diff --git a/alembic/versions/0022_source_per_artist_platform.py b/alembic/versions/0022_source_per_artist_platform.py
index f85b96a..d3e75dd 100644
--- a/alembic/versions/0022_source_per_artist_platform.py
+++ b/alembic/versions/0022_source_per_artist_platform.py
@@ -109,7 +109,7 @@ def upgrade() -> None:
         by_epid: dict = {}
         for epid, post_id, src_id in all_posts:
             by_epid.setdefault(epid, []).append((post_id, src_id))
-        for epid, posts in by_epid.items():
+        for _epid, posts in by_epid.items():
             if len(posts) <= 1:
                 continue
             # Prefer a Post already under canonical as the keep.
@@ -120,6 +120,25 @@ def upgrade() -> None:
                 keep_id = posts[0][0]  # already sorted by id ASC
             drop_ids = [p[0] for p in posts if p[0] != keep_id]
             for drop_id in drop_ids:
+                # Pre-delete image_provenance rows under drop_ whose
+                # image_record_id ALREADY has a provenance under keep —
+                # the UPDATE below would otherwise repoint them and
+                # trip uq_image_provenance_image_post (alembic 0021)
+                # row-by-row before any after-the-fact dedupe could
+                # run. Operator's v26.05.26.3 deploy 2026-05-26 tripped
+                # this at line 123.
+                conn.execute(
+                    text("""
+                        DELETE FROM image_provenance
+                        WHERE post_id = :drop_
+                          AND image_record_id IN (
+                              SELECT image_record_id FROM image_provenance
+                              WHERE post_id = :keep
+                          )
+                    """),
+                    {"keep": keep_id, "drop_": drop_id},
+                )
+                # Now safe to repoint the survivors.
                 conn.execute(
                     text("""
                         UPDATE image_provenance SET post_id = :keep
@@ -134,15 +153,6 @@ def upgrade() -> None:
                     """),
                     {"keep": keep_id, "drop_": drop_id},
                 )
-                # Repointed provenance may now collide on
-                # uq_image_provenance_image_post (alembic 0021). Dedupe.
-                conn.execute(text("""
-                    DELETE FROM image_provenance ip1
-                    USING image_provenance ip2
-                    WHERE ip1.image_record_id = ip2.image_record_id
-                      AND ip1.post_id = ip2.post_id
-                      AND ip1.id > ip2.id
-                """))
                 conn.execute(
                     text("DELETE FROM post WHERE id = :drop_"),
                     {"drop_": drop_id},