Tianyi Cui
6f4ea8a260
Supersedes the single-slot staging the execution-identity fix (06c5f17e)
kept: the one pending slot needed a mismatch-drop branch plus a defensive
coverage-ignored finally to manage orphans, and it carried a latent trap —
under the loop's documented parallel-execution TODO, two in-flight capture
trips would overwrite the slot and BOTH be dropped.
Staging in a WeakMap<ToolExecution, {value}> makes the stale-stage class
structurally impossible instead of managed: an entry orphaned by an outer
short-circuiting listener can never match a different execution's lookup
(whatever call id that execution carries), needs no drop bookkeeping (the
map reclaims it with the execution object), and staging cannot cross-clobber
under parallel execution. Staging is the only layer this future-proofs — a
parallel cut would still owe its own single-accept rule for the captured
value, which is documented rather than claimed. Behavior is pinned by the
existing orphan/call-id-reuse regression tests, which pass unchanged; the
commit listener loses two branches and the v8-ignore.
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.