The tool README claimed a "missing, disposed, or closing parent" fails the call — but acceptance is governed by the parent's registry presence: `resolveReportParent` only rejects when the durable parent id is absent from the registry, so a host-owned parent already in disposal but still registered still accepts (the pinned host-disposing-parent behavior). The claim misled callers into treating disposal state as a delivery signal. Restate the contract in both languages: absence from the registry is the only `PARENT_UNAVAILABLE` case, and a failed tool call does not prove non-delivery — a later `tools/post-execute` veto can fail a call whose report was already accepted, so the durable child transcript remains the recovery source. Adds a regression test pinning acceptance into a host-disposing but still-registered parent, and rejection after disposal settles.
subagent/ — subagent capability family
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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/ |
Subagent service: named-provider registry, vocabulary, durable descriptor, and continuable-child orchestration | ctx.subagents |
subagent-inprocess/ |
Shared in-process run driver (no provider; one cleanup effect per run) | — |
subagent-spawn/ |
In-process backend: a fresh child agent, with cold resume | (registers on ctx.subagents) |
subagent-fork/ |
In-process backend: a child seeded with the parent's completed-turn prefix, with cold resume | (registers on ctx.subagents) |
subagent-acp/ |
Out-of-process backend: a child agent in a spawned subprocess, driven over ACP (one-shot) | (registers on ctx.subagents) |
subagent-dsh-sdk/ |
Out-of-process backend: a child harness runtime in a spawned subprocess, driven over stdio JSON-RPC through the TypeScript SDK client | (registers on ctx.subagents) |
tool-subagent/ |
Model-facing subagent delegation tool over ctx.subagents |
(registers on ctx.tools) |
tool-subagent-control/ |
The optional, globally named send_message and list_agents tools over ctx.subagents |
(registers on ctx.tools) |
tool-subagent-report/ |
Child-scoped report return channel for continuable in-process children |
(registers in each child scope) |
The interface and continuation orchestration live at subagent/subagent/. One-shot provider start dispatch stays independent of persistence; an internal continuation manager owns each durable continuable child as one Session plus at most one process-local Activation, binding no Task, and exists only while the Agent service is present, resolving persistence per continuation operation. The in-process subagent-spawn / subagent-fork backends share the subagent-inprocess driver (a library with no provider of its own — both depend on it, neither on the other), and the out-of-process subagent-acp / subagent-dsh-sdk backends spawn their children through the subprocess/ seam (the shared credential scrub, tree-scoped teardown, and dispose ladder). Tests replace only the child boundary with package-local fixtures.
The design rationale: .agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.md, .agents/notes/implemented/feature/2026-07-21-continuable-background-subagents.md, and .agents/notes/implemented/simplification/2026-07-26-merge-subagent-control-service.md.