/gsd-debug

name: gsd-debug
description: "Use when a bug, failing test, or unexpected behaviour needs investigation, especially across sessions or context resets. Isolates it in a debugger subagent with persistent .planning/debug state, unlike skills/systematic-debugging."
argument-hint: "[--diagnose] [issue description]"
allowed-tools:
  - Read
  - Bash
  - Task
  - AskUserQuestion

<objective> Debug issues using scientific method with subagent isolation.

**Orchestrator role:** Gather symptoms, spawn gsd-debugger agent, handle checkpoints, spawn continuations.

**Why subagent:** Investigation burns context fast (reading files, forming hypotheses, testing). Fresh 200k context per investigation. Main context stays lean for user interaction.

**Flags:**

• `--diagnose` — Diagnose only. Find root cause without applying a fix. Returns a structured Root Cause Report. Use when you want to validate the diagnosis before committing to a fix.

</objective>

<available_agent_types> Valid GSD subagent types (use exact names — do not fall back to 'general-purpose'):

• gsd-debugger — Diagnoses and fixes issues

</available_agent_types>

<context> User's issue: $ARGUMENTS

Parse flags from $ARGUMENTS:

• If `--diagnose` is present, set `diagnose_only=true` and remove the flag from the issue description.
• Otherwise, `diagnose_only=false`.

Check for active sessions:

ls .planning/debug/*.md 2>/dev/null | grep -v resolved | head -5

</context>

<process>

0. Initialize Context

INIT=$(node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" state load)
if [[ "$INIT" == @file:* ]]; then INIT=$(cat "${INIT#@file:}"); fi

Extract `commit_docs` from init JSON. Resolve debugger model:

debugger_model=$(node "$HOME/.claude/get-shit-done/bin/gsd-tools.cjs" resolve-model gsd-debugger --raw)

1. Check Active Sessions

If active sessions exist AND no $ARGUMENTS:

• List sessions with status, hypothesis, next action
• User picks number to resume OR describes new issue

If $ARGUMENTS provided OR user describes new issue:

• Continue to symptom gathering

2. Gather Symptoms (if new issue)

Use AskUserQuestion for each:

1. **Expected behavior** - What should happen? 2. **Actual behavior** - What happens instead? 3. **Error messages** - Any errors? (paste or describe) 4. **Timeline** - When did this start? Ever worked? 5. **Reproduction** - How do you trigger it?

After all gathered, confirm ready to investigate.

3. Spawn gsd-debugger Agent

Fill prompt and spawn:

<objective>
Investigate issue: {slug}

**Summary:** {trigger}
</objective>

<symptoms>
expected: {expected}
actual: {actual}
errors: {errors}
reproduction: {reproduction}
timeline: {timeline}
</symptoms>

<mode>
symptoms_prefilled: true
goal: {if diagnose_only: "find_root_cause_only", else: "find_and_fix"}
</mode>

<debug_file>
Create: .planning/debug/{slug}.md
</debug_file>

Task(
  prompt=filled_prompt,
  subagent_type="gsd-debugger",
  model="{debugger_model}",
  description="Debug {slug}"
)

4. Handle Agent Return

**If `## ROOT CAUSE FOUND` (diagnose-only mode):**

• Display root cause, confidence level, files involved, and suggested fix strategies
• Offer options:
• "Fix now" — spawn a continuation agent with `goal: find_and_fix` to apply the fix (see step 5)
• "Plan fix" — suggest `/gsd-plan-phase --gaps`
• "Manual fix" — done

**If `## DEBUG COMPLETE` (find_and_fix mode):**

• Display root cause and fix summary
• Offer options:
• "Plan fix" — suggest `/gsd-plan-phase --gaps` if further work needed
• "Done" — mark resolved

**If `## CHECKPOINT REACHED`:**

• Present checkpoint details to user
• Get user response
• If checkpoint type is `human-verify`:
• If user confirms fixed: continue so agent can finalize/resolve/archive
• If user reports issues: continue so agent returns to investigation/fixing
• Spawn continuation agent (see step 5)

**If `## INVESTIGATION INCONCLUSIVE`:**

• Show what was checked and eliminated
• Offer options:
• "Continue investigating" - spawn new agent with additional context
• "Manual investigation" - done
• "Add more context" - gather more symptoms, spawn again

5. Spawn Continuation Agent (After Checkpoint or "Fix now")

When user responds to checkpoint OR selects "Fix now" from diagnose-only results, spawn fresh agent:

<objective>
Continue debugging {slug}. Evidence is in the debug file.
</objective>

<prior_state>
<files_to_read>
- .planning/debug/{slug}.md (Debug session state)
</files_to_read>
</prior_state>

<checkpoint_response>
**Type:** {checkpoint_type}
**Response:** {user_response}
</checkpoint_response>

<mode>
goal: find_and_fix
</mode>

Task(
  prompt=continuation_prompt,
  subagent_type="gsd-debugger",
  model="{debugger_model}",
  description="Continue debug {slug}"
)

</process>

<success_criteria>

• [ ] Active sessions checked
• [ ] Symptoms gathered (if new)
• [ ] gsd-debugger spawned with context
• [ ] Checkpoints handled correctly
• [ ] Root cause confirmed before fixing

</success_criteria>