Deep Bugs Finder

Deep Bugs Finder

Find real bugs and record each one in bugs/ as a separate .md file with a concrete proposed fix.

> Installed helper: /Users/nobrainer-tech/.claude/skills/deep-bugs-finder/scripts/bug-hunt > Bug-file template: /Users/nobrainer-tech/.claude/skills/deep-bugs-finder/assets/bug-template.md > Engine-agnostic: --engine codex (default) · --engine claude · --engine both (cross-model).

The loop is script-driven (works for Codex AND Claude)

steipete saw Codex loop internally when told a bug exists. We do not rely on any model looping by itself. The bug-hunt helper drives the loop in bash: it re-invokes the chosen engine once per round, each round fed the assertion "a bug exists, find it" plus the titles already found ("don't repeat these — find deeper ones"). So the loop behaves identically whether the engine is Codex or Claude — the universality comes from the harness, not the model. --engine both runs Codex and Claude each round for cross-model coverage (they catch different bug classes; that disagreement is signal).

The method (why this works)

Source: @steipete — "Ask it to review code for bugs and it will tell you all good; tell it there IS a bug and it will LOOP AND LOOP and will find issues." (quoting the insight that asserting a problem exists — "there is a simpler way", "there is a bug" — before the model justifies itself produces far better results than a neutral ask.)

So this skill does NOT ask "are there bugs?" (the model answers "looks good"). It asserts a real bug exists and loops, each round told what was already found and pushed to dig for different, deeper defects — until it goes dry.

But adversarial pressure invents false positives. The discipline that makes this useful instead of noisy: every candidate is verified against the real code before it becomes a bug file. Pressure to find + rigor to confirm.

Workflow

1. Pick scope

• Uncommitted work: --diff
• Branch/PR: --base origin/main (use the real PR base if gh pr view works)
• One commit: --commit
• Specific files: --paths "core/x.py core/y.py"
• No scope from the user → default to the working-tree diff; if clean, ask what to hunt (a path, a branch, or "whole module X").

2. Run the adversarial loop

/Users/nobrainer-tech/.claude/skills/deep-bugs-finder/scripts/bug-hunt --base origin/main --rounds 4

Candidates land in bugs/.bug-hunt-candidates.md (and stdout). Big scopes: codex rounds can each take minutes — that is normal, let them finish. For a large module you may also fan out: run several bug-hunt invocations over different file subsets, or spawn parallel subagents each adversarially hunting one area.

You may run the loop yourself instead of the helper when you want full control — the rule is the same: assert a bug exists, demand file:line + a concrete failure scenario + a fix, feed back what was found, repeat until two consecutive dry rounds.

3. VERIFY every candidate (gate — do not skip)

For each candidate, before writing a bug file, confirm ALL three:

1. Proven from code — open the cited file:line, read it and its callers/callees. The failure must be reachable with real inputs, not hypothetical.
2. Concrete failure mode — you can state the exact input/state/sequence that produces wrong behaviour (crash, wrong result, data loss, security hole, hang, silent failure).
3. Not intentional — it isn't a deliberate codebase pattern, a guarded case, or already handled elsewhere. Check suppressions (# noqa, # type: ignore) by reading what they suppress before calling them wrong.

Reject: style/nits, speculative risks, "could be cleaner", broad rewrites, unreachable edge cases, and anything you cannot trace to real code. A rejected candidate is dropped (or recorded with Status: rejected only if it's instructive).

4. Write each REAL bug to its own file

• Folder: bugs/ at the repo root (create if missing).
• One file per bug: bugs/BUG--.md, `` zero-padded, incrementing (continue from the highest existing number — never overwrite).
• Use the template at assets/bug-template.md: title, severity, exact location, why it's a real bug (proof, with the offending code), root cause, proposed fix (diff/code), and a regression-guard test. Fill every section; no placeholders.
• Order by severity in the title number where practical (Critical first), but never renumber existing files.

5. Maintain bugs/README.md index

A table: | ID | Severity | Title | Location | Status |, one row per bug file, newest first. Create it if absent; append/refresh rows for this run. Delete the scratch bugs/.bug-hunt-candidates.md when done (it's working state, not output).

6. Report back

• Scope + rounds run + engine.
• Count of candidates raised vs verified real bugs written vs rejected (with one-line reasons for notable rejects).
• The list of new bugs/BUG-*.md files by severity.
• Do NOT auto-apply fixes unless the user asked — this skill records bugs+fixes; applying them is a separate, explicit step.

Rules

• Assert, then verify. The adversarial framing finds more; the verification gate keeps it true. Never write a bug file you haven't traced in the real code.
• One bug per file, self-contained, with a proposed fix and a regression test idea.
• Loop until dry (≥2 empty rounds), not just one pass. The whole point is the loop.
• No fixing unless asked. Output = the bugs/ folder. Fixing is opt-in.
• Severity honestly. Critical = data loss / security / money / corruption / crash on common path. Medium is the floor; don't pad with Lows.
• Keep findings at the right ownership boundary; propose the smallest fix that kills the bug class.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: nobrainer-tech
• Source: nobrainer-tech/nobrainer-claude-skills
• License: MIT

Install and usage instructions live in the source repository linked above.