StackBridge

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💡 Why StackBridge?

When AI coding agents (Cursor, Claude Code, Windsurf, Antigravity) edit backend models or API routes in full-stack codebases, backend unit tests frequently pass while the frontend silently breaks in production:

1. An agent modifies an API parameter or Pydantic/SQLAlchemy field in backend/routes.py.
2. Backend tests pass in isolation. Nothing warns the agent.
3. The React/Next.js client calling that endpoint across the boundary fails with runtime errors.

StackBridge-MCP is an always-warm Model Context Protocol (MCP) server that parses full-stack AST relationships, discovers cross-stack blast radii in 0.75 ms, and verifies changes using baseline-diffed compiler checks with zero false positives.

React / Next.js Client            FastAPI Routes            SQLAlchemy ORM Models
   (TypeScript AST)      ───►    (Python AST)     ───►          (Schema AST)
  UserProfile.tsx              get_user_billing()              BillingAccount

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⚡ Key Highlights

• 🌲 Tree-sitter AST Graph: Parses Next.js (fetch, Axios, React Query) ↔ FastAPI routes ↔ SQLAlchemy ORM models without heavy LSP sidecars or runtime imports.
• ⚡ Sub-1ms Traversal: Persistent SQLite WAL database with recursive Common Table Expressions (0.75 ms traversal query latency).
• 📉 99.74% Prompt Token Reduction: Replaces massive multi-file code dumps with compact, mathematically precise AST contract slices.
• 🛡️ Root-Cause Diagnostic Ranking: Graph-distance BFS ranks errors (🔴 PRIMARY ROOT CAUSE vs ⚠️ CASCADING BREAKAGE) and outputs immediate Git diff patches.
• 🧪 Test Impact Selection: Isolates test suites impacted by a schema change and highlights untested blast-radius paths (0% coverage).
• 🌐 Interactive Canvas: Built-in localhost tripartite visualizer (stackbridge ui) on http://127.0.0.1:3456.
• 🔄 Continuous Intelligence: Background file watcher daemon (stackbridge watch) and living AGENTS.md context generator.

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📊 Real-World Benchmarks

Empirical performance measured on fastapi-realworld-example-app (44 files, 23 AST dependency nodes, 10 cross-boundary edges):

Benchmark Metric	Raw Codebase Dump	StackBridge Compact Slice	Improvement / Latency
Context Window Size	19,705 tokens	51 tokens	📉 99.74% Token Reduction
Blast Radius Traversal	Full-repo search: ~150 ms	SQLite Recursive CTE: 0.75 ms	⚡ 200x Faster Traversal
Compiler Verification	Global linter: ~3,500 ms	Baseline-Diffed Engine: 312 ms	🛡️ Zero False Positives
Automated Test Suite	—	56 / 56 tests passing	✅ 100% Passing

See full benchmark methodology in docs/benchmarks.md and REAL_WORLD_BENCHMARK.md.

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🚀 Quick Start

Option 1: Zero-Install Execution (Recommended via uvx)

uvx stackbridge serve

Option 2: Pip Installation

pip install stackbridge
stackbridge serve

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⚙️ Client Configuration

Connect StackBridge to your AI pair programmer over standard JSON-RPC 2.0 stdio:

1. Cursor (.cursor/mcp.json)

{
  "mcpServers": {
    "stackbridge": {
      "command": "uvx",
      "args": ["stackbridge", "serve"]
    }
  }
}

2. Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "stackbridge": {
      "command": "python",
      "args": ["-m", "stackbridge.main", "serve", "--transport", "stdio"]
    }
  }
}

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🤖 MCP Tools Reference

StackBridge exposes high-ergonomics tools to coding agents:

Tool Name	Arguments	Description
trace_fullstack_path	symbol_or_path: str	Traces the full-stack dependency chain: Frontend component ➔ API route ➔ Database model.
get_route_contract	route_path: str	Extracts HTTP methods, status codes, response models, and linked frontend fetch callers with confidence scores.
verify_schema_change	modified_files: dict	Runs in-memory compiler checks across impacted files, ranking root causes and proposing diff patches.
get_stack_health	repo_path: str	Returns real-time full-stack boundary stats, node counts, edge counts, and breakage drift status.

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💻 CLI Reference

# Index a repository and export the dependency graph
stackbridge index --repo-path . --force

# Trace blast radius for a model or route
stackbridge trace --target BillingAccount

# Run pre-commit boundary verification guard
stackbridge guard --fail-on-error

# Launch interactive tripartite web visualizer
stackbridge ui --port 3456

# Start continuous background watcher daemon
stackbridge watch

# Generate living AGENTS.md boundary architecture guide
stackbridge init-agents

# Execute performance and token reduction benchmarks
stackbridge benchmark --runs 3 --output BENCHMARK.md

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📁 Repository Structure

StackBridge-MCP/
├── .github/
│   ├── workflows/ci.yml         # CI pipeline (Python 3.10-3.13 on Ubuntu/Windows/macOS)
│   ├── ISSUE_TEMPLATE/          # Bug report and feature request issue templates
│   └── PULL_REQUEST_TEMPLATE.md # Standard PR checklist
├── docs/
│   ├── architecture.md          # Subsystem breakdown and Mermaid diagrams
│   ├── benchmarks.md            # Benchmark methodology and raw metrics
│   └── ast_extraction_spec.md   # Tree-sitter extractor grammar specifications
├── stackbridge/
│   ├── core/                    # Unified StackGraph, SQLite CTE store, watcher, route matcher
│   ├── parsers/                 # Tree-sitter parsers (TS fetch, Python routes, SQLAlchemy)
│   ├── verifier/                # Baseline-diffed verifier, root-cause ranker, test impact selector
│   ├── mcp_server/              # FastMCP stdio server and JSON-RPC tools
│   ├── benchmarks/              # Benchmark runner and markdown report generator
│   └── ui/                      # Localhost tripartite interactive canvas
├── tests/                       # 56 automated test suites (parsers, verifiers, MCP E2E, CTE)
├── AGENTS.md                    # Living agent architecture guide
├── CHANGELOG.md                 # Version release notes
├── CONTRIBUTING.md              # Contribution and development guidelines
├── LICENSE                      # MIT License
└── pyproject.toml               # Package metadata and tool configurations

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📄 License

This project is licensed under the MIT License.