Debugger Detective

⛔⛔⛔ CRITICAL: AST STRUCTURAL ANALYSIS ONLY ⛔⛔⛔

╔══════════════════════════════════════════════════════════════════════════════╗
║                                                                              ║
║   🧠 THIS SKILL USES claudemem v0.3.0 AST ANALYSIS EXCLUSIVELY               ║
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║   ❌ GREP IS FORBIDDEN                                                       ║
║   ❌ FIND IS FORBIDDEN                                                       ║
║   ❌ GLOB IS FORBIDDEN                                                       ║
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║   ✅ claudemem --nologo context <name> --raw FOR FULL CALL CHAIN            ║
║   ✅ claudemem --nologo callers <name> --raw TO TRACE BACK TO SOURCE        ║
║   ✅ claudemem --nologo callees <name> --raw TO TRACE FORWARD               ║
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║   ⭐ v0.3.0: context shows full call chain for root cause analysis          ║
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Debugger Detective Skill

Version: 3.1.0 Role: Debugger / Incident Responder Purpose: Bug investigation and root cause analysis using AST call chain tracing with blast radius impact analysis

Role Context

You are investigating this codebase as a Debugger. Your focus is on:

• Error origins - Where exceptions are thrown
• Call chains - How execution flows to the failure point
• State mutations - What changed the data before failure
• Root causes - The actual source of problems (not just symptoms)
• Impact radius - What else might be affected

Why context is Perfect for Debugging

The context command shows you:

• Symbol definition = Where the buggy code is
• Callers = How we got here (trace backwards)
• Callees = What happens next (trace forward)
• Full call chain = Complete picture for root cause analysis

Debugger-Focused Commands (v0.3.0)

Find the Bug Location

# Find the function mentioned in error
claudemem --nologo symbol authenticate --raw

# Get full context (callers + callees)
claudemem --nologo context authenticate --raw

Trace Back to Source (callers)

# Who called this function? (trace backwards)
claudemem --nologo callers authenticate --raw

# Follow the chain backwards
claudemem --nologo callers LoginController --raw
claudemem --nologo callers handleRequest --raw

Trace Forward to Effect (callees)

# What does this function call? (trace forward)
claudemem --nologo callees authenticate --raw

# Find where state changes happen
claudemem --nologo callees updateSession --raw

Blast Radius Analysis (v0.4.0+ Required)

# After finding the bug, check what else is affected
IMPACT=$(claudemem --nologo impact buggyFunction --raw)

if [ -z "$IMPACT" ] || echo "$IMPACT" | grep -q "No callers"; then
  echo "No static callers - bug is isolated (or dynamically called)"
else
  echo "$IMPACT"
  echo ""
  echo "This shows:"
  echo "- Direct callers (immediately affected)"
  echo "- Transitive callers (potentially affected)"
  echo "- Complete list for testing after fix"
fi

Use for:

• Post-fix verification (test all impacted code)
• Regression prevention (know what to test)
• Incident documentation (impact scope)

Limitations: Event-driven/callback architectures may have callers not visible to static analysis.

Error Origin Hunting

# Map error handling code
claudemem --nologo map "throw error exception" --raw

# Find specific error types
claudemem --nologo symbol AuthenticationError --raw

# Who throws this error?
claudemem --nologo callers AuthenticationError --raw

State Mutation Tracking

# Find where state changes
claudemem --nologo map "set state update mutate" --raw

# Find the mutation function
claudemem --nologo symbol updateUserState --raw

# Who calls this mutation?
claudemem --nologo callers updateUserState --raw

Workflow: Bug Investigation (v0.3.0)

Phase 1: Locate the Symptom

# Find where the error appears
claudemem --nologo map "error message keywords" --raw

# Or find the specific function
claudemem --nologo symbol failingFunction --raw

Phase 2: Get Full Context

# Get callers + callees in one command
claudemem --nologo context failingFunction --raw

Phase 3: Trace Backwards (Find Root Cause)

# For each caller, check if it's the source
claudemem --nologo callers caller1 --raw
claudemem --nologo callers caller2 --raw

# Keep tracing until you find the root

Phase 4: Verify the Chain

# Once you suspect a root cause, verify the path
claudemem --nologo callees suspectedRoot --raw

# Does it lead to the symptom?

Phase 5: Check Impact

# What else calls the buggy code?
claudemem --nologo callers buggyFunction --raw

# These are all potentially affected

Output Format: Bug Investigation Report

1. Symptom Summary

┌─────────────────────────────────────────────────────────┐
│                    BUG INVESTIGATION                     │
├─────────────────────────────────────────────────────────┤
│  Symptom: User sees "undefined" in profile name          │
│  Location: src/components/Profile.tsx:45                │
│  Error Type: Data inconsistency / Null reference         │
│  Search Method: claudemem v0.3.0 (AST call chain)       │
└─────────────────────────────────────────────────────────┘

2. Call Chain Trace

❌ SYMPTOM: undefined rendered
   └── src/components/Profile.tsx:45
       └── user.name is undefined

↑ CALLER CHAIN (trace backwards):
   └── useUser hook (src/hooks/useUser.ts:23)
       ↑
   └── fetchUser API (src/api/user.ts:67)
       ↑
   └── userMapper (src/mappers/user.ts:12)
       ↑
🔍 ROOT CAUSE FOUND HERE

3. Root Cause Analysis

🔍 ROOT CAUSE IDENTIFIED:

Location: src/mappers/user.ts:12
Problem: Field name mismatch

API Response:       { fullName: "John Doe" }
Mapper Expects:     { full_name: "..." }
Result:             name = undefined

Evidence:
- callees of fetchUser → userMapper
- callers of userMapper → useUser → Profile
- Complete chain verified via context command

4. Impact Analysis

⚠️ OTHER AFFECTED CODE:

claudemem --nologo callers userMapper --raw shows:
  - useUser hook (main app)
  - useAdmin hook (admin panel)
  - tests/user.test.ts

All 3 locations may have the same bug!

Scenarios

Scenario: Null Pointer Exception

# Step 1: Find where undefined is used
claudemem --nologo map "undefined null" --raw

# Step 2: Get context of the failing function
claudemem --nologo context renderProfile --raw

# Step 3: Trace backwards through callers
claudemem --nologo callers getUserData --raw

# Step 4: Find where null was introduced
claudemem --nologo callees fetchUser --raw

Scenario: Race Condition

# Step 1: Find async operations
claudemem --nologo map "async await promise" --raw

# Step 2: Find shared state
claudemem --nologo symbol sharedState --raw

# Step 3: Who reads it?
claudemem --nologo callers sharedState --raw

# Step 4: Who writes it?
claudemem --nologo callees updateState --raw

Scenario: Incorrect Behavior

# Step 1: Find the function with wrong behavior
claudemem --nologo symbol calculateTotal --raw

# Step 2: What does it depend on?
claudemem --nologo callees calculateTotal --raw

# Step 3: Who provides input?
claudemem --nologo callers calculateTotal --raw

Anti-Patterns

Debugging Tips

1. Start at symptom - Use symbol to find where error appears
2. Get full context - Use context for callers + callees together
3. Trace backwards - Follow callers chain to root cause
4. Verify forward - Use callees to confirm the path
5. Check impact - All callers of buggy code may be affected

Notes

• context is your primary tool - Shows full call chain
• Trace backwards with callers - Find root cause, not just symptom
• Verify with callees - Confirm the execution path
• Check all callers after fixing - Don't leave other bugs
• Works best with TypeScript, Go, Python, Rust codebases

Maintained by: tianzecn Plugin: code-analysis v2.6.0 Last Updated: December 2025 (v0.4.0 impact analysis)