feat(window): add configurable padding_x/padding_y

CHANGELOG.md

@@ -6,6 +6,7 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ## [Unreleased]
 
 ### Added
+- add `window.padding_x` and `window.padding_y` to control the inner padding between a pane's border and its grid
 - add `--maximized` and `--fullscreen` flags to start the window in that mode
 - persist and restore window size, maximized, and fullscreen state per session
 - REP (`CSI Ps b`): repeat the last printed character `Ps` times

README.md

@@ -159,6 +159,8 @@ width           = 800
 height          = 600
 title           = "mmterm"
 cursor_blink_ms = 500
+padding_x       = 4       # inner padding (px) between a pane's left/right border and its grid
+padding_y       = 4       # inner padding (px) between a pane's top/bottom border and its grid
 
 [shell]
 # program = "/bin/zsh"   # defaults to $SHELL

assets/config.toml

@@ -11,6 +11,8 @@ title           = "mmterm"
 cursor_blink_ms = 500
 inactive_dim    = 0.55
 detect_urls     = true
+padding_x       = 4
+padding_y       = 4
 
 [shell]
 # program = "/bin/zsh"

doc/SPEC.md

@@ -103,7 +103,9 @@ vim-style modal input, split panes, and multi-tab sessions.
 - Baseline alignment per glyph using fontdue `ymin` metric.
 - SGR overline (`\e[53m` / `\e[55m`): rendered as a 1 px line at the top of
   the cell; cleared with `\e[55m`.
-- 4 px inner padding on all pane edges so text never touches the border.
+- Inner padding on all pane edges so text never touches the border; the
+  horizontal and vertical amounts are configurable via `window.padding_x` and
+  `window.padding_y` (both default `4` px, DPI-scaled).
 
 ### Input
 - Four modal modes: **Insert** (default), **Normal**, **Visual**, **Search**.
@@ -221,6 +223,8 @@ Screenshot capture is a two-step flow: region selection followed by a name promp
 | window | cursor_blink_ms | uint | `500` |
 | window | inactive_dim | float | `0.55` |
 | window | detect_urls | bool | `true` |
+| window | padding_x | uint | `4` |
+| window | padding_y | uint | `4` |
 | terminal | scrollback_lines | uint | `10000` (min 100) |
 | shell | program | string? | `$SHELL` |
 | logging | auto_log | bool | `false` |

src/app_event.rs

@@ -600,8 +600,9 @@ impl App {
         self.state.tabs[ai].layout.move_separator(handle, new_pos);
         let tab_h = self.tab_h();
         let status_h = self.status_h();
-        let pane_padding = self.pane_padding();
-        Self::sync_pane_sizes_tab(&mut self.state.tabs[ai], tab_h, status_h, pane_padding);
+        let pad_x = self.pane_padding_x();
+        let pad_y = self.pane_padding_y();
+        Self::sync_pane_sizes_tab(&mut self.state.tabs[ai], tab_h, status_h, pad_x, pad_y);
         let icon = match handle.dir {
             SplitDir::H => CursorIcon::ColResize,
             SplitDir::V => CursorIcon::RowResize,

src/config/mod.rs

@@ -147,6 +147,9 @@ fn default_inactive_dim() -> f32 {
 fn default_detect_urls() -> bool {
     true
 }
+fn default_padding() -> u32 {
+    4
+}
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct WindowConfig {
@@ -158,6 +161,10 @@ pub struct WindowConfig {
     pub inactive_dim: f32,
     #[serde(default = "default_detect_urls")]
     pub detect_urls: bool,
+    #[serde(default = "default_padding")]
+    pub padding_x: u32,
+    #[serde(default = "default_padding")]
+    pub padding_y: u32,
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]

src/config/tui_config.rs

@@ -18,21 +18,23 @@ const F_WIN_TITLE: usize = 7;
 const F_BLINK_MS: usize = 8;
 const F_DIM: usize = 9;
 const F_DETECT_URLS: usize = 10;
-const F_SHELL: usize = 11;
-const F_SCROLLBACK: usize = 12;
-const F_LOG_AUTO: usize = 13;
-const F_LOG_DIR: usize = 14;
-const F_THEME_NAME: usize = 15;
-const F_COLOR_BG: usize = 16;
-const F_COLOR_FG: usize = 17;
-const F_COLOR_CUR: usize = 18;
-const F_COLOR_SEL: usize = 19;
-const F_PALETTE: usize = 20; // F_PALETTE + 0..15
-const F_STATUS_BAR_RIGHT: usize = 36;
-const F_AUTO_UPDATE_CHECK: usize = 37;
-const F_AUTO_UPDATE_INSTALL: usize = 38;
-const F_SHELL_INTEGRATION: usize = 39;
-const F_DESKTOP_NOTIFICATIONS: usize = 40;
+const F_PADDING_X: usize = 11;
+const F_PADDING_Y: usize = 12;
+const F_SHELL: usize = 13;
+const F_SCROLLBACK: usize = 14;
+const F_LOG_AUTO: usize = 15;
+const F_LOG_DIR: usize = 16;
+const F_THEME_NAME: usize = 17;
+const F_COLOR_BG: usize = 18;
+const F_COLOR_FG: usize = 19;
+const F_COLOR_CUR: usize = 20;
+const F_COLOR_SEL: usize = 21;
+const F_PALETTE: usize = 22; // F_PALETTE + 0..15
+const F_STATUS_BAR_RIGHT: usize = 38;
+const F_AUTO_UPDATE_CHECK: usize = 39;
+const F_AUTO_UPDATE_INSTALL: usize = 40;
+const F_SHELL_INTEGRATION: usize = 41;
+const F_DESKTOP_NOTIFICATIONS: usize = 42;
 
 const PALETTE_LABELS: [&str; 16] = [
     "Palette 0  black",
@@ -176,6 +178,20 @@ impl ConfigPanel {
                 kind: FieldKind::Bool,
                 section: None,
             },
+            Field {
+                label: "Padding X",
+                hint: "pixels between a pane's left/right border and its grid",
+                value: cfg.window.padding_x.to_string(),
+                kind: FieldKind::UInt,
+                section: None,
+            },
+            Field {
+                label: "Padding Y",
+                hint: "pixels between a pane's top/bottom border and its grid",
+                value: cfg.window.padding_y.to_string(),
+                kind: FieldKind::UInt,
+                section: None,
+            },
             // ── Shell ───────────────────────────────────────────────────────
             Field {
                 label: "Shell",
@@ -624,6 +640,12 @@ impl ConfigPanel {
         let detect_urls = get(F_DETECT_URLS)
             .parse::<bool>()
             .map_err(|_| "Invalid detect_urls — use true or false")?;
+        let padding_x = get(F_PADDING_X)
+            .parse::<u32>()
+            .map_err(|_| "Invalid padding_x — use a whole number of pixels")?;
+        let padding_y = get(F_PADDING_Y)
+            .parse::<u32>()
+            .map_err(|_| "Invalid padding_y — use a whole number of pixels")?;
         let shell = {
             let s = get(F_SHELL);
             if s.is_empty() { None } else { Some(s) }
@@ -687,6 +709,8 @@ impl ConfigPanel {
                 cursor_blink_ms: blink_ms,
                 inactive_dim,
                 detect_urls,
+                padding_x,
+                padding_y,
             },
             shell: ShellConfig { program: shell },
             terminal: TerminalConfig { scrollback_lines },

src/config/tui_config_test.rs

@@ -10,8 +10,8 @@ fn make_panel() -> ConfigPanel {
 #[test]
 fn from_config_has_correct_field_count() {
     let panel = make_panel();
-    // 9 base + 1 scrollback + 2 logging + 1 theme + 4 colors + 16 palette + 1 status_bar + 3 general + 2 updates + 2 shell/notify = 41
-    assert_eq!(panel.fields.len(), 41);
+    // 9 base + 2 padding + 1 scrollback + 2 logging + 1 theme + 4 colors + 16 palette + 1 status_bar + 3 general + 2 updates + 2 shell/notify = 43
+    assert_eq!(panel.fields.len(), 43);
 }
 
 #[test]
@@ -305,6 +305,8 @@ fn distinct_config() -> Config {
             cursor_blink_ms: 523,
             inactive_dim: 0.42,
             detect_urls: true,
+            padding_x: 6,
+            padding_y: 9,
         },
         shell: ShellConfig {
             program: Some("/bin/xyzsh".into()),
@@ -361,6 +363,8 @@ fn field_index_sanity() {
         F_BLINK_MS,
         F_DIM,
         F_DETECT_URLS,
+        F_PADDING_X,
+        F_PADDING_Y,
         F_SHELL,
         F_SCROLLBACK,
         F_LOG_AUTO,
@@ -680,8 +684,8 @@ fn palette_collapsed_by_default() {
 #[test]
 fn visible_indices_hides_palette_body() {
     let panel = make_panel();
-    // 41 total - 15 palette body fields = 26 visible
-    assert_eq!(panel.visible_indices().len(), 26);
+    // 43 total - 15 palette body fields = 28 visible
+    assert_eq!(panel.visible_indices().len(), 28);
 }
 
 #[test]
@@ -690,7 +694,7 @@ fn toggle_on_palette_header_expands() {
     panel.selected = F_PALETTE;
     panel.toggle_collapse();
     assert!(!panel.collapsed.contains("Palette"));
-    assert_eq!(panel.visible_indices().len(), 41);
+    assert_eq!(panel.visible_indices().len(), 43);
 }
 
 #[test]
@@ -700,7 +704,7 @@ fn toggle_twice_restores_collapsed() {
     panel.toggle_collapse();
     panel.toggle_collapse();
     assert!(panel.collapsed.contains("Palette"));
-    assert_eq!(panel.visible_indices().len(), 26);
+    assert_eq!(panel.visible_indices().len(), 28);
 }
 
 #[test]

src/geometry_test.rs

@@ -90,6 +90,56 @@ fn pixel_to_cell_offset_rect() {
     assert_eq!(result, Some((1, 1)));
 }
 
+#[test]
+fn pixel_to_cell_padded_origin_maps_to_first_cell() {
+    // App::pixel_to_cell insets the pane rect by (pad_x, pad_y) so the grid is
+    // hit-tested from the padded origin (matching the padded render origin). A
+    // click exactly at the padded origin must resolve to cell (0, 0).
+    let (rx, ry, rw, rh) = (100u32, 50u32, 200u32, 120u32);
+    let (pad_x, pad_y) = (8u32, 3u32);
+    let inset = [rx + pad_x, ry + pad_y, rw - pad_x * 2, rh - pad_y * 2];
+    // Click at the padded top-left origin → first cell.
+    assert_eq!(
+        pixel_to_cell(
+            inset,
+            10,
+            12,
+            18,
+            9,
+            (rx + pad_x) as f64,
+            (ry + pad_y) as f64
+        ),
+        Some((0, 0))
+    );
+    // One cell in on each axis from the padded origin → cell (1, 1).
+    assert_eq!(
+        pixel_to_cell(
+            inset,
+            10,
+            12,
+            18,
+            9,
+            (rx + pad_x + 10) as f64,
+            (ry + pad_y + 12) as f64
+        ),
+        Some((1, 1))
+    );
+    // A click inside the left/top padding gutter (before the padded origin) is
+    // outside the inset rect → None.
+    assert_eq!(
+        pixel_to_cell(
+            inset,
+            10,
+            12,
+            18,
+            9,
+            (rx + pad_x - 1) as f64,
+            (ry + pad_y) as f64
+        ),
+        None
+    );
+}
+
 // ── cell_url_at_scroll ────────────────────────────────────────────────────────
 
 use crate::terminal::grid::{Color, Grid, GridColors};

src/input/mouse_ops.rs

@@ -55,15 +55,26 @@ impl App {
     }
 
     pub(crate) fn pixel_to_cell(&self, pane_id: usize, px: f64, py: f64) -> Option<(usize, usize)> {
+        let (pad_x, pad_y) = (self.pane_padding_x(), self.pane_padding_y());
         let tab = self.tab();
         let entry = tab.panes.get(&pane_id)?;
         let m = &entry.metrics;
         let (grid_cols, grid_rows) = {
             let g = entry.pane.grid_read()?;
             (g.cols, g.rows)
         };
+        // The grid is rendered inset by (pad_x, pad_y) from the pane rect origin
+        // (see renderer `render_row`). Inset the rect the same way so a click at
+        // the padded origin maps to cell (0, 0); the padding gutters map to None.
+        let [rx, ry, rw, rh] = entry.pane.rect;
+        let inset = [
+            rx + pad_x,
+            ry + pad_y,
+            rw.saturating_sub(pad_x * 2),
+            rh.saturating_sub(pad_y * 2),
+        ];
         geometry::pixel_to_cell(
-            entry.pane.rect,
+            inset,
             m.cell_width,
             m.cell_height,
             grid_cols,

src/input_ops.rs

@@ -127,8 +127,9 @@ impl App {
             .nudge_pane(active, split_h, delta);
         let tab_h = self.tab_h();
         let status_h = self.status_h();
-        let pane_padding = self.pane_padding();
-        Self::sync_pane_sizes_tab(&mut self.state.tabs[ai], tab_h, status_h, pane_padding);
+        let pad_x = self.pane_padding_x();
+        let pad_y = self.pane_padding_y();
+        Self::sync_pane_sizes_tab(&mut self.state.tabs[ai], tab_h, status_h, pad_x, pad_y);
         if let Some(w) = &self.window {
             w.request_redraw();
         }
@@ -139,8 +140,9 @@ impl App {
         self.state.tabs[ai].layout.rotate_leaves(forward);
         let tab_h = self.tab_h();
         let status_h = self.status_h();
-        let pane_padding = self.pane_padding();
-        Self::sync_pane_sizes_tab(&mut self.state.tabs[ai], tab_h, status_h, pane_padding);
+        let pad_x = self.pane_padding_x();
+        let pad_y = self.pane_padding_y();
+        Self::sync_pane_sizes_tab(&mut self.state.tabs[ai], tab_h, status_h, pad_x, pad_y);
         self.request_redraw();
     }
 
@@ -232,10 +234,11 @@ impl App {
         }
         let tab_h = self.tab_h();
         let status_h = self.status_h();
-        let pane_padding = self.pane_padding();
+        let pad_x = self.pane_padding_x();
+        let pad_y = self.pane_padding_y();
         // Re-grids only the active pane: sibling metrics + rects are unchanged,
         // so their cols/rows don't change and they are left alone.
-        Self::sync_pane_sizes_tab(&mut self.state.tabs[idx], tab_h, status_h, pane_padding);
+        Self::sync_pane_sizes_tab(&mut self.state.tabs[idx], tab_h, status_h, pad_x, pad_y);
     }
 
     pub(crate) fn should_swallow_key(&mut self, event: &KeyEvent) -> bool {

src/main.rs

@@ -204,8 +204,12 @@ impl App {
         self.scale.chrome(crate::ui::layout::STATUS_BAR_H)
     }
 
-    pub(crate) fn pane_padding(&self) -> u32 {
-        self.scale.chrome(crate::ui::layout::PANE_PADDING)
+    pub(crate) fn pane_padding_x(&self) -> u32 {
+        self.scale.chrome(self.state.config.window.padding_x)
+    }
+
+    pub(crate) fn pane_padding_y(&self) -> u32 {
+        self.scale.chrome(self.state.config.window.padding_y)
     }
 
     fn handle_resize(&mut self, w: u32, h: u32) {