DeepSeek Harness SDK is built on the Cordis framework. Cordis core was at 4.0.0-rc.6 (a release candidate) when this repo started; the harness depends on framework internals (fiber lifecycle, effect disposal, waterfall dispatch) whose exact behavior matters to the agent loop's correctness guarantees.
Copy the needed Cordis packages (core, loader, include, group, timer, hmr, logger-console) and the cordiverse foundation libraries (cosmokit, schemastery) into `vendor/` as source, flattened, keeping their original npm names so workspace resolution is transparent. Truly third-party dependencies (js-yaml, chokidar, @standard-schema/spec, …) stay on npm.
`vendor/README.md` is the manifest: upstream repo + commit SHA per package and an exhaustive local-modification log. A pre-commit guard (`scripts/check-vendor-manifest.sh`) rejects vendored-source changes that don't update the manifest in the same commit.
- **Depend on the npm packages** — rejected: core was at a release candidate, and the harness leans on framework internals (fiber lifecycle, effect disposal, waterfall dispatch) whose exact behavior the agent loop's correctness guarantees depend on; an upstream RC bump could break them without a local fix path.
- **Vendor everything transitively** — rejected: truly third-party dependencies (js-yaml, chokidar, @standard-schema/spec, …) stay on npm; only the framework layer whose internals matter is owned.
