Rebased onto the activity stack (#601). An export adding its files to
Photos keeps its row through that step, with "Adding to Apple Photos…" as
the detail. The worker turns the row's ✕ off (TaskHandle::set_cancellable)
before its last look at the cancel flag and reports what it saw, so a
cancel either stops the export before Photos is asked or is refused, never
both "cancelled" and imported. activity: a per-task gate orders a cancel's
decision against a step switching cancelling off, so a cancel can't be
accepted between the switch and the step's look at the flag and then be
ignored. An import of its own (export.addToPhotos, or
the Photos step left running after a foreground app.export) holds a row of
kind applePhotos while Photos works: no ✕, no count, the album as detail.
The desktop app refuses export.addToPhotos {wait: true}: its window's
thread never waits for Photos. The label is in every catalog; tests assert
the rows, the refused cancel and the refused wait.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
