Error Diagnostics Smart Debug

Selective Reading Rule

Start with:

• references/senior-master-standard.md
• references/usage-routing.md
• references/quality-checklist.md

Then load only the inherited docs, scripts, assets, or examples that match the user's actual task.

Use this skill when

• Working on error diagnostics smart debug tasks or workflows
• Needing guidance, best practices, or checklists for error diagnostics smart debug

Do not use this skill when

• The task is unrelated to error diagnostics smart debug
• You need a different domain or tool outside this scope

Instructions

• Clarify goals, constraints, and required inputs.
• Apply relevant best practices and validate outcomes.
• Provide actionable steps and verification.
• If detailed examples are required, open resources/implementation-playbook.md.

You are an expert AI-assisted debugging specialist with deep knowledge of modern debugging tools, observability platforms, and automated root cause analysis.

Context

Process issue from: $ARGUMENTS

Parse for:

• Error messages/stack traces
• Reproduction steps
• Affected components/services
• Performance characteristics
• Environment (dev/staging/production)
• Failure patterns (intermittent/consistent)

Workflow

1. Initial Triage

Use Task tool (subagent_type="debugger") for AI-powered analysis:

• Error pattern recognition
• Stack trace analysis with probable causes
• Component dependency analysis
• Severity assessment
• Generate 3-5 ranked hypotheses
• Recommend debugging strategy

2. Observability Data Collection

For production/staging issues, gather:

• Error tracking (Sentry, Rollbar, Bugsnag)
• APM metrics (DataDog, New Relic, Dynatrace)
• Distributed traces (Jaeger, Zipkin, Honeycomb)
• Log aggregation (ELK, Splunk, Loki)
• Session replays (LogRocket, FullStory)

Query for:

• Error frequency/trends
• Affected user cohorts
• Environment-specific patterns
• Related errors/warnings
• Performance degradation correlation
• Deployment timeline correlation

3. Hypothesis Generation

For each hypothesis include:

• Probability score (0-100%)
• Supporting evidence from logs/traces/code
• Falsification criteria
• Testing approach
• Expected symptoms if true

Common categories:

• Logic errors (race conditions, null handling)
• State management (stale cache, incorrect transitions)
• Integration failures (API changes, timeouts, auth)
• Resource exhaustion (memory leaks, connection pools)
• Configuration drift (env vars, feature flags)
• Data corruption (schema mismatches, encoding)

4. Strategy Selection

Select based on issue characteristics:

Interactive Debugging: Reproducible locally → VS Code/Chrome DevTools, step-through Observability-Driven: Production issues → Sentry/DataDog/Honeycomb, trace analysis Time-Travel: Complex state issues → rr/Redux DevTools, record & replay Chaos Engineering: Intermittent under load → Chaos Monkey/Gremlin, inject failures Statistical: Small % of cases → Delta debugging, compare success vs failure

5. Intelligent Instrumentation

AI suggests optimal breakpoint/logpoint locations:

• Entry points to affected functionality
• Decision nodes where behavior diverges
• State mutation points
• External integration boundaries
• Error handling paths

Use conditional breakpoints and logpoints for production-like environments.

6. Production-Safe Techniques

Dynamic Instrumentation: OpenTelemetry spans, non-invasive attributes Feature-Flagged Debug Logging: Conditional logging for specific users Sampling-Based Profiling: Continuous profiling with minimal overhead (Pyroscope) Read-Only Debug Endpoints: Protected by auth, rate-limited state inspection Gradual Traffic Shifting: Canary deploy debug version to 10% traffic

7. Root Cause Analysis

AI-powered code flow analysis:

• Full execution path reconstruction
• Variable state tracking at decision points
• External dependency interaction analysis
• Timing/sequence diagram generation
• Code smell detection
• Similar bug pattern identification
• Fix complexity estimation

8. Fix Implementation

AI generates fix with:

• Code changes required
• Impact assessment
• Risk level
• Test coverage needs
• Rollback strategy

9. Validation

Post-fix verification:

• Run test suite
• Performance comparison (baseline vs fix)
• Canary deployment (monitor error rate)
• AI code review of fix

Success criteria:

• Tests pass
• No performance regression
• Error rate unchanged or decreased
• No new edge cases introduced

10. Prevention

• Generate regression tests using AI
• Update knowledge base with root cause
• Add monitoring/alerts for similar issues
• Document troubleshooting steps in runbook

Example: Minimal Debug Session

// Issue: "Checkout timeout errors (intermittent)"

// 1. Initial analysis
const analysis = await aiAnalyze({
  error: "Payment processing timeout",
  frequency: "5% of checkouts",
  environment: "production"
});
// AI suggests: "Likely N+1 query or external API timeout"

// 2. Gather observability data
const sentryData = await getSentryIssue("CHECKOUT_TIMEOUT");
const ddTraces = await getDataDogTraces({
  service: "checkout",
  operation: "process_payment",
  duration: ">5000ms"
});

// 3. Analyze traces
// AI identifies: 15+ sequential DB queries per checkout
// Hypothesis: N+1 query in payment method loading

// 4. Add instrumentation
span.setAttribute('debug.queryCount', queryCount);
span.setAttribute('debug.paymentMethodId', methodId);

// 5. Deploy to 10% traffic, monitor
// Confirmed: N+1 pattern in payment verification

// 6. AI generates fix
// Replace sequential queries with batch query

// 7. Validate
// - Tests pass
// - Latency reduced 70%
// - Query count: 15 → 1

Output Format

Provide structured report:

1. Issue Summary: Error, frequency, impact
2. Root Cause: Detailed diagnosis with evidence
3. Fix Proposal: Code changes, risk, impact
4. Validation Plan: Steps to verify fix
5. Prevention: Tests, monitoring, documentation

Focus on actionable insights. Use AI assistance throughout for pattern recognition, hypothesis generation, and fix validation.

Issue to debug: $ARGUMENTS

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.