# System Arm

## Daily Login
- Zerodha Kite access tokens expire daily.
- Users must complete a broker login once per trading day.
- Use `/api/broker/login` to start the login flow.

## Arm Flow
1) User logs in to Zerodha.
2) UI calls `POST /api/system/arm`.
3) Backend validates broker session and arms all active runs.
4) Scheduler resumes from the latest committed state and starts execution.

## Failure States
- Broker auth expired: `POST /api/system/arm` returns 401 with `redirect_url`.
- Run status `ERROR`: skipped and returned in `failed_runs`.
- Missing broker credentials: `/api/broker/login` returns 400.

## Recovery
- Reconnect broker via `/api/broker/login`.
- Reset runs in `ERROR` (admin or manual reset), then re-arm.
- Re-run `POST /api/system/arm` to resume.

## Determinism Guarantees
- Arm is idempotent: already `RUNNING` runs are not re-written.
- Event ledger uses logical time uniqueness to prevent duplicate events.
- Next execution is computed from stored strategy frequency and latest state.