explicit scrollback editor command

Cargo.lock

@@ -2319,6 +2319,7 @@ dependencies = [
  "png",
  "portable-pty",
  "serde",
+ "shell-words",
  "toml",
  "wgpu",
 ]

Cargo.toml

@@ -16,6 +16,7 @@ libghostty-vt = { version = "=0.2.1", features = ["png"] }
 png = "0.18"
 portable-pty = "0.9"
 serde = { version = "1", features = ["derive"] }
+shell-words = "1"
 toml = "0.9"
 wgpu = { version = "27", default-features = false, features = ["std", "vulkan", "gles", "metal", "wgsl"] }
 

config.example.toml

@@ -18,6 +18,10 @@
 # regular-only fonts retain synthetic bold/italic emphasis.
 font_size = 16
 scrollback = 10000
+# Command for opening scrollback; omit to use $EDITOR, or vi if unset.
+# Supports quoted arguments; the scrollback file path is appended automatically.
+# Runs directly without shell expansion. The editor should stay in the foreground.
+# scrollback_editor = "nvim -R"
 window_width = 1100
 window_height = 720
 
@@ -67,6 +71,8 @@ floating_max_height = 640
 "Alt+Shift+H" = "previous_tab"
 "Alt+Shift+L" = "next_tab"
 "Alt+X" = "close_pane"
+# Open scrollback in scrollback_editor (or $EDITOR/vi), returning on exit.
+"Alt+S" = "open_scrollback"
 "Ctrl+Shift+Z" = "zoom_pane"
 "Ctrl+Shift+R" = "reload_config"
 "Ctrl+Shift+C" = "copy"

flake.nix

@@ -207,6 +207,7 @@
               checkFlags = [
                 "--test-threads=1"
                 "--skip=app::tests::"
+                "--skip=pane::scrollback_tests::"
                 "--skip=tests::pty_executes_input_and_bracketed_paste_is_sanitized"
                 "--skip=tests::new_panes_start_in_the_directory_of_the_pane_they_came_from"
                 "--skip=tests::osc7_wins_over_the_process_directory_but_only_for_this_machine"

src/app.rs

@@ -235,6 +235,13 @@ impl App {
                 }
             }
             Action::Paste => ctx.send_viewport_cmd(egui::ViewportCommand::RequestPaste),
+            Action::OpenScrollback => {
+                self.panes.get_mut(&active).unwrap().open_scrollback(
+                    &self.config,
+                    &self.theme,
+                    ctx,
+                )?;
+            }
         }
         Ok(())
     }
@@ -425,6 +432,7 @@ impl eframe::App for App {
                         ("Zoom / restore", Action::ZoomPane),
                         ("Next pane", Action::NextPane),
                         ("Close pane", Action::ClosePane),
+                        ("Open scrollback in editor", Action::OpenScrollback),
                     ] {
                         if ui.button(label).clicked() {
                             action = Some(a);

src/config.rs

@@ -21,6 +21,7 @@ pub struct Config {
     pub font_bold_italic_path: Option<PathBuf>,
     pub font_fallbacks: Vec<String>,
     pub scrollback: usize,
+    pub scrollback_editor: Option<String>,
     pub window_width: f32,
     pub window_height: f32,
     pub theme: String,
@@ -77,6 +78,7 @@ pub enum Action {
     ReloadConfig,
     Copy,
     Paste,
+    OpenScrollback,
 }
 
 impl Default for Kitty {
@@ -115,6 +117,7 @@ impl Default for Config {
             font_bold_italic_path: None,
             font_fallbacks: Vec::new(),
             scrollback: 10000,
+            scrollback_editor: None,
             window_width: 1100.0,
             window_height: 720.0,
             theme: theme::DEFAULT_NAME.into(),
@@ -135,6 +138,7 @@ impl Default for Config {
                 ("Alt+Shift+H", Action::PreviousTab),
                 ("Alt+Shift+L", Action::NextTab),
                 ("Alt+X", Action::ClosePane),
+                ("Alt+S", Action::OpenScrollback),
                 ("Ctrl+Shift+Z", Action::ZoomPane),
                 ("Ctrl+Shift+R", Action::ReloadConfig),
                 ("Ctrl+Shift+C", Action::Copy),
@@ -186,6 +190,14 @@ impl Config {
             !config.shell.is_empty() && !config.shell[0].is_empty(),
             "shell must contain an executable"
         );
+        if let Some(editor) = &config.scrollback_editor {
+            let command =
+                shell_words::split(editor).context("Invalid scrollback_editor command")?;
+            ensure!(
+                !command.is_empty() && !command[0].is_empty(),
+                "scrollback_editor must contain an executable"
+            );
+        }
         ensure!(
             (8.0..=48.0).contains(&config.font_size),
             "font_size must be 8..48"
@@ -307,6 +319,10 @@ mod tests {
             "font_fallbacks = [' ']",
             "font_family = 'Test'\nfont_path = '/font.ttf'",
             "shell = []",
+            "scrollback_editor = ''",
+            "scrollback_editor = ' '",
+            "scrollback_editor = \"''\"",
+            "scrollback_editor = \"'\"",
             "background = '#xx0000'",
             "font_sze = 16",
             "[keys]\n'Hyper+Q' = 'close_pane'",
@@ -330,6 +346,7 @@ mod tests {
             ("Alt+Shift+H", Action::PreviousTab),
             ("Alt+Shift+L", Action::NextTab),
             ("Alt+X", Action::ClosePane),
+            ("Alt+S", Action::OpenScrollback),
         ] {
             assert_eq!(config.keys.get(binding), Some(&action));
             assert!(shortcut(binding).unwrap().modifiers.alt);

src/pane.rs

@@ -5,7 +5,7 @@ use crate::{
     render::{Grid, Renderer, cell_size},
     theme::{self, Theme},
 };
-use anyhow::{Result, ensure};
+use anyhow::{Context, Result, ensure};
 use egui::{FontId, Rect, Sense, vec2};
 use libghostty_vt::{
     Terminal, TerminalOptions, mouse,
@@ -33,6 +33,134 @@ pub struct Pane {
     mouse_event: mouse::Event<'static>,
     selection_start: Option<PointCoordinate>,
     focused: bool,
+    saved_session: Option<(Box<Pane>, ScrollbackFile)>,
+}
+
+struct ScrollbackFile(PathBuf);
+
+impl ScrollbackFile {
+    fn new(bytes: &[u8]) -> Result<Self> {
+        use std::{
+            fs::OpenOptions,
+            io::Write,
+            os::unix::fs::OpenOptionsExt,
+            sync::atomic::{AtomicU64, Ordering},
+        };
+        static NEXT: AtomicU64 = AtomicU64::new(0);
+        loop {
+            let path = std::env::temp_dir().join(format!(
+                "slerm-scrollback-{}-{}.txt",
+                std::process::id(),
+                NEXT.fetch_add(1, Ordering::Relaxed)
+            ));
+            match OpenOptions::new()
+                .write(true)
+                .create_new(true)
+                .mode(0o600)
+                .open(&path)
+            {
+                Ok(mut file) => {
+                    let temporary = Self(path);
+                    file.write_all(bytes)?;
+                    return Ok(temporary);
+                }
+                Err(error) if error.kind() == std::io::ErrorKind::AlreadyExists => continue,
+                Err(error) => return Err(error.into()),
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod scrollback_tests {
+    use super::*;
+    use std::time::{Duration, Instant};
+
+    #[test]
+    fn editor_receives_history_and_restores_original_session_on_exit() {
+        let ctx = egui::Context::default();
+        let config = Config {
+            shell: vec![
+                "/bin/sh".into(),
+                "-c".into(),
+                "read answer; printf ORIGINAL_ALIVE; read answer".into(),
+            ],
+            scrollback_editor: Config::parse(
+                "scrollback_editor = \"/bin/sh -c 'printf EDITOR_READY; read answer' editor\"",
+            )
+            .unwrap()
+            .scrollback_editor,
+            ..Default::default()
+        };
+        let mut pane = Pane::new(&config, &theme::DEFAULT, &ctx, None).unwrap();
+        pane.terminal.resize(12, 2, 8, 16).unwrap();
+        pane.terminal
+            .vt_write(b"history\r\n\x1b[31mred\x1b[0m\r\nlong line that wraps\r\nlast");
+        pane.open_scrollback(&config, &theme::DEFAULT, &ctx)
+            .unwrap();
+        let (original, file) = pane.saved_session.as_ref().unwrap();
+        assert!(!original.dead);
+        let path = file.0.clone();
+        let contents = std::fs::read_to_string(&path).unwrap();
+        assert!(
+            contents.contains("history\nred\nlong line that wraps\nlast"),
+            "{contents:?}"
+        );
+        assert!(!contents.contains('\x1b'));
+        pane.send(b"done\n".to_vec()).unwrap();
+        let deadline = Instant::now() + Duration::from_secs(5);
+        while pane.saved_session.is_some() && Instant::now() < deadline {
+            pane.drain(&ctx);
+            std::thread::sleep(Duration::from_millis(10));
+        }
+        assert!(pane.saved_session.is_none());
+        assert!(!pane.dead);
+        assert!(!path.exists());
+        pane.send(b"continue\n".to_vec()).unwrap();
+        let deadline = Instant::now() + Duration::from_secs(5);
+        loop {
+            pane.drain(&ctx);
+            let text = libghostty_vt::fmt::Formatter::new(
+                &pane.terminal,
+                libghostty_vt::fmt::FormatterOptions::new().with_unwrap(true),
+            )
+            .unwrap()
+            .format_alloc(None)
+            .unwrap();
+            if String::from_utf8_lossy(&text).contains("ORIGINAL_ALIVE") {
+                break;
+            }
+            assert!(
+                Instant::now() < deadline,
+                "original process did not resume input"
+            );
+            std::thread::sleep(Duration::from_millis(10));
+        }
+    }
+
+    #[test]
+    fn invalid_editor_leaves_the_original_pane_intact() {
+        let ctx = egui::Context::default();
+        let config = Config {
+            shell: vec!["/bin/sh".into()],
+            ..Default::default()
+        };
+        let mut pane = Pane::new(&config, &theme::DEFAULT, &ctx, None).unwrap();
+        for editor in ["", "'", "/no/such/slerm-editor"] {
+            assert!(
+                pane.open_scrollback_with_editor(&config, &theme::DEFAULT, &ctx, editor)
+                    .is_err()
+            );
+            assert!(pane.saved_session.is_none());
+            assert!(!pane.dead);
+        }
+    }
+}
+
+impl Drop for ScrollbackFile {
+    fn drop(&mut self) {
+        let _ = std::fs::remove_file(&self.0);
+    }
 }
 
 /// OSC 7 carries a `file://host/path` URL. Only a directory on this machine can be
@@ -181,10 +309,14 @@ impl Pane {
             mouse_event,
             selection_start: None,
             focused: false,
+            saved_session: None,
         })
     }
 
     pub fn drain(&mut self, ctx: &egui::Context) {
+        if let Some((session, _)) = &mut self.saved_session {
+            session.drain(ctx);
+        }
         // Bound work per frame as well as queued bytes, so one busy PTY cannot starve others.
         let mut drained = 0;
         for _ in 0..64 {
@@ -210,6 +342,66 @@ impl Pane {
         if drained == 64 {
             ctx.request_repaint();
         }
+        if self.dead
+            && let Some((session, _file)) = self.saved_session.take()
+        {
+            *self = *session;
+            ctx.request_repaint();
+        }
+    }
+
+    pub fn open_scrollback(
+        &mut self,
+        config: &Config,
+        theme: &Theme,
+        ctx: &egui::Context,
+    ) -> Result<()> {
+        if self.saved_session.is_some() {
+            return Ok(());
+        }
+        let editor = config
+            .scrollback_editor
+            .clone()
+            .unwrap_or_else(|| std::env::var("EDITOR").unwrap_or_else(|_| "vi".into()));
+        self.open_scrollback_with_editor(config, theme, ctx, &editor)
+    }
+
+    fn open_scrollback_with_editor(
+        &mut self,
+        config: &Config,
+        theme: &Theme,
+        ctx: &egui::Context,
+        editor: &str,
+    ) -> Result<()> {
+        use libghostty_vt::fmt::{Formatter, FormatterOptions};
+        let mut command =
+            shell_words::split(editor).context("Invalid scrollback editor command")?;
+        ensure!(
+            !command.is_empty() && !command[0].is_empty(),
+            "Scrollback editor command is empty"
+        );
+        self.drain(ctx);
+        let bytes = Formatter::new(
+            &self.terminal,
+            FormatterOptions::new().with_trim(true).with_unwrap(true),
+        )?
+        .format_alloc(None)?;
+        let file = ScrollbackFile::new(&bytes).context("Cannot save scrollback")?;
+        command.push(
+            file.0
+                .to_str()
+                .context("Scrollback path is not valid UTF-8")?
+                .into(),
+        );
+        let mut editor_config = config.clone();
+        editor_config.shell = command;
+        let mut editor_pane = Self::new(&editor_config, theme, ctx, self.cwd().as_deref())
+            .context("Cannot open scrollback editor")?;
+        editor_pane.last_rect = self.last_rect;
+        let session = std::mem::replace(self, editor_pane);
+        self.saved_session = Some((Box::new(session), file));
+        ctx.request_repaint();
+        Ok(())
     }
 
     pub fn send(&mut self, bytes: Vec<u8>) -> Result<()> {