This is the monorepo for the DeepSeek Harness group. It currently hosts the code for DeepSeek Code, DeepSeek's coding agent product.
This codebase is based on the Cordis framework, built microkernel-style: everything is a plugin. All necessary Cordis dependencies are copied into this monorepo as vendored source (under vendor/) instead of being depended on via npm.
Read docs/architecture.md before changing anything under packages/ — it defines the service map, the event taxonomy, the session/turn/step lifecycle, and the plugin cookbook.
vendor/ Vendored Cordis framework source (original npm names, private).
See vendor/README.md for the manifest, local-modification log,
and the upstream sync procedure. Do NOT edit casually — every
divergence must be logged there.
packages/ Harness packages, all named @deepseek-ai/dsh-<name>:
llm/ abstract LLM service + content-block vocabulary (no real adapter yet)
session/ event-sourced session log + in-memory store
system-prompt/ prompt-section + tool-schema assembly registry
tools/ tool registry + tools/execute waterfall
agent/ Agent interface, registry, agent/* event vocabulary
agent-loop/ THE concrete plugin: LoopAgent + the loop driver
examples/ Runnable demos (not workspaces). echo-agent = mock model + echo
tool + stdio UI + JSONL persistence, wired via cordis.yml.
docs/ architecture.md — the design doc.
scripts/ build.ts — dumble JS bundling for all packages.
yarn install # Yarn 4 workspaces (node-modules linker), node >= 24
yarn test # vitest run (packages/*/tests/**/*.spec.ts)
yarn typecheck # tsc -b tsconfig.build.json (declarations only)
yarn build # typecheck + dumble JS bundles into each package's lib/
yarn demo # run examples/echo-agent (needs --expose-internals, the
# script passes it; type "echo hi" to see a tool call)
Dev/test/demo run unbuilt via tsx + the paths map in the root
tsconfig.json (vitest resolves through tsconfig.test.json). Building is
only needed for publishing/consumption outside the repo.
@deepseek-ai/dsh-<name>
(vendored packages keep their upstream names and are private: true)."type": "module"); imports between workspace packages
use package names, never relative paths across package boundaries.
In-package imports use explicit .ts extensions (allowImportingTsExtensions).cordis is a peerDependency (+ devDependency) of every harness package,
mirroring upstream convention.ctx.effect() / ctx.on() so
disposal and HMR work. If you write a registry, register() must return the
disposer.declare module 'cordis' { interface Events { … } }, and their ctx key in
interface Context. Extensible unions use the merge-extensible-map pattern
(see ContentBlockMap, MessageSourceMap).ctx.waterfall listeners receive (...args, next)
and MUST call next() to delegate; returning without it short-circuits.
This is the veto mechanism — use deliberately.agent-loop requires updating that doc.packages/<name>/tests/*.spec.ts. Every
registry needs an HMR-safety test (dispose the contributing fiber, assert
cleanup). Excessive tests are welcome — when in doubt, write the test;
err on the side of covering edge cases, error paths, event ordering, and
concurrency races even if they seem unlikely. Review findings get regression
tests (see packages/agent-loop/tests/review-fixes.spec.ts).This codebase aims to be very type-safe and well documented for
maintainability. Code that fails to compile under strict: true (with
noImplicitAny enabled for all packages/* source) is not acceptable. Every
any that remains must have a specific justification (a comment explaining why
a narrower type is infeasible).
In the core packages (packages/llm, packages/tools, packages/agent,
packages/agent-loop, packages/session, packages/system-prompt), type
gymnastics are acceptable when they improve the DX of plugin authors for
common plugin types. The defineTool typed schema DSL in dsh-tools is the
canonical example: the SchemaSpec to InferArgs<S> type-level mapping gives
tool authors zero-cast typed execute args, and the cost of the conditional
types stays inside the core package.
Verbose documentation is fine as long as docs and code stay strictly in sync. Out-of-sync docs are worse than no docs. Every module has a module-level doc comment explaining its role. Every exported class, interface, type, function, and non-obvious method has a JSDoc that explains semantics (not just the name) — contracts (what events fire when), disposal behavior, error behavior, and extension intent. Internal helpers get docs only where non-obvious. Prefer one-liners when one line suffices.
vendor/ packages are pinned source copies (manifest with upstream commit
SHAs in vendor/README.md). To update one, follow the sync
procedure there; re-apply (or retire) the logged local modifications and rerun
yarn test && yarn build.