Systematic Debugging

Adapted from obra/superpowers for Cursor IDE.

Overview

Random fixes waste time and create new bugs. Quick patches mask underlying issues.

Core principle: ALWAYS find root cause before attempting fixes. Symptom fixes are failure.

The Iron Law

NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST

If you haven't completed Phase 1, you cannot propose fixes.

The Four Phases

Phase 1: Root Cause Investigation

BEFORE attempting ANY fix:

1. •

   Read Error Messages Carefully - Don't skip past errors. Read stack traces completely. Note line numbers, file paths, error codes.

2. •

   Reproduce Consistently - Can you trigger it reliably? What are exact steps? If not reproducible → gather more data, don't guess.

3. •

   Check Recent Changes - Git diff, recent commits, new dependencies, config changes.

4. •

   Gather Evidence in Multi-Component Systems - Add diagnostic instrumentation at each component boundary. Run once to gather evidence showing WHERE it breaks. THEN investigate that specific component.

5. •

   Trace Data Flow - Where does bad value originate? What called this with bad value? Keep tracing up until you find the source. Fix at source, not at symptom.

Phase 2: Pattern Analysis

1. •Find Working Examples - Locate similar working code in same codebase
2. •Compare Against References - Read reference implementation COMPLETELY
3. •Identify Differences - List every difference, however small
4. •Understand Dependencies - What components, settings, config does this need?

Phase 3: Hypothesis and Testing

1. •Form Single Hypothesis - "I think X is the root cause because Y"
2. •Test Minimally - SMALLEST possible change, one variable at a time
3. •Verify Before Continuing - Didn't work? Form NEW hypothesis. DON'T add more fixes on top.
4. •If ≥ 3 fixes failed - STOP. Question the architecture. Discuss with human partner.

Phase 4: Implementation

1. •Create Failing Test Case - Use the test-driven-development skill
2. •Implement Single Fix - ONE change at a time
3. •Verify Fix - Test passes? No other tests broken? Issue resolved?
4. •If 3+ Fixes Failed: Question Architecture - Pattern of each fix revealing new problems = wrong architecture. Discuss with human partner.

Red Flags - STOP and Follow Process

• •"Quick fix for now, investigate later"
• •"Just try changing X and see if it works"
• •"It's probably X, let me fix that"
• •"I don't fully understand but this might work"
• •Proposing solutions before tracing data flow
• •"One more fix attempt" (when already tried 2+)

ALL of these mean: STOP. Return to Phase 1.

Quick Reference