87a249106f
Master's #660 replaced dsh-subagent-subprocess with the dsh-subprocess capability seam (ctx.subprocess + scrubbedParentEnv, tree-scoped teardown) and moved subagent-acp onto it. Convergence for this branch's packages: - The shared out-of-process provider vocabulary this branch had grown in the deleted library (NO_START_CAPABILITIES, assertPositiveFinite, cwd resolution, settleRunResult, subprocessRunHandle) moves into the subagent seam package as out-of-process.ts — it enforces subagent-seam contracts, not process mechanics, and both out-of-process backends now import it from there (subagent-acp keeps master's shape otherwise). - subagent-sdk spawns THROUGH the SDK client (the subprocess README's documented exception for SDK-managed transports) and now applies the seam's scrubbedParentEnv() + explicit-env merge in place of the deleted buildChildEnv. - sdk-client inlines the EOF→SIGTERM→SIGKILL ladder as private helpers (it runs outside any harness context, so it cannot ride ctx.subprocess). - The child harness fixture gains the now-required dsh-subprocess-local entry for bash-local; the fixture cordis.yml keeps exercising the shipped provider default.
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/ |
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-acp/ |
Out-of-process backend: a child agent in a spawned subprocess, driven over ACP | (registers on ctx.subagents) |
subagent-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) |
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), and the out-of-process subagent-acp / subagent-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 proposal and design rationale: .agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.md.