The original Phase 3 dropped the legacy global UNIQUE(tag.name) at the end,
which meant Phase 1's prefix-strip UPDATEs ran with the old constraint still
in place. On any DB that had a pre-existing bare-name row colliding with the
stripped form of a prefixed row (e.g. 'character:Marcille Donato' stripping
to 'Marcille Donato' where another 'Marcille Donato' already existed), the
migration blew up with UniqueViolation on tag_name_key.
Fix: drop tag_name_key at the very top of upgrade() so both phases operate
against a uniqueness-free table. Add explicit collision handling to Phase 1
(mirrors the existing Phase 2 auto-merge): when the stripped name already
matches an existing row under the shape of the incoming partial-index
(same kind, or same kind+fandom_id for characters), reassign image_tags
onto the winner, cascade-rename tag_reference_embedding, and delete the
loser. Report now shows phase1_merged alongside phase1_renames.
Backwards-compatible for DBs where the failing migration already rolled
back — rerunning picks up the fix. The migration's transaction atomicity
means the DB is still in pre-migration state after the earlier failure.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
bvandeusen
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