name: aposd-verifying-correctness
description: "Verify code correctness before claiming done or committing. Run 6-dimension checklist: requirements coverage, concurrency safety, error handling, resource management, boundary conditions, and security. Output PASS/FAIL per dimension with final DONE/NOT DONE verdict. Use after implementation as pre-commit gate. Triggers on: is it done, ready to commit, verify correctness, did I miss anything, pre-commit check."

Skill: aposd-verifying-correctness

STOP - Before "Done"

Design quality ≠ correctness. Well-designed code can still have bugs, missing requirements, or safety issues.

Run ALL dimension checks before claiming done. "I think I covered everything" without explicit mapping is a red flag.

Dimension Detection & Checks

For each dimension: detect if it applies, then verify.

1. Requirements Coverage

Detect: Were requirements stated? (explicit list, user request, spec)

If YES, verify:
- [ ] List each requirement explicitly
- [ ] For each: point to code that implements it
- [ ] Any requirement without code? → Not done
- [ ] Any code without requirement? → Scope creep or missing requirement

Red flag: "I think I covered everything" without explicit mapping

2. Concurrency Safety

Detect: Any of these present?
- Multiple threads/processes accessing same data
- Async/await patterns
- Shared mutable state (class attributes, globals)
- "Thread-safe" in requirements or docstring
- Web handlers, queue workers, background tasks

If YES, verify:
- [ ] All shared mutable state identified
- [ ] Each access point protected (lock, atomic, queue, immutable)
- [ ] No time-of-check to time-of-use (TOCTOU) gaps
- [ ] Lock ordering consistent (if multiple locks)

Red flag: "It's probably fine" or "Python GIL handles it"

3. Error Handling

Detect: Can any operation fail?
- I/O (file, network, database)
- External calls (APIs, subprocesses)
- Resource acquisition (memory, connections)
- User input processing
- Parsing/deserialization

If YES, verify:
- [ ] Each failure point has explicit handling OR propagates
- [ ] No bare except: or except Exception: pass
- [ ] Error messages actionable (what failed, why, how to fix)
- [ ] Partial failures handled (rollback, cleanup, consistent state)

Red flag: "Errors are rare" or "caller handles it" without checking caller

4. Resource Management

Detect: Does code acquire resources?
- File handles, sockets, connections
- Locks, semaphores
- Memory allocations (large buffers, caches)
- External service handles
- Background threads/processes

If YES, verify:
- [ ] Every acquire has corresponding release
- [ ] Release happens in finally/context manager/destructor
- [ ] Release happens on error paths too
- [ ] No resource leaks on repeated calls
- [ ] Bounded growth (caches have limits, queues have limits)

Red flag: "It cleans up eventually" or daemon threads without shutdown

5. Boundary Conditions

Detect: Does code handle variable-size input?
- Collections (lists, dicts, sets)
- Strings, byte arrays
- Numeric ranges
- Optional/nullable values

If YES, verify:
- [ ] Empty input: What happens with [], "", None, 0?
- [ ] Single item: Edge case often different from N items
- [ ] Maximum size: What if input is huge? Memory? Time?
- [ ] Invalid values: Negative numbers, NaN, special characters?
- [ ] Type boundaries: int overflow, float precision?

Red flag: "Nobody would pass that" or "that's an edge case"

6. Security (if applicable)

Detect: Does code handle untrusted input?
- User-provided data (forms, API requests)
- File contents from external sources
- URLs, paths, identifiers from users
- Data that becomes SQL, shell, HTML, or code

If YES, verify:
- [ ] Input validated before use
- [ ] No string concatenation for SQL/shell/HTML (use parameterized)
- [ ] Path traversal prevented (no ../ exploitation)
- [ ] Secrets not logged or exposed in errors
- [ ] Auth/authz checked before action, not after

Red flag: "It's internal only" (internals get exposed)

Quick Checklist (Minimum)

Before "done", answer YES to all that apply:

Anti-Rationalization Table

Output Format

When verifying, output:

## Correctness Verification

### Requirements: [PASS/FAIL/N/A]
- Requirement 1 → implemented in X
- Requirement 2 → implemented in Y

### Concurrency: [PASS/FAIL/N/A]
- Shared state: [list]
- Protection: [how]

### Errors: [PASS/FAIL/N/A]
- Failure points: [list]
- Handling: [approach]

### Resources: [PASS/FAIL/N/A]
- Acquired: [list]
- Released: [how]

### Boundaries: [PASS/FAIL/N/A]
- Edge cases: [list]
- Handling: [approach]

### Security: [PASS/FAIL/N/A]
- Untrusted input: [list]
- Validation: [approach]

**Verdict:** [DONE / NOT DONE - list blockers]

Relationship to Other Skills

Order: Design → Implement → Verify (this skill) → Done

Chain