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# Conflicts: # docs/AGENTS.md # docs/config-catalog.md # packages/bash/bash-sandbox/src/index.ts # packages/bash/bash/src/session-mode.ts # packages/bash/tool-bash/README.md # packages/code-runtime/code-runtime-worker/README.md # packages/compact/compact/src/index.ts # packages/core/agent-core/README.md # packages/hooks/hooks-claude/src/config.ts # packages/hooks/hooks-claude/src/index.ts # packages/hooks/hooks-codex/src/config.ts # packages/hooks/hooks-codex/src/index.ts # packages/llm/llm/README.md # packages/session-persistence/session-persistence-jsonl/README.md # packages/session-persistence/session-persistence/README.md # packages/skill/skill-local/README.md # packages/support/acp-snapshot/README.md # packages/support/invariants/src/index.ts # packages/ui/acp/README.md # packages/ui/jsonrpc-agent/README.md # packages/ui/jsonrpc/README.md # packages/ui/permission/README.md # packages/ui/user-approval/README.md # packages/ui/user-interaction/README.md # packages/web/web-search-deepseek/README.md
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.