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.
- 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).
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).
The wrapper refuses to replace an existing user-owned `core.hooksPath`. If an inherited system, global, or common-repository path should remain active in other worktrees while this worktree opts into lefthook, inspect that path first and rerun with `DSH_LEFTHOOK_ALLOW_HOOKS_PATH_OVERRIDE=1`; command-scoped and worktree-scoped custom paths are never overridden and must be integrated or removed explicitly. The same rules apply when a currently inactive conditional include can provide a hook path; unrelated conditional includes remain valid. Before upgrading a format-0 repository, existing `extensions.*` keys in the common config or a conditional target require manual audit and migration because format 1 activates them. Before enabling the worktree-config extension, conditional common-config targets that may contain `core.worktree` or `core.bare=true` require manual migration. A dormant `config.worktree` in any registered worktree also requires inspection and explicit migration or removal before the extension can be enabled without changing that worktree. The common repository config and every active or dormant worktree config must be regular files. The owned hook directory may contain only unaliased regular files; replace a reported symlink, hard link, or non-file entry before retrying. After moving the checkout, rerun the wrapper so its ownership marker can replace the exact stale path it installed and regenerate hooks at the new Git directory. If the installer reports a stale or invalid lock, confirm no installer is running, remove the reported lock manually, and rerun the command. If Lefthook installation and automatic hook-path rollback both fail, the diagnostic preserves both failures; inspect the worktree config and remove the new path manually before retrying.
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.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).
`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.
`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.
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.
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.
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.
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.
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:
`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.
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.
