/nw-bugfix

name: nw-bugfix
description: "Bug fix workflow: root cause analysis → user review → regression test + fix via TDD"
user-invocable: true
argument-hint: '[bug-description] - Describe the defect observed'

NW-BUGFIX: Defect Resolution Workflow

**Wave**: CROSS_WAVE **Agents**: Rex (nw-troubleshooter) → selected crafter (OOP or FP per project paradigm)

Overview

End-to-end bug fix pipeline: diagnose root cause, review findings with user, then deliver regression tests that fail with the bug and pass with the fix. Ensures every defect produces a test that prevents recurrence.

Flow

INPUT: "{bug-description}"
  │
  ├─ Phase 1: Root Cause Analysis (@nw-troubleshooter)
  │   └─ /nw-root-why "{bug-description}"
  │   └─ Output: RCA document with root cause chain + fix proposal
  │
  ├─ Phase 2: User Review (INTERACTIVE — STOP here)
  │   └─ Present RCA findings to user
  │   └─ User confirms root cause + approves fix direction
  │   └─ If user rejects → refine RCA or stop
  │
  └─ Phase 3: Regression Test + Fix
      └─ /nw-deliver "fix-{bug-id}" — roadmap-based bugfix flow
      └─ Paradigm detection determines crafter (OOP or FP)
      └─ Regression test (RED) → fix (GREEN) → verify (COMMIT)

Execution Steps

Phase 1: Root Cause Analysis

**Skill loading**: The troubleshooter loads its skills from `~/.claude/skills/nw-{skill}/SKILL.md`:

• `nw-five-whys-methodology` — core investigation methodology
• `nw-investigation-techniques` — systematic debugging patterns
• `nw-post-mortem-framework` — structured incident analysis

Invoke @nw-troubleshooter via Agent tool:

Execute *investigate-root-cause for the following defect:

{bug-description}

Configuration:
- investigation_depth: 5
- multi_causal: true
- evidence_required: true

Produce:
1. Root cause chain (5 Whys with evidence at each level)
2. Contributing factors
3. Proposed fix with specific code changes
4. Files affected
5. Risk assessment of the fix

After the troubleshooter returns, present findings to the user. Include:

• Root cause summary (1-2 sentences)
• Evidence chain
• Proposed fix
• Files to modify
• Risk level

**STOP and wait for user confirmation before proceeding to Phase 3.**

Phase 2: User Review

Present the RCA findings and ask: 1. "Does this root cause match your understanding?" 2. "Do you approve the proposed fix direction?" 3. "Any additional constraints or context?"

If user rejects:

• Refine the RCA with additional context
• Or stop the workflow entirely

If user approves → proceed to Phase 3.

Phase 3: Regression Test + Fix

Phase 3 dispatches the fix through the roadmap-based bugfix flow. It does paradigm detection (reads project CLAUDE.md for `## Development Paradigm`), crafter selection (@nw-software-crafter for OOP, @nw-functional-software-crafter for FP), DES enforcement, and reads the rigor profile from `.nwave/des-config.json`.

**Preparation:**

1. Derive feature-id: `fix-{kebab-case-bug-summary}` (max 5 words) 2. Create `docs/feature/{feature-id}/deliver/` directory 3. Prepare RCA context from Phase 1 output (root cause, files affected, proposed fix)

Delegate to `/nw-deliver`:

/nw-deliver "fix-{bug-summary}"

The deliver orchestrator builds a minimal two-step roadmap:

**Step 01-01: Regression test (RED)**

• Write a test that reproduces the exact defect
• Test MUST fail against current code (proves the bug exists)
• Test location: `tests/regression/{component}/` or `tests/bugs/`
• Test name: `test_bug_{description}.py`

**Step 01-02: Fix implementation (GREEN)**

• Implement the minimal fix identified in RCA
• Run ALL tests — regression test must now PASS
• Existing tests must not regress

The crafter handles the TDD cycle (3-phase canon RED → GREEN → COMMIT per ADR-025) with DES monitoring.

Success Criteria

• [ ] Root cause identified with evidence at each causal level
• [ ] User reviewed and approved fix direction
• [ ] Regression test written that fails with the bug
• [ ] Fix implemented that makes the regression test pass
• [ ] All existing tests still pass (no regressions)
• [ ] Commit with conventional message: `fix(scope): description`

Examples

Example 1: Runtime crash

/nw-bugfix "DES hook crashes with FileNotFoundError when template schema is missing"

Phase 1: Rex traces to missing `step-tdd-cycle-schema.json` in plugin cache. Phase 2: User confirms. Phase 3: `/nw-deliver "fix-missing-template-schema"` → crafter writes `test_bug_missing_template_schema.py` (RED), adds fallback path resolution (GREEN), commits.

Example 2: Silent failure

/nw-bugfix "Skills plugin reports success but installs zero files when source has nw-prefixed layout"

Phase 1: Rex traces to `is_public_skill()` returning False for all nw-prefixed names due to ownership map key mismatch. Phase 2: User confirms. Phase 3: `/nw-deliver "fix-ownership-map-keys"` → crafter writes regression test with nw-prefixed fixture (RED), fixes ownership map keys (GREEN), commits.

Example 3: Functional project bug

/nw-bugfix "Pipeline composition breaks when filter predicate returns None"

Phase 1: Rex traces to missing None guard in compose() function. Phase 2: User confirms. Phase 3: `/nw-deliver "fix-compose-none-guard"` → paradigm detected as FP → @nw-functional-software-crafter writes property-based test (RED), adds None guard (GREEN), commits.

Notes

• This command is for **known defects** (something is broken). For new features, use `/nw-deliver`.
• The regression test is the primary deliverable — it prevents the bug from recurring.
• Keep the fix minimal. Refactoring belongs in `/nw-refactor`, not here.
• If the RCA reveals a design flaw (not just a code bug), escalate to `/nw-design` before fixing.
• Phase 3 delegates to `/nw-deliver`, which handles paradigm detection, DES enforcement, and rigor profile automatically.