file.revert reads and decodes the saved file first: if that fails the
document is left as it is, still modified. Otherwise Session::replace_document
swaps the content in the same tab (same place, path, format and uid; history
and selection cleared; saved state), so every tab keeps its zoom. It runs only
for saved, modified documents. In the app, Revert asks first with the shared
confirm dialog, whose OK runs file.revert {confirmed: true} on the engine.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>