Add 2-hour TTL cache check to SpaceDevs launch updater

Prevents hitting the SpaceDevs rate limit by skipping the API call
when the launches cache is still fresh (< 2 hours old), matching the
same TTL pattern already used for the active crewed flights cache.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agenda/thespacedevs.py

@@ -322,6 +322,18 @@ def summarize_launch(launch: Launch) -> Summary:
     }
 
 
+def is_launches_cache_fresh(rocket_dir: str) -> bool:
+    """Return True if the launches cache is younger than the TTL."""
+    now = datetime.now()
+    existing = [
+        x for x in (filename_timestamp(f, "json") for f in os.listdir(rocket_dir)) if x
+    ]
+    if not existing:
+        return False
+    existing.sort(reverse=True)
+    return (now - existing[0][0]).total_seconds() <= ttl
+
+
 def load_cached_launches(rocket_dir: str) -> StrDict | None:
     """Read the most recent cache of launches."""
     filename = get_most_recent_file(rocket_dir, "json")

update.py

@@ -321,6 +321,9 @@ def update_thespacedevs(config: flask.config.Config) -> None:
     existing_data = agenda.thespacedevs.load_cached_launches(rocket_dir)
     assert existing_data
 
+    if agenda.thespacedevs.is_launches_cache_fresh(rocket_dir):
+        return
+
     # Update active crewed mission cache used by the launches page.
     # Uses the 2-hour TTL; failures are handled internally with cache fallback.
     active_crewed = agenda.thespacedevs.get_active_crewed_flights(rocket_dir)