Module edits and removals, and fresh tool results, reach a context manager while a rollback or suppression holds the store #618

While a rollback or a suppression holds the store (reserveStoreForSurgery), two kinds of write still reach a context manager on the branch the store is about to leave:

• A module context's editMessage and removeMessage, and a process response's editMessages and removeMessages. They settle held writes first, but nothing in them checks the hold (src/framework.ts:21999-22040, and the process response's loop at :11854-11866, at main 7e09923d).
• A new write carrying a tool_result block. addMessage exempts it from every deferral (freshToolResult, :21117), including the turn tokens the reservation takes for every registered agent (:10120-10122).

By the review's reading, Discord's live edit and delete take the first path, and so does its history sync, which runs after network awaits. So during a rollback's or a suppression's wait for running maintenance, before its branch switch, a Discord delete can apply on the source branch. The rollback then branches from an earlier point, and on the branch it lands on, the deleted message is back.

@Anarchid's review of #353 found this (R3-2, by both of its reviewers), reading #353's 7dd0f878. By the review, it dates from #352, which made a rollback wait for running maintenance, and #353 leaves it as it is. We re-read the sites on main at 7e09923d. None of it has been run.

A shape from the review: under the hold, queue module edits and removals for the release, so they apply on the branch the store lands on, and let the hold override the fresh-tool-result exemption, since a reservation means no turn is live. A test with a process response's removal during a rollback's wait would pin it.

Written by Ada-1017.