fix: restore connected session navigator tree glyphs (#3861)

refs #3843

Co-authored-by: akbash-bot <300245827+akbash-bot@users.noreply.github.com>

3 files changed, 199 insertions, 30 deletions

diff --git a/src/client/shell/overlays.rs b/src/client/shell/overlays.rs
index faf252a8..4418c2c3 100644
--- a/src/client/shell/overlays.rs
+++ b/src/client/shell/overlays.rs
@@ -673,6 +673,24 @@ fn render_rename_overlay(
     })
 }
 
+/// Mark following siblings in preorder without rescanning descendants for each row.
+/// The reverse stack contains at most one entry per depth; every entry is pushed
+/// and popped at most once, so this pass is linear in the number of rows.
+fn navigator_following_siblings(rows: &[ClientNavigatorRow]) -> Vec<bool> {
+    let mut following = vec![false; rows.len()];
+    let mut depths = Vec::new();
+    for (index, row) in rows.iter().enumerate().rev() {
+        while depths.last().is_some_and(|depth| *depth > row.depth) {
+            depths.pop();
+        }
+        following[index] = depths.last() == Some(&row.depth);
+        if !following[index] {
+            depths.push(row.depth);
+        }
+    }
+    following
+}
+
 fn render_navigator_overlay(
     b: &mut Buffer,
     n: &ClientNavigatorOverlay,
@@ -746,15 +764,17 @@ fn render_navigator_overlay(
         .max(selected.saturating_sub(body.height.saturating_sub(1) as usize))
         .min(selected)
         .min(max);
+    let following_siblings = navigator_following_siblings(&rows);
+    let mut ancestor_siblings = Vec::new();
+    let federated = endpoints.len() > 1;
     let mut row_hits = Vec::new();
-    for (vis, (ix, r)) in rows
-        .iter()
-        .enumerate()
-        .skip(scroll)
-        .take(body.height as usize)
-        .enumerate()
-    {
-        let rect = Rect::new(body.x, body.y + vis as u16, body.width, 1);
+    for (ix, r) in rows.iter().enumerate().take(scroll + body.height as usize) {
+        ancestor_siblings.truncate(usize::from(r.depth));
+        ancestor_siblings.push(following_siblings[ix]);
+        if ix < scroll {
+            continue;
+        }
+        let rect = Rect::new(body.x, body.y + (ix - scroll) as u16, body.width, 1);
         row_hits.push((rect, r.target.clone()));
         let st = if r.stale {
             Style::default()
@@ -777,7 +797,7 @@ fn render_navigator_overlay(
         };
         b.set_style(rect, st);
         let tree = match &r.target {
-            ClientNavigatorTarget::Machine { .. } => "▾",
+            ClientNavigatorTarget::Machine { .. } => "▾".to_owned(),
             ClientNavigatorTarget::Workspace {
                 endpoint_id,
                 workspace_id,
@@ -785,32 +805,28 @@ fn render_navigator_overlay(
                 .expanded_workspaces
                 .contains(&(endpoint_id.clone(), workspace_id.clone())) =>
             {
-                if r.depth == 0 {
-                    "▾"
-                } else {
-                    "  ▾"
-                }
+                if r.depth == 0 { "▾" } else { "  ▾" }.to_owned()
             }
             ClientNavigatorTarget::Workspace { .. } => {
-                if r.depth == 0 {
-                    "▸"
-                } else {
-                    "  ▸"
-                }
+                if r.depth == 0 { "▸" } else { "  ▸" }.to_owned()
             }
-            ClientNavigatorTarget::Tab { .. } => {
-                if r.depth == 1 {
-                    "└──"
-                } else {
-                    "    └──"
+            ClientNavigatorTarget::Tab { .. } | ClientNavigatorTarget::Pane { .. } => {
+                // Machines and workspaces keep their existing caret decoration.
+                // Connected branches begin below each workspace.
+                let mut prefix = if federated { "    " } else { "" }.to_owned();
+                for &following in ancestor_siblings
+                    .iter()
+                    .take(usize::from(r.depth))
+                    .skip(if federated { 2 } else { 1 })
+                {
+                    prefix.push_str(if following { "│  " } else { "   " });
                 }
-            }
-            ClientNavigatorTarget::Pane { .. } => {
-                if r.depth == 2 {
-                    "   └──"
+                prefix.push_str(if following_siblings[ix] {
+                    "├──"
                 } else {
-                    "        └──"
-                }
+                    "└──"
+                });
+                prefix
             }
         };
         let current = if r.current { "◆ " } else { "" };
diff --git a/src/client/shell/tests/copy.rs b/src/client/shell/tests/copy.rs
index 95413f8a..fa0635af 100644
--- a/src/client/shell/tests/copy.rs
+++ b/src/client/shell/tests/copy.rs
@@ -732,6 +732,143 @@ fn copy_search_owns_prompt_repeat_highlights_selection_and_restore() {
 }
 
 #[test]
+fn navigator_renders_connected_siblings_and_ancestor_lines() {
+    let mut snapshot = snapshot();
+    snapshot.focused_pane_id = None;
+    snapshot.tabs[0].label = "editor".into();
+    snapshot.panes[0].label = Some("agent".into());
+    snapshot.panes[0].focused = false;
+    let mut shell = snapshot.panes[0].clone();
+    shell.pane_id = "pane_shell".into();
+    shell.label = Some("shell".into());
+    snapshot.panes.push(shell);
+    for label in ["notes", "logs"] {
+        let mut tab = snapshot.tabs[0].clone();
+        tab.tab_id = format!("tab_{label}");
+        tab.label = label.into();
+        tab.focused = false;
+        tab.number = snapshot.tabs.len() + 1;
+        let mut pane = snapshot.panes[0].clone();
+        pane.pane_id = format!("pane_{label}");
+        pane.tab_id = tab.tab_id.clone();
+        pane.label = Some(label.into());
+        pane.focused = false;
+        snapshot.tabs.push(tab);
+        snapshot.panes.push(pane);
+    }
+    let mut workspace = snapshot.workspaces[0].clone();
+    workspace.workspace_id = "ws_2".into();
+    workspace.active_tab_id = "tab_last".into();
+    workspace.label = "second".into();
+    workspace.number = 2;
+    workspace.focused = false;
+    let mut tab = snapshot.tabs[0].clone();
+    tab.workspace_id = workspace.workspace_id.clone();
+    tab.tab_id = workspace.active_tab_id.clone();
+    tab.label = "last".into();
+    tab.focused = false;
+    let mut pane = snapshot.panes[0].clone();
+    pane.workspace_id = workspace.workspace_id.clone();
+    pane.tab_id = tab.tab_id.clone();
+    pane.pane_id = "pane_last".into();
+    snapshot.workspaces.push(workspace);
+    snapshot.tabs.push(tab);
+    snapshot.panes.push(pane);
+    let mut state = ClientShellState::new(ClientShellConfig::from_config(&Config::default()));
+    state.set_snapshot(Box::new(snapshot));
+    state.set_pane_surface(surface());
+    state.open_navigator_overlay();
+    let prefixes = |state: &mut ClientShellState, height| {
+        let frame = state.compose(106, height).expect("navigator frame");
+        state
+            .hits
+            .navigator_rows
+            .iter()
+            .map(|(rect, _)| {
+                frame.cells[rect.y as usize * frame.width as usize + rect.x as usize + 1..]
+                    .iter()
+                    .take(6)
+                    .map(|cell| cell.symbol.as_str())
+                    .collect::<String>()
+            })
+            .collect::<Vec<_>>()
+    };
+    assert_eq!(
+        prefixes(&mut state, 30),
+        [
+            "▾ clie",
+            "├── ed",
+            "│  ├──",
+            "│  └──",
+            "├── no",
+            "│  └──",
+            "└── lo",
+            "   └──",
+            "▾ seco",
+            "└── la",
+            "   └──"
+        ]
+    );
+
+    // The editor ancestor is above this viewport; the logs sibling is below it.
+    let Some(ClientShellOverlay::Navigator(navigator)) = state.overlay.as_mut() else {
+        panic!("expected navigator");
+    };
+    navigator.scroll = 2;
+    navigator.selected = Some(ClientNavigatorTarget::Pane {
+        endpoint_id: state.active_endpoint_id.clone(),
+        pane_id: "pane_shell".into(),
+    });
+    assert_eq!(
+        prefixes(&mut state, 12),
+        ["│  ├──", "│  └──", "├── no", "│  └──"]
+    );
+
+    // Excluded siblings must not leave dangling continuation lines.
+    let Some(ClientShellOverlay::Navigator(navigator)) = state.overlay.as_mut() else {
+        panic!("expected navigator");
+    };
+    navigator.query = "shell".into();
+    navigator.scroll = 0;
+    assert_eq!(prefixes(&mut state, 30), ["▾ clie", "└── ed", "   └──"]);
+    let Some(ClientShellOverlay::Navigator(navigator)) = state.overlay.as_mut() else {
+        panic!("expected navigator");
+    };
+    navigator.query.clear();
+    navigator.expanded_workspaces.clear();
+    assert_eq!(prefixes(&mut state, 30), ["▸ clie", "▸ seco"]);
+}
+
+#[test]
+#[ignore = "manual navigator composition scaling profile"]
+fn navigator_render_scale_profile() {
+    for panes in [1, 15, 52] {
+        let mut snapshot = snapshot();
+        for index in 1..panes {
+            let mut pane = snapshot.panes[0].clone();
+            pane.pane_id = format!("pane_{index}_extra");
+            pane.focused = false;
+            snapshot.panes.push(pane);
+        }
+        let mut state = ClientShellState::new(ClientShellConfig::from_config(&Config::default()));
+        state.set_snapshot(Box::new(snapshot));
+        state.set_pane_surface(surface());
+        state.open_navigator_overlay();
+        for _ in 0..20 {
+            std::hint::black_box(state.compose(106, 30).expect("navigator frame"));
+        }
+        let start = std::time::Instant::now();
+        for _ in 0..1000 {
+            std::hint::black_box(state.compose(106, 30).expect("navigator frame"));
+        }
+        eprintln!(
+            "navigator: {panes} panes, {:.1} us/frame",
+            start.elapsed().as_secs_f64() * 1000.0
+        );
+    }
+}
+
+#[test]
 fn navigator_owns_search_mouse_selection_and_stable_target_focus() {
     let mut state = ClientShellState::new(ClientShellConfig::from_config(&Config::default()));
     state.set_snapshot(Box::new(snapshot()));
diff --git a/src/client/shell/tests/endpoints.rs b/src/client/shell/tests/endpoints.rs
index e425b794..0b69135e 100644
--- a/src/client/shell/tests/endpoints.rs
+++ b/src/client/shell/tests/endpoints.rs
@@ -1008,6 +1008,22 @@ fn navigator_uses_machine_parents_only_for_federated_clients() {
     }));
     assert_eq!(rows.iter().filter(|row| row.current).count(), 1);
 
+    let frame = state.compose(106, 30).expect("federated navigator");
+    for (rect, target) in &state.hits.navigator_rows {
+        let expected = match target {
+            ClientNavigatorTarget::Machine { .. } => " ▾ ",
+            ClientNavigatorTarget::Workspace { .. } => "   ▾ ",
+            ClientNavigatorTarget::Tab { .. } => "     └── ",
+            ClientNavigatorTarget::Pane { .. } => "        └── ",
+        };
+        let prefix = frame.cells[rect.y as usize * frame.width as usize + rect.x as usize..]
+            .iter()
+            .take(expected.chars().count())
+            .map(|cell| cell.symbol.as_str())
+            .collect::<String>();
+        assert_eq!(prefix, expected, "{target:?}");
+    }
+
     let mut local = ClientShellState::new(ClientShellConfig::from_config(&Config::default()));
     local.set_snapshot(Box::new(snapshot()));
     local.set_pane_surface(surface());