LRC-LIB-SMARTCOLL: report saved smart albums whose rules no longer check

Rules are checked when they are made, but a saved smart album can go
bad later. The usual case is a rule testing an album that is then
deleted; it silently matches nothing.

Catalog::smart_album_problems(id) checks a saved album's rules as they
are now (RuleSet::upgrade, then RuleSet::check). It is empty for a sound
smart album, a plain album or no album. albums.list reports `problems`
for every smart album, e.g. ["rule 1: no album 8"].

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/catalog/src/lib.rs

@@ -330,6 +330,15 @@ impl Catalog {
         }
     }
 
+    /// What is wrong with a saved smart album's rules now (`RuleSet::check`, after
+    /// `RuleSet::upgrade`): typically a rule testing an album that has since been deleted. Empty
+    /// for a sound smart album, a plain album or no album.
+    pub fn smart_album_problems(&self, id: AlbumId) -> Vec<rules::Problem> {
+        let Some(mut rules) = self.albums.get(&id).and_then(|a| a.smart.as_ref()).and_then(|f| f.rule_set.clone()) else { return Vec::new() };
+        rules.upgrade();
+        rules.check(self)
+    }
+
     /// The photos of an album: the stored list, or a smart album's current matches (id order).
     pub fn album_photos(&self, id: AlbumId) -> Vec<PhotoId> {
         match self.albums.get(&id) {

crates/catalog/src/tests.rs

@@ -456,3 +456,23 @@ fn random_sort_has_no_date_headers() {
     let ids = many(&mut c, 5);
     assert!(c.date_runs(&ids, SortKey::Random, GroupBy::Day).is_empty());
 }
+
+/// A saved smart album whose rules no longer check (the album a rule tests was deleted) is found,
+/// with its problems; a good one has none; an old album operator is read as it was meant.
+#[test]
+fn smart_album_problems_flag_stale_rules() {
+    let mut c = Catalog::new();
+    c.apply(Op::AddAlbum { album: Album::new(AlbumId(1), "Trip") }).unwrap();
+    let smart = |id: u64, rules: serde_json::Value| {
+        let f: Filter = serde_json::from_value(serde_json::json!({"ruleSet": {"rules": rules}})).unwrap();
+        Album { smart: Some(Box::new(f)), ..Album::new(AlbumId(id), "Smart") }
+    };
+    c.apply(Op::AddAlbum { album: smart(2, serde_json::json!([{"field": "album", "op": "is", "value": 1}])) }).unwrap();
+    c.apply(Op::AddAlbum { album: smart(3, serde_json::json!([{"field": "album", "op": "gte", "value": 1}])) }).unwrap();
+    assert!(c.smart_album_problems(AlbumId(2)).is_empty());
+    assert!(c.smart_album_problems(AlbumId(3)).is_empty(), "an old operator is upgraded, not a problem");
+    assert!(c.smart_album_problems(AlbumId(1)).is_empty(), "a plain album has no rules");
+    c.apply(Op::RemoveAlbum { id: AlbumId(1) }).unwrap();
+    let p = c.smart_album_problems(AlbumId(2));
+    assert_eq!(p.iter().map(ToString::to_string).collect::<Vec<_>>(), vec!["rule 1: no album 1".to_string()]);
+}