Add local backtest snapshot runner

README.md

@@ -247,6 +247,50 @@ cd frontend
 npm run build
 ```
 
+### Local Backtest Snapshots
+
+For research loops, run the production backtest locally from a SQLite snapshot
+instead of deploying and clicking the Admin job. The snapshot contains only the
+tables needed by `run_backtest`: tickers, OHLCV bars, SPY benchmark closes, and
+activation/recommendation settings. Secrets and cached reports are not copied.
+
+1. Open an SSH tunnel to the production Postgres instance:
+
+```bash
+ssh -N -L 15432:127.0.0.1:5432 deploy@your-server
+```
+
+2. In another terminal, create or refresh the snapshot:
+
+```bash
+# macOS/Linux
+python scripts/create_backtest_snapshot.py \
+  --database-url "postgresql+asyncpg://stock_backend:PASSWORD@127.0.0.1:15432/stock_data_backend" \
+  --output backtest_snapshots/prod.sqlite \
+  --force
+
+# Windows PowerShell
+.venv\Scripts\python.exe scripts\create_backtest_snapshot.py `
+  --database-url "postgresql+asyncpg://stock_backend:PASSWORD@127.0.0.1:15432/stock_data_backend" `
+  --output backtest_snapshots\prod.sqlite `
+  --force
+```
+
+3. Run the backtest fully offline from the snapshot:
+
+```bash
+# macOS/Linux
+python scripts/run_backtest_snapshot.py backtest_snapshots/prod.sqlite --workers 8
+
+# Windows PowerShell
+.venv\Scripts\python.exe scripts\run_backtest_snapshot.py backtest_snapshots\prod.sqlite --workers 12 --allow-spawn
+```
+
+The runner writes `reports/backtest-<timestamp>.json` and prints the headline
+metrics. Keep the SSH tunnel open only while creating the snapshot; the backtest
+run itself is local/offline. `backtest_snapshots/` and generated backtest reports
+are git-ignored.
+
 ## Environment Variables
 
 Configure in `.env` (copy from `.env.example`):