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+# DevConsole Runtime UI Baseline
+
+This document fixes the current production UI baseline for DevConsole.
+
+## Main rule
+
+The root route `/` must render:
+
+```text
+frontend/runtime.html
+```
+
+The file below is legacy and must not be used as the main UI:
+
+```text
+frontend/index.html
+```
+
+## Why
+
+`index.html` is the old editor-era interface. It contains legacy blocks that must not appear in the production runtime UI:
+
+- manual file editor;
+- GitHub settings panel in sidebar;
+- old Android device dropdown;
+- old combined logs.
+
+`runtime.html` is the active production runtime interface:
+
+- project cards;
+- clickable Android device cards;
+- selected device highlight;
+- runtime scenarios;
+- separated runtime log;
+- separated system/activity log under devices;
+- errors panel for AI;
+- system status panel;
+- project OTA settings modal.
+
+## Backend routing requirement
+
+`backend/main.py` must keep:
+
+```python
+@app.get('/')
+async def root():
+    return FileResponse(FRONTEND_DIR / 'runtime.html')
+```
+
+Optional runtime alias:
+
+```python
+@app.get('/runtime')
+async def runtime_page():
+    return FileResponse(FRONTEND_DIR / 'runtime.html')
+```
+
+## Development rule
+
+Frontend changes must be additive and targeted.
+
+Do not replace the whole `frontend/workspace.js` or `frontend/runtime.html` unless intentionally restoring from a known-good commit.
+
+Known-good runtime UI reference chain:
+
+```text
+008eae9 — GitHub-only runtime UI
+49a388c — system panel under log
+4b2bd2b — Android device model cards
+16a726c — separated system log under devices
+ec268a5 — root route switched to runtime.html
+```