tacet (Python)

Python bindings for Tacet: check a TypeScript frontend against a Spring Boot API and see what an API, file or field change would affect, plus ready-made tools for FastMCP.

The package drives the Tacet CLI (--format json), so the machine running it needs Node.js 22.13+ (and Java 17+ for extract_backend). Point it at the CLI with TACET_CLI or put tacet on PATH.

from tacet import Tacet

lens = Tacet(index=".tacet/index.db", frontend_dir="./frontend", backend_dir="./backend")
lens.index_frontend()
lens.extract_backend()

report = lens.check(changed_since="origin/main")      # PASS / WARNING / FAIL + issues with file:line
lens.impact_of_api("GET /users/{id}", graph="mermaid")
lens.page_apis(api="GET /users/{id}")      # which pages use this API, and through what
lens.impact_of_file("src/api/user.ts")
lens.impact_of_field("UserResponse.name")

FastMCP

from fastmcp import FastMCP
from tacet.fastmcp import register_tools

mcp = FastMCP("my-server")
register_tools(mcp, frontend_dir="./frontend", backend_dir="./backend", prefix="tacet_")
mcp.run()

Tools: index_frontend, extract_backend, check_contract, impact_of_api, impact_of_file, impact_of_field, search, impact_summary, render_graph, page_apis, ontology.

Tests

npm run build && npm run build:jar   # from the repository root
uv run --group dev pytest