chore(skills): add repository-local workflow skills (#2190)

.agents/skills/code-change-verification/SKILL.md

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+---
+name: code-change-verification
+description: Verify code changes by identifying correctness, regression, security, and performance risks from diffs or patches, then produce prioritized findings with file/line evidence and concrete fixes. Use when reviewing commits, PRs, and merged patches before/after release.
+---
+
+# Code Change Verification
+
+Use this skill to review code changes consistently before merge, before release, and during incident follow-up.
+
+## Quick Start
+
+1. Read the scope: commit, PR, patch, or file list.
+2. Map each changed area by risk and user impact.
+3. Inspect each risky change in context.
+4. Report findings first, ordered by severity.
+5. Close with residual risks and verification recommendations.
+
+## Core Workflow
+
+### 1) Scope and assumptions
+- Confirm change source (diff, commit, PR, files), target branch, language/runtime, and version.
+- If context is missing, state assumptions before deeper analysis.
+- Focus only on requested scope; avoid reviewing unrelated files.
+
+### 2) Risk map
+- Prioritize in this order:
+  - Data correctness and user-visible behavior
+  - API/contract compatibility
+  - Security and authz/authn boundaries
+  - Concurrency and lifecycle correctness
+  - Performance and resource usage
+- Give higher priority to stateful paths, migration logic, defaults, and error handling.
+
+### 3) Evidence-based inspection
+- Read each modified hunk with neighboring context.
+- Trace call paths and call-site expectations.
+- Check for:
+  - invariant breaks and missing guards
+  - unchecked assumptions and null/empty/error-path handling
+  - stale tests, fixtures, and configs
+  - hidden coupling to shared helpers/constants/features
+- If a point is uncertain, mark it as an open question instead of guessing.
+
+### 4) Findings-first output
+- Order findings by severity:
+  - P0: critical failure, security breach, or data loss risk
+  - P1: high-impact regression
+  - P2: medium risk correctness gap
+  - P3: low risk/quality debt
+- For each finding include:
+  - Severity
+  - `path:line` reference
+  - concise issue statement
+  - impact and likely failure mode
+  - specific fix or mitigation
+  - validation step to confirm
+- If no issues exist, explicitly state `No findings` and why.
+
+### 5) Close
+- Report assumptions and unknowns.
+- Suggest targeted checks (tests, canary checks, logs/metrics, migration validation).
+
+## Output Template
+
+1. Findings
+2. No findings (if applicable)
+3. Assumptions / Unknowns
+4. Recommended verification steps
+
+## Finding Template
+
+- `[P1] Missing timeout for downstream call`
+  - Location: `path/to/file.rs:123`
+  - Issue: ...
+  - Impact: ...
+  - Fix suggestion: ...
+  - Validation: ...
+

.agents/skills/code-change-verification/agents/openai.yaml

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+interface:
+  display_name: "Code Change Verification"
+  short_description: "Prioritize risks and verify code changes before merge."
+  default_prompt: "Inspect a patch or diff, identify correctness/security/regression risks, and return prioritized findings with file/line evidence and fixes."