74502fa8c2
Carved out of #170 per review feedback — the foundation the workflow tool builds on, now standing alone on master: - dsh-tools: the structured-output JSON Schema subset (StructuredOutputSchema, assertSupportedOutputSchema, validateStructuredValue) — rejects loud outside the enforced subset, listing every violation - dsh-subagent: SubagentStartRequest.outputSchema / SubagentResult.structured become a real capability; the service rejects a schema'd request whose provider lacks it - dsh-subagent-inprocess: the shared structured runtime — one global structured_output capture tool, a prepend final-assembly listener that strips the placeholder for plain agents and swaps in the run's own schema (plus the calling instruction as a trailing section) for structured children, an agent/turn-continuation veto once captured, and the capture/nudge loop in the run driver (structuredNudgeRetries, cancellation honored mid-nudge); lifetime refcounted by backends and live runs - subagent-spawn / subagent-fork flip outputSchema: true One deliberate divergence from the #170 revision: the backends do NOT add 'tools' to their plugin inject. Doing so deferred their apply past the todo plugin, and the delegation tool mirrors provider lifecycle — so the model-visible tool order of every existing prompt changed, invalidating every recorded snapshot fixture. The runtime now gates its capture-tool registration on tools availability itself (sync when live, a scoped inject fiber when the Loader starts the backend first), keeping this PR byte-invisible to existing transcripts: all 35 snapshot scenarios pass against master's fixtures unchanged.
subagent/ — subagent capability family
The subagent seam: an agent delegating work to a child agent. Like the bash and llm families this is a capability seam (see capability seams) — but with one defining difference: multiple provider implementations coexist in one context, registered by name, rather than the single-implementation bash shape. The registry mirrors the LLM adapter registry.
| Package | Role | ctx key |
|---|---|---|
subagent/ |
Abstract subagent seam: named-provider registry + vocabulary | ctx.subagents |
subagent-inprocess/ |
Shared in-process run driver (pure lib; registers nothing) | — |
subagent-spawn/ |
In-process backend: a fresh child agent | (registers on ctx.subagents) |
subagent-fork/ |
In-process backend: a child seeded with the parent's completed-turn prefix | (registers on ctx.subagents) |
subagent-acp/ |
Out-of-process backend: a child agent in a spawned subprocess, driven over ACP | (registers on ctx.subagents) |
tool-subagent/ |
Model-facing subagent delegation tool over ctx.subagents |
(registers on ctx.tools) |
The interface lives at subagent/subagent/. The in-process subagent-spawn / subagent-fork backends share the subagent-inprocess driver (a pure library — both depend on it, neither on the other), and the out-of-process subagent-acp backend ships alongside them here; the test-only dsh-subagent-mock (in support) is separate. All product packages except the mock.
The proposal and design rationale: docs/rfc/implemented/feature/2026-06-21-subagent-capability-seam.md.