# Atlas Index project recap

## Original request

Replace the nightly full rebuild with incremental indexing without changing the
public query contract.

## Key agent decisions

- Use partition-local checkpoints to bound replay.
- Make index writes idempotent before enabling automatic retries.
- Retain the full rebuild as a documented recovery path.

## As-built architecture

A change reader resumes from each partition checkpoint and hands batches to
idempotent workers. A scheduled audit compares source and index samples and
raises a recovery task when drift exceeds the accepted threshold.

## Implementation record

The team delivered checkpoint persistence, replay-safe workers, audit reporting,
and the recovery runbook in three sequential milestones.

## Validation evidence

Contract tests, interrupted-restart tests, duplicate-batch tests, and sampled
parity checks passed. See the fictional
[evidence index](https://docs.example.com/atlas-index/evidence).

## Outcome

Incremental indexing is active. The nightly rebuild is no longer part of normal
operation and remains documented for recovery only.
