fix(library): an out-of-range last use reads as unknown, not a failed list

database/library.py

@@ -51,7 +51,12 @@ def utc_iso(value: object) -> str | None:
     """A stored timestamp as UTC ISO text, or None when absent or unreadable.
 
     Usage writes are already UTC ISO; a naive value (SQLite's CURRENT_TIMESTAMP
-    form) is read as UTC, and an offset is converted to UTC.
+    form) is read as UTC, and an offset is converted to UTC. One bad row must
+    not fail a whole Library read, so a value past the datetime range after
+    conversion (OverflowError) is unreadable too. Python 3.11+ fromisoformat
+    accepts more ISO forms than 3.10 (e.g. a 2-digit fraction); every form the
+    app writes (utc_now_iso, the 3.2.4 backfill, CURRENT_TIMESTAMP, Z) parses
+    the same on both, so only hand-edited values can differ by version.
     """
     if not isinstance(value, str):
         return None
@@ -60,11 +65,11 @@ def utc_iso(value: object) -> str | None:
         text = text[:-1] + "+00:00"
     try:
         stamp = datetime.datetime.fromisoformat(text)
-    except ValueError:
+        if stamp.tzinfo is None:
+            stamp = stamp.replace(tzinfo=datetime.timezone.utc)
+        return stamp.astimezone(datetime.timezone.utc).isoformat()
+    except (ValueError, OverflowError):
         return None
-    if stamp.tzinfo is None:
-        return stamp.replace(tzinfo=datetime.timezone.utc).isoformat()
-    return stamp.astimezone(datetime.timezone.utc).isoformat()
 
 
 _NAME = (

tests/test_api_library.py

@@ -468,6 +468,38 @@ class TestLibraryAPI(ImageAPITestCase):
         )
         return response, await response.json()
 
+    async def test_unconvertible_last_use_does_not_fail_list_detail_or_receipt(self):
+        positive = self._save_prompt("Cat")
+        other = self._save_prompt("Dog")
+        with self.api.db.model.get_connection() as connection:
+            connection.execute(
+                "UPDATE prompts SET last_used_at=? WHERE id=?",
+                ("9999-12-31T23:59:59-01:00", positive),
+            )
+            connection.execute(
+                "UPDATE prompts SET last_used_at=? WHERE id=?",
+                ("0001-01-01T00:00:00+01:00", other),
+            )
+        response, listed = await self.get()
+        self.assertEqual(response.status, 200, listed)
+        self.assertEqual(
+            [item["last_used_at"] for item in listed["items"]], [None, None]
+        )
+        response, detail = await self.get(f"/{positive}")
+        self.assertEqual(response.status, 200, detail)
+        self.assertIsNone(detail["positive"]["last_used_at"])
+        response, receipt = await self.patch_parent(
+            positive,
+            {
+                "expected_epoch": detail["library_epoch"],
+                "if_match": detail["positive"]["edit_token"],
+                "metadata": {"title": "Portrait"},
+            },
+        )
+        self.assertEqual(response.status, 200, receipt)
+        self.assertEqual(receipt["positive"]["title"], "Portrait")
+        self.assertIsNone(receipt["positive"]["last_used_at"])
+
     async def test_native_parent_patch_strict_validation(self):
         from database.execution_history_schema import rotate_history_epoch
 

tests/test_library.py

@@ -498,10 +498,15 @@ class TestLibrary(unittest.TestCase):
         offset = self.save("Offset")
         broken = self.save("Broken")
         zulu = self.save("Zulu")
+        # Parse but cannot convert to UTC: past the datetime range either way.
+        floor = self.save("Floor")
+        ceiling = self.save("Ceiling")
         with self.db.model.get_connection() as connection:
             for prompt_id, value in (
                 (legacy, "2026-10-07 18:39:06"),
                 (zulu, "2026-10-07T18:39:06Z"),
+                (floor, "0001-01-01T00:00:00+01:00"),
+                (ceiling, "9999-12-31T23:59:59-01:00"),
                 (offset, "2026-10-07T20:39:06.250+02:00"),
                 (broken, "yesterday"),
             ):
@@ -525,6 +530,11 @@ class TestLibrary(unittest.TestCase):
         )
         self.assertIsNone(items[broken]["last_used_at"])
         self.assertEqual(items[zulu]["last_used_at"], "2026-10-07T18:39:06+00:00")
+        self.assertIsNone(items[floor]["last_used_at"])
+        self.assertIsNone(items[ceiling]["last_used_at"])
+        self.assertIsNone(
+            self.db.get_library_positive(floor)["positive"]["last_used_at"]
+        )
         self.assertEqual(type(items[broken]["run_count"]), int)
         detail = self.db.get_library_positive(used)["positive"]
         self.assertEqual(detail["run_count"], 3)