96c3c94f85
Re-auditing the review-fix commits surfaced a regression the REPLACE re-assert (825cbab3) introduced: unconditionally rebuilding both arrays as filter(...)+append moved structured_output to the END of the model-visible tool list on every untampered assembly (overriding the registry's toolOrder/lexicographic contract) and moved the instruction section to the absolute array end — renderPrompt reads ARRAY order, so any section above order 190 would render before the trailing instruction, violating the sections-sorted-ascending contract. The presence-check version it replaced touched neither array when the entries were intact. The re-assert keeps its REPLACE content semantics but is now placement-preserving: the tool is replaced IN PLACE (duplicates collapse, append only when stripped); the section is re-inserted at its ascending-order position (the first entry above 190 — exactly where the registry's stable sort put it, so the untampered path reaches the model byte-identical). Pinned by two regression tests that fail against the filter+append form: untampered placement (tool before a lexicographically later tool, instruction before an order-200 section) and tamper recovery (stripped section re-enters its band; an added duplicate collapses to one right-schema entry).
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.