No way existed to change which fandom a character tag belongs to after
creation — PATCH /tags/<id> only renamed.
- TagService.set_fandom(tag_id, fandom_id, merge=False): set / change /
clear (fandom_id=None) a character's fandom, with the same validation as
find_or_create. On a name collision in the target fandom it raises
TagMergeConflict (→ 409, same shape as rename); merge=True resolves it by
merging this tag INTO the existing character.
- Extract _do_merge(source, target) from merge() so set_fandom can perform
the deliberate CROSS-fandom merge the public merge() validation forbids.
- PATCH /tags/<id> now accepts optional fandom_id (+ merge flag) alongside
name, and returns fandom_id.
Tests: set/change/clear, non-character + bad-ref rejection, collision
raises, merge resolves; API set/clear + collision→merge.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
bvandeusen
d9ab6e15c6