1 files changed, 117 insertions, 0 deletions
diff --git a/src/app/state.rs b/src/app/state.rs
index 0321a6ee..ee9c69be 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -869,6 +869,48 @@ pub(crate) struct NavigatorRow {
     pub is_tab: bool,
     pub expanded: bool,
     pub search_text: String,
+    /// Whether this row itself matched the active query/state filter, as
+    /// opposed to being included as ancestor context or cascaded subtree of a
+    /// matching workspace or tab. Always true when no filter is active.
+    pub matched: bool,
+}
+
+/// One rendered line in the navigator body. Spacer lines separate workspace
+/// groups visually and are not selectable.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum NavigatorDisplayLine {
+    Spacer,
+    Row(usize),
+}
+
+pub(crate) fn navigator_display_lines(rows: &[NavigatorRow]) -> Vec<NavigatorDisplayLine> {
+    let mut lines = Vec::with_capacity(rows.len().saturating_mul(2));
+    for (idx, row) in rows.iter().enumerate() {
+        if row.is_workspace && !lines.is_empty() {
+            lines.push(NavigatorDisplayLine::Spacer);
+        }
+        lines.push(NavigatorDisplayLine::Row(idx));
+    }
+    lines
+}
+
+pub(crate) fn navigator_display_index_of_row(
+    lines: &[NavigatorDisplayLine],
+    row_idx: usize,
+) -> Option<usize> {
+    lines
+        .iter()
+        .position(|line| *line == NavigatorDisplayLine::Row(row_idx))
+}
+
+pub(crate) fn navigator_first_row_at_or_after(
+    lines: &[NavigatorDisplayLine],
+    line_idx: usize,
+) -> Option<usize> {
+    lines.get(line_idx..)?.iter().find_map(|line| match line {
+        NavigatorDisplayLine::Row(idx) => Some(*idx),
+        NavigatorDisplayLine::Spacer => None,
+    })
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -2289,6 +2331,81 @@ mod tests {
         state.assert_invariants_for_test();
     }
 
+    fn navigator_row_for_display(is_workspace: bool) -> NavigatorRow {
+        NavigatorRow {
+            target: NavigatorTarget::Workspace { ws_idx: 0 },
+            depth: if is_workspace { 0 } else { 1 },
+            label: String::new(),
+            meta: String::new(),
+            status: crate::detect::AgentState::Idle,
+            seen: true,
+            is_current: false,
+            is_workspace,
+            is_tab: false,
+            expanded: true,
+            search_text: String::new(),
+            matched: true,
+        }
+    }
+
+    #[test]
+    fn navigator_display_lines_separate_workspace_groups() {
+        let rows = vec![
+            navigator_row_for_display(true),
+            navigator_row_for_display(false),
+            navigator_row_for_display(true),
+            navigator_row_for_display(false),
+        ];
+        assert_eq!(
+            navigator_display_lines(&rows),
+            vec![
+                NavigatorDisplayLine::Row(0),
+                NavigatorDisplayLine::Row(1),
+                NavigatorDisplayLine::Spacer,
+                NavigatorDisplayLine::Row(2),
+                NavigatorDisplayLine::Row(3),
+            ]
+        );
+    }
+
+    #[test]
+    fn navigator_display_lines_have_no_leading_spacer() {
+        let rows = vec![
+            navigator_row_for_display(true),
+            navigator_row_for_display(false),
+        ];
+        assert_eq!(
+            navigator_display_lines(&rows),
+            vec![NavigatorDisplayLine::Row(0), NavigatorDisplayLine::Row(1)]
+        );
+        assert!(navigator_display_lines(&[]).is_empty());
+    }
+
+    #[test]
+    fn navigator_display_index_maps_row_to_line() {
+        let rows = vec![
+            navigator_row_for_display(true),
+            navigator_row_for_display(false),
+            navigator_row_for_display(true),
+        ];
+        let lines = navigator_display_lines(&rows);
+        assert_eq!(navigator_display_index_of_row(&lines, 2), Some(3));
+        assert_eq!(navigator_display_index_of_row(&lines, 9), None);
+    }
+
+    #[test]
+    fn navigator_first_row_skips_spacer_lines() {
+        let rows = vec![
+            navigator_row_for_display(true),
+            navigator_row_for_display(false),
+            navigator_row_for_display(true),
+        ];
+        let lines = navigator_display_lines(&rows);
+        // Line 2 is the spacer before the second workspace.
+        assert_eq!(navigator_first_row_at_or_after(&lines, 2), Some(2));
+        assert_eq!(navigator_first_row_at_or_after(&lines, 4), None);
+    }
+
     #[test]
     fn built_in_theme_names_resolve() {
         for name in THEME_NAMES {