 PR 의 유일 합법 트리거**(S2-0d).
+#
+#   exit: 0 = 드리프트 없음(체크된 것 중) · 1 = breaking 드리프트 · 2 = 아무것도 체크 못함(전부 도달불가)
+#   env override: AIFABRIC_LOCALMLX_URL, AIFABRIC_DS_URL
+#
+# 스킵은 항상 *가시적*으로 출력(silent green 금지, [[feedback_silent_skip_accumulation]]).
+set -uo pipefail   # NOT -e: 개별 체크 실패를 모아 보고
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+FIX="$SCRIPT_DIR/fixtures"
+PY="$(command -v python3 || echo /usr/bin/python3)"
+LLM_URL="${AIFABRIC_LOCALMLX_URL:-http://100.76.254.116:8890}"
+DS_URL="${AIFABRIC_DS_URL:-https://document.hyungi.net/api}"
+TMP="$(mktemp -d)"; trap 'rm -rf "$TMP"' EXIT
+
+breaking=0
+checked=0
+
+echo "== S2-Ff contract drift check =="
+echo "   llm-router: $LLM_URL"
+echo "   DS:         $DS_URL"
+
+# --- 1) llm-router /v1/chat/completions  (S2 fixture) ---
+echo
+echo "[1] llm-router /v1/chat/completions  ↔  llm-router-chat.response.json"
+# 동결 request fixture 에서 _meta 떼고 그대로 wire body 로 POST(call-shape 도 함께 검증).
+"$PY" -c 'import json,sys; o=json.load(open(sys.argv[1],encoding="utf-8")); o.pop("_meta",None); json.dump(o,open(sys.argv[2],"w"))' \
+    "$FIX/llm-router-chat.request.json" "$TMP/req.json" 2>"$TMP/strip_err" || { echo "  SKIP — request fixture 처리 실패: $(head -c160 "$TMP/strip_err")"; }
+if [ -s "$TMP/req.json" ]; then
+    code="$(curl -sS -m 60 -o "$TMP/llm_live.json" -w '%{http_code}' \
+        -H 'Content-Type: application/json' --data @"$TMP/req.json" \
+        "$LLM_URL/v1/chat/completions" 2>"$TMP/llm_err" || true)"
+    if [ "$code" = "200" ]; then
+        checked=$((checked + 1))
+        if "$PY" "$SCRIPT_DIR/shape_diff.py" "$FIX/llm-router-chat.response.json" "$TMP/llm_live.json"; then
+            echo "  PASS — shape 일치"
+        else
+            echo "  >> 드리프트: llm-router-chat.{request,response}.json 재캡처 PR 필요"
+            breaking=1
+        fi
+    else
+        echo "  SKIP — 도달 불가/비200 (http=${code:-curlfail}; 맥미니 offline?) $(head -c120 "$TMP/llm_err" 2>/dev/null)"
+    fi
+fi
+
+# --- 2) DS /search/ask  (S1 fixture, best-effort: 인증 필요할 수 있음) ---
+echo
+echo "[2] DS /search/ask  ↔  ask.json   (best-effort)"
+code="$(curl -sS -m 30 -G -o "$TMP/ds_live.json" -w '%{http_code}' \
+    --data-urlencode 'q=충격시험은 언제 면제되나' --data-urlencode 'backend=mac-mini-default' \
+    "$DS_URL/search/ask" 2>"$TMP/ds_err" || true)"
+case "$code" in
+    200)
+        checked=$((checked + 1))
+        if "$PY" "$SCRIPT_DIR/shape_diff.py" "$FIX/ask.json" "$TMP/ds_live.json"; then
+            echo "  PASS — shape 일치"
+        else
+            echo "  >> 드리프트: ask.json(S1) 재캡처 검토"
+            breaking=1
+        fi ;;
+    401|403) echo "  SKIP — 인증 필요(JWT). DS ask 체크는 토큰 주입 시에만(S1 도메인)." ;;
+    *)       echo "  SKIP — 도달 불가/비200 (http=${code:-curlfail})." ;;
+esac
+
+echo
+if [ "$breaking" -ne 0 ]; then
+    echo "RESULT: DRIFT 발견 — 위 fixture 재캡처 PR 필요(S2-0d 의 유일 합법 fixture 변경 경로)."
+    exit 1
+elif [ "$checked" -eq 0 ]; then
+    echo "RESULT: 체크한 엔드포인트 0건(전부 도달 불가) — 드리프트 판정 불가. (green 아님 → exit 2)"
+    exit 2
+else
+    echo "RESULT: OK — 체크 ${checked}건 모두 shape 일치, 드리프트 없음."
+    exit 0
+fi
diff --git a/clients/ds-app/contract/fixtures/ask.json b/clients/ds-app/contract/fixtures/ask.json
new file mode 100644
index 0000000..a650751
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/ask.json
@@ -0,0 +1,47 @@
+{
+  "results": [
+    {
+      "id": 4912,
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "ai_domain": "Engineering",
+      "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+      "file_format": "pdf",
+      "score": 0.8714,
+      "snippet": "...UCS-66 면제 곡선과 MDMT 적용...",
+      "match_reason": "vector+rerank",
+      "chunk_id": 88213,
+      "chunk_index": 3,
+      "section_title": "2. UCS-66 면제 곡선",
+      "rerank_score": 0.913,
+      "freshness_debug": null
+    }
+  ],
+  "ai_answer": "충격시험 면제는 UCS-66 면제 곡선으로 판정합니다 [1]. 재료군(Curve A~D)과 거버닝 두께에 따라 최소설계금속온도(MDMT)에서 면제 여부가 정해지며, 설계 응력비가 낮으면 UCS-66.1에 따라 MDMT를 추가로 낮출 수 있습니다 [1].",
+  "citations": [
+    {
+      "n": 1,
+      "chunk_id": 88213,
+      "doc_id": 4912,
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "section_title": "2. UCS-66 면제 곡선",
+      "span_text": "재료군(Curve A~D)과 거버닝 두께에 따라 최소설계금속온도(MDMT)에서의 충격시험 면제 여부를 결정한다.",
+      "full_snippet": "재료군(Curve A~D)과 거버닝 두께에 따라 최소설계금속온도(MDMT)에서의 충격시험 면제 여부를 결정한다. 설계 응력비가 낮으면 UCS-66.1에 따라 MDMT를 추가로 낮출 수 있다. 면제되지 않는 경우 UG-84에 따라 Charpy V-notch 시험을 수행한다.",
+      "relevance": 0.91,
+      "rerank_score": 0.913
+    }
+  ],
+  "synthesis_status": "completed",
+  "synthesis_ms": 2841.5,
+  "confidence": "high",
+  "refused": false,
+  "no_results_reason": null,
+  "query": "충격시험은 언제 면제되나",
+  "total": 1,
+  "completeness": "full",
+  "covered_aspects": ["면제 곡선", "MDMT 적용"],
+  "missing_aspects": null,
+  "confirmed_items": null,
+  "backend_requested": "mac-mini-default",
+  "backend_used": "gemma-macmini",
+  "debug": null
+}
diff --git a/clients/ds-app/contract/fixtures/auth_login.json b/clients/ds-app/contract/fixtures/auth_login.json
new file mode 100644
index 0000000..cea80a3
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/auth_login.json
@@ -0,0 +1,4 @@
+{
+  "access_token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJoeXVuZ2kiLCJ0eXBlIjoiYWNjZXNzIiwiZXhwIjoxNzQ5MDAwMDAwfQ.FIXTURE_SIGNATURE_NOT_REAL",
+  "token_type": "bearer"
+}
diff --git a/clients/ds-app/contract/fixtures/auth_me.json b/clients/ds-app/contract/fixtures/auth_me.json
new file mode 100644
index 0000000..c92ea4f
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/auth_me.json
@@ -0,0 +1,7 @@
+{
+  "id": 1,
+  "username": "hyungi",
+  "is_active": true,
+  "totp_enabled": false,
+  "last_login_at": "2026-06-04T07:55:12.330Z"
+}
diff --git a/clients/ds-app/contract/fixtures/digest.json b/clients/ds-app/contract/fixtures/digest.json
new file mode 100644
index 0000000..3c78d0e
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/digest.json
@@ -0,0 +1,54 @@
+{
+  "digest_date": "2026-06-03",
+  "window_start": "2026-05-27T00:00:00.000Z",
+  "window_end": "2026-06-03T00:00:00.000Z",
+  "decay_lambda": 0.18,
+  "total_articles": 312,
+  "total_countries": 4,
+  "total_topics": 9,
+  "generation_ms": 18420,
+  "llm_calls": 11,
+  "llm_failures": 0,
+  "status": "completed",
+  "countries": [
+    {
+      "country": "KR",
+      "topics": [
+        {
+          "topic_rank": 1,
+          "topic_label": "산업안전 규제 개정",
+          "summary": "중대재해처벌법 후속 시행령 개정 논의가 이어지며 제조업 현장 점검이 강화되는 흐름.",
+          "article_ids": [880123, 880140, 880155],
+          "articles": [
+            { "id": 880123, "title": "고용부, 중대재해 시행령 개정안 입법예고" },
+            { "id": 880140, "title": "제조 현장 안전점검 확대" },
+            { "id": 880155, "title": "압력설비 검사 주기 단축 검토" }
+          ],
+          "article_count": 3,
+          "importance_score": 0.91,
+          "raw_weight_sum": 2.74,
+          "llm_fallback_used": false
+        }
+      ]
+    },
+    {
+      "country": "US",
+      "topics": [
+        {
+          "topic_rank": 1,
+          "topic_label": "ASME 코드 업데이트",
+          "summary": "ASME BPVC 2025 에디션 관련 산업계 적용 사례와 해설 자료가 늘어남.",
+          "article_ids": [880301, 880322],
+          "articles": [
+            { "id": 880301, "title": "ASME BPVC 2025 adoption notes" },
+            { "id": 880322, "title": "Impact test exemption clarifications" }
+          ],
+          "article_count": 2,
+          "importance_score": 0.77,
+          "raw_weight_sum": 1.62,
+          "llm_fallback_used": false
+        }
+      ]
+    }
+  ]
+}
diff --git a/clients/ds-app/contract/fixtures/document_content.json b/clients/ds-app/contract/fixtures/document_content.json
new file mode 100644
index 0000000..b5430c3
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/document_content.json
@@ -0,0 +1,12 @@
+{
+  "id": 4912,
+  "title": "ASME Section VIII Div 1 — Impact Test 요건",
+  "domain": "Engineering",
+  "sub_group": "압력용기",
+  "document_type": "standard",
+  "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+  "ai_tags": ["ASME", "Section VIII", "충격시험", "UCS-66"],
+  "content": "ASME Section VIII Division 1 Impact Test Requirements\nUCS-66 면제 곡선과 MDMT 적용 ... (최대 15000자) ...",
+  "content_length": 8421,
+  "truncated": false
+}
diff --git a/clients/ds-app/contract/fixtures/document_detail.json b/clients/ds-app/contract/fixtures/document_detail.json
new file mode 100644
index 0000000..e285003
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/document_detail.json
@@ -0,0 +1,63 @@
+{
+  "id": 4912,
+  "file_path": "Engineering/ASME/ASME_SecVIII_Div1_Impact_Test.pdf",
+  "file_format": "pdf",
+  "file_size": 1338920,
+  "file_type": "document",
+  "title": "ASME Section VIII Div 1 — Impact Test 요건",
+  "ai_domain": "Engineering",
+  "ai_sub_group": "압력용기",
+  "ai_tags": ["ASME", "Section VIII", "충격시험", "UCS-66"],
+  "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+  "document_type": "standard",
+  "importance": "high",
+  "ai_confidence": 0.93,
+  "user_note": "MDMT 판정 시 자주 참조",
+  "user_tags": ["자주봄"],
+  "pinned": true,
+  "ask_includable": true,
+  "derived_path": "Engineering/ASME/ASME_SecVIII_Div1_Impact_Test.md",
+  "original_format": "pdf",
+  "conversion_status": "completed",
+  "is_read": true,
+  "review_status": "approved",
+  "edit_url": null,
+  "preview_status": "ready",
+  "source_channel": "upload",
+  "data_origin": "external",
+  "doc_purpose": "reference",
+  "facet_company": "ASME",
+  "facet_topic": "압력용기",
+  "facet_year": 2023,
+  "facet_doctype": "standard",
+  "category": "library",
+  "ai_suggestion": null,
+  "ai_tldr": "충격시험 면제 곡선(UCS-66)과 MDMT 적용.",
+  "ai_bullets": ["UCS-66 면제 곡선", "UCS-66.1 감액", "UG-84 시험 요건"],
+  "ai_detail_summary": "본 표준 절은 탄소강·저합금강 압력용기 재료의 노치 인성(충격시험) 요구를 다룬다. UCS-66 면제 곡선은 재료군(A~D)과 두께에 따라 최소설계금속온도(MDMT)에서의 시험 면제 여부를 정한다.",
+  "ai_inconsistencies": [],
+  "ai_analysis_tier": "deep",
+  "extracted_at": "2026-05-22T05:00:11.000Z",
+  "ai_processed_at": "2026-05-22T05:04:40.000Z",
+  "embedded_at": "2026-05-22T05:06:02.000Z",
+  "created_at": "2026-05-22T04:59:50.000Z",
+  "updated_at": "2026-06-01T09:21:33.000Z",
+  "read_count": 11,
+  "last_read_at": "2026-06-03T18:02:10.000Z",
+  "original_filename": "ASME_SecVIII_Div1_Impact_Test.pdf",
+  "duplicate_of": null,
+  "duplicate_count": 1,
+  "extracted_text": "ASME Section VIII Division 1 Impact Test Requirements\nUCS-66 ... (원문 추출 텍스트, 폴백용) ...",
+  "md_content": "# ASME Section VIII Div 1 — 충격시험 요건\n\n## 1. 범위\n탄소강 및 저합금강 압력용기 재료의 노치 인성(충격시험) 요구를 규정한다.\n\n## 2. UCS-66 면제 곡선\n재료군(Curve A~D)과 거버닝 두께에 따라 **최소설계금속온도(MDMT)** 에서의 충격시험 면제 여부를 결정한다.\n\n| 곡선 | 대표 재료 | 비고 |\n|---|---|---|\n| A | SA-516 (비정규화) | 가장 보수적 |\n| B | SA-516 정규화 | |\n| C | SA-537 | |\n| D | 인성 우수 재료 | 가장 관대 |\n\n## 3. UCS-66.1 감액\n설계 응력비(stress ratio)가 낮으면 MDMT 를 추가로 낮출 수 있다.\n\n## 4. UG-84 시험 요건\n면제되지 않는 경우 Charpy V-notch 시험으로 흡수에너지/측면팽창 기준을 만족해야 한다.\n",
+  "md_frontmatter": {
+    "title": "ASME Section VIII Div 1 — 충격시험 요건",
+    "domain": "Engineering",
+    "source": "ASME_SecVIII_Div1_Impact_Test.pdf"
+  },
+  "md_status": "completed",
+  "md_extraction_quality": { "page_count": 14, "table_count": 3, "ocr_used": false },
+  "md_extraction_error": null,
+  "md_extraction_engine": "marker",
+  "md_extraction_engine_version": "1.10.2",
+  "md_generated_at": "2026-05-22T05:03:30.000Z"
+}
diff --git a/clients/ds-app/contract/fixtures/document_detail_pending_md.json b/clients/ds-app/contract/fixtures/document_detail_pending_md.json
new file mode 100644
index 0000000..f664d71
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/document_detail_pending_md.json
@@ -0,0 +1,59 @@
+{
+  "id": 5301,
+  "file_path": "General/매뉴얼/02_왕복압축기_운전매뉴얼.docx",
+  "file_format": "docx",
+  "file_size": 73402,
+  "file_type": "document",
+  "title": "02 왕복압축기 운전 매뉴얼",
+  "ai_domain": "General",
+  "ai_sub_group": "설비매뉴얼",
+  "ai_tags": ["왕복압축기", "운전", "매뉴얼"],
+  "ai_summary": "왕복동식 압축기 기동/정지/점검 절차 매뉴얼.",
+  "document_type": "manual",
+  "importance": "normal",
+  "ai_confidence": 0.81,
+  "user_note": null,
+  "user_tags": null,
+  "pinned": false,
+  "ask_includable": true,
+  "derived_path": null,
+  "original_format": "docx",
+  "conversion_status": "pending",
+  "is_read": false,
+  "review_status": "pending",
+  "edit_url": null,
+  "preview_status": "pending",
+  "source_channel": "upload",
+  "data_origin": "internal",
+  "doc_purpose": "reference",
+  "facet_company": null,
+  "facet_topic": "설비매뉴얼",
+  "facet_year": 2024,
+  "facet_doctype": "manual",
+  "category": "library",
+  "ai_suggestion": null,
+  "ai_tldr": null,
+  "ai_bullets": null,
+  "ai_detail_summary": null,
+  "ai_inconsistencies": null,
+  "ai_analysis_tier": "triage",
+  "extracted_at": "2026-06-03T01:20:00.000Z",
+  "ai_processed_at": "2026-06-03T01:22:14.000Z",
+  "embedded_at": null,
+  "created_at": "2026-06-03T01:19:55.000Z",
+  "updated_at": "2026-06-03T01:22:14.000Z",
+  "read_count": 0,
+  "last_read_at": null,
+  "original_filename": "02_왕복압축기_운전매뉴얼.docx",
+  "duplicate_of": null,
+  "duplicate_count": 0,
+  "extracted_text": "왕복압축기 운전 매뉴얼\n1. 기동 전 점검\n - 윤활유 레벨 확인\n - 흡입/토출 밸브 상태 확인\n2. 기동 절차 ...",
+  "md_content": null,
+  "md_frontmatter": null,
+  "md_status": "pending",
+  "md_extraction_quality": null,
+  "md_extraction_error": null,
+  "md_extraction_engine": null,
+  "md_extraction_engine_version": null,
+  "md_generated_at": null
+}
diff --git a/clients/ds-app/contract/fixtures/documents_duplicates.json b/clients/ds-app/contract/fixtures/documents_duplicates.json
new file mode 100644
index 0000000..0095e2c
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/documents_duplicates.json
@@ -0,0 +1,18 @@
+{
+  "groups": [
+    {
+      "canonical_id": 4912,
+      "members": [4912, 4977],
+      "reason": "content_hash",
+      "detail": "동일 본문 해시 (md_content normalized SHA-256 일치)"
+    },
+    {
+      "canonical_id": 5120,
+      "members": [5120, 5121, 5260],
+      "reason": "near_duplicate",
+      "detail": "제목/본문 유사도 0.97 (cross-format: pdf + docx 동일 문서)"
+    }
+  ],
+  "total_groups": 2,
+  "total_duplicate_docs": 3
+}
diff --git a/clients/ds-app/contract/fixtures/documents_list.json b/clients/ds-app/contract/fixtures/documents_list.json
new file mode 100644
index 0000000..2b892f5
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/documents_list.json
@@ -0,0 +1,157 @@
+{
+  "items": [
+    {
+      "id": 5187,
+      "file_path": "Engineering/기계가공/엘보_내경가공_절차서.pdf",
+      "file_format": "pdf",
+      "file_size": 482113,
+      "file_type": "document",
+      "title": "엘보 내경가공 절차서",
+      "ai_domain": "Engineering",
+      "ai_sub_group": "기계가공",
+      "ai_tags": ["엘보", "내경가공", "절차서", "가공공차"],
+      "ai_summary": "엘보 내경 가공 시 공차 관리와 가공 순서를 정리한 사내 절차서.",
+      "document_type": "procedure",
+      "importance": "normal",
+      "ai_confidence": 0.86,
+      "user_note": null,
+      "user_tags": null,
+      "pinned": false,
+      "ask_includable": true,
+      "derived_path": "Engineering/기계가공/엘보_내경가공_절차서.md",
+      "original_format": "pdf",
+      "conversion_status": "completed",
+      "is_read": true,
+      "review_status": "approved",
+      "edit_url": null,
+      "preview_status": "ready",
+      "source_channel": "upload",
+      "data_origin": "internal",
+      "doc_purpose": "reference",
+      "facet_company": null,
+      "facet_topic": "기계가공",
+      "facet_year": 2025,
+      "facet_doctype": "procedure",
+      "category": "library",
+      "ai_suggestion": null,
+      "ai_tldr": "엘보 내경 가공 공차·순서 절차.",
+      "ai_bullets": ["가공 전 소재 검사", "내경 공차 +0.1/-0.0", "최종 치수 검사 기록"],
+      "ai_detail_summary": null,
+      "ai_inconsistencies": null,
+      "ai_analysis_tier": "triage",
+      "extracted_at": "2026-05-30T02:11:04.000Z",
+      "ai_processed_at": "2026-05-30T02:13:51.000Z",
+      "embedded_at": "2026-05-30T02:15:09.000Z",
+      "created_at": "2026-05-30T02:10:58.000Z",
+      "updated_at": "2026-05-30T02:15:09.000Z",
+      "read_count": 3,
+      "last_read_at": "2026-06-02T13:40:22.000Z",
+      "original_filename": "엘보_내경가공_절차서.pdf",
+      "duplicate_of": null,
+      "duplicate_count": 0
+    },
+    {
+      "id": 4912,
+      "file_path": "Engineering/ASME/ASME_SecVIII_Div1_Impact_Test.pdf",
+      "file_format": "pdf",
+      "file_size": 1338920,
+      "file_type": "document",
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "ai_domain": "Engineering",
+      "ai_sub_group": "압력용기",
+      "ai_tags": ["ASME", "Section VIII", "충격시험", "UCS-66"],
+      "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+      "document_type": "standard",
+      "importance": "high",
+      "ai_confidence": 0.93,
+      "user_note": "MDMT 판정 시 자주 참조",
+      "user_tags": ["자주봄"],
+      "pinned": true,
+      "ask_includable": true,
+      "derived_path": "Engineering/ASME/ASME_SecVIII_Div1_Impact_Test.md",
+      "original_format": "pdf",
+      "conversion_status": "completed",
+      "is_read": true,
+      "review_status": "approved",
+      "edit_url": null,
+      "preview_status": "ready",
+      "source_channel": "upload",
+      "data_origin": "external",
+      "doc_purpose": "reference",
+      "facet_company": "ASME",
+      "facet_topic": "압력용기",
+      "facet_year": 2023,
+      "facet_doctype": "standard",
+      "category": "library",
+      "ai_suggestion": null,
+      "ai_tldr": "충격시험 면제 곡선(UCS-66)과 MDMT 적용.",
+      "ai_bullets": ["UCS-66 면제 곡선", "UCS-66.1 감액", "UG-84 시험 요건"],
+      "ai_detail_summary": null,
+      "ai_inconsistencies": null,
+      "ai_analysis_tier": "deep",
+      "extracted_at": "2026-05-22T05:00:11.000Z",
+      "ai_processed_at": "2026-05-22T05:04:40.000Z",
+      "embedded_at": "2026-05-22T05:06:02.000Z",
+      "created_at": "2026-05-22T04:59:50.000Z",
+      "updated_at": "2026-06-01T09:21:33.000Z",
+      "read_count": 11,
+      "last_read_at": "2026-06-03T18:02:10.000Z",
+      "original_filename": "ASME_SecVIII_Div1_Impact_Test.pdf",
+      "duplicate_of": null,
+      "duplicate_count": 1
+    },
+    {
+      "id": 5301,
+      "file_path": "General/매뉴얼/02_왕복압축기_운전매뉴얼.docx",
+      "file_format": "docx",
+      "file_size": 73402,
+      "file_type": "document",
+      "title": "02 왕복압축기 운전 매뉴얼",
+      "ai_domain": "General",
+      "ai_sub_group": "설비매뉴얼",
+      "ai_tags": ["왕복압축기", "운전", "매뉴얼"],
+      "ai_summary": "왕복동식 압축기 기동/정지/점검 절차 매뉴얼.",
+      "document_type": "manual",
+      "importance": "normal",
+      "ai_confidence": 0.81,
+      "user_note": null,
+      "user_tags": null,
+      "pinned": false,
+      "ask_includable": true,
+      "derived_path": null,
+      "original_format": "docx",
+      "conversion_status": "pending",
+      "is_read": false,
+      "review_status": "pending",
+      "edit_url": null,
+      "preview_status": "pending",
+      "source_channel": "upload",
+      "data_origin": "internal",
+      "doc_purpose": "reference",
+      "facet_company": null,
+      "facet_topic": "설비매뉴얼",
+      "facet_year": 2024,
+      "facet_doctype": "manual",
+      "category": "library",
+      "ai_suggestion": null,
+      "ai_tldr": null,
+      "ai_bullets": null,
+      "ai_detail_summary": null,
+      "ai_inconsistencies": null,
+      "ai_analysis_tier": "triage",
+      "extracted_at": "2026-06-03T01:20:00.000Z",
+      "ai_processed_at": "2026-06-03T01:22:14.000Z",
+      "embedded_at": null,
+      "created_at": "2026-06-03T01:19:55.000Z",
+      "updated_at": "2026-06-03T01:22:14.000Z",
+      "read_count": 0,
+      "last_read_at": null,
+      "original_filename": "02_왕복압축기_운전매뉴얼.docx",
+      "duplicate_of": null,
+      "duplicate_count": 0
+    }
+  ],
+  "total": 783,
+  "page": 1,
+  "page_size": 20
+}
diff --git a/clients/ds-app/contract/fixtures/documents_stats.json b/clients/ds-app/contract/fixtures/documents_stats.json
new file mode 100644
index 0000000..f4e8edc
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/documents_stats.json
@@ -0,0 +1,14 @@
+{
+  "total": 1163,
+  "documents": 783,
+  "by_domain": {
+    "Industrial_Safety": 426,
+    "Engineering": 351,
+    "General": 189,
+    "Programming": 60,
+    "법령": 23,
+    "Philosophy": 12
+  },
+  "review_pending": 725,
+  "pipeline_failed": 19
+}
diff --git a/clients/ds-app/contract/fixtures/documents_tree.json b/clients/ds-app/contract/fixtures/documents_tree.json
new file mode 100644
index 0000000..d2fe617
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/documents_tree.json
@@ -0,0 +1,16 @@
+[
+  { "name": "Industrial_Safety", "path": "Industrial_Safety", "count": 426,
+    "children": [
+      { "name": "위험성평가", "path": "Industrial_Safety/위험성평가", "count": 118, "children": [] },
+      { "name": "KGS", "path": "Industrial_Safety/KGS", "count": 73, "children": [] }
+    ] },
+  { "name": "Engineering", "path": "Engineering", "count": 351,
+    "children": [
+      { "name": "압력용기", "path": "Engineering/압력용기", "count": 96, "children": [] },
+      { "name": "기계가공", "path": "Engineering/기계가공", "count": 54, "children": [] }
+    ] },
+  { "name": "General", "path": "General", "count": 189, "children": [] },
+  { "name": "Programming", "path": "Programming", "count": 60, "children": [] },
+  { "name": "법령", "path": "법령", "count": 23, "children": [] },
+  { "name": "Philosophy", "path": "Philosophy", "count": 12, "children": [] }
+]
diff --git a/clients/ds-app/contract/fixtures/foundationmodels-respond.json b/clients/ds-app/contract/fixtures/foundationmodels-respond.json
new file mode 100644
index 0000000..294cd2d
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/foundationmodels-respond.json
@@ -0,0 +1,96 @@
+{
+  "_meta": {
+    "fixture": "foundationmodels-respond",
+    "purpose": "S2-3a — Apple FoundationModels live capture (OnDeviceProvider 결선 + 테스트 동결 기준)",
+    "captured_on": "M5 Max MacBook Pro (128GB, Apple Intelligence)",
+    "captured_date": "2026-06-04",
+    "sdk": "macOS 26.5 SDK / FoundationModels.framework",
+    "note": "SDK 가 marshaling 하므로 raw request_body 는 없음. 이 파일은 응답 모양 + 에러 타입 + 취소 동작의 동결 기준."
+  },
+
+  "availability": {
+    "observed": "available",
+    "is_available_convenience": true,
+    "read_is_synchronous": true,
+    "api": "SystemLanguageModel.default.availability",
+    "enum": {
+      "available": "case available",
+      "unavailable_reasons": ["deviceNotEligible", "appleIntelligenceNotEnabled", "modelNotReady"]
+    },
+    "supports_korean": true,
+    "supported_language_count": 23
+  },
+
+  "happy_path": {
+    "api": "session.respond(to: String, options: GenerationOptions) async throws -> Response<String>",
+    "content_accessor": "response.content   (Response<String>.content : String)",
+    "observed_content": "압력용기의 충격시험(Charpy) 면제 판정은, 용기의 압력 등급이 10MPa 이하인 경우, 충격 시험을 면제할 수 있으며, 이는 용기의 안전성을 보장하기 위한 중요한 기준입니다.",
+    "observed_latency_ms": 1291.3,
+    "transcript_entries_count": 1,
+    "is_responding_after": false,
+    "quality_note": "내용은 부정확(온디바이스 ~3B/2-bit QAT). corpusAsk 부적합·quickSummarize/classify 적합 라우팅 정합 — 사실성은 RemoteDS 코퍼스가 담당."
+  },
+
+  "session_init": {
+    "api": "LanguageModelSession(model: .default, tools: [], instructions: String?)",
+    "instructions_timing": "init (per-call 아님)",
+    "instructions_nil_handling": "systemPrompt == nil 이면 instructions 인자 생략 (빈 문자열 금지)",
+    "prewarm": "session.prewarm() — 동기 반환(관찰 ~1.3ms), 백그라운드 워밍",
+    "stateless_per_request": "호출마다 새 세션 생성 → instructions(init-time) + rateLimited/concurrentRequests(세션 상태) 둘 다 우회"
+  },
+
+  "generation_options": {
+    "api": "GenerationOptions(sampling: SamplingMode? = nil, temperature: Double? = nil, maximumResponseTokens: Int? = nil)",
+    "mapping": "AICompletionRequest.maxTokens -> maximumResponseTokens",
+    "temperature_note": "AICompletionRequest 에 temperature 필드 없음(동결) → 미설정(모델 기본). LocalMLX 와 동일 정책(둘 다 미설정)."
+  },
+
+  "generation_error": {
+    "_source": "Xcode jump-to-def / swiftinterface (LanguageModelSession.GenerationError) — authoritative, version-accurate",
+    "type": "LanguageModelSession.GenerationError : Error, LocalizedError",
+    "associated_value": "각 case 는 GenerationError.Context (refusal 은 (Refusal, Context))",
+    "cases": [
+      "exceededContextWindowSize(Context)",
+      "assetsUnavailable(Context)",
+      "guardrailViolation(Context)",
+      "unsupportedGuide(Context)",
+      "unsupportedLanguageOrLocale(Context)",
+      "decodingFailure(Context)",
+      "rateLimited(Context)",
+      "concurrentRequests(Context)",
+      "refusal(Refusal, Context)"
+    ],
+    "plan_corrections": [
+      "plan 가정 'refusal 케이스명 없음' = 틀림 → refusal 은 별도 case 로 존재(guardrailViolation 과 구분).",
+      "plan 에 없던 concurrentRequests case 존재 — rateLimited 와 함께 stateless 세션에서 뜨면 세션 공유 버그 신호.",
+      "assetsUnavailable 정확명 확정(모델 자산 미가용)."
+    ],
+    "reproduced_live": {
+      "exceededContextWindowSize": {
+        "trigger": "의도적 컨텍스트 오버플로(긴 프롬프트)",
+        "errorDescription": "Exceeded model context window size"
+      }
+    },
+    "finish_reason_mapping": {
+      "guardrailViolation": ".refused",
+      "refusal": ".refused",
+      "exceededContextWindowSize": ".unavailable",
+      "rateLimited": ".unavailable + loud log (stateless 인데 발생 = 세션 재사용 버그 신호)",
+      "concurrentRequests": ".unavailable + loud log (동일 — stateless 위반 신호)",
+      "unsupportedLanguageOrLocale": ".unavailable (+ supportedLocale 사전체크로 회피)",
+      "unsupportedGuide": ".unavailable",
+      "decodingFailure": ".unavailable",
+      "assetsUnavailable": ".unavailable",
+      "@unknown default": ".unavailable + loud log"
+    }
+  },
+
+  "cancellation": {
+    "_finding": "S2-Fe 전제 확정 — COOPERATIVE",
+    "cancel_requested_at_ms": 500,
+    "threw": "CancellationError",
+    "elapsed_ms": 533.6,
+    "interpretation": "respond() 는 mid-flight Task 취소를 협조적으로 honor(요청 33ms 후 CancellationError throw).",
+    "implication": "OnDevice complete() 에 surrounding Task.checkCancellation() 은 belt-and-suspenders(실제 중단은 respond() 내부). streamResponse 토큰단위 취소 폴백 불필요(선전환 금지)."
+  }
+}
diff --git a/clients/ds-app/contract/fixtures/llm-router-chat.request.json b/clients/ds-app/contract/fixtures/llm-router-chat.request.json
new file mode 100644
index 0000000..bc6bb08
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/llm-router-chat.request.json
@@ -0,0 +1,18 @@
+{
+  "_meta": {
+    "fixture": "llm-router-chat.request",
+    "status": "CAPTURED_LIVE",
+    "captured_date": "2026-06-05",
+    "captured_via": "MacBook → Tailscale 100.76.254.116:8890 (맥미니 llm-router, GUI 로그인 복구 후)",
+    "endpoint": "POST http://100.76.254.116:8890/v1/chat/completions",
+    "model_note": "llm-router /v1/models 노출 ID = {gemma-4-26b-a4b-it-8bit, mac-mini-default, qwen-macbook, claude-cloud}. LocalMLXProvider 기본 = 'mac-mini-default'(별칭 → 라우터가 gemma-4-26b 로 resolve). 이전 provisional 의 'gemma-macmini' 는 llm-router 모델 ID 아님(그건 DS /search/ask?backend= 쪽 이름).",
+    "call_shape_note": "messages=[system,user] 분리 고정(load-bearing). system.content = AICompletionRequest.systemPrompt ?? \"\". max_tokens = AICompletionRequest.maxTokens."
+  },
+  "model": "mac-mini-default",
+  "messages": [
+    { "role": "system", "content": "You are a concise technical assistant." },
+    { "role": "user", "content": "충격시험 면제 기준을 한 문장으로 요약해줘." }
+  ],
+  "max_tokens": 512,
+  "stream": false
+}
diff --git a/clients/ds-app/contract/fixtures/llm-router-chat.response.json b/clients/ds-app/contract/fixtures/llm-router-chat.response.json
new file mode 100644
index 0000000..c290105
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/llm-router-chat.response.json
@@ -0,0 +1,25 @@
+{
+  "_meta": {
+    "fixture": "llm-router-chat.response",
+    "status": "CAPTURED_LIVE",
+    "captured_date": "2026-06-05",
+    "endpoint": "POST http://100.76.254.116:8890/v1/chat/completions",
+    "note": "raw llm-router 응답(맥미니 Gemma 4 26B, MLX). 요청 model='mac-mini-default' → 응답 model='mlx-community/gemma-4-26b-a4b-it-8bit' 로 resolve. 매핑: choices[0].message.content→text, finish_reason→AIFinishReason, latency=측정값.",
+    "latency_observed_s": 1.73
+  },
+  "id": "chatcmpl-1780610323",
+  "object": "chat.completion",
+  "created": 1780610323,
+  "model": "mlx-community/gemma-4-26b-a4b-it-8bit",
+  "choices": [
+    {
+      "index": 0,
+      "message": {
+        "role": "assistant",
+        "content": "충격시험은 제품의 설계, 재질, 구조적 특성상 충격 에너지를 흡수할 수 있거나 파손 위험이 극히 낮음을 기술적으로 입증할 경우 면제될 수 있습니다."
+      },
+      "finish_reason": "stop"
+    }
+  ],
+  "usage": { "prompt_tokens": 42, "completion_tokens": 48, "total_tokens": 90 }
+}
diff --git a/clients/ds-app/contract/fixtures/memo_detail.json b/clients/ds-app/contract/fixtures/memo_detail.json
new file mode 100644
index 0000000..0495a0e
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/memo_detail.json
@@ -0,0 +1,23 @@
+{
+  "id": 20238,
+  "title": "엘보 발주 확인 건",
+  "content": "엘보 내경가공 발주서 금요일까지 확인.\n- [ ] 도면 rev C 기준 공차 재확인\n- [ ] 발주처에 납기 회신",
+  "file_format": "txt",
+  "user_tags": ["업무"],
+  "ai_tags": ["발주", "엘보"],
+  "ai_domain": "General",
+  "ai_sub_group": "업무메모",
+  "ai_summary": "엘보 발주서 금요일까지 확인, 도면 rev C 공차 재확인.",
+  "pinned": true,
+  "archived": false,
+  "ask_includable": true,
+  "memo_task_state": { "0": { "checked_at": "2026-06-03T10:02:00.000Z" } },
+  "ai_event_kind": "task",
+  "ai_event_confidence": 0.78,
+  "source_channel": "memo",
+  "source_metadata": {},
+  "file_type": "note",
+  "file_path": null,
+  "created_at": "2026-06-03T09:40:00.000Z",
+  "updated_at": "2026-06-03T10:02:00.000Z"
+}
diff --git a/clients/ds-app/contract/fixtures/memos_list.json b/clients/ds-app/contract/fixtures/memos_list.json
new file mode 100644
index 0000000..53ea0ea
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/memos_list.json
@@ -0,0 +1,53 @@
+{
+  "items": [
+    {
+      "id": 20238,
+      "title": "엘보 발주 확인 건",
+      "content": "엘보 내경가공 발주서 금요일까지 확인. 도면 rev C 기준으로 공차 재확인 필요.",
+      "file_format": "txt",
+      "user_tags": ["업무"],
+      "ai_tags": ["발주", "엘보"],
+      "ai_domain": "General",
+      "ai_sub_group": "업무메모",
+      "ai_summary": "엘보 발주서 금요일까지 확인, 도면 rev C 공차 재확인.",
+      "pinned": true,
+      "archived": false,
+      "ask_includable": true,
+      "memo_task_state": { "0": { "checked_at": "2026-06-03T10:02:00.000Z" } },
+      "ai_event_kind": "task",
+      "ai_event_confidence": 0.78,
+      "source_channel": "memo",
+      "source_metadata": {},
+      "file_type": "note",
+      "file_path": null,
+      "created_at": "2026-06-03T09:40:00.000Z",
+      "updated_at": "2026-06-03T10:02:00.000Z"
+    },
+    {
+      "id": 20251,
+      "title": "음성 메모 — 현장 점검",
+      "content": "3공장 압축기 베어링 소음. 다음 점검 때 진동 측정 추가하기로.",
+      "file_format": "m4a",
+      "user_tags": null,
+      "ai_tags": ["현장", "압축기", "점검"],
+      "ai_domain": "Industrial_Safety",
+      "ai_sub_group": "현장메모",
+      "ai_summary": "3공장 압축기 베어링 소음, 진동 측정 추가 예정.",
+      "pinned": false,
+      "archived": false,
+      "ask_includable": true,
+      "memo_task_state": {},
+      "ai_event_kind": "note",
+      "ai_event_confidence": 0.64,
+      "source_channel": "voice",
+      "source_metadata": { "duration_s": 23, "device": "iPhone" },
+      "file_type": "audio",
+      "file_path": "memos/voice/2026/06/test-voice-memo.m4a",
+      "created_at": "2026-06-02T17:11:00.000Z",
+      "updated_at": "2026-06-02T17:11:40.000Z"
+    }
+  ],
+  "total": 4807,
+  "page": 1,
+  "page_size": 20
+}
diff --git a/clients/ds-app/contract/fixtures/search.json b/clients/ds-app/contract/fixtures/search.json
new file mode 100644
index 0000000..f17e72e
--- /dev/null
+++ b/clients/ds-app/contract/fixtures/search.json
@@ -0,0 +1,38 @@
+{
+  "results": [
+    {
+      "id": 4912,
+      "title": "ASME Section VIII Div 1 — Impact Test 요건",
+      "ai_domain": "Engineering",
+      "ai_summary": "압력용기 재료의 충격시험 면제/요구 조건(UCS-66 등)을 정리.",
+      "file_format": "pdf",
+      "score": 0.8714,
+      "snippet": "...UCS-66 면제 곡선과 MDMT 적용. 충격시험 면제 여부는 재료군과 두께로 결정...",
+      "match_reason": "vector+rerank",
+      "chunk_id": 88213,
+      "chunk_index": 3,
+      "section_title": "2. UCS-66 면제 곡선",
+      "rerank_score": 0.913,
+      "freshness_debug": null
+    },
+    {
+      "id": 5044,
+      "title": "KGS FU211 §2.5 — 가스설비 충격 관련 요건",
+      "ai_domain": "Industrial_Safety",
+      "ai_summary": "KGS FU211 가스 사용시설 기준 중 충격/내압 관련 조항.",
+      "file_format": "pdf",
+      "score": 0.7321,
+      "snippet": "...§2.5 충격에 의한 손상 방지... §2.8 내압 시험...",
+      "match_reason": "vector",
+      "chunk_id": 90122,
+      "chunk_index": 1,
+      "section_title": "2.5",
+      "rerank_score": 0.742,
+      "freshness_debug": null
+    }
+  ],
+  "total": 2,
+  "query": "충격시험 면제",
+  "mode": "hybrid",
+  "debug": null
+}
diff --git a/clients/ds-app/contract/shape_diff.py b/clients/ds-app/contract/shape_diff.py
new file mode 100755
index 0000000..bbfd29a
--- /dev/null
+++ b/clients/ds-app/contract/shape_diff.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+"""S2-Ff shape diff — frozen fixture ↔ live response 의 *모양*(키/타입)만 비교.
+
+스칼라 *값*은 무시한다(LLM 응답 본문·id·토큰수는 호출마다 다름). 비교 대상 = 키 존재 + 타입.
+argv[1] = frozen fixture 경로, argv[2] = live 응답 JSON 경로.
+exit 1 = breaking 드리프트(frozen 키 삭제 / 타입 변경), exit 0 = clean(동일 or live 신규키만).
+양쪽 top-level `_meta`(우리 주석)는 비교에서 제외.
+"""
+import json
+import sys
+
+
+def strip_meta(o):
+    return {k: v for k, v in o.items() if k != "_meta"} if isinstance(o, dict) else o
+
+
+def tag(v):
+    if v is None:
+        return "null"
+    if isinstance(v, bool):
+        return "bool"
+    if isinstance(v, (int, float)):
+        return "number"
+    if isinstance(v, str):
+        return "string"
+    if isinstance(v, list):
+        return "array"
+    if isinstance(v, dict):
+        return "object"
+    return "unknown"
+
+
+breaking = []
+info = []
+
+
+def diff(live, frozen, path):
+    lt, ft = tag(live), tag(frozen)
+    # nullability 는 드리프트로 보지 않음(fixture 의 null = nullable 표식).
+    if lt == "null" or ft == "null":
+        if lt != ft:
+            info.append(f"{path or '<root>'}: null↔{ft if lt == 'null' else lt} (nullable, 무시 가능)")
+        return
+    if lt != ft:
+        breaking.append(f"{path or '<root>'}: frozen={ft} live={lt} (타입 변경)")
+        return
+    if ft == "object":
+        for k, fv in frozen.items():
+            p = f"{path}.{k}" if path else k
+            if k in live:
+                diff(live[k], fv, p)
+            else:
+                breaking.append(f"{p}: frozen 에 있으나 live 에 없음 (키 삭제)")
+        for k in live:
+            if k not in frozen:
+                p = f"{path}.{k}" if path else k
+                info.append(f"{p}: live 신규 키 (비파괴)")
+    elif ft == "array":
+        if frozen:
+            if live:
+                diff(live[0], frozen[0], f"{path}[0]")
+            else:
+                info.append(f"{path}[]: live 빈 배열 — element shape 검증 불가")
+
+
+def main():
+    if len(sys.argv) != 3:
+        print("usage: shape_diff.py <frozen_fixture> <live_json>", file=sys.stderr)
+        sys.exit(2)
+    frozen = strip_meta(json.load(open(sys.argv[1], encoding="utf-8")))
+    live = strip_meta(json.load(open(sys.argv[2], encoding="utf-8")))
+    diff(live, frozen, "")
+    for m in breaking:
+        print(f"  DRIFT  {m}")
+    for m in info:
+        print(f"  info   {m}")
+    if not breaking and not info:
+        print("  (shape identical)")
+    sys.exit(1 if breaking else 0)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/clients/ds-app/project.yml b/clients/ds-app/project.yml
new file mode 100644
index 0000000..ba780af
--- /dev/null
+++ b/clients/ds-app/project.yml
@@ -0,0 +1,76 @@
+# A-6 — real macOS .app target for the DS app shell.
+#
+# Why this exists: opening Package.swift directly in Xcode produced an *executable* SwiftPM target
+# with no .app bundle / Info.plist, so macOS treated it as an accessory and Cmd+R never opened a
+# window (see ds-native-app-program memory). This generates a proper application target whose @main
+# lives in App/DSApp.swift and which links the AppFeature library product from the local SwiftPM
+# package. project.yml is the source of truth; DSApp.xcodeproj + Support/*.plist|.entitlements are
+# generated artifacts (gitignored). Regenerate with: xcodegen generate
+name: DSApp
+options:
+  bundleIdPrefix: net.hyungi
+  deploymentTarget:
+    macOS: "26.0"
+  createIntermediateGroups: true
+  minimumXcodeGenVersion: "2.40.0"
+
+settings:
+  base:
+    SWIFT_VERSION: "6.0"               # Swift 6 language mode (matches package .swiftLanguageMode(.v6))
+    SWIFT_STRICT_CONCURRENCY: complete
+    MACOSX_DEPLOYMENT_TARGET: "26.0"
+    CODE_SIGN_STYLE: Automatic
+    # Local dev: no signing identity needed to build/run on this Mac.
+    CODE_SIGNING_ALLOWED: "NO"
+    CODE_SIGNING_REQUIRED: "NO"
+
+packages:
+  # Local SwiftPM package = this repo (Package.swift): AIFabric + DSKit + AppFeature libraries.
+  DSPackage:
+    path: .
+
+targets:
+  DSApp:
+    type: application
+    platform: macOS
+    deploymentTarget: "26.0"
+    sources:
+      - path: App          # App/DSApp.swift only — @main window + DI shell
+    dependencies:
+      - package: DSPackage
+        product: AppFeature
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: net.hyungi.dsapp
+        PRODUCT_NAME: DS
+        GENERATE_INFOPLIST_FILE: "NO"
+        MARKETING_VERSION: "0.1"
+        CURRENT_PROJECT_VERSION: "1"
+        ENABLE_HARDENED_RUNTIME: "YES"
+    info:
+      path: Support/Info.plist
+      properties:
+        CFBundleName: DS
+        CFBundleDisplayName: DS
+        CFBundleShortVersionString: "0.1"
+        CFBundleVersion: "1"
+        CFBundlePackageType: APPL
+        LSMinimumSystemVersion: "26.0"
+        LSApplicationCategoryType: public.app-category.productivity
+        NSHumanReadableCopyright: ""
+    entitlements:
+      path: Support/DSApp.entitlements
+      properties:
+        com.apple.security.app-sandbox: true
+        com.apple.security.network.client: true                 # LiveDSClient HTTP → DS / mac mini :8890
+        com.apple.security.files.user-selected.read-write: true # FU-C upload / FU-D download save
+
+schemes:
+  DSApp:
+    build:
+      targets:
+        DSApp: all
+    run:
+      config: Debug
+    test:
+      config: Debug