mirror of
https://github.com/deepseek-ai/deepseek-harness
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Introduce HarnessError in dsh-llm (the leaf package): a stable machine-routable
code distinct from the message, cause chaining, name from the subclass, plus
isHarnessError. LlmError, ToolArgsError, and InvariantError now extend it.
Tool failures carry the structure end-to-end: ToolExecutionResult gains
error: { name, code } (populated from a thrown HarnessError), and the loop
forwards it onto the tool/result session event (which gained the same optional
field) for retry/sandbox plugins and replay. The loop's toError wraps non-Error
throws in a HarnessError(code: UNKNOWN, cause) instead of a bare Error.
Landed last and in isolation so it's a pure upgrade over the plain Error+code
the earlier PRs used — independently revertible. Graduates RFC 005 pt 2 ->
ADR 0015; RFC 005 now fully implemented.
74 lines
4.1 KiB
Markdown
74 lines
4.1 KiB
Markdown
# dsh-tools
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Tool registry and execution waterfall. Tool plugins register their schemas and executors; the agent loop executes calls through the `tools/execute` waterfall.
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## Service: `ToolRegistry` (ctx key: `tools`)
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### Public API
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- `ctx.tools.register(definition: ToolDefinition): () => void` Register a tool. Disposed with the calling fiber.
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- `ctx.tools.get(name: string): ToolDefinition | undefined`
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- `ctx.tools.schemas(): ToolSchema[]` Schemas of all registered tools (without the `execute` functions).
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- `ctx.tools.execute(exec: ToolExecution): Promise<ToolExecutionResult>` Execute one tool call through the `tools/execute` waterfall.
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### Injected services
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`SystemPrompt` — the registry automatically feeds its tool schemas into the system-prompt assembly via `ctx.systemPrompt.tools()`.
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### Events
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| Event | Mode | Purpose |
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|---|---|---|
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| `tools/execute` | waterfall | Wrap/veto tool execution (sandbox, permission, hooks, plan mode) |
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| `tools/change` | emit | A tool was registered or unregistered |
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### Key types
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- `ToolDefinition` — `ToolSchema` + `execute(args, exec): Promise<ContentBlock[]>`.
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- `ToolExecution` — one pending tool call: `{ callId, name, arguments, agent?, signal? }`.
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- `ToolExecutionResult` — outcome: `{ callId, content, isError, error? }`. On failure with a `HarnessError`, `error: { name, code }` carries the structured failure class alongside the model-facing text (the loop forwards it onto the `tool/result` session event for retry/sandbox plugins and replay).
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### Extension points
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- Tool plugins call `ctx.tools.register()` — schemas flow into the assembly automatically.
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- The `tools/execute` waterfall is the single seam for sandbox, permission, hooks, and plan-mode plugins to wrap or veto a call. Listeners receive `(exec, next)`: call `next()` to proceed, or return a result without calling `next()` to short-circuit (veto).
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- MCP servers: one plugin per server, discover tools, call `ctx.tools.register()` with the server's schemas.
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### Typed tool parameter schemas
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First-party plugin authors can use the `defineTool()` helper (exported from this package) for typed tool parameter schemas:
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```ts
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import { readFile } from 'node:fs/promises'
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import type { Context } from 'cordis'
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import { defineTool } from '@deepseek-ai/dsh-tools'
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declare const ctx: Context
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ctx.tools.register(defineTool({
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name: 'read_file',
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description: 'Read a file from disk.',
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parameters: {
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path: { type: 'string', required: true, description: 'Absolute file path' },
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offset: { type: 'number' },
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limit: { type: 'number' },
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},
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async execute(args, exec) {
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// args is typed: { path: string; offset?: number; limit?: number }
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const text = await readFile(args.path, 'utf8')
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return [{ type: 'text', text }]
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},
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}))
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```
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The helper converts the author-facing `SchemaSpec` (with `required: true` as a per-property boolean) to standard JSON Schema for the wire format. Raw JSON-Schema tool definitions (from MCP servers) are still accepted by the registry directly.
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A `defineTool` tool also **validates the model-generated arguments against its `SchemaSpec` before `execute` runs** (`validateArgs`). The model's JSON is untrusted — `InferArgs<S>` is a compile-time claim, not a runtime guarantee — so on a mismatch (missing required key, wrong primitive, bad enum member, nested violation) the tool throws a `ToolArgsError` (`code: 'INVALID_ARGS'`); the registry turns it into an `isError` result whose text lists the violations, which the model sees and self-corrects from. Validation mirrors the JSON Schema conversion exactly: extra keys are allowed, `default` is not applied, and an `object`/`array` prop without `properties`/`items` only type-checks. Raw-registered tools (MCP) are **not** validated by the harness — they validate their own input.
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See `defineTool`, `validateArgs`, `ToolArgsError`, `SchemaSpec`, `InferArgs`, and `schemaSpecToJsonSchema` in the public API for details.
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### What is NOT here (TODO)
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- **Tool shapes review** — when real tools land (e.g. a concurrency-safety hint for parallel execution); phase 1 executes tool calls sequentially.
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- **Parallel execution** — the loop currently iterates tool calls sequentially.
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