Resolves add/add conflict in diff-cache.ts (kept typed PhaseMetaResponse/
FileDiffResponse interfaces from HEAD over unknown-typed singletons from test
branch) and content conflict in phase.ts (kept both phaseMetaCache and
fileDiffCache imports; removed auto-merged duplicate firstClone/headHash/
cacheKey/cached declarations and unreachable empty-projects guard).
Also cleans auto-merged duplicate getHeadCommitHash in orchestrator.test.ts
and simple-git-branch-manager.ts.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Creates diff-cache.ts module with generic DiffCache<T> class (TTL, prefix
invalidation, env-var configuration) and exports phaseMetaCache / fileDiffCache
singletons. Wires cache into getPhaseReviewDiff via getHeadCommitHash on
BranchManager. Adds 6 unit tests for DiffCache and 5 integration tests
verifying cache hit/miss behaviour, prefix invalidation, and NOT_FOUND guard.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Adds DiffCache<T> module, extends BranchManager with getHeadCommitHash,
and wires phase-level caching into getPhaseReviewDiff and getFileDiff.
Cache is invalidated in ExecutionOrchestrator after each task merges into
the phase branch, ensuring stale diffs are never served after new commits.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
