rot-canary

name

rot-canary

description

Code-health scan — dead code, bug-prone logic, resource leaks, concurrency bugs, silent failures, input-boundary issues, doc rot. Triggers on: "/rot-canary", "rot-canary", "code-health" (legacy aliases: "/rotcanary", "rotcanary"). Auto-runs at session end on touched files (QUICK, report only) via platform hooks — auto-wired by the Claude Code plugin, manual elsewhere. Run manually for fix mode. Reports; fixes on request via choice-gated menu.

Rot-Canary

Scan code for rot. Report CONFIRMED findings. Fix on request.

Parameters

• SCOPE: touched files (default) | diff | named files | whole repo. Touched-files scan is hybrid-capped: all if ≤ autoScanFileCap, else the autoScanFileCapSlice most-recently-modified files (warn the user). A touched file matching scanExcludePaths (lab/throwaway tooling only — never shipped/tracked source) is dropped before the cap; the nudge notes the skip count.
• DEPTH: QUICK (default) | DEEP

Categories

1. Bug-risk — null deref, wrong operator, off-by-one, missing return
2. Dead / unreachable — zero-ref symbols, code after return/throw, always-true guards
3. Disconnected — exists but never wired to entry point, half-done refactor
4. Duplication — copy-paste diverged, two sources of truth for one constant
5. Resource leak — undisposed handle/stream/COM, subscription never removed
6. Async — unawaited task, .Result/.Wait() deadlock, blocking on UI thread
7. Silent failure — empty catch, success on partial completion, ignored return code
8. Input security — unvalidated input, injection, path traversal, secret in code/log
9. Performance — O(n²) in hot path, N+1, unbounded growth, work on UI thread
10. Doc rot — comment contradicts code, stale TODO, wrong param in docstring

Discipline

• Report only CONFIRMED. Unverifiable → separate "SUSPECTED" list.
• Cite evidence (file:line, call-site count, the absent catch).
• "Dead" = zero-reference reachability (the static heuristic): zero references across ALL entry routes — reflection, DI, events, public API, tests — not a single-file grep.

Fix mode (choice-gated)

Standing consent: honor .coalmine.json autoFixMode as the pre-chosen option (the config IS the chosen option) — off = report only, no menu · safe = apply safe/reversible fixes automatically (still checkpoint → build/test → revert if red) · interactive (default) = present the menu below.

After any scan report in an interactive session — manual run OR hook-nudged auto-scan — you MUST present this menu via ask_question (skip only when findings are zero, no user is present, or autoFixMode pre-decided above):

• Apply safe fixes: mechanical, fully reversible edits only (dead imports, commented-out blocks, formatting). Each fix: checkpoint (git stash/commit in a git repo; else copy the file aside — never assume git exists) → apply → build + tests → auto-revert if newly red.
• Let me pick: list findings; user selects.
• Report only: exit unchanged.

NEVER auto-fix: live/reachable path · logic change · "API looks wrong" (ground via source-grounding first) · framework-wired code that only looks dead · SUSPECTED findings.

Output

| # | path:line | category | severity | finding | evidence | fix |

Then: SUSPECTED list · coverage gaps · counts + top 3 to fix.

Severity: CRITICAL (data loss/security/crash on normal path) · HIGH (real bug/leak on reachable path) · MEDIUM (dead/dup/unwired) · LOW (style/doc rot)

Cadence

Stop hook → auto QUICK on the session's touched files (report only), hybrid-capped per .coalmine.json (see Parameters). Manual whole-repo DEEP sweep when needed. Auto-wiring is platform-dependent — read references/cadence.md before claiming auto-scan works on the current platform.

Tooling

Per-stack build/dead-code/lint commands: read references/tooling.md when selecting scan tools.