R1: tomllib accepting a file is not herdr accepting it (a schema error makes
herdr drop the whole file, restore included). The shim passes REAL_HERDR and
the written file must pass `herdr config check` ("parse error"/"using defaults"
reject; unknown keys and sound-file notices do not), else the key-only file is
written and checked. A non-table `session` and a source that is not UTF-8 reach
that fallback instead of raising.
R2: the line edit is replaced by parse -> set -> serialize; the result must
parse back to the source plus the key, so dotted keys and inline tables keep
the user's other settings.
R3: the output is never the source (aliases included) nor a file not generated
for the same source; then a per-source name beside it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
GodopuandClaude Opus 5.5
811b080966