fix: pin review harness model to available Vertex AI version

[fullsend-ai-coder]

Summary

• Pin the review harness model from the generic sonnet alias to claude-sonnet-4-5@20250929 in .fullsend/harness/review.yaml
• The sonnet alias resolved to claude-sonnet-4-6, which is not provisioned on the repo's GCP Vertex AI endpoint, causing all review runs to fail since PR chore: upgrade fullsend review harness #181 merged
• Using an explicit version pin avoids future breakage when the alias advances to unprovisioned models

Testing

• Verified YAML syntax is valid
• The fix can be validated by triggering /fs-review on any open PR and confirming the review agent starts without a model availability error

---

Closes #187

Post-script verification

• Branch is not main/master (agent/187-fix-review-model)
• Secret scan passed (gitleaks — 968ad8a9d2fcd3a530702bcf9a91446b9406577a..HEAD)
• PR body secret scan passed (gitleaks — no-git)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[fullsend-ai-review]

🤖 Finished Review · ❌ Failure (validation failed after 1 iteration(s)) · Started 8:37 AM UTC · Completed 8:39 AM UTC

Commit: 1436b7a · View workflow run →

Runtime: claude · Model: sonnet → claude-sonnet-4-6 · Effort: high

[fullsend-ai-retro]

🤖 Finished Retro · ✅ Success · Started 10:16 AM UTC · Completed 10:23 AM UTC

Commit: 1436b7a · View workflow run →

Runtime: claude · Model: opus → claude-opus-4-6 · Effort: high · Cost: $2.56

[fullsend-ai-retro]

Retro: PR #188 — pin review harness model to available Vertex AI version

Timeline

1. PR #181 merged (2026-09-09 08:11 UTC), introducing .fullsend/harness/review.yaml with model: sonnet to address Opus timeout issues on large PRs.
2. The sonnet alias resolved to claude-sonnet-4-6, which is not provisioned on the repo's GCP Vertex AI endpoint — breaking all review agent runs.
3. 08:25 — Retro agent detected the breakage and filed issue #187 with a clear description and proposed fix.
4. 08:26–08:35 — Triage ($0.69) and code ($0.82) agents processed the issue autonomously, producing PR #188 with the correct 1-line fix in ~10 minutes.
5. 08:35 — PR Semantic check failed: the code agent's title fix(#187): ... used # in the scope, which the repo's headerPattern regex rejects (run 34329926417).
6. 08:37 — Review agent failed on PR fix: pin review harness model to available Vertex AI version #188 (run 34329926023) — chicken-and-egg: it used the same broken sonnet config this PR was fixing.
7. 10:08 — Human renamed the PR title to fix: pin review harness model to available Vertex AI version.
8. 10:09 — Human (gashcrumb) approved; 10:14 — merged.

What went well

• Retro → triage → code pipeline worked excellently. The retro agent identified the breakage post-merge, filed a clear issue with a proposed fix, and the triage + code agents resolved it autonomously in ~10 minutes for $1.51 total. This is the detection-and-repair loop working as designed.
• Code agent produced the correct fix on the first try — a clean 1-line model pin to claude-sonnet-4-5@20250929.
• Low rework: only 1 iteration needed (modulo the PR title rename).

Existing issue coverage (no new proposals filed)

• Model alias fallback/validation is extensively tracked in fullsend-ai/fullsend: #7026 (no automatic fallback when aliased model is not served), #6967 (fallback on policy_denied), #6964 (pre-dispatch model validation), #6883 (per-repo model catalog + preflight). This retro provides additional evidence: the sonnet → claude-sonnet-4-6 resolution failure blocked reviews on the entire repo until a manual pin was merged.
• Config validation deadlock (review agent failing on the PR that fixes its own config) is covered by fullsend-ai/fullsend#6186. This retro provides a concrete instance: the review agent on PR fix: pin review harness model to available Vertex AI version #188 failed immediately with 0 tokens because it was using the broken config that the PR itself was fixing.

Proposal filed

1 proposal: document PR title scope character restrictions in AGENTS.md so the code agent avoids invalid scopes like (#187).

Proposals filed

• Document PR title scope character restrictions in AGENTS.md (in redhat-developer/rhdh-cli)