8bb8ac8b3c
The background-task change repeated its lifecycle design across implemented RFCs, package READMEs, JSDoc, test commentary, and model-visible schemas. That repetition obscured the contracts that maintainers must preserve and added avoidable prompt tokens. Rewrite the implemented RFCs around the current design, keep authorization, exact-owner cleanup, wait/abort ordering, producer quiescence, and teardown-failure guarantees at their owning surfaces, and remove peer surveys, review history, control-flow narration, and emphatic restatement. Shorten the task and subagent schema wording, synchronize the bilingual tool cookbook, and regenerate the config, service, RFC, tool, and replay snapshot derivatives. Runtime behavior is unchanged; test edits update prose-only assertions and descriptions.
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 (no provider; one cleanup effect per run) | — |
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-subprocess/ |
Shared out-of-process machinery: env scrub, dispose ladder, isolated config dirs (pure lib; registers nothing) | — |
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 library with no provider of its own — both depend on it, neither on the other), the out-of-process subagent-acp backend builds on the subagent-subprocess library (the credential env scrub, the dispose ladder, isolated config dirs) and 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.