## What changed
- Make `local_thread_store_compression` compress cold rollout files across shared and forked histories without a separate compression mode.
- Retire `local_thread_store_shared_compression` while continuing to accept it in strict configuration without changing compression behavior.
- Read rollout files through the compressed-rollout reader when `codex exec resume` determines the latest turn's working directory.
## Testing
- Cover compression and restoration of an archived fork chain.
- Cover cwd-based resume selection when only the compressed rollout remains.
- Cover the removed compatibility key in strict configuration.
GitOrigin-RevId: 8edebf61eccc1f79cabb8e641f8982c76f337bf1
## Why
Archiving a thread only needs to locate rollout files that have not already
been moved, so reading the entire rollout archive on every request is
unnecessary.
## What changed
- Add `RolloutReferenceIndex::scan_unarchived` to scan only the active
`sessions` directory.
- Use the active-only index when archiving threads while retaining full scans
for operations that require archived-history reference counts.
- Cover discovery of compressed and uncompressed active rollouts and exclusion
of archived and unrelated rollouts.
GitOrigin-RevId: 46367127578f20bfa46a8db5c6f2b7f59d29f7a9
## Why
`thread/revert` preserves a thread ID while creating a new immutable rollout. Rollout persistence and filesystem fallback therefore need to distinguish the logical thread from each physical history file.
## What changed
- Add a `RolloutId` alias and canonical filename parsing for both ordinary rollouts and reverted rollouts with a distinct rollout ID.
- Allow the recorder to create a replacement rollout without changing the thread ID, and add lookup by either the stable thread ID or an exact rollout ID.
- Index history references and compression safety checks by rollout ID so multiple rollouts for one thread remain distinct.
- Preserve the rollout path selected in SQLite when filesystem repair encounters another rollout for the same thread.
## Testing
Add coverage for filename round trips, replacement rollout metadata, thread and rollout lookup, reference indexing, compression, and database path preservation.
GitOrigin-RevId: 14b1d0b4a9432b341a1307afc0abadd507e7ae7d
## Why
Paginated forks can retain a `history_base` pointer to another rollout. Deleting or compressing either side of that relationship can leave the fork without the rollout history it references.
## What changed
- Add a rollout reference index that scans active, archived, and compressed rollout metadata.
- Reject deletion when a rollout is still referenced by a fork outside the requested deletion set.
- Delete spawned thread subtrees as one store operation so internal references do not block deleting the complete subtree, while external references preflight the request before any files are removed.
- Skip referenced rollouts, fork-pointer rollouts, and rollouts with unreadable metadata during background compression.
## Testing
- Cover reference indexing across active, archived, compressed, duplicate, and self-referencing rollouts.
- Verify deletion rejects external references without partially deleting a subtree and permits batch deletion of internally referenced threads.
- Verify compression preserves fork pointer chains and continues past unreadable metadata.
GitOrigin-RevId: a8672727f8706e743d7fb3ca895a1d9ceac98a3c
jif