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name: troubleshooting description: Diagnose and resolve build failures, performance issues, and deployment problems using the RAPID framework. Covers TypeScript/build errors, performance bottlenecks, Edge Functions, environment configs. Parallel specialist to fail-fast-debugging (bugs) and root-cause-tracing (code investigation).

Troubleshooting Guide

Purpose

Systematic diagnosis and resolution of infrastructure-level issues: build failures, performance problems, deployment errors, and environment misconfigurations. Uses the RAPID framework for structured troubleshooting.

When to Use

Activate this skill for:

• Build/compile errors (TypeScript, Vite, webpack)
• Performance issues (slow queries, memory leaks, N+1)
• Deployment failures (Edge Functions, production errors)
• Environment problems (missing env vars, CORS, auth errors)
• Dependency conflicts (npm, peer dependencies)

When NOT to Use (Handoffs)

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RAPID Framework

R - Reproduce

Confirm the issue is reproducible and gather exact error output.

Copy# Capture exact error
npm run build 2>&1 | tee build-error.log

# Note environment
node --version
npm --version
npx supabase --version

A - Analyze

Parse error messages, identify the failing component.

Copy# TypeScript errors - get detailed output
npx tsc --noEmit --pretty 2>&1 | head -50

# Vite build errors
npm run build -- --debug

# Dependency tree issues
npm ls --all | grep -i error

P - Propose

Form a hypothesis based on the error pattern.

I - Implement

Apply the minimal fix for the hypothesis.

D - Document

Record what worked for future reference.

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Common Build Errors

TypeScript Errors

Copy# Check types without building
npx tsc --noEmit

# Find specific error location
npx tsc --noEmit 2>&1 | grep -A 3 "error TS"

Common Fixes:

Vite Build Errors

Copy# Debug build
npm run build -- --debug

# Check for circular dependencies
npx madge --circular src/

Common Issues:

Dependency Errors

Copy# Clear cache and reinstall
rm -rf node_modules package-lock.json
npm install

# Check for peer dependency issues
npm ls 2>&1 | grep "peer dep"

# Force resolution
npm install --legacy-peer-deps

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Performance Troubleshooting

Identifying Slow Queries

Copy// Add timing to Supabase queries
const start = performance.now();
const { data, error } = await supabase.from('contacts').select('*');
console.log(`Query took ${performance.now() - start}ms`);

N+1 Query Detection

Copy// BAD - N+1 pattern
const contacts = await supabase.from('contacts').select('*');
for (const contact of contacts.data) {
  const notes = await supabase
    .from('notes')
    .select('*')
    .eq('contact_id', contact.id); // N queries!
}

// GOOD - Single query with join
const contacts = await supabase
  .from('contacts')
  .select('*, notes(*)');

Memory Leak Detection

Copy# Check heap usage over time
node --expose-gc -e "
  setInterval(() => {
    global.gc();
    console.log(process.memoryUsage().heapUsed / 1024 / 1024, 'MB');
  }, 1000);
"

React Performance

Copy// Use React DevTools Profiler
// Or add console timing:
console.time('render');
// ... component renders
console.timeEnd('render');

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Deployment Troubleshooting

Edge Function Errors

Copy# Check function logs
npx supabase functions logs my-function --local

# Test locally first
npx supabase functions serve my-function --env-file .env.local

# Deploy with debug output
npx supabase functions deploy my-function --debug

Common Edge Function Issues:

CORS Configuration

Copy// Required headers for Edge Functions
const corsHeaders = {
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Headers":
    "authorization, x-client-info, apikey, content-type",
};

// Handle preflight
if (req.method === "OPTIONS") {
  return new Response("ok", { headers: corsHeaders });
}

// Include in all responses
return new Response(JSON.stringify(data), {
  headers: { ...corsHeaders, "Content-Type": "application/json" },
});

Environment Variables

Copy# Check which env vars are set
env | grep SUPABASE

# Verify .env file is loaded
cat .env.local

# Set secrets for Edge Functions
npx supabase secrets set MY_SECRET=value
npx supabase secrets list

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HTTP Error Codes

401 Unauthorized

Copy// Check auth header is present
const authHeader = req.headers.get("Authorization");
if (!authHeader) {
  return new Response("Missing Authorization header", { status: 401 });
}

// Verify token
const { data: { user }, error } = await supabase.auth.getUser(
  authHeader.replace("Bearer ", "")
);

403 Forbidden

Usually an RLS policy issue:

Copy-- Check RLS policies
SELECT * FROM pg_policies WHERE tablename = 'contacts';

-- Test as authenticated user
SET request.jwt.claim.role = 'authenticated';
SELECT * FROM contacts;

500 Internal Server Error

Copy# Check Supabase logs
npx supabase logs --type api

# Check Edge Function logs
npx supabase functions logs <function-name>

# Enable verbose logging in code
console.error("Full error:", JSON.stringify(error, null, 2));

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Quick Diagnostic Commands

Copy# Full system check
npm run build && npx tsc --noEmit && npm test

# Database connection test
npx supabase db reset --dry-run

# Local stack health
npx supabase status

# Dependency audit
npm audit
npm outdated

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Escalation Path

If troubleshooting fails after 2 attempts:

1. Document findings - What was tried, what failed
2. Use mcp__zen__thinkdeep - For architectural analysis
3. Check if it's a code bug - Hand off to fail-fast-debugging
4. Check if it needs tracing - Hand off to root-cause-tracing

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Related Skills

• fail-fast-debugging - For code bugs (logic errors)
• root-cause-tracing - For call chain investigation
• supabase-cli - For Supabase CLI commands
• supabase-crm - For database/RLS patterns
• verification-before-completion - Run before claiming "fixed"