# Development guide

English | [中文](development.zh.md)

This onboarding guide helps project contributors get started with the local environment, daily workflow, and CI flow; see the Agent Notes for design rationale and technical trade-offs.

## Prerequisites

- Node.js supports 22.19+ and 24+. CI covers 22.19, 24, and 26; see the [Node engine floor Agent Note](../.agents/notes/implemented/process/2026-07-06-node-engine-floor.md).
- 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 2.26 or newer; hook setup enables Git's worktree-specific configuration extension.
- Optional: a DeepSeek API key for the TUI, headless, and ACP automation demos and real-API e2e tests.

## First-time setup

Install dependencies from the repo root:

```sh
pnpm install
```

The install also runs the root `postinstall` script, which installs lefthook from the repo dev dependency through `scripts/install-lefthook.mjs`. With `CI=true` or `GITHUB_ACTIONS=true`, the wrapper returns before Git discovery because automated jobs do not consume contributor hooks. Otherwise, it requires Git 2.26 or newer and gives the current worktree an explicit hook directory under its own Git directory; linked worktrees therefore use their own lefthook binary and configuration instead of rewriting common hooks. The first install enables Git's worktree-specific configuration extension and repository format 1; see the [worktree-local hooks Agent Note](../.agents/notes/implemented/process/2026-07-27-worktree-local-lefthook.md).

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

```sh
node scripts/install-lefthook.mjs
```

The wrapper refuses user-owned `core.hooksPath` values. An inherited system, global, or common-repository path requires `DSH_LEFTHOOK_ALLOW_HOOKS_PATH_OVERRIDE=1`. When Git seeds a new worktree with another registered worktree's marker-backed hook path, the wrapper replaces that copied value with the new worktree's own path; command-scoped and other worktree-scoped paths must be integrated or removed explicitly.

Before enabling worktree config, migrate direct `extensions.*` in a format-0 common config, direct `core.worktree` or `core.bare=true`, and any non-empty dormant `config.worktree`. The common config and every worktree config must be regular files, while the owned hook directory may contain only unaliased regular files.

After moving a checkout, rerun the wrapper to relocate its owned path and regenerate hooks. For a stale or invalid installer lock, first confirm no installer is running, then remove the reported lock and retry. If installation and hook-path rollback both fail, inspect the reported worktree config before retrying. The [worktree-local hooks Agent Note](../.agents/notes/implemented/process/2026-07-27-worktree-local-lefthook.md) owns the full safety contract.

Run typecheck once after a fresh clone:

```sh
pnpm run typecheck
```

That first typecheck runs the whole-repo `tsc -b` graph: it emits every package/vendor `lib/types` and checks examples, tests, and scripts through the two no-emit aggregates described below.

## TypeScript project layout

The repository's TypeScript configuration has exactly three roles; every tsconfig file plays one of them.

| File | Role | Forms a program? |
|---|---|---|
| `tsconfig.json` | Solution root: `extends` base, `files: []`, references to the two aggregates. The whole-repo `tsc -b tsconfig.json` graph, the tsserver discovery entry, and — through the inherited `paths` — the resolution config for tsx running `examples/` and `scripts/` (their nearest tsconfig is this file). | No |
| `tsconfig.host.json` | Host aggregate: host-side packages (via references), examples, tests, scripts, website. Excludes `packages/client`. | Yes |
| `tsconfig.client.json` | Client aggregate: `packages/client/*` packages and their tests, `apps/web`. | Yes |
| `tsconfig.base.json` | Shared compilerOptions and the source `paths` map. Also the resolution facade the vitest configs point vite-tsconfig-paths at: it has no `include`, so its `paths` apply to every importer. | No |
| `tsconfig.base.client.json` | Browser compiler shape (`jsx`, DOM libs, `types: []`) extended by the client aggregate and every `packages/client/*` package. | No |

Host and client stay two aggregate programs because both sides declaration-merge the cordis `Context` interface under the same keys with different services; one program seeing both merges reports a collision. The collision exists only inside a `ts.Program` — module resolution never triggers it — which is why the solution may reference both aggregates and one paths facade may span both sides. Two disciplines follow:

- `tsconfig.base.json` never gains `include` or `files`: they would leak into every extending package project and narrow the facade's match-all scope.
- A script that builds a repo-wide `ts.Program` seeds `tsconfig.host.json` or `tsconfig.client.json` explicitly — never the root solution, because flattening both aggregates into one program collides the `Context` merges. Program-backed generators and gates (`scripts/ts-project.ts` consumers, doc-typecheck standalone mode) are host-only by decision; the client side gains program-backed tooling only with a concrete need.

Static analysis and tests resolve workspace imports through the base `paths` map to `src` and must pass on a clean tree; gates that consume built `lib/` output declare that dependency explicitly. Decision record: [solution-root note](../.agents/notes/implemented/process/2026-07-22-tsconfig-solution-root-two-aggregates.md); the tsc-first emit pipeline is the [ts-build-config note](../.agents/notes/implemented/process/2026-06-17-ts-build-config.md).

If a relevant local check consumes built package output, build once first:

```sh
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; ordinary commits and pushes do not require that build unless their selected checks consume it.

## 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:

```sh
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 a fast local checkpoint:

- `pre-commit` runs staged-file ESLint fixes, checks the staged diff for whitespace errors, and runs the vendor manifest guard.
- `pre-push` runs only the incremental repository typecheck (`tsc -b` over the root solution, covering both the host and client aggregates).

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.

The hooks intentionally do not run tests, snapshots, documentation checks, builds, or hygiene. Contributors run the [checks relevant to the changed behavior](../AGENTS.md#run-relevant-checks-locally) once; CI owns exhaustive coverage, built-artifact smokes, and the Node 22.19, 24, and 26 compatibility matrix.

Contributors can opt into the comprehensive local gate set with `pnpm run check:all`. The command is independent of both Git hooks and is not an agent instruction.

## CI gates

The keyless [CI workflow](../.github/workflows/ci.yml) groups independent gates into broad lanes and runs a smaller compatibility signal across supported Node versions. Artifact consumers wait for one build within their lane. The separate real-API workflow runs `pnpm run test:e2e` with its configured worker bound. See [scripts/run-gates.ts](../scripts/run-gates.ts) and the workflow files for the current gate and job inventory.

## Daily commands

Use these from the repo root:

```sh
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 check:all      # comprehensive opt-in gate set; not wired to Git hooks
pnpm run typecheck      # tsc -b over the root solution: emits package/vendor lib/types, checks both aggregates
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 verify-export-jsdoc    # fail if a module-level package export lacks complete JSDoc
pnpm run gen-doc-graphs     # regenerate generated relationship docs from source and curated graph definitions
pnpm run verify-doc-graphs  # fail if generated relationship docs are stale
pnpm run verify-md-wrap  # fail on hard-wrapped prose paragraphs in docs/README markdown
pnpm run verify-mermaid  # fail if a ```mermaid diagram has invalid Mermaid syntax
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 gen-translation-brief   # print the minimal-update briefing for out-of-sync translation pairs (--apply splices code-only edits)
pnpm run doc-sync       # all Markdown/doc gates, scheduled concurrently; the doc-sync leaf list in scripts/run-gates.ts is 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, generated doc freshness, markdown wrap/link drift, type equivalence, translation pairing, Mermaid syntax, and doc budgets, but broader prose/API sync still needs review.

## Demos

The one-shot Headless coding agent needs `DEEPSEEK_API_KEY` in the environment or repo-root `.env`:

```sh
pnpm run demo:headless "summarize this workspace"
```

The full-screen interactive coding agent needs `DEEPSEEK_API_KEY` in the environment or repo-root `.env`:

```sh
pnpm run demo:tui
```

The self-referential cordis-agent demo can inspect and modify its live plugin runtime and needs the same credentials:

```sh
pnpm run demo:cordis
```

The ACP automation server exposes fresh agent sessions over JSON-RPC stdio and also needs `DEEPSEEK_API_KEY`:

```sh
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](core-data-structures/core.md) docs paste source-equivalent declarations together with their original JSDoc so a reader sees the exact shape and source contract. 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:

```json
{ "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 and attached JSDoc from source via the TypeScript parser and asserts the block matches both. For a class whose implementation bodies do not belong in the catalog, use ` ```ts public-api ` and set `"projection": "public-api"`; the checked projection retains the public fields, constructor, accessors, methods, and original class/member JSDoc while omitting bodies and private or protected members. Comparison ignores whitespace and non-JSDoc comments but requires every original JSDoc comment, including member documentation, so readers see the source contract beside the exact shape. The gate enforces a 1:1 correspondence by document, symbol, and projection between primary blocks and manifest entries; a paired `.zh.md` block reuses its unsuffixed sibling's entry only when the whole tracked fence sequence is byte-identical and ordered identically. `doc-typecheck` applies the same derivative rule to compilable fences, while skipping both source-equivalence fence kinds from compilation and its opt-out ratio. When you change a documented declaration or its JSDoc, the gate fails until you update the paste; when you add or remove a primary 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.
