deepseek-harness/docs/cookbook/adding-a-vendored-package.md

Cookbook: adding a vendored package

When the harness needs another upstream Cordis package (e.g. @cordisjs/plugin-http), it is vendored as pinned source under vendor/, not added as an npm dependency — see the vendoring decision for why. vendor/README.md covers updating an already-vendored package; this guide is the file-by-file checklist for adding a new one. (Verified against the existing vendored set; if it drifts, fix it here.)

1. Copy the source in

vendor/<dir>/
  package.json     # from upstream; set "private": true, keep name/exports/type
  tsconfig.json    # extends ../../tsconfig.base.json (see shape below)
  src/             # the upstream src/ verbatim
  README.md LICENSE # if upstream ships them

tsconfig.json mirrors the other vendored packages — rootDir: src, outDir: lib/types, the strictness relaxations upstream code needs, and a references entry for every other vendored package it imports:

{
  "extends": "../../tsconfig.base.json",
  "compilerOptions": {
    "rootDir": "src", "outDir": "lib/types",
    "noUncheckedIndexedAccess": false, "exactOptionalPropertyTypes": false,
    "noImplicitOverride": false, "noUnusedLocals": false, "noUnusedParameters": false
  },
  "include": ["src"],
  "references": [{ "path": "../cordis" }, { "path": "../cosmokit" }]
}

package.json invariants: "private": true (vendored packages are never published), keep upstream's name/version/exports/type, point declaration metadata at lib/types, publish .d.ts and .d.ts.map declaration outputs, and list its cordis deps in peerDependencies (matching the upstream manifest). Transitive upstream deps must themselves be vendored or already present — vendoring one package often means vendoring its dependency tree (e.g. @cordisjs/plugin-http pulls @cordisjs/fetch-file).

Local relative imports/exports in vendored TypeScript source use explicit .ts specifiers after copying. This is a repo-local build-shape divergence from upstream: rewriteRelativeImportExtensions emits .js runtime imports while declarations keep explicit .ts specifiers that NodeNext/Node16 TypeScript consumers can resolve.

2. Register it in the root configs

File	Change
tsconfig.base.json	add "<npm-name>": ["./vendor/<dir>/src"] to paths
tsconfig.json	add { "path": "./vendor/<dir>" } to references
tsconfig.build.json	add { "path": "./vendor/<dir>" } to references (before the packages/* entries)
vendor/README.md	add a manifest table row (dir, npm name, version, upstream repo, commit SHA) and log any local modifications
scripts/publint-all.ts	only if the vendored package is itself published from here (vendored deps normally are not — skip)

Covered automatically by globs — no edits needed: root package.json workspaces (vendor/*), tsdown.config.ts, vitest.config.ts, eslint.config.mjs. A per-package vendor/<dir>/tsdown.config.ts is needed ONLY if the build shape diverges from the root default (dual ESM/CJS or multiple entries — see vendor/schemastery and vendor/logger-console); its entry should read the JS emitted under lib/types.

3. Mind the manifest guard

scripts/check-vendor-manifest.sh (a pre-commit hook) fails if anything under vendor/*/src is staged without vendor/README.md also staged. Stage the manifest update alongside the source so the commit passes.

4. Verify

pnpm install        # registers the workspace
pnpm run typecheck
pnpm run build && pnpm run test && pnpm run constraints

The source paths map is shared by build and root typecheck configs. The important isolation boundary is the project-reference graph: vendored source must be referenced through its own vendor/<dir>/tsconfig.json, not pulled into a root strict program.