alembic/versions/0113_redate_native_images.py

@@ -0,0 +1,60 @@
+"""Re-date images whose post's date arrived after they were linked.
+
+#4431. The native ingesters import a post's media before its record, and the
+date travels in the record (`_post.json`). Every natively downloaded image was
+therefore linked to an undated post and kept its download time in both gallery
+date columns, while the post itself was dated correctly. The importer now
+re-dates a post's images when its record lands; this repairs the images that
+landed before that.
+
+Both columns get back the rules the importer keeps:
+
+* `effective_date` is the primary post's date (left alone when that post has
+  none, as the importer does);
+* `earliest_post_date` is the earliest dated post the image is linked to.
+
+Only rows that differ are written. The downgrade does nothing: the old values
+were download times that no one chose.
+
+Revision ID: 0113
+Revises: 0112
+Create Date: 2026-09-25
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0113"
+down_revision = "0112"
+branch_labels = None
+depends_on = None
+
+
+def redate_images(conn) -> None:
+    """The data step, on a plain connection, so a test can run it directly."""
+    conn.execute(sa.text("""
+        UPDATE image_record ir SET effective_date = p.post_date
+        FROM post p
+        WHERE p.id = ir.primary_post_id
+          AND p.post_date IS NOT NULL
+          AND ir.effective_date IS DISTINCT FROM p.post_date
+    """))
+    conn.execute(sa.text("""
+        UPDATE image_record ir SET earliest_post_date = m.earliest
+        FROM (
+          SELECT ip.image_record_id, MIN(p.post_date) AS earliest
+          FROM image_provenance ip JOIN post p ON p.id = ip.post_id
+          WHERE p.post_date IS NOT NULL
+          GROUP BY ip.image_record_id
+        ) m
+        WHERE m.image_record_id = ir.id
+          AND ir.earliest_post_date IS DISTINCT FROM m.earliest
+    """))
+
+
+def upgrade():
+    redate_images(op.get_bind())
+
+
+def downgrade():
+    pass

backend/app/services/importer.py

@@ -1130,9 +1130,51 @@ class Importer:
         if post.artist_id is None:
             post.artist_id = artist.id
         self._apply_post_fields(post, sd)
+        self._redate_post_images(post)
         self.session.commit()
         return True
 
+    def _redate_post_images(self, post: Post) -> None:
+        """Carry a post's date onto the images already linked to it (#4431).
+
+        The native ingesters import a post's media BEFORE its record: the
+        per-media sidecar holds only the image identity (post-first, #856), and
+        the date arrives with `_post.json`. So `_attach_provenance` links each
+        image to a post that has no date yet, and the image keeps its download
+        time. This runs when the record lands, and applies the same two rules
+        `_attach_provenance` applies: `effective_date` is the PRIMARY post's
+        date, and `earliest_post_date` is the earliest date across every post
+        the image is linked to. Only rows that differ are written."""
+        if post.post_date is None:
+            return
+        self.session.flush()
+        self.session.execute(
+            update(ImageRecord)
+            .where(ImageRecord.primary_post_id == post.id)
+            .where(ImageRecord.effective_date.is_distinct_from(post.post_date))
+            .values(effective_date=post.post_date)
+            .execution_options(synchronize_session=False)
+        )
+        linked = select(ImageProvenance.image_record_id).where(
+            ImageProvenance.post_id == post.id
+        )
+        earliest = (
+            select(func.min(Post.post_date))
+            .select_from(ImageProvenance)
+            .join(Post, Post.id == ImageProvenance.post_id)
+            .where(ImageProvenance.image_record_id == ImageRecord.id)
+            .where(Post.post_date.is_not(None))
+            .correlate(ImageRecord)
+            .scalar_subquery()
+        )
+        self.session.execute(
+            update(ImageRecord)
+            .where(ImageRecord.id.in_(linked))
+            .where(ImageRecord.earliest_post_date.is_distinct_from(earliest))
+            .values(earliest_post_date=earliest)
+            .execution_options(synchronize_session=False)
+        )
+
     def attach_in_place(
         self,
         path: Path,

tests/test_redate_images_migration.py

@@ -0,0 +1,70 @@
+"""Migration 0113 (#4431): images linked to a post before its date arrived get
+the post's date back. Runs the migration's data step against real rows."""
+import importlib.util
+from datetime import UTC, datetime
+from pathlib import Path
+
+import pytest
+
+from backend.app.models import Artist, ImageProvenance, ImageRecord, Post
+from tests.factories import make_image as _img
+
+pytestmark = pytest.mark.integration
+
+_MIGRATION = (
+    Path(__file__).resolve().parents[1]
+    / "alembic" / "versions" / "0113_redate_native_images.py"
+)
+
+
+def _redate():
+    spec = importlib.util.spec_from_file_location("m0113", _MIGRATION)
+    mod = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(mod)
+    return mod.redate_images
+
+
+def _post(db, artist, epid, when):
+    p = Post(artist_id=artist.id, external_post_id=epid, post_date=when)
+    db.add(p)
+    db.flush()
+    return p
+
+
+def _link(db, img, post, *, primary):
+    db.add(ImageProvenance(image_record_id=img.id, post_id=post.id))
+    if primary:
+        img.primary_post_id = post.id
+    db.flush()
+
+
+def test_redate_images_from_their_posts(db_sync):
+    sent = datetime(2024, 3, 1, 18, 30, tzinfo=UTC)
+    earlier = datetime(2023, 1, 5, tzinfo=UTC)
+    artist = Artist(name="Alice", slug="alice")
+    db_sync.add(artist)
+    db_sync.flush()
+    undated = _post(db_sync, artist, "u1", None)
+    dated = _post(db_sync, artist, "d1", sent)
+    repost = _post(db_sync, artist, "r1", earlier)
+
+    stale = _img(db_sync, "a" * 64)          # primary post dated, image not
+    reposted = _img(db_sync, "b" * 64)       # also in an earlier post
+    orphan = _img(db_sync, "c" * 64)         # only an undated post
+    _link(db_sync, stale, dated, primary=True)
+    _link(db_sync, reposted, dated, primary=True)
+    _link(db_sync, reposted, repost, primary=False)
+    _link(db_sync, orphan, undated, primary=True)
+    orphan_before = orphan.effective_date
+
+    _redate()(db_sync.connection())
+    db_sync.expire_all()
+
+    stale = db_sync.get(ImageRecord, stale.id)
+    reposted = db_sync.get(ImageRecord, reposted.id)
+    orphan = db_sync.get(ImageRecord, orphan.id)
+    assert stale.effective_date == sent
+    assert stale.earliest_post_date == sent
+    assert reposted.effective_date == sent             # the primary post's date
+    assert reposted.earliest_post_date == earlier      # the earliest post's date
+    assert orphan.effective_date == orphan_before      # no date to take

tests/test_sidecar_import.py

@@ -382,3 +382,36 @@ def test_external_links_not_duplicated_on_reimport(importer, import_layout):
     assert importer.session.execute(
         select(func.count()).select_from(ExternalLink)
     ).scalar_one() == 1
+
+
+def test_post_record_redates_images_linked_before_it(importer, import_layout):
+    """#4431: the native ingesters import a message's media before its record,
+    and only the record carries the date. The images start on their download
+    time; when the record lands they take the post's date."""
+    import_root, _ = import_layout
+    artist = Artist(name="Alice", slug="alice")
+    importer.session.add(artist)
+    importer.session.flush()
+    m = import_root / "Alice" / "20240301_123_01_art.jpg"
+    _split(m, "v")
+    _sidecar(m, {"category": "discord", "message_id": "123"})
+    r = importer.import_one(m)
+    assert r.status == "imported"
+    rec = importer.session.get(ImageRecord, r.image_id)
+    post = importer.session.execute(select(Post)).scalar_one()
+    assert post.post_date is None
+    download_time = rec.effective_date
+
+    sc = import_root / "Alice" / "20240301_123_post.json"
+    sc.write_text(json.dumps({
+        "category": "discord", "message_id": "123", "message": "",
+        "date": "2024-03-01T18:30:00.000000+00:00",
+    }))
+    assert importer.upsert_post_record(sc, artist=artist) is True
+    importer.session.expire_all()
+    rec = importer.session.get(ImageRecord, r.image_id)
+    post = importer.session.execute(select(Post)).scalar_one()
+    assert post.post_date is not None
+    assert post.post_date != download_time
+    assert rec.effective_date == post.post_date
+    assert rec.earliest_post_date == post.post_date