test(search): cover title edge cases in session title resolution

entity_api/src/search/session_title_mock_tests.rs

@@ -84,3 +84,67 @@ async fn no_ids_issue_no_query() {
 
     assert!(titles.is_empty());
 }
+
+#[tokio::test]
+async fn a_whitespace_only_session_title_falls_back_to_the_date() {
+    // Trimmed to empty, so compose_display_title is None and the date fallback applies.
+    let s = session(Some(" \t\n "), NaiveDate::from_ymd_opt(2026, 3, 9).unwrap());
+    let id = s.id;
+    let db = db_with(vec![s]);
+
+    let titles = resolve_session_titles(&db, &[id]).await.unwrap();
+
+    assert_eq!(
+        titles.get(&id).map(String::as_str),
+        Some("Coaching session — 2026-03-09")
+    );
+}
+
+#[tokio::test]
+async fn a_title_with_surrounding_spaces_is_returned_trimmed() {
+    let s = session(
+        Some("  Kickoff  "),
+        NaiveDate::from_ymd_opt(2026, 3, 9).unwrap(),
+    );
+    let id = s.id;
+    let db = db_with(vec![s]);
+
+    let titles = resolve_session_titles(&db, &[id]).await.unwrap();
+
+    assert_eq!(titles.get(&id).map(String::as_str), Some("Kickoff"));
+}
+
+#[tokio::test]
+async fn a_mixed_batch_resolves_known_ids_and_omits_the_unknown() {
+    // One call: titled session, untitled session, and an id never inserted.
+    let titled = session(Some("Intro"), NaiveDate::from_ymd_opt(2026, 3, 9).unwrap());
+    let untitled = session(None, NaiveDate::from_ymd_opt(2026, 4, 1).unwrap());
+    let unknown_id = Id::new_v4();
+    let titled_id = titled.id;
+    let untitled_id = untitled.id;
+    let db = db_with(vec![titled, untitled]);
+
+    let titles = resolve_session_titles(&db, &[titled_id, untitled_id, unknown_id])
+        .await
+        .unwrap();
+
+    assert_eq!(
+        titles,
+        HashMap::from([
+            (titled_id, "Intro".to_string()),
+            (untitled_id, "Coaching session — 2026-04-01".to_string()),
+        ])
+    );
+}
+
+#[tokio::test]
+async fn duplicate_ids_in_the_input_resolve_to_one_map_entry() {
+    // Same id twice: must not panic and must collapse to a single entry.
+    let s = session(Some("Intro"), NaiveDate::from_ymd_opt(2026, 3, 9).unwrap());
+    let id = s.id;
+    let db = db_with(vec![s]);
+
+    let titles = resolve_session_titles(&db, &[id, id]).await.unwrap();
+
+    assert_eq!(titles, HashMap::from([(id, "Intro".to_string())]));
+}