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๐ŸŒ‰ StackBridge-MCP

Sub-1ms Cross-Stack AST Contract & Verification Layer for AI Coding Agents

PyPI version Python 3.10+ License: MIT CI Tests FastMCP Compatible


๐Ÿ’ก 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)      โ”€โ”€โ”€โ–บ    (Python AST)     โ”€โ”€โ”€โ–บ          (Schema AST)
  UserProfile.tsx              get_user_billing()              BillingAccount

โšก Key Highlights

  • ๐ŸŒฒ Tree-sitter AST Graph: Parses Next.js (fetch, Axios, React Query) โ†” FastAPI routes โ†” SQLAlchemy ORM models without heavy LSP sidecars or runtime imports.

  • โšก Sub-1ms Traversal: Persistent SQLite WAL database with recursive Common Table Expressions (0.75 ms traversal query latency).

  • ๐Ÿ“‰ 99.74% Prompt Token Reduction: Replaces massive multi-file code dumps with compact, mathematically precise AST contract slices.

  • ๐Ÿ›ก๏ธ Root-Cause Diagnostic Ranking: Graph-distance BFS ranks errors (๐Ÿ”ด PRIMARY ROOT CAUSE vs โš ๏ธ CASCADING BREAKAGE) and outputs immediate Git diff patches.

  • ๐Ÿงช Test Impact Selection: Isolates test suites impacted by a schema change and highlights untested blast-radius paths (0% coverage).

  • ๐ŸŒ Interactive Canvas: Built-in localhost tripartite visualizer (stackbridge ui) on http://127.0.0.1:3456.

  • ๐Ÿ”„ Continuous Intelligence: Background file watcher daemon (stackbridge watch) and living AGENTS.md context generator.


๐Ÿ“Š 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

๐Ÿ“‰ 99.74% Token Reduction

Blast Radius Traversal

Full-repo search: ~150 ms

SQLite Recursive CTE: 0.75 ms

โšก 200x Faster Traversal

Compiler Verification

Global linter: ~3,500 ms

Baseline-Diffed Engine: 312 ms

๐Ÿ›ก๏ธ Zero False Positives

Automated Test Suite

โ€”

56 / 56 tests passing

โœ… 100% Passing

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


๐Ÿš€ Quick Start

uvx stackbridge serve

Option 2: Pip Installation

pip install stackbridge
stackbridge serve

โš™๏ธ 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"]
    }
  }
}

๐Ÿค– 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 โž” API route โž” 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.


๐Ÿ’ป 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

๐Ÿ“ Repository Structure

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

๐Ÿ“„ License

This project is licensed under the MIT License.

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