feat: show masked config/secrets on dashboard for deployment debugging

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webui.py

@@ -495,6 +495,17 @@ async def dashboard():
     pull_html = _sync_entry_html(s["last_pull"])
     push_html = _sync_entry_html(s["last_push"])
 
+    def _mask(val: str) -> str:
+        if not val:
+            return '<span style="color:#dc3545">NOT SET</span>'
+        if len(val) <= 10:
+            return "***"
+        return f'<code>{val[:6]}***{val[-4:]}</code>'
+
+    outline_url = os.environ.get("OUTLINE_URL", "")
+    outline_tok = _mask(os.environ.get("OUTLINE_TOKEN", ""))
+    ts_authkey  = _mask(os.environ.get("TS_AUTHKEY", ""))
+
     body = f"""
 <div class="card">
   <h2>Vault Status</h2>
@@ -511,6 +522,16 @@ async def dashboard():
     <a href="/changes" class="btn btn-secondary">Preview Changes</a>
   </div>
   <div id="output"></div>
+</div>
+<div class="card" style="margin-top:12px">
+  <h2>Config</h2>
+  <table>
+    <tr><th>Key</th><th>Value</th></tr>
+    <tr><td>OUTLINE_URL</td><td><code>{outline_url or '<span style="color:#dc3545">NOT SET</span>'}</code></td></tr>
+    <tr><td>OUTLINE_TOKEN</td><td>{outline_tok}</td></tr>
+    <tr><td>TS_AUTHKEY</td><td>{ts_authkey}</td></tr>
+    <tr><td>APP_VERSION</td><td><code>{APP_VERSION}</code></td></tr>
+  </table>
 </div>"""
     return HTMLResponse(_page("Dashboard", body))