Draw the date histogram over the collection you are looking at

The timeline counted the whole library whatever the grid was showing, so
opening a collection left a fortnight in Arosa as one column of a
fifteen-year axis — an axis describing photographs that were not on
screen.

Scope the buckets and the span to the same collection and rating filter
the grid uses. `timeline_range` counts `images` alone and cannot express
the membership join, so the scoped query lives beside the other scoped
readers in the UI and shares their descendants-of-scope rule.

`catalog_span` now delegates to the same scoped reader. Zoom and scrub
measured the full library while the bars were scoped, so a scrub could
land on an instant the collection did not contain and send the view
somewhere the user had not asked to go.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ui/dr-ui/src/library_ui.rs

@@ -2720,7 +2720,12 @@ fn start_sweep(window: &AppWindow, ctl: &Rc<LibraryController>) {
 /// from the data rather than fixing it means the histogram is informative at
 /// both scales instead of one flat bar or ten thousand slivers.
 fn refresh_timeline(window: &AppWindow, catalog: &Catalog, ctl: &Rc<LibraryController>) {
-    let span = match catalog_span(catalog) {
+    // Scoped to whatever the grid is showing. A collection's histogram drawn
+    // over the whole library's span said almost nothing: every bar for a
+    // fortnight in Arosa landed in one column of a fifteen-year axis.
+    let scope = *ctl.scope.borrow();
+    let filter = *ctl.filter.borrow();
+    let span = match library::span_scoped(catalog, scope, &filter) {
         Some(s) => s,
         None => {
             // No dated images yet. An empty histogram is honest — EXIF is read
@@ -2737,13 +2742,7 @@ fn refresh_timeline(window: &AppWindow, catalog: &Catalog, ctl: &Rc<LibraryContr
     let (from, to) = zoomed_span(span, zoom, *ctl.timeline_centre.borrow());
 
     let granularity = dr_catalog::Granularity::for_span(to - from);
-    let buckets = match catalog.timeline_range(
-        &dr_catalog::Query::default(),
-        granularity,
-        from,
-        to,
-        now_secs(),
-    ) {
+    let buckets = match library::timeline_scoped(catalog, scope, &filter, granularity, from, to) {
         Ok(b) => b,
         Err(e) => {
             log::debug!("timeline: {e}");
@@ -2875,17 +2874,14 @@ fn zoomed_span(full: (i64, i64), zoom: i32, centre: Option<i64>) -> (i64, i64) {
 }
 
 /// Earliest and latest capture time in the catalog.
-fn catalog_span(catalog: &Catalog) -> Option<(i64, i64)> {
-    catalog
-        .connection()
-        .query_row(
-            "SELECT min(captured_at), max(captured_at)
-               FROM images WHERE captured_at IS NOT NULL",
-            [],
-            |r| Ok((r.get::<_, Option<i64>>(0)?, r.get::<_, Option<i64>>(1)?)),
-        )
-        .ok()
-        .and_then(|(lo, hi)| Some((lo?, hi?)))
+/// The timeline's extent, over exactly the images the grid is showing.
+///
+/// Scrubbing and zooming must measure the same span the histogram is drawn
+/// over. When this read the whole library while the bars were scoped to a
+/// collection, a scrub landed at an instant the collection did not contain and
+/// the view jumped somewhere the user had not asked for.
+fn catalog_span(catalog: &Catalog, ctl: &Rc<LibraryController>) -> Option<(i64, i64)> {
+    library::span_scoped(catalog, *ctl.scope.borrow(), &ctl.filter.borrow())
 }
 
 /// Capture time of the image at row `ordinal` in the grid's own ordering.
@@ -3003,13 +2999,6 @@ fn civil_from_unix(t: i64) -> (i64, i64, i64, i64) {
     (if m <= 2 { y + 1 } else { y }, m, d, secs / 3600)
 }
 
-fn now_secs() -> i64 {
-    std::time::SystemTime::now()
-        .duration_since(std::time::UNIX_EPOCH)
-        .map(|d| d.as_secs() as i64)
-        .unwrap_or(0)
-}
-
 /// Copy decoded RGBA into a Slint image.
 ///
 /// This is a CPU copy, which is acceptable here and not in the develop path:
@@ -3318,7 +3307,7 @@ pub fn wire<F>(
 
                         let zoom = *ctl.timeline_zoom.borrow();
                         let centre = *ctl.timeline_centre.borrow();
-                        if let Some(full) = catalog_span(catalog) {
+                        if let Some(full) = catalog_span(catalog, &ctl) {
                             let (from, to) = zoomed_span(full, zoom, centre);
                             w.set_library_current_bucket(when as i32);
                             w.set_library_current_fraction(
@@ -3362,7 +3351,7 @@ pub fn wire<F>(
             let Some(catalog) = borrow.as_ref() else {
                 return;
             };
-            let Some(full) = catalog_span(catalog) else {
+            let Some(full) = catalog_span(catalog, &ctl) else {
                 return;
             };
 
@@ -3410,7 +3399,7 @@ pub fn wire<F>(
             let Some(catalog) = borrow.as_ref() else {
                 return;
             };
-            let Some(full) = catalog_span(catalog) else {
+            let Some(full) = catalog_span(catalog, &ctl) else {
                 return;
             };