Parent threads cannot see a child blocked on an approval #58

Outcome

A parent thread knows when a child it spawned is blocked on an approval, and a planner cannot silently start an unattended child in a mode that needs approvals or has no network.

Evidence (2026-09-27 to 2026-09-28)

• A planner started a worker with spawn_thread(role: worker, runtimeMode: "auto") on OpenCode. For OpenCode, "auto" falls back to asking (apps/server/src/provider/opencodeRuntime.ts:514; docs/user/permission-modes.md), so the session had bash: ask and edit: ask. Its first command waited for an approval nobody saw, was aborted, and the worker made no progress for about 20 hours.
• Throughout, list_child_threads and read_thread reported the child as running with a normal-looking last message. reportBack only fires when a turn finishes, so the parent got no signal. The user noticed the pending prompt in the UI; the planner did not.
• The same planner started a reviewer with runtimeMode: "auto" on Codex. "auto" maps to sandbox: "workspace-write" (CodexSessionRuntime.ts:535-539), which has no network, so the reviewer could not reach GitHub and returned a blocker saying it could not read the Issue or PR.
• The spawn_thread description does not say what each runtimeMode means per provider.

Acceptance criteria

• When a child has a pending approval or user-input request, list_child_threads and read_thread report a distinct status (for example awaiting_approval) with the requested action.
• With reportBack, the parent receives a message when a child starts waiting for approval, not only when a turn ends.
• The spawn_thread description states, per provider, what each runtimeMode allows (network, commands, edits) and which modes need a human to approve.
• Children default to the role kit's or the parent's mode when runtimeMode is omitted (current behavior), and the description recommends omitting it for unattended work.

Non-goals

• Letting a parent approve on the user's behalf (a separate authority decision).
• Changing provider permission semantics.

Blockers

None known.

Proof

Spawn an OpenCode child in "auto" that runs a bash command: the parent sees awaiting_approval and receives a report-back message. The spawn_thread description lists the per-provider meaning of each mode.