deepseek-harness/docs/development.md

Development guide

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This guide covers the local setup needed to work on DeepSeek Harness and understand the local hooks, daily checks, and CI gates.

Prerequisites

• Node.js 24 or newer. The repo declares node >=24; CI runs the matrix on Node 24 and 26.
• Corepack-enabled pnpm. The repo pins pnpm@11.7.0 in package.json; run corepack enable if pnpm --version does not resolve through Corepack.
• Git.
• Optional: a DeepSeek API key for the REPL/ACP agent demos and real-API e2e tests.

First-time setup

Install dependencies from the repo root:

pnpm install

The install also runs the root postinstall script, which installs lefthook from the repo dev dependency through scripts/install-lefthook.mjs; the wrapper uses lefthook's reviewed --force mode so linked worktrees with an existing core.hooksPath do not fail normal pnpm run … commands.

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

pnpm exec lefthook install --force

Run typecheck once after a fresh clone:

pnpm run typecheck

That first typecheck runs the package/vendor build graph and the root no-emit tsconfig.json graph for examples, tests, and scripts. The root graph uses the same source paths map but relies on project references so vendored code is checked under its own tsconfig settings.

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

pnpm run build

pnpm run hygiene includes publint, which validates package entrypoints against the built lib/*.js files, and verify-node-next-types, which validates built declarations against a temporary NodeNext consumer. A fresh worktree has no bundled JS or declarations until pnpm run build runs.

Environment variables

The real DeepSeek adapter and key-backed agent demos 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 as an early local checkpoint before review:

• pre-commit runs staged-file ESLint fixes, pnpm run typecheck, and the vendor manifest guard.
• pre-push runs pnpm run test, pnpm run test:snapshot, pnpm run hygiene, pnpm run doc-sync, and pnpm run verify-module-graph.

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.

These hooks do not exactly mirror CI. Notably, pre-push runs unit tests without coverage, while CI runs pnpm run test:coverage; CI also runs echo-agent and built-bin smoke tests and exercises the matrix on Node 24 and 26.

CI gates

The GitHub workflow runs these gates on each pull request:

• pnpm install --frozen-lockfile
• pnpm run constraints
• pnpm run typecheck
• pnpm run lint
• pnpm run doc-sync
• pnpm run verify-module-graph
• pnpm run test:coverage
• pnpm run test:snapshot
• pnpm run build
• pnpm run hygiene
• an echo-agent smoke test that checks the demo's tool call, tool result, and JSONL output
• built-bin smoke tests that run the published lib/bin.js entrypoints under plain node

pnpm run hygiene is the local shorthand for pnpm run knip && pnpm run publint && pnpm run constraints && pnpm run verify-node-next-types; CI also runs pnpm run constraints as an earlier fail-fast step, then runs the full hygiene script after pnpm run build.

Daily commands

Use these from the repo root:

pnpm run test           # unit tests
pnpm run test:coverage  # unit tests with per-file coverage gates
pnpm run test:e2e       # real-API tests; self-skips without DEEPSEEK_API_KEY
pnpm run typecheck      # build package/vendor outputs, then typecheck examples, tests, and scripts
pnpm run lint           # eslint .
pnpm run lint:fix       # eslint . --fix
pnpm run doc-typecheck  # compile checked TypeScript snippets in Markdown docs
pnpm run gen-cordis-catalog     # regenerate docs/cordis-catalog/events.md + services.md from source
pnpm run verify-cordis-catalog  # fail if either cordis catalog is stale
pnpm run gen-rfc-index          # regenerate the docs/rfc/README.md index tables from the RFC tree
pnpm run verify-md-wrap  # fail on hard-wrapped prose paragraphs in docs/README markdown
pnpm run verify-type-equiv  # fail if a ```ts type-equiv doc block drifts from its source type
pnpm run verify-doc-budgets  # fail if a budgeted standing doc exceeds its word ceiling
pnpm run doc-sync       # all Markdown/doc gates; see the doc-sync script in package.json for the full list
pnpm run gen-module-graph     # regenerate docs/module-graph.md from package peerDeps
pnpm run verify-module-graph  # fail if docs/module-graph.md is stale
pnpm run build          # emit lib/types intermediates, then bundle lib/index.* runtime files
pnpm run verify-node-next-types  # fail if built declarations are not NodeNext-consumable
pnpm run hygiene        # knip, publint, workspace constraints, and NodeNext declaration check

When changing package public behavior, update the relevant README or JSDoc in the same change. pnpm run doc-sync catches checked TypeScript snippets, cordis events/services catalog drift, and hard-wrapped markdown prose, but broader prose/API sync still needs review.

Demos

The echo demo does not need API credentials:

pnpm run demo:echo

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

pnpm run demo:repl

The ACP server agent demo exposes the agent over JSON-RPC stdio and also needs DEEPSEEK_API_KEY:

pnpm run demo:acp

TODO markers

Use one of three comment tags to flag known issues in the code, ordered by urgency:

• FIXME — an issue that should block a new release. A release should not ship with an open FIXME unless reviewers explicitly agree the change can be merged anyway.
• TODO — an issue that should be fixed soon, once we have the resources.
• XXX — an issue that we may fix someday; lowest priority, no commitment.

Pick the tag that matches the urgency so anyone scanning the code can tell a release blocker from a someday-maybe.

Documenting types verbatim (ts type-equiv)

The core data structures docs paste real type definitions so a reader sees the exact shape. To keep a paste from drifting when source changes, fence it as ```ts type-equiv (instead of ```ts) and register it in scripts/type-equiv.manifest.json with the source file and symbol it mirrors:

{ "doc": "docs/core-data-structures/session.md", "symbol": "SessionEvent", "source": "packages/core/session/src/types.ts" }

pnpm run verify-type-equiv (part of doc-sync) then extracts that symbol's declaration from source via the TypeScript parser and asserts the block matches it (whitespace- and comment-insensitive, so a doc block may show a clean definition and the prose can carry the semantics). It also enforces a 1:1 correspondence: every ts type-equiv block has exactly one manifest entry and vice-versa, so a block can't go silently unchecked and a stale entry can't linger. doc-typecheck skips ts type-equiv blocks (they aren't standalone-compilable) and excludes them from its opt-out ratio. When you change a documented type, the gate fails until you update the paste; when you add or remove a block, update the manifest in the same change.

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.