## What changed
- Add `codex migrate-rollouts` with dry-run inspection by default, explicit `--apply`, thread filtering, optional I/O throttling, progress output, and JSON or verbose reports.
- Add the disabled-by-default `background_paginated_rollout_migration` feature to migrate legacy local sessions at startup before rollout compression begins.
- Persist a migration cursor and skipped-file fingerprints so later startups avoid full rescans while retrying changed files and recovering pending migrations.
- Coordinate migration with live writers and emit metrics for manual and startup runs.
## Testing
- Cover startup cursor advancement and lookback, pending migration recovery, live-writer coordination, changed empty rollouts, and progress reporting.
GitOrigin-RevId: 276ac506c50ebec5140fd319faca1bb998172061
## What changed
- Add `LocalThreadStore::migrate_rollouts` with dry-run and apply modes,
optional thread selection, throughput limiting, and per-rollout outcomes.
- Canonicalize legacy JSONL records into paginated history while preserving
model-visible conversation context, including compressed rollouts and copied
fork history.
- Publish replacements atomically and journal migrations so interrupted SQLite
projections can be recovered. Coordinate migration with rollout compression
and skip rollouts with active writers.
- Make paginated history a one-way SQLite promotion so stale metadata cannot
downgrade a migrated thread.
## Testing
- Cover legacy record normalization, dry runs, idempotency, malformed input,
compressed rollouts, active writers, interrupted migration recovery, and a
cold app-server resume after migration.
GitOrigin-RevId: b9991b659f28ebb52da39ce62e8b4e0bae2ba2bb
Owen Lin