Debug

Systematic Debugging

vs problem-discuss: debug to głębokie dochodzenie pojedynczego, znanego failure (error / stack trace / test fail / cicha rozbieżność, którą już zidentyfikowano). Jeśli masz mgliste, wieloelementowe zgłoszenie od klienta, w którym nie wiadomo jeszcze, czy każda sprawa to bug, gap featurowy, błąd danych czy nieporozumienie — zacznij od problem-discuss (intake + triage), który sklasyfikuje sprawy i odeśle potwierdzone bugi tutaj.

Handoff Input

OPTIONAL — only applies when invoked with a path to a problem-{slug}.md file.

If invoked with a path to absolutpowers/problem/problem-{slug}.md (and optionally a case number, e.g. "Sprawa 2"), read that file BEFORE Phase 1 and use the named case's evidence as the Phase 1 starting point:

• reguła biznesowa (contract / expected behavior)
• flow przejścia (step-by-step trigger path)
• file:line references found in the investigation
• facts extracted from attachments

What this means: confirm and deepen — do NOT re-derive from zero. Phase 1 still happens in full, but you start with evidence already gathered by problem-discuss rather than a blank slate.

When no path is given: start Phase 1 normally. Zero regression for solo debug invocations.

Edge cases:

• Multi-case file + no case number given → ask which case before reading evidence.
• Evidence from problem-discuss contradicted by deeper investigation → trust the fresh evidence; note the divergence explicitly in your response (consistent with "memory is context, not proof").

Iron Law is unchanged. The handoff gives a head start; it does not waive root-cause investigation. Debug may refute problem-discuss's preliminary hypothesis — with evidence.

Context Files

Before starting investigation, also read (if they exist):

• ./absolutpowers/project-memory.md — durable traps, warning signs, and workarounds discovered in earlier tasks

Use project memory as prior context, not as a substitute for fresh evidence. If memory conflicts with current evidence, trust the evidence. When reading project-memory.md, use only entries with Status: active as investigation context. Ignore entries with Status: superseded or Status: archived.

Project Memory

Read references/project-memory.md for read rules, formats, and promotion. Debugging often yields high-value lessons — only durable traps belong in memory. Source label: debug / {bug or CI context}.

At end of session: if a durable lesson exists, create a candidate (or promote simple lessons after approval). See references/project-memory.md → Promotion rules.

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):

   # 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:

Step 0: Classify fix size (run once, at the start of Phase 4)

Before writing any code, classify the fix using the same heuristic as generate-tasks single-file vs orchestrated:

• Small — 1 file / 1 layer, no migration, no public API change, no security boundary, no shared-core impact → inline (proceed to steps 1–3 below as today).
• Large — multiple layers/modules, database migration, public API change, security boundary, shared-core impact, OR any Phase 4.5 escalation (3+ fixes failed / architectural problem) → do NOT implement inline. Write absolutpowers/feature/planning-fix-{slug}.md and route to generate-tasks (see template below and Phase 4.5 for escalation path).

Borderline small/large → choose handoff (gates > ungated inline fix). Justify the choice explicitly in your response.

Threshold = same heuristic as single-file vs orchestrated in generate-tasks. One size model across the whole pipeline.

---

planning-fix-{slug}.md template (write to absolutpowers/feature/):

# Fix: {short description}

## Problem
{root cause with evidence — file:line, mechanism, NOT just symptoms}

## Wybrane rozwiązanie
{chosen fix approach}

## Zakres
{files / layers / modules affected}

## Acceptance Criteria
{optional but recommended for large fixes — what must be true after the fix;
root cause defines expected post-fix behavior, which maps naturally to AC
and enables downstream Intent Fidelity / AC Fulfillment checks}

After writing planning-fix-{slug}.md, nudge: Wypisz jedną pełną, copy-paste'owalną komendę generate-tasks z absolutpowers/feature/planning-fix-{slug}.md w składni aktywnego harnessu zgodnie z references/harness-command-contract.md.

Do NOT implement the fix inline. Stop here and let the pipeline take over.

---

1. Create Failing Test Case

   • Simplest possible reproduction
   • Automated test if possible
   • One-off test script if no framework
   • MUST have before fixing

2. Implement Single Fix

   • Address the root cause identified
   • ONE change at a time
   • No bundled refactoring
   • Boy-scout rule for anything you spot nearby: a strictly trivial one-liner (typo, missing/dead import, obvious null-check — one line, no semantic risk) fix inline and note it; anything larger, name it (file:line, what is wrong) and ask the user whether to fix rather than silently patching or staying quiet. Keep it out of the root-cause fix itself.

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 (Phase 4.5)

   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?

   This is NOT a failed hypothesis — this is a wrong architecture. Discuss the architectural question with the user. Then, regardless of whether you continue the same approach or pivot, escalate through the artefact exit:

   Write absolutpowers/feature/planning-fix-{slug}.md capturing:

   • current root cause (with file:line evidence)
   • failed hypotheses and what each revealed (valuable context for generate-tasks)
   • architectural question / pivot decision

   Nudge: wypisz jedną pełną, copy-paste'owalną komendę generate-tasks z absolutpowers/feature/planning-fix-{slug}.md w składni aktywnego harnessu zgodnie z references/harness-command-contract.md.

   This is automatically a Large fix (3+ failed attempts = architectural scope). Do NOT attempt Fix #4 inline. The pipeline with its gates is the correct path forward.

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)

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	Classify fix size → small: inline (test, fix, verify); large: write planning-fix-{slug}.md, route to generate-tasks	Bug resolved (small) or handed off to pipeline (large)

When Process Reveals "No Root Cause"

If systematic investigation reveals issue is truly environmental, timing-dependent, or external:

1. You've completed the process
2. Document what you investigated
3. 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

Canonical AbsolutPowers debug path (see references/fork-policy.md). Vendored systematic-debugging is the MIT library sibling — prefer techniques in this directory.

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

Memory Capture at the End

Follow references/project-memory.md. If a durable lesson was found: write candidate and ask about promotion; if none, do nothing. Apply Scope routing first — a package-local trap is promoted to that package's CLAUDE.md → ## Gotchas (+ AGENTS.md mirror), not to global project-memory.md; state the destination when asking.

Terminal state

Stan terminalny zależy od rozmiaru fixa (Phase 4 Step 0):

Wynik	Oddaje	Dalej
Small fix inline	root cause + fix + tests green	opcjonalnie wypisz pełną natywną komendę review jeśli branch feature; done dla hotfixu
Large / 3+ failed	planning-fix-{slug}.md	wypisz pełną natywną komendę generate-tasks na tym pliku zgodnie z references/harness-command-contract.md
Routed from problem-discuss	potwierdzony/obalony root cause	jak wyżej; zaktualizuj understanding w odpowiedzi

Nie kończ sesji na „quick patch" bez Phase 1. Iron Law obowiązuje do końca.