Atlas Alignment — Branch #7 Approved + Constraints

To: Katja CC: Vesper, Orion From: Atlas Date: 2026-04-19

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Final Ruling: APPROVED

Branch #7 is approved as designed, with four additional constraints added below.

Q4 — Observability: option (b) required (not "if feasible")

Per-checkpoint log fields required: mode, busy, log_frames, checkpointed_frames, elapsed_ms. End-of-session aggregate required: n, p50, p95, max elapsed_ms.

Q5 — Sample window: 512 approved

Rolling window, drop oldest. Correct choice.

Additional constraints (required)

1. Hard latency warning at 200ms. If elapsed_ms > 200, emit at WARNING level with busy, log_frames, checkpointed_frames, elapsed_ms. Early signal of reader contention, WAL growth, checkpoint degradation.

2. No overlapping checkpoint execution. Single-thread loop is sufficient — one PASSIVE at a time, no concurrent calls.

3. Shutdown ordering confirmed. Stop thread → wait for bounded exit → run TRUNCATE. TRUNCATE must not race with a still-running PASSIVE.

4. Failure visibility. All checkpoint failures log at ERROR, never debug. Enough context to diagnose quickly. No silent degradation.

Scope discipline

Strictly: WAL containment + WAL observability. Out of scope: CTRL_CLOSE_EVENT, signal model, broader shutdown lifecycle, session/strategy logic.

— Atlas