Summary
When your production app throws errors with stack traces pointing to minified JavaScript at column 47821, this server maps them back to the original TypeScript file, line, and column using source maps. It exposes three tools: retrace_stack decodes the full trace, retrieve_code_context shows the surrounding source lines with a column pointer, and audit_sourcemap_match validates that your dist directory's .map files are present and point to sources that actually exist. You point it at a stack trace and your dist folder, and it tells you which TypeScript file and line crashed instead of leaving you staring at obfuscated bundles. Useful when debugging production incidents or helping an agent understand what actually failed.
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🗺️ sourcemap-retrace-mcp
Your app crashed in production. The stack trace is useless. Your AI agent has no idea where the bug is.
MCP server that decodes minified production stack traces back to original TypeScript source files, lines, and columns — using source maps. Before your agent spends 20 minutes guessing at obfuscated code.
🤔 The problem
Your monitoring tool sends you this:
TypeError: Cannot read properties of undefined (reading 'userId')
at e.<anonymous> (main.a3f2c1.js:1:47821)
at h (vendor.d4e5f6.js:1:12045)
at processQueue (main.a3f2c1.js:1:89234)
You ask your agent to debug it. The agent reads main.a3f2c1.js. It's 40,000 characters of minified JavaScript. It has no idea what e.<anonymous> at column 47821 means.
sourcemap-retrace-mcp maps that back to:
at validateSession (src/auth/session.ts:142:8)
at handleRequest (src/api/middleware.ts:67:3)
Now the agent knows exactly where to look.
🛠️ Tools
retrace_stack
Decode a minified stack trace back to original TypeScript source locations. Pass the raw stack trace and the directory containing your .js.map files.
Retrace Results
Frames mapped: 3 | Unmapped: 1
TypeError: Cannot read properties of undefined (reading 'userId')
at validateSession (src/auth/session.ts:142:8)
at handleRequest (src/api/middleware.ts:67:3)
at processQueue (src/queue/processor.ts:28:12)
at Module._compile (node:internal/modules/cjs/loader:1376:14)
retrieve_code_context
Show the original source lines surrounding a mapped error location — with line numbers and a column pointer.
Code Context
File: src/auth/session.ts
Target: line 142, column 8
139 │ const session = await getSession(token);
140 │ if (!session) throw new AuthError("invalid token");
141 │
> 142 │ return session.userId;
│ ^
143 │ }
144 │
145 │ export async function refreshSession(token: string) {
audit_sourcemap_match
Validate that .map files in your dist directory are present and point to source files that actually exist on disk. Catches stale or missing maps before deployment.
Sourcemap Audit
Directory: dist/
Files checked: 4
OK: 3 | Missing maps: 0 | Broken sources: 1
✓ main.a3f2c1.js — 47 source(s) mapped
✓ vendor.d4e5f6.js — 312 source(s) mapped
✓ worker.b1c2d3.js — 8 source(s) mapped
⚠ legacy.e7f8a9.js — 2 source(s) not found on disk:
../src/utils/deprecated.ts
../src/utils/compat.ts
⚡ Setup
{
"mcpServers": {
"sourcemap-retrace": {
"command": "npx",
"args": ["-y", "sourcemap-retrace-mcp"]
}
}
}
🚀 Usage
"I have a production error. Here's the stack trace: [paste]. My dist files are in /path/to/dist. Retrace it, show me the code around the error, and tell me what's wrong."
The agent runs retrace_stack, then retrieve_code_context on the mapped location, and can finally read the actual TypeScript that crashed.
Works great alongside:
- env-secret-exposure-analyzer-mcp — scan for secrets before deploying
- release-readiness-triage-mcp — CI health check before release
📦 Links
License
MIT
Featured
Keep your Mac awake while Claude Code and 40+ AI agents run. Sleeps when they're idle.
One time payment $9 →Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →On Capafy, your Skill runs online 24/7 as an agent product, and you get paid every time someone uses it.
Start earning →