datasette.create_scratch_database() / delete_scratch_database() /
rename_scratch_database() / list_scratch_databases() manage SQLite files in
a scratch directory (--scratch-dir, config_dir/scratch, or a temporary
directory created on first use).
- Registry: a SQLite sidecar (.datasette-scratch.db) with intent states
(creating/deleting/renaming); startup reconciles it with the directory,
which is the source of truth (hand-copied files are adopted, hand-deleted
ones dropped, orphan -wal/-shm/-journal removed). flock() per directory.
- Scratch databases are attached at startup without opening them, use
schema watch mode "owned", and track last_used in memory (flushed to the
registry at most once a minute and on close).
- Delete/rename: queued reads and writes fail with ScratchDatabaseDeleted,
running ones finish; files are unlinked only once no connection
(including the SchemaWatcher's, now counted) has them open.
- Datasette.close() records final fingerprints of owned file databases in a
persistent internal database, so restarts reuse their catalog rows
without opening them.
- Scratch databases are not attached to crossdb _memory and are skipped by
check_databases().
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwkLo2rJWidpkDVT3HkvNv
