# TASK-009: Implement history and diff API contracts

Status: planned — depends on TASK-004
Owner: Codex
Reviewer: Claude

## Outcome

Provide frozen read-only domain and data contracts for commit history, changed files, bounded patches, and ref comparison so Claude can implement TASK-007 without editing shared layers.

## Writable paths

- `app/src/main/java/com/ubisam/ubgitea/domain/history/`
- `app/src/main/java/com/ubisam/ubgitea/data/history/`
- `app/src/test/java/com/ubisam/ubgitea/domain/history/`
- `app/src/test/java/com/ubisam/ubgitea/data/history/`
- `tasks/009-history-diff-api-contract.md`

## Acceptance criteria

- [ ] Domain contracts distinguish added, modified, renamed, and deleted files.
- [ ] Commit history and comparison pagination is explicit and immutable.
- [ ] Patch size and line limits produce an explicit truncated state.
- [ ] Base and head refs are encoded independently exactly once.
- [ ] Empty repository, missing ref, 401, 403, 404, 409, 422, rate-limit, network, parse, and server failures map to typed results.
- [ ] Representative JSON and fake-server tests cover commit detail, rename/delete, comparison, pagination, and truncation.
- [ ] No write endpoint is exposed.
- [ ] Evidence records the reviewed contract-freeze commit for TASK-007.

## Required checks

```text
./gradlew assembleDebug
./gradlew testDebugUnitTest
./gradlew lintDebug
```