diff --git a/tests/test_patreon_ingester.py b/tests/test_patreon_ingester.py
index 2363a6a..774722b 100644
--- a/tests/test_patreon_ingester.py
+++ b/tests/test_patreon_ingester.py
@@ -1156,14 +1156,16 @@ def _iso(days_ago):
     return (datetime.now(UTC) - timedelta(days=days_ago)).isoformat()
 
 
-def _seed_seen(sync_engine, source_id, media):
-    factory = sessionmaker(sync_engine, expire_on_commit=False)
-    with factory() as s:
-        for m in media:
-            s.add(PatreonSeenMedia(
-                source_id=source_id, filehash=_ledger_key(m), post_id=m.post_id,
-            ))
-        s.commit()
+def _seed_all_seen(sync_engine, source_id, media):
+    """Several media through the module's existing one-key `_seed_seen`.
+
+    A distinct NAME, not a second definition: the first version of this shadowed
+    `_seed_seen` from the bottom of the file, and the two #830 recapture tests
+    that pass it a `post_id=` kwarg broke on a TypeError. A helper defined below
+    the tests that use it is invisible at the point of use.
+    """
+    for m in media:
+        _seed_seen(sync_engine, source_id, _ledger_key(m), post_id=m.post_id)
 
 
 @pytest.mark.asyncio
@@ -1174,7 +1176,7 @@ async def test_a_run_of_seen_items_does_not_stop_a_tick_inside_the_window(
     around at the second and never looked at the third, which is exactly where
     an edited post lives."""
     seen = [_media(f"p{i}", 1) for i in range(1, 4)]
-    _seed_seen(sync_engine, source_id, seen)
+    _seed_all_seen(sync_engine, source_id, seen)
 
     client = _FakeClient(
         [(None, [(m.post_id, [m]) for m in seen])],
@@ -1201,7 +1203,7 @@ async def test_the_early_out_still_fires_once_the_walk_is_below_the_horizon(
     did. Asserted beside the test above because the window is only correct if
     BOTH conditions are required; either one alone is a different feature."""
     seen = [_media(f"p{i}", 1) for i in range(1, 4)]
-    _seed_seen(sync_engine, source_id, seen)
+    _seed_all_seen(sync_engine, source_id, seen)
 
     client = _FakeClient(
         [(None, [(m.post_id, [m]) for m in seen])],
@@ -1226,7 +1228,7 @@ async def test_a_window_of_zero_is_the_behaviour_that_shipped_before_it(
     """The off switch. Recent posts, a window of 0 → the walk stops on the
     count alone, so an operator who wants the old cheap tick has one."""
     seen = [_media(f"p{i}", 1) for i in range(1, 4)]
-    _seed_seen(sync_engine, source_id, seen)
+    _seed_all_seen(sync_engine, source_id, seen)
 
     client = _FakeClient(
         [(None, [(m.post_id, [m]) for m in seen])],
@@ -1252,7 +1254,7 @@ async def test_a_backfill_ignores_the_window_because_it_never_early_outs(
     every body — a horizon there would be a third answer to a two-answer
     question."""
     seen = [_media(f"p{i}", 1) for i in range(1, 4)]
-    _seed_seen(sync_engine, source_id, seen)
+    _seed_all_seen(sync_engine, source_id, seen)
 
     client = _FakeClient(
         [(None, [(m.post_id, [m]) for m in seen])],
@@ -1407,7 +1409,7 @@ async def test_a_post_whose_date_will_not_parse_falls_back_to_the_count(
     into the window. It reads as "not provably recent", which leaves that post
     on the behaviour it had before the window existed."""
     seen = [_media(f"p{i}", 1) for i in range(1, 4)]
-    _seed_seen(sync_engine, source_id, seen)
+    _seed_all_seen(sync_engine, source_id, seen)
 
     client = _FakeClient(
         [(None, [(m.post_id, [m]) for m in seen])],