Backfill existing sound files to generated names, as a resumable command #991

Refactoring Proposal

Follow-up to #699. #982 makes new sound uploads land at sounds/<uuid>.<ext>, but says nothing about the rows already in the database, which still point at files stored under the name their uploader chose. Those are the ones actually exposed today.

#699 asks for "a migration to rename all the objects in the current database". This issue proposes doing it as a resumable management command instead.

Describe the design issue(s) you have identified in the code

A data migration is the wrong shape for this work:

• It renames live objects in S3. A run that dies halfway — a network blip, a throttle, a deploy timeout — leaves rows pointing at keys that no longer exist, and a migration cannot be resumed from where it stopped.
• It runs inside the deploy, so it cannot be scheduled for a quiet window, rehearsed against a copy, or aborted after the first few rows look wrong.
• It gives no way to see what would change before anything does.

Which source files are affected to this issue(s)?

1. src/core/management/commands/ — new command;
2. src/core/models.py — reuses the sound_file_path helper added in Store sound uploads under a generated name (#699) #982;
3. src/core/tests/ — tests for the command.

Describe refactoring alternatives to redesign the code

A command with these properties:

1. Idempotent, so resuming is just running it again: rows whose name already matches sounds/<uuid>.<ext> are skipped.
2. Safe ordering — write the new object, update the row, then delete the old object. Interrupted at any point, the worst outcome is an orphaned old file, never a row pointing at nothing.
3. --dry-run to list what would change without touching storage.
4. --limit N so a first batch can be small and inspected.
5. Per-row error isolation: a failure is logged with the key and the run continues, rather than aborting and leaving the job half-done with no record of where.
6. Backfills file_name_original from the old key when it is empty, so the original name is preserved as Save media content with random names #699 asks.

Blocked on #982, which introduces the sound_file_path helper the command needs so backfilled names match new ones.

Generated by Claude Code