[xvcezrqpbxtpzblrt]

Problem

A helper (subagent) row could stay working after its run ended. The page has no other source for the row, so it kept showing a helper that was no longer running, with a duration that kept growing. Reopening the chat showed the same ghost row.

Fix

• inishTurn now seals every helper of the run that has not finished: the row is marked interrupted before its stream closes and before the page is told the turn ended.
• ChildProjector.finished now counts interrupted as final, so a sealed row stops being "live" and its duration stops growing.
• markStopped() lets a stop the person asked for read "stopped, can continue" instead of "cancelled".

Validation

• node --test tests/agent-children.test.mjs — 6 pass, 0 fail (includes a new test: a sealed row reads interrupted, is final, and sealing twice changes nothing).
• Not run: the real Harness end-to-end (needs a running agent), and the page (no browser run). The row frame path is covered by the projector test only.

Scope

This is the seal half of #4218. Kept apart from the row store and the subagent panel so it can be reviewed on its own.

[github-actions]

Thanks for the pull request. To keep the tracker readable, every item needs an area prefix in the title and the parts of the pull request template filled in. This one is missing:

• Fill in "Validation": the exact commands, the revision and environment tested, what you saw. Keep Passed, Failed and Not run apart.

Edit the pull request (title and description) and this note goes away on its own. If it is still missing parts in 5 days it will be closed, which is not a rejection: fix it and comment /reopen.

Details: CONTRIBUTING.md

[xvcezrqpbxtpzblrt]

Superseded by #4606, which carries this change with the rest of the 0.2.7 branch. Closing so the review has one place.