DE

debug-with-file

Improves debugging accuracy by documenting exploration and analyzing logs systematically.

Install

mkdir -p .claude/skills/debug-with-file && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/2368" && unzip -o skill.zip -d .claude/skills/debug-with-file && rm skill.zip

Installs to .claude/skills/debug-with-file

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

Interactive hypothesis-driven debugging with documented exploration, understanding evolution, and analysis-assisted correction.
127 charsno explicit “when” trigger
Advanced

Key capabilities

  • Document exploration in understanding.md
  • Generate testable hypotheses
  • Add NDJSON logging instrumentation
  • Analyze evidence from debug logs
  • Consolidate learning and insights

How it works

The agent maintains a structured session folder containing logs and an evolving understanding document to track hypotheses and evidence.

Inputs & outputs

You give it
Bug description or error message
You get back
Debug logs, hypothesis history, and understanding document

When to use debug-with-file

  • Debug complex application errors
  • Document root cause analysis
  • Fix persistent bugs systematically

About this skill

Codex Debug-With-File Prompt

Overview

Enhanced evidence-based debugging with documented exploration process. Records understanding evolution, consolidates insights, and uses analysis to correct misunderstandings.

Core workflow: Explore → Document → Log → Analyze → Correct Understanding → Fix → Verify

Key enhancements over /prompts:debug:

  • understanding.md: Timeline of exploration and learning
  • Analysis-assisted correction: Validates and corrects hypotheses
  • Consolidation: Simplifies proven-wrong understanding to avoid clutter
  • Learning retention: Preserves what was learned, even from failed attempts

Target Bug

$BUG

Project Context

Run ccw spec load --category debug for known issues, workarounds, and root-cause notes.

Execution Process

Session Detection:
   ├─ Check if debug session exists for this bug
   ├─ EXISTS + understanding.md exists → Continue mode
   └─ NOT_FOUND → Explore mode

Explore Mode:
   ├─ Locate error source in codebase
   ├─ Document initial understanding in understanding.md
   ├─ Generate testable hypotheses with analysis validation
   ├─ Add NDJSON logging instrumentation
   └─ Output: Hypothesis list + await user reproduction

Analyze Mode:
   ├─ Parse debug.log, validate each hypothesis
   ├─ Use analysis to evaluate hypotheses and correct understanding
   ├─ Update understanding.md with:
   │   ├─ New evidence
   │   ├─ Corrected misunderstandings (strikethrough + correction)
   │   └─ Consolidated current understanding
   └─ Decision:
       ├─ Confirmed → Fix root cause
       ├─ Inconclusive → Add more logging, iterate
       └─ All rejected → Assisted new hypotheses

Fix & Cleanup:
   ├─ Apply fix based on confirmed hypothesis
   ├─ User verifies
   ├─ Document final understanding + lessons learned
   ├─ Remove debug instrumentation
   └─ If not fixed → Return to Analyze mode

Implementation Details

Session Setup & Mode Detection

Step 0: Determine Project Root

检测项目根目录,确保 .workflow/ 产物位置正确:

PROJECT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || pwd)

优先通过 git 获取仓库根目录;非 git 项目回退到 pwd 取当前绝对路径。 存储为 {projectRoot},后续所有 .workflow/ 路径必须以此为前缀。

const getUtc8ISOString = () => new Date(Date.now() + 8 * 60 * 60 * 1000).toISOString()
const projectRoot = bash('git rev-parse --show-toplevel 2>/dev/null || pwd').trim()

const bugSlug = "$BUG".toLowerCase().replace(/[^a-z0-9]+/g, '-').substring(0, 30)
const dateStr = getUtc8ISOString().substring(0, 10)

const sessionId = `DBG-${dateStr}-${bugSlug}`
const sessionFolder = `${projectRoot}/.workflow/.debug/${sessionId}`
const debugLogPath = `${sessionFolder}/debug.log`
const understandingPath = `${sessionFolder}/understanding.md`
const hypothesesPath = `${sessionFolder}/hypotheses.json`

// Auto-detect mode
const sessionExists = fs.existsSync(sessionFolder)
const hasUnderstanding = sessionExists && fs.existsSync(understandingPath)
const logHasContent = sessionExists && fs.existsSync(debugLogPath) && fs.statSync(debugLogPath).size > 0

const mode = logHasContent ? 'analyze' : (hasUnderstanding ? 'continue' : 'explore')

if (!sessionExists) {
  bash(`mkdir -p ${sessionFolder}`)
}

Explore Mode

Step 1.1: Locate Error Source

// Extract keywords from bug description
const keywords = extractErrorKeywords("$BUG")

// Search codebase for error locations
const searchResults = []
for (const keyword of keywords) {
  const results = Grep({ pattern: keyword, path: ".", output_mode: "content", "-C": 3 })
  searchResults.push({ keyword, results })
}

// Identify affected files and functions
const affectedLocations = analyzeSearchResults(searchResults)

Step 1.2: Document Initial Understanding

Create understanding.md:

# Understanding Document

**Session ID**: ${sessionId}
**Bug Description**: $BUG
**Started**: ${getUtc8ISOString()}

---

## Exploration Timeline

### Iteration 1 - Initial Exploration (${timestamp})

#### Current Understanding

Based on bug description and initial code search:

- Error pattern: ${errorPattern}
- Affected areas: ${affectedLocations.map(l => l.file).join(', ')}
- Initial hypothesis: ${initialThoughts}

#### Evidence from Code Search

${searchResults.map(r => `
**Keyword: "${r.keyword}"**
- Found in: ${r.results.files.join(', ')}
- Key findings: ${r.insights}
`).join('\n')}

#### Next Steps

- Generate testable hypotheses
- Add instrumentation
- Await reproduction

---

## Current Consolidated Understanding

${initialConsolidatedUnderstanding}

Step 1.3: Generate Hypotheses

Analyze the bug and generate 3-5 testable hypotheses:

// Hypothesis generation based on error pattern
const HYPOTHESIS_PATTERNS = {
  "not found|missing|undefined|未找到": "data_mismatch",
  "0|empty|zero|registered": "logic_error",
  "timeout|connection|sync": "integration_issue",
  "type|format|parse": "type_mismatch"
}

function generateHypotheses(bugDescription, affectedLocations) {
  // Generate targeted hypotheses based on error analysis
  // Each hypothesis includes:
  // - id: H1, H2, ...
  // - description: What might be wrong
  // - testable_condition: What to log
  // - logging_point: Where to add instrumentation
  // - evidence_criteria: What confirms/rejects it
  return hypotheses
}

Save to hypotheses.json:

{
  "iteration": 1,
  "timestamp": "2025-01-21T10:00:00+08:00",
  "hypotheses": [
    {
      "id": "H1",
      "description": "Data structure mismatch - expected key not present",
      "testable_condition": "Check if target key exists in dict",
      "logging_point": "file.py:func:42",
      "evidence_criteria": {
        "confirm": "data shows missing key",
        "reject": "key exists with valid value"
      },
      "likelihood": 1,
      "status": "pending"
    }
  ]
}

Step 1.4: Add NDJSON Instrumentation

For each hypothesis, add logging at the specified location:

Python template:

# region debug [H{n}]
try:
    import json, time
    _dbg = {
        "sid": "{sessionId}",
        "hid": "H{n}",
        "loc": "{file}:{line}",
        "msg": "{testable_condition}",
        "data": {
            # Capture relevant values here
        },
        "ts": int(time.time() * 1000)
    }
    with open(r"{debugLogPath}", "a", encoding="utf-8") as _f:
        _f.write(json.dumps(_dbg, ensure_ascii=False) + "\n")
except: pass
# endregion

JavaScript/TypeScript template:

// region debug [H{n}]
try {
  require('fs').appendFileSync("{debugLogPath}", JSON.stringify({
    sid: "{sessionId}",
    hid: "H{n}",
    loc: "{file}:{line}",
    msg: "{testable_condition}",
    data: { /* Capture relevant values */ },
    ts: Date.now()
  }) + "\n");
} catch(_) {}
// endregion

Step 1.5: Output to User

## Hypotheses Generated

Based on error "$BUG", generated {n} hypotheses:

{hypotheses.map(h => `
### ${h.id}: ${h.description}
- Logging at: ${h.logging_point}
- Testing: ${h.testable_condition}
- Evidence to confirm: ${h.evidence_criteria.confirm}
- Evidence to reject: ${h.evidence_criteria.reject}
`).join('')}

**Debug log**: ${debugLogPath}

**Next**: Run reproduction steps, then come back for analysis.

Analyze Mode

Step 2.1: Parse Debug Log

// Parse NDJSON log
const entries = Read(debugLogPath).split('\n')
  .filter(l => l.trim())
  .map(l => JSON.parse(l))

// Group by hypothesis
const byHypothesis = groupBy(entries, 'hid')

// Validate each hypothesis
for (const [hid, logs] of Object.entries(byHypothesis)) {
  const hypothesis = hypotheses.find(h => h.id === hid)
  const latestLog = logs[logs.length - 1]

  // Check if evidence confirms or rejects hypothesis
  const verdict = evaluateEvidence(hypothesis, latestLog.data)
  // Returns: 'confirmed' | 'rejected' | 'inconclusive'
}

Step 2.2: Analyze Evidence and Correct Understanding

Review the debug log and evaluate each hypothesis:

  1. Parse all log entries
  2. Group by hypothesis ID
  3. Compare evidence against expected criteria
  4. Determine verdict: confirmed | rejected | inconclusive
  5. Identify incorrect assumptions from previous understanding
  6. Generate corrections

Step 2.3: Update Understanding with Corrections

Append new iteration to understanding.md:

### Iteration ${n} - Evidence Analysis (${timestamp})

#### Log Analysis Results

${results.map(r => `
**${r.id}**: ${r.verdict.toUpperCase()}
- Evidence: ${JSON.stringify(r.evidence)}
- Reasoning: ${r.reason}
`).join('\n')}

#### Corrected Understanding

Previous misunderstandings identified and corrected:

${corrections.map(c => `
- ~~${c.wrong}~~ → ${c.corrected}
  - Why wrong: ${c.reason}
  - Evidence: ${c.evidence}
`).join('\n')}

#### New Insights

${newInsights.join('\n- ')}

${confirmedHypothesis ? `
#### Root Cause Identified

**${confirmedHypothesis.id}**: ${confirmedHypothesis.description}

Evidence supporting this conclusion:
${confirmedHypothesis.supportingEvidence}
` : `
#### Next Steps

${nextSteps}
`}

---

## Current Consolidated Understanding (Updated)

${consolidatedUnderstanding}

Step 2.4: Update hypotheses.json

{
  "iteration": 2,
  "timestamp": "2025-01-21T10:15:00+08:00",
  "hypotheses": [
    {
      "id": "H1",
      "status": "rejected",
      "verdict_reason": "Evidence shows key exists with valid value",
      "evidence": {...}
    },
    {
      "id": "H2",
      "status": "confirmed",
      "verdict_reason": "Log data confirms timing issue",
      "evidence": {...}
    }
  ],
  "corrections": [
    {
      "wrong_assumption": "...",
      "corrected_to": "...",
      "reason": "..."
    }
  ]
}

Fix & Verification

Step 3.1: Apply Fix

Based on confirmed hypothesis, implement the fix in the affected files.

Step 3.2: Document Resolution

Append to understanding.md:

### Iteration ${n} - Resolution (${timestamp})

#### Fix Applied

- Modified files: ${mo

---

*Content truncated.*

When not to use it

  • Simple, one-off bug fixes
  • Bugs requiring immediate hotfixes

Prerequisites

Git repository root

Limitations

  • Requires manual reproduction steps
  • Overhead for simple issues

How it compares

This method forces a rigorous, documented process for complex bugs, whereas standard debugging often lacks a persistent record of failed attempts.

Compared to similar skills

debug-with-file side by side with the closest alternatives in the catalog.

SkillInstallsUpdatedSafetyDifficulty
debug-with-file (this skill)13moReviewAdvanced
python-testing-patterns772moReviewIntermediate
error-handling-patterns352moNo flagsIntermediate
codex-claude-loop139moReviewAdvanced

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