PaperclipOrg
Claude Agent Skill · by Obra

Systematic Debugging

Forces you to investigate root causes before attempting any fixes through a rigid four-phase process: evidence gathering with diagnostic logging at component bo

Install
Terminal · npx
$npx skills add https://github.com/obra/superpowers --skill systematic-debugging
Works with Paperclip

How Systematic Debugging fits into a Paperclip company.

Systematic Debugging drops into any Paperclip agent that handles this kind of work. Assign it to a specialist inside a pre-configured PaperclipOrg company and the skill becomes available on every heartbeat — no prompt engineering, no tool wiring.

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Source file
SKILL.md296 lines
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---name: systematic-debuggingdescription: Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes--- # Systematic Debugging ## 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. **Violating the letter of this process is violating the spirit of debugging.** ## The Iron Law ```NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST``` If you haven't completed Phase 1, you cannot propose fixes. ## When to Use Use for ANY technical issue:- Test failures- Bugs in production- Unexpected behavior- Performance problems- Build failures- Integration issues **Use this ESPECIALLY when:**- Under time pressure (emergencies make guessing tempting)- "Just one quick fix" seems obvious- You've already tried multiple fixes- Previous fix didn't work- You don't fully understand the issue **Don't skip when:**- Issue seems simple (simple bugs have root causes too)- You're in a hurry (rushing guarantees rework)- Manager wants it fixed NOW (systematic is faster than thrashing) ## The Four Phases You MUST complete each phase before proceeding to the next. ### Phase 1: Root Cause Investigation **BEFORE attempting ANY fix:** 1. **Read Error Messages Carefully**   - Don't skip past errors or warnings   - They often contain the exact solution   - Read stack traces completely   - Note line numbers, file paths, error codes 2. **Reproduce Consistently**   - Can you trigger it reliably?   - What are the exact steps?   - Does it happen every time?   - If not reproducible → gather more data, don't guess 3. **Check Recent Changes**   - What changed that could cause this?   - Git diff, recent commits   - New dependencies, config changes   - Environmental differences 4. **Gather Evidence in Multi-Component Systems**    **WHEN system has multiple components (CI → build → signing, API → service → database):**    **BEFORE proposing fixes, add diagnostic instrumentation:**   ```   For EACH component boundary:     - Log what data enters component     - Log what data exits component     - Verify environment/config propagation     - Check state at each layer    Run once to gather evidence showing WHERE it breaks   THEN analyze evidence to identify failing component   THEN investigate that specific component   ```    **Example (multi-layer system):**   ```bash   # Layer 1: Workflow   echo "=== Secrets available in workflow: ==="   echo "IDENTITY: ${IDENTITY:+SET}${IDENTITY:-UNSET}"    # Layer 2: Build script   echo "=== Env vars in build script: ==="   env | grep IDENTITY || echo "IDENTITY not in environment"    # Layer 3: Signing script   echo "=== Keychain state: ==="   security list-keychains   security find-identity -v    # Layer 4: Actual signing   codesign --sign "$IDENTITY" --verbose=4 "$APP"   ```    **This reveals:** Which layer fails (secrets → workflow ✓, workflow → build ✗) 5. **Trace Data Flow**    **WHEN error is deep in call stack:**    See `root-cause-tracing.md` in this directory for the complete backward tracing technique.    **Quick version:**   - 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 **Find the pattern before fixing:** 1. **Find Working Examples**   - Locate similar working code in same codebase   - What works that's similar to what's broken? 2. **Compare Against References**   - If implementing pattern, read reference implementation COMPLETELY   - Don't skim - read every line   - Understand the pattern fully before applying 3. **Identify Differences**   - What's different between working and broken?   - List every difference, however small   - Don't assume "that can't matter" 4. **Understand Dependencies**   - What other components does this need?   - What settings, config, environment?   - What assumptions does it make? ### Phase 3: Hypothesis and Testing **Scientific method:** 1. **Form Single Hypothesis**   - State clearly: "I think X is the root cause because Y"   - Write it down   - Be specific, not vague 2. **Test Minimally**   - Make the SMALLEST possible change to test hypothesis   - One variable at a time   - Don't fix multiple things at once 3. **Verify Before Continuing**   - Did it work? Yes → Phase 4   - Didn't work? Form NEW hypothesis   - DON'T add more fixes on top 4. **When You Don't Know**   - Say "I don't understand X"   - Don't pretend to know   - Ask for help   - Research more ### Phase 4: Implementation **Fix the root cause, not the symptom:** 1. **Create Failing Test Case**   - Simplest possible reproduction   - Automated test if possible   - One-off test script if no framework   - MUST have before fixing   - Use the `superpowers:test-driven-development` skill for writing proper failing tests 2. **Implement Single Fix**   - Address the root cause identified   - ONE change at a time   - No "while I'm here" improvements   - No bundled refactoring 3. **Verify Fix**   - Test passes now?   - No other tests broken?   - Issue actually resolved? 4. **If Fix Doesn't Work**   - STOP   - Count: How many fixes have you tried?   - If < 3: Return to Phase 1, re-analyze with new information   - **If ≥ 3: STOP and question the architecture (step 5 below)**   - DON'T attempt Fix #4 without architectural discussion 5. **If 3+ Fixes Failed: Question Architecture**    **Pattern indicating architectural problem:**   - Each fix reveals new shared state/coupling/problem in different place   - Fixes require "massive refactoring" to implement   - Each fix creates new symptoms elsewhere    **STOP and question fundamentals:**   - Is this pattern fundamentally sound?   - Are we "sticking with it through sheer inertia"?   - Should we refactor architecture vs. continue fixing symptoms?    **Discuss with your human partner before attempting more fixes**    This is NOT a failed hypothesis - this is a wrong architecture. ## Red Flags - STOP and Follow Process If you catch yourself thinking:- "Quick fix for now, investigate later"- "Just try changing X and see if it works"- "Add multiple changes, run tests"- "Skip the test, I'll manually verify"- "It's probably X, let me fix that"- "I don't fully understand but this might work"- "Pattern says X but I'll adapt it differently"- "Here are the main problems: [lists fixes without investigation]"- Proposing solutions before tracing data flow- **"One more fix attempt" (when already tried 2+)**- **Each fix reveals new problem in different place** **ALL of these mean: STOP. Return to Phase 1.** **If 3+ fixes failed:** Question the architecture (see Phase 4.5) ## your human partner's Signals You're Doing It Wrong **Watch for these redirections:**- "Is that not happening?" - You assumed without verifying- "Will it show us...?" - You should have added evidence gathering- "Stop guessing" - You're proposing fixes without understanding- "Ultrathink this" - Question fundamentals, not just symptoms- "We're stuck?" (frustrated) - Your approach isn't working **When you see these:** STOP. Return to Phase 1. ## Common Rationalizations | Excuse | Reality ||--------|---------|| "Issue is simple, don't need process" | Simple issues have root causes too. Process is fast for simple bugs. || "Emergency, no time for process" | Systematic debugging is FASTER than guess-and-check thrashing. || "Just try this first, then investigate" | First fix sets the pattern. Do it right from the start. || "I'll write test after confirming fix works" | Untested fixes don't stick. Test first proves it. || "Multiple fixes at once saves time" | Can't isolate what worked. Causes new bugs. || "Reference too long, I'll adapt the pattern" | Partial understanding guarantees bugs. Read it completely. || "I see the problem, let me fix it" | Seeing symptoms ≠ understanding root cause. || "One more fix attempt" (after 2+ failures) | 3+ failures = architectural problem. Question pattern, don't fix again. | ## Quick Reference | Phase | Key Activities | Success Criteria ||-------|---------------|------------------|| **1. Root Cause** | Read errors, reproduce, check changes, gather evidence | Understand WHAT and WHY || **2. Pattern** | Find working examples, compare | Identify differences || **3. Hypothesis** | Form theory, test minimally | Confirmed or new hypothesis || **4. Implementation** | Create test, fix, verify | Bug resolved, tests pass | ## When Process Reveals "No Root Cause" If systematic investigation reveals issue is truly environmental, timing-dependent, or external: 1. You've completed the process2. Document what you investigated3. Implement appropriate handling (retry, timeout, error message)4. Add monitoring/logging for future investigation **But:** 95% of "no root cause" cases are incomplete investigation. ## Supporting Techniques These techniques are part of systematic debugging and available in this directory: - **`root-cause-tracing.md`** - Trace bugs backward through call stack to find original trigger- **`defense-in-depth.md`** - Add validation at multiple layers after finding root cause- **`condition-based-waiting.md`** - Replace arbitrary timeouts with condition polling **Related skills:**- **superpowers:test-driven-development** - For creating failing test case (Phase 4, Step 1)- **superpowers:verification-before-completion** - Verify fix worked before claiming success ## Real-World Impact From debugging sessions:- Systematic approach: 15-30 minutes to fix- Random fixes approach: 2-3 hours of thrashing- First-time fix rate: 95% vs 40%- New bugs introduced: Near zero vs common