Tianyi Cui
1a81f2cccd
Introduce the `packages/subagent/` group and the abstract subagent seam — an agent delegating to a child agent — as a named-provider registry (`ctx.subagents`), unlike the single-implementation bash seam, so multiple transports (in-process, ACP, future A2A) coexist. This first PR lands the interface, a scripted test backend, and the model-facing tool, validated through the real cordis load path. - dsh-subagent: SubagentService registry + SubagentProvider/SubagentRun vocabulary + subagent/start|end events. Start-time capabilities (outputSchema, depthLimit, toolFilter) are checked pre-start and rejected loud; runtime capabilities (sendMessage, resume) are optional methods on SubagentRun. - dsh-subagent-mock (support): scripted provider for keyless, deterministic tests through the real Loader/export path. - dsh-tool-subagent: the model-facing `subagent` tool, config-bound to one provider; synchronous collect with try/finally dispose, signal->cancel bridging, and non-completed-stop-reason -> isError mapping. - Proposed RFC documenting the seam, the fork-vs-spawn-as-separate-backends decision, own-session isolation, synchronous-collect scope, and the deferral of background/poll/spill to a future unification with bash. - Wire the new group into tsconfigs, build refs, package hierarchy docs, the module graph, and the cordis catalog. RFC: docs/rfc/proposed/feature/2026-06-21-subagent-capability-seam.md
@deepseek-ai/dsh-tool-subagent
The model-facing subagent tool: delegate a self-contained task to a child agent and return its final output. Pure schema + lifecycle shaping over the ctx.subagents provider registry — an in-process, ACP, or future A2A backend swaps in without changing what the model sees.
Provider selection is config, not model-facing
This plugin binds to exactly one provider (Config.provider). The model sees only { description, prompt } — there is no provider/type parameter in the schema. To expose more than one transport, load the plugin more than once, each bound to a different provider. Keeping selection in config (not the schema) is the deliberate split: the service holds a multi-provider registry; the tool picks one.
| Config key | Meaning |
|---|---|
provider (required) |
The ctx.subagents provider name to start runs on (spawn, fork, acp, …). |
agentOptions |
Default per-child { model?, systemPrompt? } applied to every spawned child. |
Lifecycle (synchronous collect)
execute starts a run on the configured provider and awaits run.result inside a try/finally that always dispose()s the run — the owned child agent/session is torn down on every path (success, error, abort), never leaked. The tool's abort signal (exec.signal) is bridged to run.cancel(). A non-completed stop reason (aborted/error/max-tokens/refusal) maps to an isError tool result rather than returning partial output as success.
Background / poll collection is deferred (see the RFC); this cut blocks the parent turn until the child finishes.