diff --git a/.gitea/workflows/cd.yaml b/.gitea/workflows/cd.yaml
index 41fa69f..f4ab1b4 100644
--- a/.gitea/workflows/cd.yaml
+++ b/.gitea/workflows/cd.yaml
@@ -93,11 +93,10 @@ jobs:
         run: |
           CHANGED=$(git diff --name-only HEAD~1 HEAD 2>/dev/null || echo "")
           echo "$CHANGED"
-          if echo "$CHANGED" | grep -qE '^(templates/admin/.*|templates/ewoooc_base\.html|templates/components/_ewoooc_shell\.html|static/css/observability-system\.css|web/static/css/observability-system\.css|routes/admin_observability_routes\.py|scripts/(check_observability_|check_observability_suite\.sh|observability_contract|quick_review\.sh|sync_observability_css)|docs/guides/observability_ui_governance\.md|docs/guides/deployment_sop\.md)'; then
-            echo "needed=true" >> $GITHUB_OUTPUT
+          printf '%s\n' "$CHANGED" | python3 scripts/check_observability_deploy_gate.py --stdin --github-output "$GITHUB_OUTPUT"
+          if grep -q '^needed=true$' "$GITHUB_OUTPUT"; then
             echo "🎛️ AI 觀測台 QA: required"
           else
-            echo "needed=false" >> $GITHUB_OUTPUT
             echo "ℹ️ AI 觀測台 QA: skipped"
           fi
           CHANGED=$(git diff --name-only HEAD~1 HEAD 2>/dev/null || echo "")
diff --git a/docs/guides/deployment_sop.md b/docs/guides/deployment_sop.md
index 7feb782..f64015b 100644
--- a/docs/guides/deployment_sop.md
+++ b/docs/guides/deployment_sop.md
@@ -78,6 +78,7 @@ CD 也會自動判斷觀測台相關變更：
 - Deploy 後跑 `./scripts/quick_review.sh --observability-smoke --base-url https://mo.wooo.work --timeout 12`。
 - 若變更與觀測台無關，CD 會跳過這組額外 QA，避免拖慢一般後端部署。
 - 觸發範圍包含觀測台 templates、shell/topbar、觀測台 CSS、`routes/admin_observability_routes.py`、`quick_review.sh`、`check_observability_*`、`observability_contract.py`、`sync_observability_css.py`。
+- 觸發判斷集中在 `scripts/check_observability_deploy_gate.py`，不要在 workflow 內新增第二份長 regex。
 
 ## 🔍 維運指令
 - **查看日誌**: `docker logs -f momo-pro-system --tail 100`
diff --git a/docs/memory/observability_ui_qa_guardrails_20260505.md b/docs/memory/observability_ui_qa_guardrails_20260505.md
index b686e98..1b8ba8d 100644
--- a/docs/memory/observability_ui_qa_guardrails_20260505.md
+++ b/docs/memory/observability_ui_qa_guardrails_20260505.md
@@ -56,6 +56,7 @@ bash scripts/check_observability_suite.sh
 - 觀測台頁面清單、URL、`active_page`、內容 marker 不要分散維護，先改 `scripts/observability_contract.py`。
 - `quick_review.sh --observability-qa` 預設打 production `https://mo.wooo.work`；測 staging/localhost 時要明確帶 `--base-url`。
 - Gitea CD 會偵測觀測台 template/CSS/route/QA script/guide 變更：deploy 前跑 CSS mirror check + static QA，deploy 後跑 production smoke。QA script 範圍包含 `quick_review.sh`、`check_observability_*`、`observability_contract.py`、`sync_observability_css.py`。CD 不會偷偷修 mirror；若 check fail，先本地跑 sync 後提交。
+- CD 觸發判斷集中在 `scripts/check_observability_deploy_gate.py`；不要在 `.gitea/workflows/cd.yaml` 另維護一份長 regex。
 
 ## 已鎖住的回歸
 
diff --git a/scripts/check_observability_deploy_gate.py b/scripts/check_observability_deploy_gate.py
new file mode 100644
index 0000000..06e6de4
--- /dev/null
+++ b/scripts/check_observability_deploy_gate.py
@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+"""Decide whether AI observability deploy QA should run.
+
+Input is a list of changed files via argv or stdin. The script prints matched
+files and can write `needed=true|false` to a GitHub/Gitea Actions output file.
+It exits 0 for both true and false so workflow control stays explicit.
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import re
+from pathlib import Path
+
+
+TRIGGER_PATTERNS = (
+    r"^templates/admin/.*",
+    r"^templates/ewoooc_base\.html$",
+    r"^templates/components/_ewoooc_shell\.html$",
+    r"^static/css/observability-system\.css$",
+    r"^web/static/css/observability-system\.css$",
+    r"^routes/admin_observability_routes\.py$",
+    r"^scripts/check_observability_.*",
+    r"^scripts/check_observability_suite\.sh$",
+    r"^scripts/observability_contract\.py$",
+    r"^scripts/quick_review\.sh$",
+    r"^scripts/sync_observability_css\.py$",
+    r"^docs/guides/observability_ui_governance\.md$",
+    r"^docs/guides/deployment_sop\.md$",
+)
+
+
+def normalize_paths(raw_paths: list[str]) -> list[str]:
+    paths: list[str] = []
+    for raw in raw_paths:
+        for line in raw.splitlines():
+            path = line.strip()
+            if path:
+                paths.append(path)
+    return paths
+
+
+def match_paths(paths: list[str]) -> list[str]:
+    regexes = [re.compile(pattern) for pattern in TRIGGER_PATTERNS]
+    return [path for path in paths if any(regex.search(path) for regex in regexes)]
+
+
+def write_output(output_path: str | None, needed: bool) -> None:
+    if not output_path:
+        return
+    path = Path(output_path)
+    with path.open("a", encoding="utf-8") as handle:
+        handle.write(f"needed={'true' if needed else 'false'}\n")
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="Check observability deploy QA trigger")
+    parser.add_argument("paths", nargs="*", help="Changed file paths")
+    parser.add_argument("--stdin", action="store_true", help="Read changed paths from stdin")
+    parser.add_argument(
+        "--github-output",
+        default=os.environ.get("GITHUB_OUTPUT"),
+        help="Actions output file to append needed=true|false.",
+    )
+    args = parser.parse_args()
+
+    raw_paths = list(args.paths)
+    if args.stdin:
+        import sys
+
+        raw_paths.append(sys.stdin.read())
+
+    paths = normalize_paths(raw_paths)
+    matches = match_paths(paths)
+    needed = bool(matches)
+
+    write_output(args.github_output, needed)
+
+    print(f"observability_qa_needed={'true' if needed else 'false'}")
+    if matches:
+        print("matched_files:")
+        for path in matches:
+            print(f"- {path}")
+    else:
+        print("matched_files: none")
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())