feat: filter reviews by commit author, date, message and branch

[muhammetsafak]

git diff has no --author/--since/--until/--grep — those are git log options — so a filter that selects commits cannot ride the normal diff-acquisition path. Add a commit-selection layer behind the existing fetchDiff seam, plus the path denylist that was missing next to --file/--dir.

New global flags:

--author / --committer name or email, case-insensitive; repeatable
--start-date/--end-date strict YYYY-MM-DD, both ends inclusive
--text commit message, and branch names
--max-commits / --merges modifiers; error if used alone
--exclude-file/--exclude-dir path denylist, --file/--dir rules inverted

AND across filter kinds, OR within one kind.

internal/git/select.go runs a two-phase select-then-show: a git log metadata walk, an optional for-each-ref + rev-list pass for branch-name hits, then git show -m --first-parent for exactly the chosen hashes.

Three decisions worth recording:

• Identity and text matching happen in Go, not git. git log --author=A --grep=B ORs the two by default, and --all-match would then also AND multiple --author values together, breaking OR-within-a-kind.
• git show, not git log -p. The latter indents the commit body four spaces, and internal/diff's parser reads a leading-space line as hunk context, so a message body would be silently absorbed into the previous hunk.
• The patches are concatenated, not reduced to one cumulative A..B diff. A cumulative diff would include every unmatched commit in between, making the filter a lie. The cost is that a file touched by three matching commits appears three times.

--end-date is expanded to 23:59:59 so the named day is included; git's bare --until stops at that day's midnight and drops it.

Scope: no positional range walks HEAD, bounded by --max-commits; a subcommand's range bounds it instead. Conflicts with --staged/--unstaged, which have no commits. Rejected by commit (describes the staged index) and remote pr (its diff comes from gh pr diff).

Also carries the filters across the MCP/guard seam, which resets the global flag state — this makes --file/--dir reachable there for the first time. Adds meta.filtered_commits (omitempty, schema stays 1) and commit/exclusion accounting to dry-run. No cache-key change: the key already hashes the post-filter diff text.

Fixes: remote pr now applies --file/--dir on the posting path too, not only under --no-post.

Docs: ADR-0035, contracts/{cli-surface,json-schema-v1,cache-key}, TECHNICAL_ARCHITECTURE, architecture/{overview,diagrams}, PRD, README, CHANGELOG, man pages.

Summary

Related issues

Type of change

• Bug fix (non-breaking)
• New feature (non-breaking)
• Breaking change (behavior or API)
• Documentation only
• Refactor / cleanup (no behavior change)
• Build / release / CI

Test plan

• make lint test passes locally
• Added or updated tests for the new behavior
• Manually verified the affected commands in a real repo

Notes for reviewers

Checklist

• I have read the Contributing guide.
• My contribution is licensed under GPL-3.0-or-later (inbound = outbound).
• User-facing strings use internal/i18n (no hard-coded text).
• If this changes user-visible behavior, the README / man page / commitbrief list output has been updated accordingly.