A kit with no manifest under the Sedona home folder called sys.exit(1),
tearing down the whole app over one unopenable file.
schema now raises MissingManifestError instead, collecting every
unresolved kit first so one dialog names them all rather than the user
fixing them one reopen at a time. describe_missing_manifests builds the
body, pointing at the configured Sedona home and at Preferences.
open_file catches it, reports it, and calls the new
reset_to_startup_state to return to the just-launched state: no file,
empty tree, empty sheet, cleared registries and undo stack. The generic
except now resets too, since a half-parsed file previously left
current_file_path and a stale root behind.
Placing a palette component hits the same loader, where a full reset
would be too destructive: it rolls back the <kit> entry it just added,
rebuilds the previous registry, and abandons only that placement.
schema no longer imports sys or tkinter, so it reports nothing itself
and stays testable without a display. base_window_title moves to
app_state so the reset can restore the title without duplicating it.
README: document the new behaviour, drop the fixed gap, and correct the
stale "no undo, no keyboard shortcuts for save" claim.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
