diff --git a/backend/app/services/gallery_service.py b/backend/app/services/gallery_service.py
index 4c449c5..3331510 100644
--- a/backend/app/services/gallery_service.py
+++ b/backend/app/services/gallery_service.py
@@ -20,6 +20,7 @@ from datetime import datetime
 
 from sqlalchemy import Select, and_, exists, func, or_, select
 from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import aliased
 
 from ..models import Artist, ImageProvenance, ImageRecord, Post, Tag
 from ..models.tag import image_tag
@@ -139,10 +140,17 @@ def _provenance_clause(post_id, artist_id):
         # path now drops NULL-source provenance rows (filesystem-imported
         # content) which would otherwise vanish from artist-filtered
         # gallery views.
+        # ALIAS Post: the gallery query outer-joins Post on
+        # ImageRecord.primary_post_id (`_outer_join_primary_post`).
+        # SQLAlchemy would otherwise correlate a bare `Post` reference
+        # in this EXISTS subquery to that outer Post (which is NULL for
+        # images with no primary post), and the filter would silently
+        # match nothing.
+        post_inner = aliased(Post)
         return exists().where(
             ImageProvenance.image_record_id == ImageRecord.id,
-            ImageProvenance.post_id == Post.id,
-            Post.artist_id == artist_id,
+            ImageProvenance.post_id == post_inner.id,
+            post_inner.artist_id == artist_id,
         )
     return None
 
diff --git a/tests/test_importer_provenance_race.py b/tests/test_importer_provenance_race.py
index 68ba96c..970a76e 100644
--- a/tests/test_importer_provenance_race.py
+++ b/tests/test_importer_provenance_race.py
@@ -29,7 +29,6 @@ from backend.app.models import (
     ImageProvenance,
     ImageRecord,
     ImportSettings,
-    Source,
 )
 from backend.app.services.importer import Importer
 from backend.app.services.thumbnailer import Thumbnailer
@@ -139,9 +138,11 @@ def test_apply_sidecar_recovers_from_integrity_error(
     r = importer.import_one(m)
     assert r.status == "imported"
     rec = importer.session.get(ImageRecord, r.image_id)
-    src = importer.session.execute(select(Source)).scalar_one()
+    # alembic 0030 stopped creating synthetic Source rows for filesystem
+    # sidecars; the Post sits null-source and the provenance row points at
+    # it directly. The race-recovery path tested below operates on
+    # ImageProvenance regardless of Source presence.
     assert rec is not None
-    assert src is not None
 
     # Monkeypatch session.execute so the FIRST select inside _apply_sidecar's
     # existence-check returns a "no row" wrapper. Subsequent selects (e.g.
diff --git a/tests/test_phash_dedup.py b/tests/test_phash_dedup.py
index 83b5725..da57ac2 100644
--- a/tests/test_phash_dedup.py
+++ b/tests/test_phash_dedup.py
@@ -15,7 +15,6 @@ from backend.app.models import (
     ImageRecord,
     ImportSettings,
     Post,
-    Source,
     Tag,
     TagKind,
 )
@@ -197,10 +196,11 @@ def test_supersede_applies_new_file_sidecar(importer, import_layout):
     assert post.post_title == "Set 1"
     assert "big version" in (post.description or "")
 
-    source = importer.session.execute(
-        select(Source).where(Source.id == post.source_id)
-    ).scalar_one()
-    assert source.platform == "patreon"
+    # Filesystem sidecars no longer create a synthetic Source (alembic 0030).
+    # The Post sits null-source; the platform context is captured in the
+    # sidecar JSON / raw_metadata, not in a phantom Source row.
+    assert post.source_id is None
+    assert post.artist_id is not None
 
     prov_count = importer.session.execute(
         select(func.count(ImageProvenance.id))
diff --git a/tests/test_sidecar_import.py b/tests/test_sidecar_import.py
index f9ebabc..1984d99 100644
--- a/tests/test_sidecar_import.py
+++ b/tests/test_sidecar_import.py
@@ -75,9 +75,15 @@ def test_sidecar_creates_provenance(importer, import_layout):
     r = importer.import_one(m)
     assert r.status == "imported"
     rec = importer.session.get(ImageRecord, r.image_id)
-    src = importer.session.execute(select(Source)).scalar_one()
     post = importer.session.execute(select(Post)).scalar_one()
-    assert src.platform == "patreon"
+    # Filesystem-imported sidecar posts no longer create a synthetic Source
+    # (alembic 0030 / nullable post.source_id refactor). The Post is linked
+    # to the artist via Post.artist_id; Post.source_id stays NULL until a
+    # real subscription for the (artist, platform) gets added.
+    assert post.source_id is None
+    assert importer.session.execute(
+        select(func.count()).select_from(Source)
+    ).scalar_one() == 0
     assert post.external_post_id == "555"
     assert post.post_url == "https://patreon.com/posts/555"
     assert post.post_title == "Set 1"
@@ -106,9 +112,11 @@ def test_reimport_same_post_idempotent(importer, import_layout):
     _sidecar(m2, payload)
     r2 = importer.import_one(m2)
     assert r2.status == "imported"
+    # No synthetic Source after alembic 0030; both imports still resolve to
+    # a single null-source Post (deduped by uq_post_artist_external_id_null_source).
     assert importer.session.execute(
         select(func.count()).select_from(Source)
-    ).scalar_one() == 1
+    ).scalar_one() == 0
     assert importer.session.execute(
         select(func.count()).select_from(Post)
     ).scalar_one() == 1
@@ -164,5 +172,11 @@ def test_sidecar_artist_used_when_no_folder_artist(importer, import_layout):
     a = importer.session.execute(
         select(Artist).where(Artist.slug == "yuki")
     ).scalar_one()
-    src = importer.session.execute(select(Source)).scalar_one()
-    assert src.artist_id == a.id
+    # No synthetic Source after alembic 0030; the artist linkage lives on
+    # Post.artist_id (NOT NULL FK).
+    post = importer.session.execute(select(Post)).scalar_one()
+    assert post.artist_id == a.id
+    assert post.source_id is None
+    assert importer.session.execute(
+        select(func.count()).select_from(Source)
+    ).scalar_one() == 0