Parse batch number and date from upload filename for live API lookup

AGENTS.md

@@ -9,6 +9,7 @@
 - `batch_store.py` — shared SQLite persistence + batch state machine.
 - `counter_dashboard.py` — Flask dashboard on port 5000, same DB.
 - `recounting_dashboard.py` — Flask recounting dashboard on port 5002, consumes live + recount APIs.
+- `recounting_dashboard_upload.py` — Flask upload+recount dashboard on port 5003; uploads MP4 first, then launches `RECOUNT_CMD --source <mp4>`; START RECOUNT stays disabled until an upload completes.
 
 ## No build / test / lint
 
@@ -30,6 +31,9 @@ PYTHONNOUSERSITE=1 venv/bin/python counter_live_rknn_bytetrack.py
 
 # Run dashboard
 PYTHONNOUSERSITE=1 venv/bin/python counter_dashboard.py
+
+# Run upload recounting dashboard
+PYTHONNOUSERSITE=1 venv/bin/python recounting_dashboard_upload.py
 ```
 
 ## Key environment & install quirks
@@ -42,6 +46,8 @@ PYTHONNOUSERSITE=1 venv/bin/python counter_dashboard.py
 - Two systemd units: `bytetrack-counter.service` + `bytetrack-counter-dashboard.service`.
 - `counter_live.py` (TensorRT) is Jetson-only and won't work on RK3588.
 - **Reset flow**: `POST /api/reset` → deletes state JSON + touches `{SHM_DIR}/.reset`. `batch_store._check_reset_signal()` watches this marker and clears in-memory state on next crossing.
+- **Upload filename contract**: uploads are expected as `batch_XX_YYYYMMDD_HHmmSS.mp4` (XX = batch number, timestamp = date). `recounting_dashboard_upload.py` parses both to query the live API's `/api/day-detail/<YYYY-MM-DD>` for the recorded count.
+- **`RECOUNT_CMD`** in the upload dashboard is a template with a `{path}` placeholder, e.g. `bytetrack-counter config.env --source {path}`; the uploaded file path is `shlex.quote()`d before substitution.
 
 ## Code conventions