domains / software-engineering / error-diagnostics-smart-debug / error-diagnostics-smart-debug

error-diagnostics-smart-debug

Skill card

combined

Both copies describe the same 10-step debugging workflow, but they disagree on how to run triage, how to score hypotheses, and how to handle production chaos/instrumentation. The first copy mandates a debugger subagent, uses numeric probability scores, and lists Chaos Engineering as a strategy. The second copy requires user authorization for delegation, uses qualitative confidence, and restricts fault injection to isolated environments. Crowning one copy would hide these real operational differences.

Repositories

Other copies

Combined skill

---
name: error-diagnostics-smart-debug
description: "Diagnose software failures using observability data, ranked hypotheses, and targeted instrumentation. Use when the cause is unclear or an issue requires systematic investigation."
---

## Use this skill when

- A reproducible failure or intermittent incident needs evidence-driven debugging.
- Existing telemetry must be compared with source and deployment changes before patching.

## 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.

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
Analyze directly; use a debugger subagent only when the user authorizes delegation and the host exposes that capability:
- 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:
- Qualitative confidence and what evidence would change it; do not invent calibrated probabilities
- 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
**Controlled Fault Reproduction**: Use an isolated test environment and bounded authorized faults; never infer permission for production chaos tests
**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 Techniques Requiring Review

Instrumentation, debug endpoints and traffic shifts are changes with privacy, cost and availability effects. Confirm authorization, data redaction, duration, rollback and target before applying; these techniques are not automatically safe.
**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: Illustrative Debug Session

The helpers, spans and metrics below are pseudocode for a hypothetical case; no implementation, telemetry integration or measured improvement is bundled. Replace them with actual configured tools, and never report the example numbers as observed evidence.

```typescript
// 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 the workflow.