---
type: SQLite Table
title: attendance_events
description: Append-only log of clock_in/clock_out/break_start/break_end events, and the state machine built on top of it.
resource: backend/src/db/index.ts
tags: [data-model, sqlite]
timestamp: 2026-08-12T00:00:00Z
---

# attendance_events

Append-only event log — there is no "shift" or "session" row. Shifts are
derived at read time by walking events chronologically
(`buildSessions` in `backend/src/services/attendance.ts`).

# Schema

| Column | Type | Description |
|---|---|---|
| `id` | INTEGER PK | autoincrement |
| `employee_id` | INTEGER | references [employees.id](./employees.md) |
| `type` | TEXT | one of `clock_in`, `clock_out`, `break_start`, `break_end` (CHECK constraint) |
| `ts` | TEXT | ISO 8601 UTC, set by SQLite default |

Indexed on `(employee_id, ts)`.

# State machine

`getLiveStatus` derives one of three states from an employee's most recent
event:

| Last event | Status |
|---|---|
| none / `clock_out` | `clocked_out` |
| `clock_in` / `break_end` | `working` |
| `break_start` | `on_break` |

`recordEvent` only allows the transition that's valid from the current
status (`NEXT_ALLOWED` map) — e.g. you can't `break_start` while already
`clocked_out`. An invalid attempt throws `InvalidTransitionError`, surfaced
by the API as `409`.

```
clocked_out --clock_in--> working
working --break_start--> on_break
on_break --break_end--> working
working --clock_out--> clocked_out
```

# Deriving shifts

`buildSessions(events, now)` walks a chronological event list and pairs
`clock_in`...`clock_out` into a `Session`, with nested `breaks`. A session
still missing its `clock_out` is `open: true` and its `workedMs`/`breakMs`
are computed against `now` (the request time) rather than a real end —
that's why the frontend re-derives it against a live clock between polls
(see [Frontend stores](/docs/frontend/stores.md)) instead of trusting a
stale fetch forever.

`summarize(events, now)` reduces sessions into `totalWorkedMs`,
`totalBreakMs`, `shiftCount` for a date range — the shape returned by both
the employee's own stats endpoint and the admin per-employee endpoint (see
[Attendance API](/docs/api/attendance-routes.md), [Admin API](/docs/api/admin-routes.md)).

# Related

- [employees](./employees.md)
- [Attendance API](/docs/api/attendance-routes.md)
