---
name: kata-debug
description: Systematically debug issues, investigating bugs, troubleshooting problems, or tracking down errors with persistent state across context resets. Triggers include "debug", "investigate bug", "troubleshoot", "find the problem", "why isn't this working", and "debug session".
metadata:
  version: "0.1.0"
---

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

**Orchestrator role:** Gather symptoms, spawn kata-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.
</objective>

<context>
User's issue: $ARGUMENTS

Check for active sessions:

```bash
find .planning/debug -maxdepth 1 -name "*.md" 2>/dev/null | grep -v resolved | head -5
```

</context>

<process>

## 0. Resolve Model Profile

Read model profile for agent spawning:

```bash
MODEL_PROFILE=$(cat .planning/config.json 2>/dev/null | grep -o '"model_profile"[[:space:]]*:[[:space:]]*"[^"]*"' | grep -o '"[^"]*"$' | tr -d '"' || echo "balanced")
```

Default to "balanced" if not set.

**Model lookup table:**

| Agent         | quality | balanced | budget |
| ------------- | ------- | -------- | ------ |
| kata-debugger | opus    | sonnet   | sonnet |

Store resolved model for use in Task calls below.

## 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. Read Instruction Files

Before spawning agents, read agent instructions using the Read tool:

- `references/debugger-instructions.md` (relative to skill base directory) — store as `debugger_instructions_content`

## 4. Spawn Debugger Agent

Fill prompt and spawn:

```markdown
<objective>
Investigate issue: {slug}

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

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

<mode>
symptoms_prefilled: true
goal: find_and_fix
</mode>

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

```
Task(
  prompt="<agent-instructions>\n{debugger_instructions_content}\n</agent-instructions>\n\n" + filled_prompt,
  subagent_type="general-purpose",
  model="{debugger_model}",
  description="Debug {slug}"
)
```

## 5. Handle Agent Return

**If `## ROOT CAUSE FOUND`:**

- Display root cause and evidence summary
- Offer options:
  - "Fix now" - spawn fix subagent
  - "Plan fix" - suggest /kata-plan-phase --gaps
  - "Manual fix" - done

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

- Present checkpoint details to user
- Get user response
- 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

## 6. Spawn Continuation Agent (After Checkpoint)

When user responds to checkpoint, spawn fresh agent:

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

<prior_state>
Debug file: @.planning/debug/{slug}.md
</prior_state>

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

<mode>
goal: find_and_fix
</mode>
```

```
Task(
  prompt="<agent-instructions>\n{debugger_instructions_content}\n</agent-instructions>\n\n" + continuation_prompt,
  subagent_type="general-purpose",
  model="{debugger_model}",
  description="Continue debug {slug}"
)
```

</process>

<success_criteria>

- [ ] Active sessions checked
- [ ] Symptoms gathered (if new)
- [ ] kata-debugger spawned with context
- [ ] Checkpoints handled correctly
- [ ] Root cause confirmed before fixing
      </success_criteria>