feat(review): codebase-aware context beyond the diff (cross-file analysis)

[devops-thiago]

Problem Statement

Reviews see only the PR diff plus a base..head comparison, so the bot cannot reason about callers/callees outside the diff. Indexing the wider repository to trace logic across file boundaries would catch cross-file bugs that diff-only review misses.

Proposed Solution

Add optional codebase-aware context: pull related files referenced by the diff (definitions/callers of changed symbols) and include them in the prompt, or build a lightweight semantic/dependency index of the repo to retrieve relevant context per review. Bound by cost/latency and the per-PR spend cap (#42). Large, exploratory effort — likely warrants its own spike.

Alternatives Considered

• Diff + base comparison only (current) — cheap and simple, but blind to cross-file impact.
• Full embeddings index — powerful but heavy for a small-footprint self-hosted bot; evaluate scope first.

Priority

Important

Code of Conduct

• I have searched for existing issues and this is not a duplicate.

[devops-thiago]

Dogfood evidence — PR #99 (Fixes #95): the headline bug needed exactly this. evaluateCiChecks built a list of all CI checks while the caller (buildResult) gated APPROVE on !offendingCiChecks.isEmpty() — a producer/consumer mismatch split across two hunks. With only file.patch() in context (no enclosing functions/callers), the model could see both hunks but had no structural push to trace the contract between them. Pulling the full enclosing functions would make this class of cross-hunk bug visible. (Companion: the data-flow-contract rule that uses this context is filed separately as the producer→consumer trace dimension.)