Bounded internal-review cycle (PR-body fill, review-feedback-re-review, merge on approve)

[Ryan-Atkinson87]

Implement the internal review cycle — Spec §4.2 steps f–g: the engine opens an internal feature-branch PR (AI fills the body), an AI orchestrator reviews it, and a bounded request-changes/feedback/re-review loop runs until approval, on which the engine merges and deletes the feature branch.

Spec §4.2 (steps f–g), §5.3 (feature branches / internal review on a local diff), §15/§16.3 limits.review_cycles (default 2), §4.1 (orchestrator review / implementor feedback roles), §9 (park on exhausted cycles).

Acceptance criteria

• The engine opens the internal PR/diff (feature branch → agent branch, local only — no GitHub PR mid-wave, Spec §5.2/§5.3) via Feature-branch lifecycle: per-issue branch, review diff, serialised merge, delete #11; the AI implementor session fills the body (§4.2 step f).
• An AI orchestrator review session (reviewer persona, composed Persona composition (type x speciality with stage-skill filtering) #20, rendered Provider-format renderer (compose personas to CLAUDE.md + skill files) #22, run via Implement Claude provider adapter via Claude Agent SDK #17) judges the diff against spec and boundaries, returning approve or request-changes (§4.1, §4.2 step g).
• On request-changes: an AI implementor feedback session addresses the comments, then re-review — a bounded loop (limits.review_cycles, default 2, from project.yaml Pydantic schema and fail-fast loader #4). Exhausting the bound without approval → park as a blocker (§9), do not loop forever.
• On approve: the engine merges the feature branch into the agent branch and deletes it (§5.3) — merge is serialised via the scheduler (Wave concurrency scheduler (parallel-across-repos, serialised merge queue, configurable cap) #25).
• Review sessions may run concurrently with other repos' work; only the merge moment serialises (§18.6).
• The reviewer persona is composed so it loads only the relevant stage/speciality skills — e.g. a backend review does not load accessibility/responsiveness skills (§17.1 structural guarantee, via Provider-format renderer (compose personas to CLAUDE.md + skill files) #22).
• State markers (Per-issue state markers and resume-or-reset crash recovery #24) record review state so a crash during review re-reads and resumes (§18.2 f/g row).
• Tests: approve-first-pass merges and deletes the branch; one request-changes cycle then approve; exceed review_cycles → parked blocker; merge invoked through the serialised queue.

Notes

GitHub self-review constraints do not apply here — this is a local internal PR/diff reviewed by an AI session, not a gh pr review. The real GitHub hand-off PR (one per repo) is Phase 2 #14, triggered by the driver (#29) at wave end.

Depends on: #11, #17, #22, #24