diff --git a/app/api/search.py b/app/api/search.py
index 2cd43ed..d70c5af 100644
--- a/app/api/search.py
+++ b/app/api/search.py
@@ -710,7 +710,9 @@ async def ask(
     # 30s 로 align → classifier 동작 안정. ask 응답 latency 상한 ↑ 의도.
     try:
         classifier_result = await asyncio.wait_for(classifier_task, timeout=30.0)
-    except (asyncio.TimeoutError, Exception):
+    except asyncio.CancelledError:
+        raise  # 요청 취소는 전파 — broad except 가 삼키지 않게 명시 (R3)
+    except Exception:
         classifier_result = ClassifierResult("timeout", None, [], [], 0.0)
 
     defense_log["classifier"] = {
@@ -872,7 +874,9 @@ async def ask(
         # → classifier 와 동일 패턴 (search.py:522 가 6s→15s swap 했던 case). 10s 로 align.
         try:
             verifier_result = await asyncio.wait_for(verifier_task, timeout=10.0)
-        except (asyncio.TimeoutError, Exception):
+        except asyncio.CancelledError:
+            raise  # 요청 취소는 전파 — broad except 가 삼키지 않게 명시 (R3)
+        except Exception:
             verifier_result = VerifierResult("timeout", [], 0.0)
 
     # Verifier contradictions → grounding flags 머지 (prefix 로 구분, severity 3단계)
diff --git a/app/workers/deep_summary_worker.py b/app/workers/deep_summary_worker.py
index 728c181..077ff54 100644
--- a/app/workers/deep_summary_worker.py
+++ b/app/workers/deep_summary_worker.py
@@ -144,9 +144,13 @@ async def process(
         logger.info(f"[deep] id={document_id} 맥북 일시 불가 — 보류 (deferred)")
         raise
     except Exception as exc:
+        # 호출 실패(네트워크/API 5xx 등)는 삼키지 않고 전파 (R3) — queue_consumer 가
+        # attempts 소진까지 재시도 후 status=failed(dead-letter)로 가시화한다. 삼키면
+        # worker_fn 이 정상 반환 → 큐가 completed 로 확정 → ai_detail_summary 영구 누락 +
+        # tier 가 triage 에 고착(silent 영구 손실). extract/marker/fulltext/stt 정본과 일치.
+        # 완주 전 doc 쓰기(168~)는 일어나지 않으므로 부분 쓰기 0 (sleep-안전).
         logger.warning(f"[deep] 호출 실패 id={document_id} model={used_cfg.model}: {exc}")
-        parse_error = "call_failed"
-        raw = ""
+        raise
     finally:
         await client.close()
 
diff --git a/app/workers/queue_consumer.py b/app/workers/queue_consumer.py
index 4903ff1..c7c2ebb 100644
--- a/app/workers/queue_consumer.py
+++ b/app/workers/queue_consumer.py
@@ -275,7 +275,15 @@ async def _process_stage(stage, worker_fn):
                                 item.status = "completed"
                                 item.completed_at = datetime.now(timezone.utc)
                                 await skip_session.commit()
-                        await enqueue_next_stage(document_id, stage)
+                        # 완료 커밋 후 enqueue — 실패가 outer except 로 전파돼 completed 재오픈
+                        # 되지 않게 격리 (R3, 정상 완료 경로와 동일 처리).
+                        try:
+                            await enqueue_next_stage(document_id, stage)
+                        except Exception as enq_err:
+                            logger.error(
+                                f"[{stage}] document_id={document_id} skip(note) 완료됐으나 "
+                                f"다음 단계 enqueue 실패: {enq_err}"
+                            )
                         logger.info(f"[{stage}] document_id={document_id} skip (note)")
                         continue
 
@@ -293,7 +301,15 @@ async def _process_stage(stage, worker_fn):
                 item.completed_at = datetime.now(timezone.utc)
                 await session.commit()
 
-            await enqueue_next_stage(document_id, stage)
+            # 완료는 이미 커밋됨. enqueue_next_stage 실패가 outer except 로 전파되면
+            # completed 항목을 재오픈(pending/failed)해 같은 단계를 재실행 = 비싼 작업 중복
+            # + 부분 재쓰기. 자체 try 로 격리하고 ERROR 로 가시화한다 (R3).
+            try:
+                await enqueue_next_stage(document_id, stage)
+            except Exception as enq_err:
+                logger.error(
+                    f"[{stage}] document_id={document_id} 완료됐으나 다음 단계 enqueue 실패: {enq_err}"
+                )
             logger.info(f"[{stage}] document_id={document_id} 완료")
 
         except StageDeferred as defer:
diff --git a/app/workers/study_question_embed_worker.py b/app/workers/study_question_embed_worker.py
index 016da7b..28fdbf1 100644
--- a/app/workers/study_question_embed_worker.py
+++ b/app/workers/study_question_embed_worker.py
@@ -102,7 +102,9 @@ async def _process_one(session: AsyncSession, qid: int, client: AIClient) -> boo
     try:
         async with asyncio.timeout(EMBED_TIMEOUT_S):
             vec = await client.embed(text)
-    except (asyncio.TimeoutError, Exception) as e:
+    except asyncio.CancelledError:
+        raise  # 취소는 전파 — broad except 가 삼키지 않게 명시 (R3)
+    except Exception as e:
         logger.warning("study_q_embed_failed qid=%s err=%s: %s", qid, type(e).__name__, e)
         # 실패 — status='failed'. 직전 embedding 보존.
         q.embedding_status = "failed"
diff --git a/app/workers/thumbnail_worker.py b/app/workers/thumbnail_worker.py
index 89bd3eb..8a1b360 100644
--- a/app/workers/thumbnail_worker.py
+++ b/app/workers/thumbnail_worker.py
@@ -121,7 +121,12 @@ async def process(document_id: int, session: AsyncSession) -> None:
 
     ok = _extract_thumbnail(source, output, seek)
     if not ok:
-        return
+        # 썸네일 추출 실패(ffmpeg)는 삼키지 않고 raise (R3) — queue_consumer 가 attempts
+        # 소진까지 재시도 후 status=failed 로 가시화. silent return 이면 큐가 completed 로
+        # 확정 + 썸네일 영구 누락 + 재시도/추적 0 (silent skip). 손상 영상이면 failed 로 안착.
+        raise RuntimeError(
+            f"thumbnail 추출 실패: document_id={document_id} source={source}"
+        )
 
     doc.thumbnail_path = str(output)
     doc.updated_at = datetime.now(timezone.utc)