subagent: capture overrides at delegation; stamp ahead of prompt vetoes

Review fixes (ds-review-bot on #623):

- Capture-at-delegation: the driver now reads overrideOf(parent.session)
  for both knobs synchronously before its first await, and the prompt-submit
  listener stamps those captured values — a parent switch racing the child's
  asynchronous creation belongs to the parent's future, not the child. The
  inheritOverride(parent, child) service method is split into its two halves
  (overrideOf / stampOverride) accordingly.
- Veto safety: the one-shot prompt-submit listener registers with
  prepend: true, so a veto-capable listener (a denying UserPromptSubmit
  hook) cannot close the child's first turn without the durable stamp.

Both regressions are pinned red-first in inheritance.spec.ts: the
delegation-vs-late-switch race (delegate tool flips the caller wider while
the creation transaction is pending) and a blocking prompt-submit listener
(stamp survives a promptless first turn). Service contract tests renamed to
the split API; READMEs and the bilingual Agent Note updated.
This commit is contained in:
kingwl
2026-07-25 10:51:25 +08:00
parent 669771097d
commit 6fa2377e34
12 changed files with 192 additions and 91 deletions
@@ -16,7 +16,7 @@ The driver follows this sequence:
The child gets the parent's working-directory/session lineage and inherits the parent model unless `request.agentOptions` overrides it. It gets a fresh flat registration scope: parent ownership does not import parent tool restrictions or establish an authority subset.
The child also inherits the parent's session POLICY overrides: a one-shot `agent/prompt-submit` listener installed during setup stamps the parent's effective `sandbox/mode` and `approval/policy` overrides onto the child through `ctx.sandboxPolicy.inheritOverride` / `ctx.approval.inheritOverride` (both consumed opportunistically — compositions without them delegate policy-free). Anchoring inside the child's first turn keeps the stamp turn-enclosed (durable) and ahead of the first request, and its log position after any fork-seed switch lets the ordinary last-event-wins fold resolve stale-seed timing; only the override chain is copied, so an unswitched parent stamps nothing and the child follows the live deployment default. Nesting composes: each stamp folds the delegating session's already-stamped log ([rationale](../../../.agents/notes/implemented/feature/2026-07-25-subagent-policy-inheritance.md)).
The child also inherits the parent's session POLICY overrides. The driver captures `ctx.sandboxPolicy.overrideOf(parent.session)` and `ctx.approval.overrideOf(parent.session)` synchronously before its first await — the delegation moment is the snapshot point, so a parent switch racing the asynchronous child creation belongs to the parent's future — and a one-shot PREPENDED `agent/prompt-submit` listener stamps the captured values through `stampOverride` (both services consumed opportunistically — compositions without them delegate policy-free). Anchoring inside the child's first turn keeps the stamp turn-enclosed (durable) and ahead of the first request; prepending puts it before veto-capable listeners, so a denying UserPromptSubmit hook cannot close the first turn without the stamp; its log position after any fork-seed switch lets the ordinary last-event-wins fold resolve stale-seed timing. Only the override chain is copied, so an unswitched parent stamps nothing and the child follows the live deployment default. Nesting composes: each capture folds the delegating session's already-stamped log ([rationale](../../../.agents/notes/implemented/feature/2026-07-25-subagent-policy-inheritance.md)).
## Cancellation and ownership