An artist first downloaded by gallery-dl gets Post rows keyed by the per-
attachment id; a later native walk keys the SAME real post by the post id. They
never dedup (uq_post_source_external_id is on external_post_id) → duplicate post
rows (cheunart: 943→1109). The real post id is recoverable in-DB from
raw_metadata['post_id'] (both eras store the sidecar there).
reconcile_duplicate_posts (cleanup_service): group posts by (source_id, canonical
post_id = raw_metadata.post_id else external_post_id); for each group >1, keep the
row already keyed by the post id (the format the CURRENT native downloader
produces, so future walks dedup and this can't recur), re-point
ImageRecord.primary_post_id / ImageProvenance / PostAttachment / ExternalLink onto
it conflict-safe (drop the loser's row where the keeper already has the equivalent,
per each table's uniqueness), backfill the keeper's empty date/title/body/raw_meta
from a loser, set external_post_id=post_id + derive post_url, delete losers.
IMAGES ARE NOT TOUCHED (content-addressed/deduped already; operator-confirmed).
Preview/apply share find_duplicate_post_groups (rule 93). API
/api/admin/posts/reconcile-duplicates (dry_run→{groups,posts_to_merge,sample};
apply→{groups,merged,sample}; optional source_id). UI: a second section on
PostMaintenanceCard (preview groups+sample → confirm merge). Tests: merge +
metadata backfill + image move, no-op when unique, provenance-collision dedup.
Design: milestone #73. Forensics: note #917. Out of scope (flagged): cheunart vs
Cheunart case-variant artist dirs/rows.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
bvandeusen
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