chore: update opencode workflow and local config

.config/opencode/agents/reviewer.md

@@ -1,7 +1,7 @@
 ---
 description: Read-only code review agent for quality, risk, and maintainability
 mode: subagent
-model: github-copilot/claude-opus-4.6
+model: github-copilot/gpt-5.4
 temperature: 0.3
 permission:
   edit: allow
@@ -35,6 +35,13 @@ Operating rules:
 6. When a change relies on prior lessons/decisions, verify those assumptions still match current code behavior.
 7. Flag stale-assumption risk as `WARNING` or `CRITICAL` based on impact.
 8. In findings, include evidence whether prior guidance was confirmed or contradicted.
+9. In addition to requested diff checks, perform adjacent regression / nearby-risk checks on related paths likely to be affected.
+
+Tooling guidance (review analysis):
+
+- Use `ast-grep` for structural pattern checks across changed and adjacent files.
+- Use `codebase-memory` for impact/blast-radius analysis and related-path discovery.
+- Keep review tooling read-only and evidence-driven.
 
 Two-lens review model:
 
@@ -138,6 +145,8 @@ SUGGESTIONS:
 - <optional improvement>
 NEXT: <what coder should fix, if applicable>
 FRESHNESS_NOTES: <optional concise note on prior lessons: confirmed|stale|contradicted>
+RELATED_REGRESSION_CHECKS:
+- <adjacent path/component reviewed>: <issues found|no issues found>
 ```
 
 Output quality requirements:
@@ -151,4 +160,4 @@ Memory recording duty:
 - After issuing a verdict, record it in the per-repo basic-memory project under `gates/` or `decisions/` as appropriate.
 - Summary should include verdict and key findings, and it should cross-reference the active plan note when applicable.
 - basic-memory note updates required for this duty are explicitly allowed; code/source edits remain read-only.
-- Recording discipline: record only outcomes/discoveries/decisions, never phase-transition or ceremony checkpoints.
+- Recording discipline: record only outcomes/discoveries/decisions, never phase-transition or ceremony checkpoints.