c53e9c90db
Review fix (ds-review-bot critical #2 on #623): the first-turn event stamp had a durability hole no turn anchoring can close — an idle SessionStart- style injection persists a complete one-shot turn before any prompt turn opens, so a crash in that window left a resumable-looking child with no inherited policy, falling back to a possibly wider deployment default. The captured overrides now ride the child's creation meta into its immutable SessionHeader (sandboxMode/approvalPolicy, neutral strings at the session boundary — the delegationDepth precedent), durable from the moment the session exists: no listener ordering can starve the baseline and no crash window can lose it. overrideOf(session) on both policy services resolves fold(events past header.seedLength) ?? header baseline, validating against the closed vocabulary on read; stampOverride and the prompt-submit listener machinery are deleted. The header field rides both persistence backends (JSONL header line; SQLite sessions columns, SCHEMA_VERSION 11 — pre-release, no migration). pty-local reads through overrideOf so PTY spawns see the baseline too. Red-first: header-durability-before-any-turn test (the injection crash window shape), baseline/seed-boundary/closed-vocabulary contract tests in both service suites; the real-wall suite (race, veto, fork stale-seed, grandchild) re-anchored on header assertions and green. The Agent Note's Alternatives now records the superseded event-stamping iteration with the review evidence; bilingual docs updated.
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-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), and the out-of-process subagent-acp backend builds on the subagent-subprocess library (the credential env scrub, the dispose ladder, isolated config dirs). 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.