diff --git a/apps/api/src/main.py b/apps/api/src/main.py
index e4225961..c806f682 100644
--- a/apps/api/src/main.py
+++ b/apps/api/src/main.py
@@ -287,6 +287,13 @@ else:
 # Middleware
 # =============================================================================
 
+# 2026-04-03 ogt: Nginx 反向代理修正 — 讓 FastAPI 信任 X-Forwarded-Proto
+# 解決問題: /api/v1/knowledge (無結尾斜線) 307 redirect 產生 http:// Location
+# 原因: FastAPI 不知道自己在 HTTPS 後面，redirect 回 http://
+# 效果: 有了此中間件，307 Location 會是 https://
+from uvicorn.middleware.proxy_headers import ProxyHeadersMiddleware
+app.add_middleware(ProxyHeadersMiddleware, trusted_hosts="*")
+
 # CORS - Strict Whitelist (Iron Law #2)
 # NO wildcards, NO UAT
 app.add_middleware(