diff --git a/app/services/briefing/clustering.py b/app/services/briefing/clustering.py
index 2b62569..6896f6e 100644
--- a/app/services/briefing/clustering.py
+++ b/app/services/briefing/clustering.py
@@ -5,7 +5,7 @@ Phase 4 와 axis 반대: country 별 cluster 가 아닌 **전체 doc 합쳐서 t
 
 파라미터 (5h 윈도우용):
 - LAMBDA = ln(2)/2h ≈ 0.347 (2시간 반감기, 야간 5h 윈도우라 빠른 감쇠)
-- threshold = 0.78 고정 (Phase 4 0.75~0.80 중간값)
+- threshold = 0.70 (2026-05-13 조정 — 0.78 에서 spread case kept=1 발생 후 완화)
 - MIN_ARTICLES_PER_TOPIC = 2 (야간 sparse 대비 완화)
 - MIN_COUNTRIES_PER_TOPIC = 2 (cross-country 가치 핵심)
 - MAX_TOPICS = 7 (1페이지 분량)
@@ -22,7 +22,7 @@ from services.clustering_common import (
 logger = setup_logger("briefing_clustering")
 
 LAMBDA = math.log(2) / (2.0 / 24.0)   # 2시간 반감기 (단위: 일)
-THRESHOLD = 0.78
+THRESHOLD = 0.70
 CENTROID_ALPHA = 0.7
 MIN_ARTICLES_PER_TOPIC = 2
 MIN_COUNTRIES_PER_TOPIC = 2
diff --git a/migrations/262_seed_tech_ai_news_sources.sql b/migrations/262_seed_tech_ai_news_sources.sql
new file mode 100644
index 0000000..6866a48
--- /dev/null
+++ b/migrations/262_seed_tech_ai_news_sources.sql
@@ -0,0 +1,26 @@
+-- 2026-05-13 — 기술/AI 뉴스 source seed (14건, 8개국)
+-- WHERE NOT EXISTS 로 idempotent. 기존 row 보존, 신규만 insert.
+-- briefing/digest 의 cross-country tech 토픽 cluster 다양성 확보.
+-- 8 country: CN, DE, FR, GB, IN, JP, KR, US. category = Tech / AI.
+
+INSERT INTO news_sources (name, country, language, feed_type, feed_url, category, enabled)
+SELECT v.name, v.country, v.language, v.feed_type, v.feed_url, v.category, v.enabled
+FROM (VALUES
+    ('GeekNews (Hada)',          'KR', 'ko', 'rss', 'https://feeds.feedburner.com/geeknews-feed',                'Tech', true),
+    ('AI Times',                 'KR', 'ko', 'rss', 'https://www.aitimes.com/rss/S1N1.xml',                      'AI',   true),
+    ('Hacker News',              'US', 'en', 'rss', 'https://hnrss.org/frontpage?count=30',                      'Tech', true),
+    ('ArsTechnica AI',           'US', 'en', 'rss', 'https://arstechnica.com/ai/feed/',                          'AI',   true),
+    ('The Verge Tech',           'US', 'en', 'rss', 'https://www.theverge.com/rss/index.xml',                    'Tech', true),
+    ('TechCrunch',               'US', 'en', 'rss', 'https://techcrunch.com/feed/',                              'Tech', true),
+    ('The Register',             'GB', 'en', 'rss', 'https://www.theregister.com/headlines.atom',                'Tech', true),
+    ('Heise Online',             'DE', 'de', 'rss', 'https://www.heise.de/rss/heise-atom.xml',                   'Tech', true),
+    ('ITmedia News',             'JP', 'ja', 'rss', 'https://rss.itmedia.co.jp/rss/2.0/aiplus.xml',              'AI',   true),
+    ('Gigazine',                 'JP', 'ja', 'rss', 'https://gigazine.net/news/rss_2.0/',                        'Tech', true),
+    ('36Kr',                     'CN', 'zh', 'rss', 'https://36kr.com/feed',                                     'Tech', true),
+    ('Numerama',                 'FR', 'fr', 'rss', 'https://www.numerama.com/feed',                             'Tech', true),
+    ('YourStory',                'IN', 'en', 'rss', 'https://yourstory.com/feed',                                   'Tech', true),
+    ('BBC Technology',           'GB', 'en', 'rss', 'https://feeds.bbci.co.uk/news/technology/rss.xml',          'Tech', true)
+) AS v(name, country, language, feed_type, feed_url, category, enabled)
+WHERE NOT EXISTS (
+    SELECT 1 FROM news_sources ns WHERE ns.name = v.name
+);