deepseek-harness/docs/development.md

Development guide

This guide covers the local setup needed to work on DeepSeek Harness and run the same checks the hooks and CI run.

Prerequisites

• Node.js 24 or newer. The repo declares node >=24, and CI also exercises Node 24.
• Corepack-enabled Yarn. The repo pins yarn@4.14.1 in package.json; run corepack enable if yarn --version does not resolve through Corepack.
• Git.
• Optional: a DeepSeek API key for the coding-agent demo and real-API e2e tests.

First-time setup

Install dependencies from the repo root:

yarn install

Yarn uses the node-modules linker in this repo. The install also runs the root postinstall script, which installs lefthook from the repo dev dependency.

If hooks are missing because dependencies were restored from cache or postinstall was skipped, install them manually:

yarn lefthook install

Run typecheck once after a fresh clone:

yarn typecheck

That first typecheck builds declaration output used by type-aware linting for vendored packages. Without it, yarn lint can report unresolved-type no-unsafe-* errors even when source code is fine.

If you are preparing to push from a fresh clone or worktree, also build once:

yarn build

yarn hygiene includes publint, which validates package entrypoints against the built lib/*.js files. A fresh worktree has no bundled JS until yarn build runs.

Environment variables

The real DeepSeek adapter and coding-agent demo read credentials from the environment or from a gitignored .env at the repo root:

DEEPSEEK_API_KEY=sk-...
DEEPSEEK_BASE_URL=https://... # optional

DEEPSEEK_BASE_URL is optional and defaults to the public API. Never commit real credentials. The real-API e2e suites self-skip when DEEPSEEK_API_KEY is not set.

Git hooks

lefthook is configured in lefthook.yml and calls the same package scripts used by CI:

• pre-commit runs staged-file ESLint fixes, yarn typecheck, and the vendor manifest guard.
• pre-push runs yarn test and yarn hygiene.

The vendor manifest guard checks that changes under vendor/*/src are staged with the matching vendor/README.md manifest update. See vendor/README.md before editing vendored code.

Daily commands

Use these from the repo root:

yarn test           # unit tests
yarn test:coverage  # unit tests with per-file coverage gates
yarn test:e2e       # real-API tests; self-skips without DEEPSEEK_API_KEY
yarn typecheck      # build declarations, then typecheck source, tests, and examples
yarn lint           # eslint .
yarn lint:fix       # eslint . --fix
yarn build          # build declarations and JS bundles
yarn hygiene        # knip, publint, and yarn constraints

When changing package public behavior, update the relevant README or JSDoc in the same change. The repo does not have an automated doc-sync gate.

Demos

The echo demo does not need API credentials:

yarn demo:echo

The coding-agent demo uses the real DeepSeek adapter and needs DEEPSEEK_API_KEY in the environment or repo-root .env:

yarn demo:coding

Architecture context

Read docs/architecture.md before changing anything under packages/. The codebase is built around Cordis plugins, event-sourced sessions, typed service seams, and explicit extension points.