feat: make outer pane borders configurable (#2535)

7 files changed, 96 insertions, 12 deletions

diff --git a/src/app/agent_resume.rs b/src/app/agent_resume.rs
index 1b459628..29c2c317 100644
--- a/src/app/agent_resume.rs
+++ b/src/app/agent_resume.rs
@@ -130,6 +130,7 @@ impl App {
             terminal_area,
             self.state.pane_borders,
             self.state.pane_gaps,
+            self.state.pane_outer_borders,
         );
 
         if self.state.active == Some(ws_idx)
@@ -290,15 +291,21 @@ fn derived_pending_agent_resume_pane_infos(
     terminal_area: Rect,
     pane_borders: bool,
     pane_gaps: bool,
+    pane_outer_borders: bool,
 ) -> Vec<crate::layout::PaneInfo> {
-    crate::ui::apply_pane_chrome(tab.layout.panes(terminal_area), pane_borders, pane_gaps)
-        .into_iter()
-        .map(|mut info| {
-            let pane_inner = crate::ui::pane_inner_rect(info.rect, info.borders);
-            info.inner_rect = stable_terminal_inner_rect(pane_inner);
-            info
-        })
-        .collect()
+    crate::ui::apply_pane_chrome(
+        tab.layout.panes(terminal_area),
+        pane_borders,
+        pane_gaps,
+        pane_outer_borders,
+    )
+    .into_iter()
+    .map(|mut info| {
+        let pane_inner = crate::ui::pane_inner_rect(info.rect, info.borders);
+        info.inner_rect = stable_terminal_inner_rect(pane_inner);
+        info
+    })
+    .collect()
 }
 
 fn stable_terminal_inner_rect(pane_inner: Rect) -> Rect {
diff --git a/src/app/api/panes.rs b/src/app/api/panes.rs
index 4cbdd661..6615fa0a 100644
--- a/src/app/api/panes.rs
+++ b/src/app/api/panes.rs
@@ -1714,6 +1714,7 @@ impl App {
             tab.layout.panes(area),
             self.state.pane_borders,
             self.state.pane_gaps,
+            self.state.pane_outer_borders,
         )
         .into_iter()
         .filter_map(|pane| {
diff --git a/src/app/mod.rs b/src/app/mod.rs
index 7fb8a01c..70d5fe93 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -631,6 +631,7 @@ impl App {
             prompt_new_tab_name: config.ui.prompt_new_tab_name,
             prompt_new_workspace_name: config.ui.prompt_new_workspace_name,
             pane_borders: config.ui.pane_borders,
+            pane_outer_borders: config.ui.pane_outer_borders,
             pane_scrollbars: config.ui.pane_scrollbars,
             pane_gaps: config.ui.pane_gaps,
             show_agent_labels_on_pane_borders: config.ui.show_agent_labels_on_pane_borders,
@@ -1439,6 +1440,7 @@ impl App {
                 self.state.prompt_new_tab_name = config.ui.prompt_new_tab_name;
                 self.state.prompt_new_workspace_name = config.ui.prompt_new_workspace_name;
                 self.state.pane_borders = config.ui.pane_borders;
+                self.state.pane_outer_borders = config.ui.pane_outer_borders;
                 self.state.pane_scrollbars = config.ui.pane_scrollbars;
                 self.state.pane_gaps = config.ui.pane_gaps;
                 self.state.show_agent_labels_on_pane_borders =
diff --git a/src/app/state.rs b/src/app/state.rs
index 97266344..04876290 100644
--- a/src/app/state.rs
+++ b/src/app/state.rs
@@ -1464,6 +1464,7 @@ pub struct AppState {
     pub prompt_new_tab_name: bool,
     pub prompt_new_workspace_name: bool,
     pub pane_borders: bool,
+    pub pane_outer_borders: bool,
     pub pane_scrollbars: bool,
     pub pane_gaps: bool,
     pub show_agent_labels_on_pane_borders: bool,
@@ -1833,6 +1834,7 @@ impl AppState {
             prompt_new_tab_name: true,
             prompt_new_workspace_name: false,
             pane_borders: true,
+            pane_outer_borders: true,
             pane_scrollbars: true,
             pane_gaps: false,
             show_agent_labels_on_pane_borders: false,
diff --git a/src/config/model.rs b/src/config/model.rs
index 5cbafaec..ba700731 100644
--- a/src/config/model.rs
+++ b/src/config/model.rs
@@ -838,6 +838,8 @@ pub struct UiConfig {
     pub prompt_new_workspace_name: bool,
     /// Draw borders around split panes. Default: true.
     pub pane_borders: bool,
+    /// Draw borders along the outside edge of the pane area. Default: true.
+    pub pane_outer_borders: bool,
     /// Draw interactive scrollbars beside terminal panes. Default: true.
     pub pane_scrollbars: bool,
     /// Keep split panes visually separated instead of sharing divider borders. Default: true.
@@ -1052,6 +1054,7 @@ impl Default for UiConfig {
             prompt_new_tab_name: true,
             prompt_new_workspace_name: false,
             pane_borders: true,
+            pane_outer_borders: true,
             pane_scrollbars: true,
             pane_gaps: true,
             show_agent_labels_on_pane_borders: false,
@@ -1304,6 +1307,7 @@ status_indicators = "symbols"
     fn pane_appearance_defaults_and_parse() {
         let default_config = Config::default();
         assert!(default_config.ui.pane_borders);
+        assert!(default_config.ui.pane_outer_borders);
         assert!(default_config.ui.pane_scrollbars);
         assert!(default_config.ui.pane_gaps);
         assert!(!default_config.ui.show_agent_labels_on_pane_borders);
@@ -1316,6 +1320,7 @@ status_indicators = "symbols"
         let toml = r#"
 [ui]
 pane_borders = false
+pane_outer_borders = false
 pane_scrollbars = false
 pane_gaps = true
 show_agent_labels_on_pane_borders = true
@@ -1324,6 +1329,7 @@ tab_bar_position = "bottom"
 "#;
         let config: Config = toml::from_str(toml).unwrap();
         assert!(!config.ui.pane_borders);
+        assert!(!config.ui.pane_outer_borders);
         assert!(!config.ui.pane_scrollbars);
         assert!(config.ui.pane_gaps);
         assert!(config.ui.show_agent_labels_on_pane_borders);
diff --git a/src/main.rs b/src/main.rs
index 7f79730d..c3269675 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -306,6 +306,10 @@ const DEFAULT_CONFIG: &str = r##"# herdr configuration
 # Draw borders around split panes.
 # pane_borders = true
 
+# Draw borders along the outside edge of the pane area.
+# Disable for tmux-style internal splitters without an outside frame.
+# pane_outer_borders = true
+
 # Draw interactive scrollbars beside terminal panes.
 # Set false to reclaim the scrollbar column and keep it out of terminal-native selections.
 # pane_scrollbars = true
diff --git a/src/ui/panes.rs b/src/ui/panes.rs
index b904ce00..22daddf8 100644
--- a/src/ui/panes.rs
+++ b/src/ui/panes.rs
@@ -91,8 +91,21 @@ pub(crate) fn apply_pane_chrome(
     panes: Vec<PaneInfo>,
     pane_borders: bool,
     pane_gaps: bool,
+    pane_outer_borders: bool,
 ) -> Vec<PaneInfo> {
     let multi_pane = panes.len() > 1;
+    let outer_left = panes.iter().map(|info| info.rect.x).min().unwrap_or(0);
+    let outer_top = panes.iter().map(|info| info.rect.y).min().unwrap_or(0);
+    let outer_right = panes
+        .iter()
+        .map(|info| info.rect.x.saturating_add(info.rect.width))
+        .max()
+        .unwrap_or(0);
+    let outer_bottom = panes
+        .iter()
+        .map(|info| info.rect.y.saturating_add(info.rect.height))
+        .max()
+        .unwrap_or(0);
     panes
         .iter()
         .cloned()
@@ -121,6 +134,20 @@ pub(crate) fn apply_pane_chrome(
                         borders.remove(Borders::BOTTOM);
                     }
                 }
+                if !pane_outer_borders {
+                    if info.rect.x == outer_left {
+                        borders.remove(Borders::LEFT);
+                    }
+                    if info.rect.y == outer_top {
+                        borders.remove(Borders::TOP);
+                    }
+                    if info.rect.x.saturating_add(info.rect.width) == outer_right {
+                        borders.remove(Borders::RIGHT);
+                    }
+                    if info.rect.y.saturating_add(info.rect.height) == outer_bottom {
+                        borders.remove(Borders::BOTTOM);
+                    }
+                }
                 borders
             };
             info
@@ -179,7 +206,7 @@ pub(super) fn resize_tab_panes(
     if tab.zoomed {
         let focused_id = tab.layout.focused();
         if let Some((terminal_id, rt)) = runtime_for_tab_pane(terminal_runtimes, tab, focused_id) {
-            let borders = if multi_pane && app.pane_borders {
+            let borders = if multi_pane && app.pane_borders && app.pane_outer_borders {
                 Borders::ALL
             } else {
                 Borders::NONE
@@ -198,7 +225,12 @@ pub(super) fn resize_tab_panes(
         return;
     }
 
-    for info in apply_pane_chrome(tab.layout.panes(area), app.pane_borders, app.pane_gaps) {
+    for info in apply_pane_chrome(
+        tab.layout.panes(area),
+        app.pane_borders,
+        app.pane_gaps,
+        app.pane_outer_borders,
+    ) {
         let pane_inner = pane_inner_rect(info.rect, info.borders);
 
         if let Some((terminal_id, rt)) = runtime_for_tab_pane(terminal_runtimes, tab, info.id) {
@@ -234,7 +266,7 @@ pub(super) fn compute_pane_infos(
 
     if ws.zoomed {
         let focused_id = ws.layout.focused();
-        let borders = if multi_pane && app.pane_borders {
+        let borders = if multi_pane && app.pane_borders && app.pane_outer_borders {
             Borders::ALL
         } else {
             Borders::NONE
@@ -268,7 +300,12 @@ pub(super) fn compute_pane_infos(
         }];
     }
 
-    let mut pane_infos = apply_pane_chrome(ws.layout.panes(area), app.pane_borders, app.pane_gaps);
+    let mut pane_infos = apply_pane_chrome(
+        ws.layout.panes(area),
+        app.pane_borders,
+        app.pane_gaps,
+        app.pane_outer_borders,
+    );
 
     for info in &mut pane_infos {
         let pane_inner = pane_inner_rect(info.rect, info.borders);
@@ -1054,6 +1091,7 @@ mod tests {
             workspace.tabs[0].layout.panes(Rect::new(0, 0, 100, 20)),
             true,
             false,
+            true,
         );
         let left = infos.iter().find(|info| info.id == root).unwrap();
         let right = infos.iter().find(|info| info.id == right).unwrap();
@@ -1074,6 +1112,7 @@ mod tests {
             workspace.tabs[0].layout.panes(Rect::new(0, 0, 100, 20)),
             true,
             false,
+            true,
         );
         let top = infos.iter().find(|info| info.id == root).unwrap();
         let bottom = infos.iter().find(|info| info.id == bottom).unwrap();
@@ -1084,6 +1123,26 @@ mod tests {
     }
 
     #[test]
+    fn disabled_outer_borders_keep_only_shared_pane_dividers() {
+        let mut workspace = Workspace::test_new("test");
+        let root = workspace.tabs[0].root_pane;
+        let right = workspace.test_split(ratatui::layout::Direction::Horizontal);
+        workspace.tabs[0].layout.focus_pane(root);
+
+        let infos = apply_pane_chrome(
+            workspace.tabs[0].layout.panes(Rect::new(0, 0, 100, 20)),
+            true,
+            false,
+            false,
+        );
+        let left = infos.iter().find(|info| info.id == root).unwrap();
+        let right = infos.iter().find(|info| info.id == right).unwrap();
+
+        assert_eq!(left.borders, Borders::NONE);
+        assert_eq!(right.borders, Borders::LEFT);
+    }
+
+    #[test]
     fn pane_gaps_keep_independent_bordered_panes() {
         let mut workspace = Workspace::test_new("test");
         let root = workspace.tabs[0].root_pane;
@@ -1094,6 +1153,7 @@ mod tests {
             workspace.tabs[0].layout.panes(Rect::new(0, 0, 100, 20)),
             true,
             true,
+            true,
         );
         let left = infos.iter().find(|info| info.id == root).unwrap();
         let right = infos.iter().find(|info| info.id == right).unwrap();
@@ -1114,6 +1174,7 @@ mod tests {
             workspace.tabs[0].layout.panes(Rect::new(0, 0, 100, 20)),
             false,
             true,
+            true,
         );
         let left = infos.iter().find(|info| info.id == root).unwrap();
         let right = infos.iter().find(|info| info.id == right).unwrap();
@@ -1133,6 +1194,7 @@ mod tests {
             workspace.tabs[0].layout.panes(Rect::new(0, 0, 100, 20)),
             false,
             false,
+            true,
         );
 
         for info in infos {