dafb81be7b
The seam vocabulary (SubagentStartRequest.outputSchema, SubagentResult .structured) existed but no in-process backend honored it — spawn/fork advertised outputSchema: false. This lands the missing half: - dsh-tools gains a structured-output JSON Schema subset (json-schema.ts): StructuredOutputSchema, assertSupportedOutputSchema (rejects loud outside the enforced subset, every violation listed), validateStructuredValue (path-qualified issues, total). outputSchema's seam type becomes this raw JSON-Schema subset instead of the author-facing SchemaSpec DSL — the schema travels verbatim to the model as a forced tool's parameters. - dsh-subagent-inprocess gains the shared structured runtime: one global structured_output capture tool (placeholder parameters) + a prepend:true agent/request listener doing FINAL-REQUEST enforcement (strip for plain agents, per-run schema for structured children — survives downstream request-replacing listeners) + an agent/turn-continuation veto that stops a child's turn once captured (no wasted extra model step). Lifetime is refcounted by backends (plugin lifetime) AND live runs (start→settle). - startInProcessRun drives the capture: subset asserted before the child exists, instruction appended to the child's system prompt, clean-finish nudge loop (structuredNudgeRetries, backend Config, default 1), captured value on result.structured; a clean finish without a capture settles 'error' (never a silent success with a missing field). - spawn + fork flip outputSchema: true and inject 'tools'.
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.