<status stage="impl" state="done"/>

@fact:WHAT-IT-IS `jtd-codegen` generates strictly-typed, language-specific code from JTD ([JSON Type Definition, RFC 8927](https://www.rfc-editor.org/rfc/rfc8927)) schemas. A consuming project derives its wire types from committed `*.jtd.json` schemas through this binary — schema-first codegen instead of hand-maintained duplicates on either side of a contract. @status:impl/done

@fact:THIS-PACKAGE-IS-THE-RECIPE-NOT-THE-BINARY **This package ships the provisioning recipe, never the binary.** The binary is fetched from the upstream release page into the consuming project's local `tools/jtd-codegen/` directory, which the consumer keeps gitignored — only the recipe (this document) and the version pin travel with source trees. That is the same posture the binary's first consumer records in its own `tools/.gitignore`: toolchain binaries are vendored per machine, never committed. @status:impl/done

@fact:UPSTREAM Upstream: <https://github.com/jsontypedef/json-typedef-codegen>. @status:impl/done

@fact:PINNED-VERSION **`jtd-codegen 0.4.1`** — the most recent stable release at the time of pinning. This README is the pin's single home: bump by editing this line (a new package version), never by restating the number in a consumer tree. CI asserts that schemas do not drift from generated code; it does not enforce a particular generator build. @status:impl/done

@fact:INSTALL-TARGET Drop the platform binary at `tools/jtd-codegen/jtd-codegen` (or `jtd-codegen.exe` on Windows) inside the consuming project, and keep that directory gitignored. @status:impl/done

@fact:INSTALL-WINDOWS From the project root, in PowerShell or Git Bash: @status:impl/done

@fact:WINDOWS-GNU-BUILD Upstream ships a `gnu` build, not `msvc` — the static binary works on the Windows hosts the projects target. @status:impl/done

@fact:INSTALL-MACOS Apple Silicon (Intel: swap in `x86_64-apple-darwin.tar.gz`): @status:impl/done

@fact:INSTALL-LINUX One command: @status:impl/done

@fact:VERIFY-VERSION The installed binary answers with the pinned version: @status:impl/done

@fact:CONSUMER-WIRES-ITS-OWN-TASK The consumer wires the binary into its own regeneration task and drift check — generate, then byte-compare in CI. The first consumer (the vibevm host) runs it as `cargo xtask codegen` / `cargo xtask check-codegen`, preferring the project-local binary and falling back to PATH; its task preflights the binary and errors actionably, pointing at this recipe, when both are missing. @status:impl/done