debug

[IMPORTANT] Use TaskCreate to break ALL work into small tasks BEFORE starting — including tasks for each file read. This prevents context loss from long files. For simple tasks, AI MUST ask user whether to skip.

Understand Code First — Search codebase for 3+ similar implementations BEFORE writing any code. Read existing files, validate assumptions with grep evidence, map dependencies via graph trace. Never invent new patterns when existing ones work. MUST READ .claude/skills/shared/understand-code-first-protocol.md for full protocol and checklists.

Evidence-Based Reasoning — Speculation is FORBIDDEN. Every claim needs file:line proof. Confidence: >95% recommend freely, 80-94% with caveats, <80% DO NOT recommend — gather more evidence. Cross-service validation required for architectural changes. MUST READ .claude/skills/shared/evidence-based-reasoning-protocol.md for full protocol and checklists.

• docs/project-reference/domain-entities-reference.md — Domain entity catalog, relationships, cross-service sync (read when task involves business entities/models) (content auto-injected by hook — check for [Injected: ...] header before reading)

Estimation Framework — SP scale: 1(trivial) → 2(small) → 3(medium) → 5(large) → 8(very large, high risk) → 13(epic, SHOULD split) → 21(MUST split). MUST provide story_points and complexity estimate after investigation. MUST READ .claude/skills/shared/estimation-framework.md for full protocol and checklists. Red Flag STOP Conditions — STOP current approach when: 3+ fix attempts on same issue (root cause not identified), each fix reveals NEW problems (upstream root cause), fix requires 5+ files for "simple" change (wrong abstraction layer), using "should work"/"probably fixed" without verification evidence. After 3 failed attempts, report all outcomes and ask user before attempt #4. MUST READ .claude/skills/shared/red-flag-stop-conditions-protocol.md for full protocol and checklists.

Quick Summary

Goal: Investigate and identify root cause of a bug with evidence.

Workflow:

1. Reproduce — Understand expected vs actual behavior
2. Hypothesize — Form theories about root cause
3. Trace — Follow code paths with file:line evidence
4. Confirm — Verify root cause with grep/read evidence
5. Report — Output root cause with confidence level

Key Rules:

• Debug Mindset: every claim needs file:line proof
• Never assume first hypothesis is correct
• Output: confirmed root cause OR "hypothesis, not confirmed" with evidence gaps
• This is investigation-only — hand off to /fix for implementation

[MANDATORY] Read .claude/skills/shared/root-cause-debugging-protocol.md BEFORE proposing any fix. Responsibility attribution and data lifecycle tracing are required.

Debug Mindset (NON-NEGOTIABLE)

Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).

• Do NOT assume the first hypothesis is correct — verify with actual code traces
• Every root cause claim must include file:line evidence
• If you cannot prove a root cause with a code trace, state "hypothesis, not confirmed"
• Question assumptions: "Is this really the cause?" → trace the actual execution path
• Challenge completeness: "Are there other contributing factors?" → check related code paths

Confidence & Evidence Gate

MANDATORY IMPORTANT MUST declare Confidence: X% with evidence list + file:line proof for EVERY claim.

Workflow Details

Step 1: Reproduce

• Clarify expected vs actual behavior
• Identify trigger conditions (user action, data state, timing)

Step 2: Hypothesize

• Form 2-3 theories about root cause
• Rank by likelihood based on symptoms

Step 3: Trace

• For each hypothesis, trace the code path:
  • Find entry point (API, UI, job, event)
  • Follow through handlers/services
  • Check data transformations and state changes
  • Verify error handling paths
• Use grep/read to collect file:line evidence

Step 4: Confirm

• Match evidence to a single root cause
• Verify the root cause explains ALL symptoms
• Check for secondary contributing factors

Dependency Tracing (MANDATORY — DO NOT SKIP when graph.db exists)

If .code-graph/graph.db exists, you MUST use structural queries to trace dependencies:

Graph reveals ALL callers and consumers of buggy code — grep alone misses structural relationships.

• Who calls the buggy function: python .claude/scripts/code_graph query callers_of <function> --json
• Who imports the buggy module: python .claude/scripts/code_graph query importers_of <file> --json
• What tests exist: python .claude/scripts/code_graph query tests_for <function> --json
• What does this function call: python .claude/scripts/code_graph query callees_of <function> --json

Graph-Assisted Debugging

After identifying suspect files, use graph trace to understand the full context:

1. python .claude/scripts/code_graph trace <suspect-file> --direction both --json — see what calls this code AND what it triggers downstream
2. python .claude/scripts/code_graph trace <suspect-file> --direction upstream --json — find all callers that could trigger the bug
3. This reveals implicit connections (MESSAGE_BUS, event handlers) that may propagate the issue across services

Step 5: Report

• Output: confirmed root cause with evidence chain
• Include: affected files, data flow, fix recommendation
• Hand off to /fix for implementation

⚠️ MANDATORY: Post-Fix Verification

After /fix applies changes, /prove-fix MUST be run. It builds code proof traces per change with confidence scores. This is non-negotiable in all fix workflows.

Red Flags — STOP (Debugging-Specific)

If you're thinking:

• "I see the problem, let me fix it" — Seeing symptoms is not understanding root cause. Investigate first.
• "Quick fix for now, investigate later" — Quick fixes mask bugs and create debt. Find root cause.
• "Just try changing X and see" — One hypothesis at a time. Scientific method, not trial and error.
• "Already tried 2+ fixes, one more" — 3+ failed fixes = STOP. Question the architecture, not the fix.
• "The error message is misleading" — Read it again carefully. Error messages are usually right.
• "It works on my machine" — Reproduce in the failing environment. Your environment hides bugs.
• "This can't be the cause" — Verify with evidence, not intuition. Unlikely causes are still causes.

IMPORTANT Task Planning Notes (MUST FOLLOW)

• Always plan and break work into many small todo tasks using TaskCreate
• Always add a final review todo task to verify work quality and identify fixes/enhancements

Workflow Recommendation

IMPORTANT MUST: If you are NOT already in a workflow, use AskUserQuestion to ask the user:

1. Activate bugfix workflow (Recommended) — scout → investigate → debug → plan → fix → prove-fix → review → test
2. Execute /debug directly — run this skill standalone

Next Steps

MANDATORY IMPORTANT MUST after completing this skill, use AskUserQuestion to recommend:

• "/fix (Recommended)" — Apply fix based on debug findings
• "/plan" — If fix requires planning
• "Skip, continue manually" — user decides

Standalone Review Gate (Non-Workflow Only)

MANDATORY IMPORTANT MUST: If this skill is called outside a workflow (standalone /debug), you MUST create a TaskCreate todo task for /review-changes as the last task in your task list. This ensures all changes are reviewed before commit even without a workflow enforcing it.

If already running inside a workflow (e.g., bugfix), skip this — the workflow sequence handles /review-changes at the appropriate step.

Closing Reminders

MANDATORY IMPORTANT MUST break work into small todo tasks using TaskCreate BEFORE starting. MANDATORY IMPORTANT MUST validate decisions with user via AskUserQuestion — never auto-decide. MANDATORY IMPORTANT MUST add a final review todo task to verify work quality. MANDATORY IMPORTANT MUST READ the following files before starting:

• MUST READ .claude/skills/shared/understand-code-first-protocol.md before starting
• MUST READ .claude/skills/shared/evidence-based-reasoning-protocol.md before starting
• MUST READ .claude/skills/shared/estimation-framework.md before starting
• MUST READ .claude/skills/shared/red-flag-stop-conditions-protocol.md before starting