0.3.33 still ships blank screenshots because the whole toolbar-menu → auto-
open-editor path can't be made race-free: the moment the editor tab opens
it becomes the active tab, and a snapshot of the editor's own tab (before
its canvas has drawn from storage) is a valid-looking 24 KB all-white PNG.
The lastCapturableTabId fallback I added in a279864 catches the second
click, but the first click can still land on the addon-owned tab whenever
the user re-triggers before setActive has settled.
Rebuild the UX so this class of race can't happen at all:
- Drop the toolbar-menu capability. Manifest is back to sidebar-panel +
capture-tab + open-tab, so the dock icon opens the panel (never the
editor directly). No dropdown, no clip-under-tab-view issue, no auto-
jump into an addon-owned tab.
- Sidebar has the three capture buttons + a preview <img> + a "Open in
editor tab" button. The preview is fed a data:image/png URL returned
straight from api.captureTab, rendered inside the sidebar's own
document — same origin, no file:// cross-directory gotcha, and the user
can see immediately whether the shot actually landed.
- Editor.html tab opens only on an explicit "Open in editor tab" click.
The addon rewrites __pending at that moment (so the editor always sees
the just-selected capture even if a prior editor tab drained the entry),
then api.openTab("editor.html", {name}). The editor's storage-based
load path is unchanged.
- Recent captures ring is kept and now exposed as a horizontal thumbnail
strip in the sidebar; clicking a tile re-previews that capture and
arms "Open in editor tab" for it.
Editor page (editor.html/js/css) unchanged — same crop / arrow / rect /
ellipse / pen / text / mosaic-redact / undo / redo / copy / save.
Bundled but not shipped — leaving version bump + deploy to the parent
session.