Phase gated debugging

Skill newmindsgroup/ai-agent-skills-library/dist/skills/phase-gated-debugging

Shared library of AI agent skills — works across Claude Code, Cursor, Codex, Windsurf, OpenCode, and Google Antigravity via a single universal installer.

Install

npx -y skills add newmindsgroup/ai-agent-skills-library --skill phase-gated-debugging

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Use when debugging any bug. Enforces a 5-phase protocol where code edits are blocked until root cause is confirmed. Prevents premature fix attempts.

The file declares its own license as MIT. That is the author’s claim about this one file, and it is not the same thing as the license GitHub reports for the repository, which is listed with the other numbers below.

SKILL.md

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Phase-Gated Debugging

Overview

AI coding agents see an error and immediately edit code. They guess at fixes, get it wrong, and spiral. This skill enforces a strict 5-phase protocol where you CANNOT edit source code until the root cause is identified and confirmed.

Based on claude-debug (full plugin with PreToolUse hook enforcement).

When to Use

Use this skill when:

a bug keeps getting "fixed" without resolving the underlying issue
you need to slow an agent down and force disciplined debugging before code edits
the failure is intermittent, a regression, performance-related, or otherwise hard to isolate
you want an explicit user confirmation checkpoint before any fix is applied

The Protocol

Phase 1: REPRODUCE

Run the failing command/test. Capture the exact error. Run 2-3 times for consistency.

Do NOT read source code
Do NOT hypothesize
Do NOT edit any files

Phase 2: ISOLATE

Read code. Add diagnostic logging marked // DEBUG. Re-run with diagnostics. Binary search to narrow down.

Only // DEBUG marked logging is allowed
Do NOT fix the bug even if you see it

Phase 3: ROOT CAUSE

Analyze WHY at the isolated location. Use "5 Whys" technique. Remove debug logging.

State: "This is my root cause analysis: [explanation]. Do you agree, or should I investigate further?"

WAIT for user confirmation. Do NOT proceed without it.

Phase 4: FIX

Remove all // DEBUG lines. Apply minimal change addressing confirmed root cause.

Only edit files related to root cause
Do NOT refactor unrelated code

Phase 5: VERIFY

Run original failing test — must pass. Run related tests. For intermittent bugs, run 5+ times. If verification fails: root cause was wrong, go back to Phase 2.

Bug-Type Strategies

Type	Technique
Crash/Panic	Stack trace backward — trace the bad value to its source
Wrong Output	Binary search — log midpoint, halve search space each iteration
Intermittent	Compare passing vs failing run logs — find ordering divergence
Regression	`git bisect` — find the offending commit
Performance	Timing at stage boundaries — find the bottleneck

Key Rules

NEVER edit source code in phases 1-3 (except // DEBUG in phase 2)
NEVER proceed past phase 3 without user confirmation
ALWAYS reproduce before investigating
ALWAYS verify after fixing

Limitations

Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.