`sidecar/claude-sdk` is the repo's second TypeScript package, wired to the
root only through `npm --prefix`. It reads length-prefixed MessagePack
frames on stdin, runs one SDK query, forwards every tool call to Rust, and
returns Rust's answer to the model verbatim. It computes no tool result,
reads no credential, logs no prompt, argument, or result, and writes nothing
outside its own stdout.
The query is opened with a custom system prompt, `settingSources: []`,
`tools: []`, `strictMcpConfig`, `persistSession: false`, and `alwaysLoad` on
every tool, so no CLAUDE.md, settings file, output style, built-in tool, or
persisted transcript reaches a caller-derived prompt.
`schema.ts` converts exactly the grammar `tool_schema.rs` emits and throws on
anything else, so an emitter that outgrows it fails a test rather than
registering a looser tool. Two Rust tests publish the fixtures the sidecar
tests read — the frame bytes and every real `parameters_json` — so the halves
cannot drift apart silently.
Dependencies are exact-pinned: @anthropic-ai/claude-agent-sdk 0.3.261,
@msgpack/msgpack 3.1.3, zod 4.5.4, and dev typescript 5.9.3 with
@types/node 24.13.3. `engines.node` is the installed major.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
