yoi/docs/report/2026-08-06-subworker-completion-idle-auto-run.md

SubWorker completion notification did not wake an idle parent

Date: 2026-08-06 Ticket: 00001KZKNWP5X

Observed behavior

A Reviewer SubWorker finished after its parent Worker had returned to idle. Although the completion notification was marked auto_run: true, the parent did not run until the user submitted another message. The notification appeared only in that later turn.

Root cause

The completion callback called NotifyBuffer::push_notify(..., true) directly. A running parent checks that buffer at turn end and can stage a follow-up, but an idle controller waits on its method channel. Writing the buffer alone therefore could not wake an already-idle parent.

Fix

Normal controller-owned Workers now give the SubWorker tool a weak sender for the parent method channel. Completion is delivered through the existing:

Method::Notify {
    message,
    auto_run: true,
}

path, which commits the notification through the normal inbox and wakes an idle controller. A WeakSender avoids a controller/tool/channel reference cycle that would otherwise keep the controller alive after external handles are dropped. Internal Worker sessions without a controller retain the direct buffer target.

Regression coverage

• SubWorker completion sends exactly one Method::Notify { auto_run: true } to the parent controller channel.
• The controller notification target does not keep the method channel alive after the strong sender is dropped.
• Existing running-parent notification follow-up tests remain green.
• cargo test -p worker --lib: 514 passed.