The first real agent wiring: DeepSeek V4 + the bash tool suite + stdio chat + JSONL persistence, runnable via yarn demo:coding (reads the gitignored repo-root .env through process.loadEnvFile). - examples/coding-agent: cordis.yml wiring both real plugin families (llm-deepseek with !!js env secrets; bash-local + tool-bash), a bash-only coding system prompt, a max-steps-guard plugin (bounds runaway turns via the agent/turn-continuation waterfall — abort() from step-end is a no-op by then), and a stdio UI with dimmed reasoning and exit-on-idle for piped stdin. - e2e (yarn test:e2e, key-gated): full-loop.e2e.ts runs a real model against the real bash tool; coding-task.e2e.ts is the swebench-style smoke — the model fixes a buggy add.js in a temp dir and the test re-runs node add.test.js itself rather than trusting the agent. - docs/cookbook: adding-a-package (the verified checklist), adding-a-tool (execute() contract, background pattern, seams), adding-an-llm-adapter (protocol obligations, mock-server testing, e2e policy). AGENTS.md layout/commands/secrets sections updated; architecture.md points at both examples and the cookbook. - vitest.e2e.config.ts: serialize test files + retry twice — parallel e2e files trip the shared internal key's concurrency quota. - fix: the !js YAML tag spelling in docs/JSDoc is actually !!js (js-yaml resolves custom tags under tag:yaml.org,2002:js).
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Cookbook: adding a tool
How to give the model a new capability. Reference implementations:
examples/echo-agent/src/echo-tool.ts (minimal) and
packages/tool-bash (production-grade, three-package seam).
The minimal shape
import type { Context } from 'cordis'
import { defineTool } from '@deepseek-ai/dsh-tools'
export const name = 'my-tool'
export const inject = ['tools']
export function apply(ctx: Context) {
ctx.tools.register(defineTool({
name: 'read_file',
description: 'Read a file from disk.', // what the model sees
parameters: {
path: { type: 'string', required: true, description: 'Absolute path' },
limit: { type: 'number' }, // optional by default
},
async execute(args, exec) {
// args is TYPED from the schema: { path: string; limit?: number }
// exec carries { callId, name, arguments, agent?, signal? }
return [{ type: 'text', text: await readFile(args.path, 'utf8') }]
},
}))
}
Registration is effect-based: disposing the plugin fiber unregisters the tool (write the HMR test). Schemas flow into the system-prompt assembly automatically.
Rules of the execute() contract
- Validate args at runtime.
defineTool'sInferArgstyping is compile-time only; at runtimeargumentsis whatever JSON the model emitted. Check every field; throw a descriptive Error for bad input. - Throwing means isError. The registry catches anything
execute()throws and returns{isError: true}to the model. Use that for infrastructure failures (bad input, spawn errors, aborts) — but REPORT domain failures in the result text instead (e.g. tool-bash returns[exit code: 9]withisError: false: the model decides what a failing command means). - Honor
exec.signal. Cancel in-flight work when it fires. - Use
exec.agentfor async notifications.agent.inject(content, {source: {kind: 'plugin', plugin: '<name>'}})appends durable context the NEXT model request sees — it is not a wake-up (an idle agent stays idle). Guard against disposed agents (try/catch).
Long-running work
Follow tool-bash's background pattern: a run_in_background flag returns a
task id immediately; companion tools poll incrementally and kill; completion
notices arrive via agent.inject(). Bound buffers and spill full output to
disk so nothing is silently lost.
TODO: each tool reimplements this background pattern by hand today. At some point we need a generic long-running-tool layer that handles task ids, incremental polling, kill, and completion notices uniformly.
Permissions / sandboxing
Prefer not to build policy into the tool. The seam is the tools/execute waterfall
(veto or wrap — see the permission-gate example in docs/architecture.md), or
a sandboxing implementation behind the tool's executor seam.
Tests every tool needs
Arg-validation rejections, result shaping for every outcome, the HMR
disposal test, and — for tools with side effects — an integration spec that
drives the tool through the agent loop with a scripted MockAdapter
(packages/agent-loop/tests/mock-adapter.ts), asserting the tool/call /
tool/result session events.