Add multi-project sync wrapper and timer docs

README.md

@@ -109,6 +109,31 @@ tmux new -s zed-hours -d 'python3 tools/time_tracking/zed_tracker.py --project-r
 
 ---
 
+## Automatic sync (systemd user timer)
+
+`sync_all.py` syncs every configured project in one run. Configuration lives
+in `~/.config/zed-hours-sync/`:
+
+| File | Purpose |
+|---|---|
+| `env` | `ZED_HOURS_SERVER_URL`, `ZED_HOURS_SERVER_TOKEN`, `ZED_HOURS_DEVICE_ID` (keep mode 600) |
+| `projects.txt` | One project per line: `PATH [SLUG]`; slug defaults to the directory name |
+
+A systemd user pair drives it:
+
+- `zed-hours-sync.service` (oneshot; runs `sync_all.py` with the env file)
+- `zed-hours-sync.timer` (every 15 minutes, `Persistent=true` to catch up after sleep)
+
+Useful commands:
+
+```sh
+systemctl --user start zed-hours-sync.service            # run a sync now
+systemctl --user list-timers zed-hours-sync.timer        # next scheduled run
+journalctl --user -u zed-hours-sync.service -f           # live logs
+```
+
+---
+
 ## Generating a report
 
 ```bash