TracePact: Catch AI agent tool-call regressions before production

You changed a prompt. The output still looks fine. But your agent stopped reading the config before deploying and switched from running tests to running builds. Nobody noticed until production broke. The problem Most agent failures aren't bad text — they're bad behavior . The agent calls the wrong tools, in the wrong order, with the wrong arguments. Output evals don't catch this because the final response still looks plausible. Teams try to catch it manually: reviewing traces in agent UIs parsing raw session logs comparing old vs new runs by hand debugging regressions only after users report them What TracePact does TracePact is a behavioral testing framework for AI agents. It works at the tool-call level , not the text level. 1. Write behavior contracts: import { TraceBuilder } from ' @tracepact/vitest ' ; const trace = new TraceBuilder () . addCall ( ' read_file ' , { path : ' src/service.ts ' }, ' ... ' ) . addCall ( ' write_file ' , { path : ' src/service.ts ' , content : ' ... ' }