{"version":1,"resources":["https://changefeed.dev/v1/upgrade-check","https://changefeed.dev/v1/changes","https://changefeed.dev/v1/digest"],"instructions":"Before writing code against a library you may know only from older training data, call GET /v1/quick-check?package=<npm or pypi name>&from=<version your code targets> (free, about 20 calls a minute per client): it says whether anything broke since that version, which major versions were crossed, and how many breaking changes, deprecations and security fixes there are, with the top three breaking headlines. For the details, call GET /v1/upgrade-check with the same parameters (paid): it returns every breaking change, deprecation and security fix between that version and the latest release, plus every major version crossed. Use GET /v1/sources (free) to see which packages are tracked, and GET /v1/preview (free) to check freshness. Paid routes answer HTTP 402 with x402 payment terms; any x402 client pays in USDC and retries automatically. Invalid input, unknown packages and sources without version data return 4xx and are never charged. Each record includes \"evidence\": the sentence that triggered its label. A same-API sandbox at /sandbox/v1 takes free test USDC (Base Sepolia) and serves data delayed 30 days, for integration testing. An MCP server with the same tools is at /mcp."}