deadends-dev 0.4.0
Structured failure knowledge for AI agents — dead ends, workarounds, error chains
License: MIT
Requires Python: >=3.10
Keywords: error, debugging, dead-end, workaround, ai-agent, mcp, error-handling, troubleshooting

# deadends.dev

<!-- mcp-name: dev.deadends/deadends-dev -->

[![Errors](https://img.shields.io/badge/errors-1028-blue)](https://deadends.dev)
[![Domains](https://img.shields.io/badge/domains-20-green)](https://deadends.dev)
[![MCP Tools](https://img.shields.io/badge/MCP_tools-8-purple)](https://smithery.ai/server/deadend/deadends-dev)
[![PyPI](https://img.shields.io/pypi/v/deadends-dev)](https://pypi.org/project/deadends-dev/)
[![License](https://img.shields.io/badge/license-MIT%20%2F%20CC%20BY%204.0-lightgrey)](LICENSE)

**Structured failure knowledge for AI coding agents.**

1028 error entries across 20 domains. When AI coding agents encounter errors, they waste tokens on approaches that are known to fail. deadends.dev tells agents what NOT to try, what actually works, and what error comes next.

> **Website:** [deadends.dev](https://deadends.dev) · **MCP Server:** [Smithery](https://smithery.ai/server/deadend/deadends-dev) · **PyPI:** [deadends-dev](https://pypi.org/project/deadends-dev/) · **API:** [/api/v1/index.json](https://deadends.dev/api/v1/index.json)

## Installation

```bash
pip install deadends-dev
```

**Requirements:** Python 3.10+

## MCP Server

The MCP server exposes 8 tools for AI coding agents:

| Tool | Description |
|------|-------------|
| `lookup_error` | Match an error message against 1028 known patterns. Returns dead ends, workarounds, and error chains. |
| `get_error_detail` | Get full details for a specific error by ID (e.g., `python/modulenotfounderror/py311-linux`). |
| `list_error_domains` | List all 20 error domains and their counts. |
| `search_errors` | Fuzzy keyword search across all domains (e.g., "memory limit", "permission denied"). |
| `list_errors_by_domain` | List all errors in a specific domain, sorted by fix rate, name, or confidence. |
| `batch_lookup` | Look up multiple error messages at once (max 10). |
| `get_domain_stats` | Get quality metrics for a domain: avg fix rate, resolvability, confidence breakdown. |
| `get_error_chain` | Traverse the error transition graph: what errors follow, precede, or get confused with this one. |

### Local (Claude Desktop / Cursor)

Add to `~/.claude/claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "deadend": {
      "command": "python",
      "args": ["-m", "mcp.server"],
      "cwd": "/path/to/deadends.dev"
    }
  }
}
```

### Hosted (Smithery — no local setup)

Install via [Smithery](https://smithery.ai/server/deadend/deadends-dev):

```bash
# Claude Code
npx -y @smithery/cli@latest install deadend/deadends-dev --client claude

# Cursor
npx -y @smithery/cli@latest install deadend/deadends-dev --client cursor
```

Or connect directly: `https://server.smithery.ai/deadend/deadends-dev`

### Example Response

When an agent encounters `ModuleNotFoundError: No module named 'torch'`, the `lookup_error` tool returns:

```
## ModuleNotFoundError: No module named 'X' (Python 3.11+)
Resolvable: true | Fix rate: 0.88

### Dead Ends (DO NOT TRY):
- pip install X with system Python (fails 70%): venv not activated

### Workarounds (TRY THESE):
- Create venv, activate, then pip install (works 95%)
- Use python -m pip install instead of bare pip (works 90%)
```

## Quick Start — Python SDK

```python
from generator.lookup import lookup, batch_lookup, search

# Single error lookup
result = lookup("ModuleNotFoundError: No module named 'torch'")

# What NOT to try (saves tokens and time)
for d in result["dead_ends"]:
    print(f"AVOID: {d['action']} — fails {int(d['fail_rate']*100)}%")

# What actually works
for w in result["workarounds"]:
    print(f"TRY: {w['action']} — works {int(w['success_rate']*100)}%")

# Batch lookup (multiple errors at once)
results = batch_lookup([
    "ModuleNotFoundError: No module named 'torch'",
    "CUDA error: out of memory",
    "CrashLoopBackOff",
])

# Keyword search
hits = search("memory limit", domain="docker", limit=5)
```

## Quick Start — CLI

```bash
pip install deadends-dev
deadends "CUDA error: out of memory"
deadends --list  # show all known errors
```

## API Endpoints

| Endpoint | Description |
|----------|-------------|
| [`/api/v1/match.json`](https://deadends.dev/api/v1/match.json) | Lightweight regex matching (fits in context window) |
| [`/api/v1/index.json`](https://deadends.dev/api/v1/index.json) | Full error index with all metadata |
| [`/api/v1/{domain}/{slug}/{env}.json`](https://deadends.dev/api/v1/python/modulenotfounderror/py311-linux.json) | Individual ErrorCanon ([example](https://deadends.dev/api/v1/python/modulenotfounderror/py311-linux.json)) |
| [`/api/v1/openapi.json`](https://deadends.dev/api/v1/openapi.json) | OpenAPI 3.1 spec with response examples |
| [`/api/v1/stats.json`](https://deadends.dev/api/v1/stats.json) | Dataset quality metrics by domain |
| [`/api/v1/errors.ndjson`](https://deadends.dev/api/v1/errors.ndjson) | NDJSON streaming (one error per line) |
| [`/api/v1/version.json`](https://deadends.dev/api/v1/version.json) | Service metadata and endpoint directory |
| [`/llms.txt`](https://deadends.dev/llms.txt) | LLM-optimized error listing ([llmstxt.org](https://llmstxt.org) standard) |
| [`/llms-full.txt`](https://deadends.dev/llms-full.txt) | Complete database dump |
| [`/.well-known/ai-plugin.json`](https://deadends.dev/.well-known/ai-plugin.json) | AI plugin manifest |
| [`/.well-known/agent-card.json`](https://deadends.dev/.well-known/agent-card.json) | Google A2A agent card |
| [`/.well-known/security.txt`](https://deadends.dev/.well-known/security.txt) | Security contact (RFC 9116) |

## Covered Domains (20)

| Domain | Errors | Examples |
|--------|--------|----------|
| Python | 85 | ModuleNotFoundError, TypeError, KeyError, MemoryError, RecursionError |
| Node | 67 | ERR_MODULE_NOT_FOUND, EACCES, EADDRINUSE, heap OOM, ERR_REQUIRE_ESM |
| Docker | 63 | no space left, exec format error, bind address in use, healthcheck |
| Kubernetes | 61 | CrashLoopBackOff, ImagePullBackOff, OOMKilled, RBAC forbidden, HPA |
| Git | 59 | failed to push, merge conflicts, detached HEAD, stash apply, tags |
| Go | 53 | nil pointer, unused import, interface conversion, slice out of range |
| Java | 52 | NullPointerException, ClassNotFound, OutOfMemoryError, connection pool |
| Database | 52 | deadlock, connection pool, slow query, replication lag, constraint violation |
| AWS | 51 | AccessDenied, S3 NoSuchBucket, Lambda timeout, CloudFormation rollback |
| TypeScript | 49 | TS2307, TS2322, TS2345, TS2532, TS7053, TS2769, TS18048 |
| Rust | 47 | E0382 borrow, E0308 mismatch, E0277 trait, E0106 lifetime, E0507 |
| PHP | 47 | headers already sent, too many connections, autoload, memory exhaustion |
| CUDA | 47 | OOM, device-side assert, NCCL, cuDNN, tensor device mismatch |
| Terraform | 46 | state lock, cycle, provider not found, moved block, backend init |
| CI/CD | 46 | GitHub Actions timeout, secret not found, Docker rate limit, cache miss |
| React | 44 | invalid hook call, too many re-renders, unique key, context, act() |
| Next.js | 44 | hydration failed, dynamic server, server-only import, RSC serialization |
| Networking | 42 | connection refused, ECONNRESET, SSL certificate, DNS timeout, EPIPE |
| pip | 41 | build wheel failed, conflicting deps, externally-managed, hash mismatch |
| .NET | 32 | NullReferenceException, LINQ translation, DI circular, EF concurrency |

## ErrorCanon Data Format

Each error is a JSON file with:

```json
{
  "error": { "signature": "...", "regex": "...", "domain": "..." },
  "verdict": { "resolvable": "true|partial|false", "fix_success_rate": 0.88 },
  "dead_ends": [{ "action": "...", "why_fails": "...", "fail_rate": 0.75 }],
  "workarounds": [{ "action": "...", "success_rate": 0.92, "how": "..." }],
  "transition_graph": { "leads_to": [...], "preceded_by": [...] }
}
```

## AI Coding Agent Integration — 18 Discovery Formats

Every page on deadends.dev includes machine-readable data in 18 formats:

| Format | Location | Purpose |
|--------|----------|---------|
| JSON API | `/api/v1/{id}.json` | RESTful error data per ErrorCanon |
| match.json | `/api/v1/match.json` | Compact regex-only file (load entire DB into context) |
| index.json | `/api/v1/index.json` | Master error index with metadata |
| stats.json | `/api/v1/stats.json` | Dataset quality metrics per domain |
| errors.ndjson | `/api/v1/errors.ndjson` | Streaming NDJSON for batch processing |
| OpenAPI | `/api/v1/openapi.json` | Full API spec with response examples |
| JSON-LD | Every `<head>` | Schema.org TechArticle + FAQPage |
| ai-summary | Every page | `<pre id="ai-summary">` KEY=VALUE blocks |
| llms.txt | `/llms.txt` | llmstxt.org standard |
| llms-full.txt | `/llms-full.txt` | Complete database dump |
| ai-plugin.json | `/.well-known/` | OpenAI plugin manifest |
| agent-card.json | `/.well-known/` | Google A2A protocol |
| security.txt | `/.well-known/` | RFC 9116 security contact |
| robots.txt | `/robots.txt` | 34 AI crawlers explicitly welcomed |
| CLAUDE.md | `/CLAUDE.md` | Claude Code instructions |
| AGENTS.md | `/AGENTS.md` | OpenAI Codex CLI instructions |
| .clinerules | `/.clinerules` | Cline AI instructions |

## Development

```bash
pip install -e ".[dev]"

# Full pipeline (validate → generate → build → test)
python -m generator.pipeline

# Individual steps
python -m generator.bulk_generate     # Generate canons from seeds
python -m generator.build_site        # Build static site
python -m generator.validate          # Validate data + site
python -m pytest tests/ -v            # Run tests
```

## Contributing

Add error definitions to `generator/bulk_generate.py` or create JSON files directly in `data/canons/`.

```bash
python -m generator.validate --data-only  # Validate before submitting
```

## License

MIT (code) · CC BY 4.0 (data)

<!-- mcp-name: io.github.dbwls99706/deadends-dev -->