Fix WASM panic: move use_sessions() out of use_signal initializer; add session tests

Co-authored-by: gfauredev <19304085+gfauredev@users.noreply.github.com>

Author: Copilot

src/components/active_session.rs

@@ -6,8 +6,13 @@ use crate::Route;
 
 #[component]
 pub fn ActiveSessionPage() -> Element {
-    let mut session = use_signal(|| {
-        storage::get_active_session().unwrap_or_else(WorkoutSession::new)
+    // use_sessions() must be called at the top level of the component, not inside
+    // use_signal's initializer. Calling use_context (via use_sessions) inside another
+    // use_hook's initializer causes a double-borrow of the hooks RefCell → panic.
+    let sessions = storage::use_sessions();
+    let mut session = use_signal(move || {
+        sessions.read().iter().find(|s| s.is_active()).cloned()
+            .unwrap_or_else(WorkoutSession::new)
     });
 
     let mut search_query = use_signal(|| String::new());

src/models/mod.rs

@@ -368,6 +368,50 @@ mod tests {
         assert_eq!(session.version, DATA_VERSION);
     }
 
+    #[test]
+    fn find_active_session_returns_first_without_end_time() {
+        let sessions = vec![
+            WorkoutSession {
+                id: "s1".into(),
+                start_time: 1000,
+                end_time: Some(2000),
+                exercise_logs: vec![],
+                version: DATA_VERSION,
+            },
+            WorkoutSession {
+                id: "s2".into(),
+                start_time: 3000,
+                end_time: None,
+                exercise_logs: vec![],
+                version: DATA_VERSION,
+            },
+        ];
+        let active = sessions.iter().find(|s| s.is_active()).cloned();
+        assert_eq!(active.unwrap().id, "s2");
+    }
+
+    #[test]
+    fn find_active_session_returns_none_when_all_finished() {
+        let sessions = vec![
+            WorkoutSession {
+                id: "s1".into(),
+                start_time: 1000,
+                end_time: Some(2000),
+                exercise_logs: vec![],
+                version: DATA_VERSION,
+            },
+        ];
+        let active = sessions.iter().find(|s| s.is_active()).cloned();
+        assert!(active.is_none());
+    }
+
+    #[test]
+    fn find_active_session_returns_none_for_empty_list() {
+        let sessions: Vec<WorkoutSession> = vec![];
+        let active = sessions.iter().find(|s| s.is_active()).cloned();
+        assert!(active.is_none());
+    }
+
     // ── Exercise ──────────────────────────────────────────────────────────────
 
     #[test]