The original report: clicking a backup sidebar tab loaded content on top of
the old content. Root cause (flagged in the unmount comment as deferred):
BackupPage.bindEvents() attaches document-level click/input/change listeners
guarded only by the instance-level this.eventBound, and unmount() nulled
window.backupPage WITHOUT removing them. Each revisit added another full set of
listeners bound to a stale BackupPage, all firing on every click and mutating
the live DOM (double tab-switches, double modal opens, stale-instance renders).
Fix (mirrors the kernel's MountContext pattern): give BackupPage an
AbortController, bind the three document listeners to its signal, add dispose()
that aborts them (+ drops the task-refresh reg + clears the timer), and call it
from the feature module's unmount(). Revisits now start clean — one live
instance, one set of listeners.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>