close panes when process closes, rework open scrollback to not open with /bin/sh -c

src/main/java/com/gregor/jprototerm/AppConfig.java

@@ -5,6 +5,7 @@ import io.github.wasabithumb.jtoml.document.TomlDocument;
 import io.github.wasabithumb.jtoml.except.TomlException;
 import io.github.wasabithumb.jtoml.key.TomlKey;
 import io.github.wasabithumb.jtoml.value.TomlValue;
+import io.github.wasabithumb.jtoml.value.array.TomlArray;
 import io.github.wasabithumb.jtoml.value.primitive.TomlPrimitive;
 import io.github.wasabithumb.jtoml.value.table.TomlTable;
 
@@ -12,6 +13,7 @@ import java.nio.file.Files;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -20,7 +22,7 @@ public record AppConfig(
         int columns,
         int rows,
         long maxScrollback,
-        String shell,
+        List<String> shell,
         String fontFamily,
         double fontSize,
         double windowWidth,
@@ -62,7 +64,7 @@ public record AppConfig(
                     intValue(document, "terminal.columns", defaults.columns),
                     intValue(document, "terminal.rows", defaults.rows),
                     longValue(document, "terminal.max_scrollback", defaults.maxScrollback),
-                    stringValue(document, "terminal.shell", defaults.shell),
+                    stringListValue(document, "terminal.shell", defaults.shell),
                     stringValue(document, "terminal.font_family", defaults.fontFamily),
                     doubleValue(document, "terminal.font_size", defaults.fontSize),
                     doubleValue(document, "window.width", defaults.windowWidth),
@@ -140,8 +142,10 @@ public record AppConfig(
         return Path.of(System.getProperty("user.home"), ".config", "jprototerm", "config.toml");
     }
 
-    private static String defaultShell() {
+    private static List<String> defaultShell() {
-        return "/bin/bash";
+        // The executable plus its arguments, spawned verbatim. -i makes bash interactive; a
+        // different shell can use whatever flags it needs (or none) by editing this list.
+        return List.of("/bin/bash", "-i");
     }
 
     private static String defaultScrollbackEditorCommand() {
@@ -188,7 +192,7 @@ public record AppConfig(
         builder.append("columns = ").append(columns).append('\n');
         builder.append("rows = ").append(rows).append('\n');
         builder.append("max_scrollback = ").append(maxScrollback).append('\n');
-        builder.append("shell = ").append(quoted(shell)).append('\n');
+        builder.append("shell = ").append(quotedList(shell)).append('\n');
         builder.append("font_family = ").append(quoted(fontFamily)).append('\n');
         builder.append("font_size = ").append(trimDouble(fontSize)).append("\n\n");
         builder.append("[window]\n");
@@ -213,6 +217,17 @@ public record AppConfig(
         return builder.toString();
     }
 
+    private static String quotedList(List<String> values) {
+        StringBuilder builder = new StringBuilder("[");
+        for (int i = 0; i < values.size(); i++) {
+            if (i > 0) {
+                builder.append(", ");
+            }
+            builder.append(quoted(values.get(i)));
+        }
+        return builder.append("]").toString();
+    }
+
     private static String quoted(String value) {
         return "\"" + value
                 .replace("\\", "\\\\")
@@ -272,6 +287,26 @@ public record AppConfig(
         return primitive == null ? fallback : primitive.asString();
     }
 
+    /** Reads a TOML array of strings (e.g. {@code shell = ["/bin/bash", "-i"]}), or the fallback. */
+    private static List<String> stringListValue(TomlTable table, String key, List<String> fallback) {
+        TomlValue value = table.get(key);
+        if (value == null || !value.isArray()) {
+            return fallback;
+        }
+        List<String> result = new ArrayList<>();
+        for (TomlValue element : value.asArray()) {
+            if (element.isPrimitive()) {
+                try {
+                    result.add(element.asPrimitive().asString());
+                } catch (RuntimeException ignored) {
+                    // Skip non-string entries; a shell command line is a list of strings.
+                }
+            }
+        }
+        // An empty or all-invalid array would mean "no program to run"; keep the default instead.
+        return result.isEmpty() ? fallback : List.copyOf(result);
+    }
+
     private static int intValue(TomlTable table, String key, int fallback) {
         TomlPrimitive primitive = primitive(table, key);
         if (primitive == null) {

src/main/java/com/gregor/jprototerm/Compositor.java

@@ -61,11 +61,13 @@ public final class Compositor {
     private long lastContentVersion = Long.MIN_VALUE;
     private boolean mouseButtonPressed;
     private MouseButton pressedButton = MouseButton.UNKNOWN;
+    // Run when the last pane closes (so the window can quit). No-op until Main sets it.
+    private Runnable onEmpty = () -> {};
 
     public Compositor(AppConfig config, TerminalMetrics metrics) {
         this.config = config;
         this.metrics = metrics;
-        tabs.add(new Tab(config, metrics));
+        tabs.add(new Tab(config, metrics, this::closePane));
         canvas.setFocusTraversable(true);
         canvas.setOnMousePressed(this::handleMousePressed);
         canvas.setOnMouseReleased(this::handleMouseReleased);
@@ -78,6 +80,11 @@ public final class Compositor {
         return canvas;
     }
 
+    /** Sets the callback run when the last pane closes (e.g. to quit the application). */
+    public void setOnEmpty(Runnable onEmpty) {
+        this.onEmpty = onEmpty;
+    }
+
     /** The kitty-image overlay, to be stacked directly above {@link #canvas()} in the window. */
     public Node imageOverlay() {
         return imageOverlay.node();
@@ -131,6 +138,19 @@ public final class Compositor {
         return pane;
     }
 
+    /**
+     * Opens a floating pane running {@code command} directly (auto-closing when it exits), makes it
+     * active, and returns it (null when no tab exists).
+     */
+    public TerminalPane openFloatingPane(String command) {
+        if (isEmpty()) {
+            return null;
+        }
+        TerminalPane pane = currentTab().createFloatingPane(command);
+        layoutVersion++;
+        return pane;
+    }
+
     public void nextFloatingPane() {
         if (isEmpty()) {
             return;
@@ -151,23 +171,46 @@ public final class Compositor {
         if (isEmpty()) {
             return;
         }
-        currentTab().closeActivePane();
+        TerminalPane active = currentTab().activePane();
-        if (currentTab().isEmpty()) {
+        if (active != null) {
-            // Closing a tab's last pane closes the tab. When no tabs remain the surface is
+            closePane(active);
-            // empty and Main quits.
+        }
-            tabs.remove(currentTabIndex);
+    }
-            if (currentTabIndex >= tabs.size()) {
+
-                currentTabIndex = Math.max(0, tabs.size() - 1);
+    /**
+     * Closes a specific pane, wherever it lives. Driven both by the key-bound close (via
+     * {@link #closeActivePane()}) and by a pane whose process exited on its own. Drops the owning
+     * tab if it becomes empty, and fires {@link #setOnEmpty} when the last pane is gone. Must run on
+     * the FX thread.
+     */
+    public void closePane(TerminalPane pane) {
+        for (int i = 0; i < tabs.size(); i++) {
+            Tab tab = tabs.get(i);
+            if (tab.closePane(pane)) {
+                if (tab.isEmpty()) {
+                    // Closing a tab's last pane closes the tab. Keep currentTabIndex pointing at the
+                    // same tab (or clamp it when the current/last tab went away).
+                    tabs.remove(i);
+                    if (i < currentTabIndex) {
+                        currentTabIndex--;
+                    } else if (currentTabIndex >= tabs.size()) {
+                        currentTabIndex = Math.max(0, tabs.size() - 1);
+                    }
+                }
+                layoutVersion++;
+                if (isEmpty()) {
+                    onEmpty.run();
+                }
+                return;
             }
         }
-        layoutVersion++;
     }
 
     public void newTab() {
         // Open the new tab in the currently active pane's working directory, so it lands where the
         // user currently is rather than always in home.
         String workingDirectory = isEmpty() ? null : currentTab().activePane().currentWorkingDirectory();
-        tabs.add(new Tab(config, metrics, workingDirectory));
+        tabs.add(new Tab(config, metrics, workingDirectory, this::closePane));
         currentTabIndex = tabs.size() - 1;
         layoutVersion++;
     }

src/main/java/com/gregor/jprototerm/Main.java

@@ -35,6 +35,12 @@ public final class Main extends Application {
 
         metrics = new TerminalMetrics(config.fontFamily(), config.fontSize());
         compositor = new Compositor(config, metrics);
+        // When the last pane closes — whether via the close-pane key or because a pane's process
+        // exited on its own — tear down and quit.
+        compositor.setOnEmpty(() -> {
+            compositor.close();
+            Platform.exit();
+        });
 
         StackPane root = new StackPane(compositor.canvas(), compositor.imageOverlay());
         compositor.canvas().widthProperty().bind(root.widthProperty());
@@ -113,13 +119,9 @@ public final class Main extends Application {
             compositor.promoteActiveFloating();
             event.consume();
         } else if (config.keybindings().get("close_pane").matches(event)) {
+            // Closing the last pane quits the app, via the compositor's onEmpty hook.
             compositor.closeActivePane();
             event.consume();
-            if (compositor.isEmpty()) {
-                // Closing the last pane quits the app.
-                compositor.close();
-                Platform.exit();
-            }
         } else if (config.keybindings().get("new_tab").matches(event)) {
             compositor.newTab();
             event.consume();
@@ -217,10 +219,10 @@ public final class Main extends Application {
             Files.writeString(file, compositor.activePane().scrollbackText());
             file.toFile().deleteOnExit();
 
-            TerminalPane pane = compositor.openFloatingPane();
+            // Run the editor as the floating pane's process (via /bin/sh -c) rather than typing the
-            if (pane != null) {
+            // command into an interactive shell. The command runs deterministically from the start
-                pane.send(scrollbackEditorCommand(file) + "\r");
+            // — no shell startup/rc race — and the pane auto-closes when the editor exits.
-            }
+            compositor.openFloatingPane(scrollbackEditorCommand(file));
         } catch (IOException ex) {
             System.err.println("Could not open scrollback in editor: " + ex.getMessage());
         }

src/main/java/com/gregor/jprototerm/ShellSession.java

@@ -2,6 +2,7 @@ package com.gregor.jprototerm;
 
 import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -20,28 +21,56 @@ public final class ShellSession implements AutoCloseable {
         });
     }
 
-    public static ShellSession start(String shell, Map<String, String> envOverride, TerminalPane pane,
+    /**
+     * Starts the configured shell. {@code shellCommand} is the executable plus its arguments (e.g.
+     * {@code ["/bin/bash", "-i"]}), spawned verbatim — any interactive flag is the user's choice in
+     * config, not assumed here.
+     */
+    public static ShellSession start(List<String> shellCommand, Map<String, String> envOverride, TerminalPane pane,
             int columns, int rows, String workingDirectory) {
         try {
-            Map<String, String> environment = new HashMap<>(System.getenv());
+            return spawn(shellCommand.toArray(new String[0]), envOverride, columns, rows, workingDirectory);
-            environment.put("TERM", "xterm-kitty");
-            environment.put("COLORTERM", "truecolor");
-            sanitizeWrapperEnvironment(environment);
-            environment.putAll(envOverride);
-
-            LinuxPty pty = LinuxPty.spawn(
-                    new String[] {shell, "-i"},
-                    environment,
-                    workingDirectory != null ? workingDirectory : System.getProperty("user.home"));
-            ShellSession session = new ShellSession(pty);
-            session.resize(columns, rows);
-            return session;
         } catch (RuntimeException ex) {
             pane.write("failed to start shell: " + ex.getMessage() + "\r\n");
-            throw new IllegalStateException("Could not start shell " + shell, ex);
+            throw new IllegalStateException("Could not start shell " + String.join(" ", shellCommand), ex);
         }
     }
 
+    /**
+     * Starts a session whose first and only process is {@code /bin/sh -c command}, so the program
+     * runs deterministically from the start rather than being typed into an interactive shell —
+     * there is no startup/rc race to lose or mangle the input. When the process exits the pty
+     * closes and the pane auto-closes. {@code /bin/sh -c} is used (not the user's configured shell)
+     * because it is the portable way to run a command line and does not depend on shell-specific
+     * flags. {@code command} must not be null.
+     */
+    public static ShellSession startCommand(Map<String, String> envOverride, TerminalPane pane,
+            int columns, int rows, String workingDirectory, String command) {
+        try {
+            return spawn(new String[] {"/bin/sh", "-c", command}, envOverride, columns, rows, workingDirectory);
+        } catch (RuntimeException ex) {
+            pane.write("failed to run command: " + ex.getMessage() + "\r\n");
+            throw new IllegalStateException("Could not run command: " + command, ex);
+        }
+    }
+
+    private static ShellSession spawn(String[] argv, Map<String, String> envOverride,
+            int columns, int rows, String workingDirectory) {
+        Map<String, String> environment = new HashMap<>(System.getenv());
+        environment.put("TERM", "xterm-kitty");
+        environment.put("COLORTERM", "truecolor");
+        sanitizeWrapperEnvironment(environment);
+        environment.putAll(envOverride);
+
+        LinuxPty pty = LinuxPty.spawn(
+                argv,
+                environment,
+                workingDirectory != null ? workingDirectory : System.getProperty("user.home"));
+        ShellSession session = new ShellSession(pty);
+        session.resize(columns, rows);
+        return session;
+    }
+
     /**
      * Strips the variables injected by the Nix launcher wrapper from the shell's
      * environment so they do not leak into terminal subprocesses.
@@ -119,6 +148,11 @@ public final class ShellSession implements AutoCloseable {
                 pane.write("\r\nshell output stopped: " + ex.getMessage() + "\r\n");
             }
         }
+        // The stream ended without us closing the session, so the process exited on its own (the
+        // user typed `exit`, or a one-shot command pane finished). Let the pane tear itself down.
+        if (!closed) {
+            pane.handleSessionExit();
+        }
     }
 
     @Override

src/main/java/com/gregor/jprototerm/Tab.java

@@ -7,6 +7,7 @@ import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Consumer;
 import java.util.stream.Stream;
 
 /**
@@ -19,6 +20,9 @@ import java.util.stream.Stream;
 final class Tab implements AutoCloseable {
     private final AppConfig config;
     private final TerminalMetrics metrics;
+    // Notified (on the FX thread) when one of this tab's panes' process exits on its own, so the
+    // compositor can close that pane and reap the tab/app if it was the last one.
+    private final Consumer<TerminalPane> onPaneExit;
     private final List<TerminalPane> tiled = new ArrayList<>();
     private final List<TerminalPane> floating = new ArrayList<>();
     private boolean floatingVisible;
@@ -39,17 +43,19 @@ final class Tab implements AutoCloseable {
     // tab's value each frame as an O(1) "anything to repaint?" check.
     private final AtomicLong contentVersion = new AtomicLong();
 
-    Tab(AppConfig config, TerminalMetrics metrics) {
+    Tab(AppConfig config, TerminalMetrics metrics, Consumer<TerminalPane> onPaneExit) {
-        this(config, metrics, null);
+        this(config, metrics, null, onPaneExit);
     }
 
     /**
      * Creates a tab whose first pane starts in {@code initialWorkingDirectory} (e.g. the cwd of the
      * pane that was active when this tab was opened), or the user's home when {@code null}.
      */
-    Tab(AppConfig config, TerminalMetrics metrics, String initialWorkingDirectory) {
+    Tab(AppConfig config, TerminalMetrics metrics, String initialWorkingDirectory,
+            Consumer<TerminalPane> onPaneExit) {
         this.config = config;
         this.metrics = metrics;
+        this.onPaneExit = onPaneExit;
         this.lastWidth = config.windowWidth();
         this.lastHeight = config.windowHeight();
         this.initialWorkingDirectory = initialWorkingDirectory;
@@ -241,19 +247,35 @@ final class Tab implements AutoCloseable {
     }
 
     void closeActivePane() {
-        TerminalPane closing = active;
+        if (active != null) {
-        boolean wasFloating = floating.remove(closing);
+            closePane(active);
-        if (!wasFloating) {
-            tiled.remove(closing);
         }
+    }
+
+    /**
+     * Closes {@code closing} (the active pane on a key-bound close, or any pane whose process just
+     * exited) and re-selects the active pane only when the one that closed was active. Returns
+     * false when the pane is not in this tab. Leaves the tab empty ({@code active == null}) when its
+     * last pane closes, so the compositor can drop it.
+     */
+    boolean closePane(TerminalPane closing) {
+        boolean wasFloating = floating.remove(closing);
+        boolean wasTiled = !wasFloating && tiled.remove(closing);
+        if (!wasFloating && !wasTiled) {
+            return false; // not one of this tab's panes (already gone)
+        }
+        boolean wasActive = closing == active;
         if (closing == lastFocusedFloating) {
             lastFocusedFloating = null;
         }
+        if (closing == lastFocusedTiled) {
+            lastFocusedTiled = null;
+        }
         closing.close();
 
         if (tiled.isEmpty() && floating.isEmpty()) {
             active = null; // tab is now empty; the compositor drops it
-            return;
+            return true;
         }
 
         // Always keep a tiled base: if the last tiled pane just closed, promote a floating one
@@ -265,19 +287,21 @@ final class Tab implements AutoCloseable {
             floating.remove(promote);
             tiled.add(promote);
             if (promote == lastFocusedFloating) {
-                lastFocusedFloating = null;
+                lastFocusedFloating = floating.isEmpty() ? null : floating.get(nextFocussed);
-                if (!floating.isEmpty()) {
-                    lastFocusedFloating = floating.isEmpty() ? null : floating.get(nextFocussed);
-                }
             }
         }
         if (floating.isEmpty()) {
             floatingVisible = false;
         }
 
-        setActive(wasFloating && floatingVisible
+        // Only the active pane closing forces a re-selection; closing a background pane (e.g. one
-                ? floating.get(floating.size() - 1)
+        // whose process exited while another is focused) leaves focus where it is.
-                : tiled.contains(lastFocusedTiled) ? lastFocusedTiled : tiled.get(0));
+        if (wasActive) {
+            setActive(wasFloating && floatingVisible
+                    ? floating.get(floating.size() - 1)
+                    : tiled.contains(lastFocusedTiled) ? lastFocusedTiled : tiled.get(0));
+        }
+        return true;
     }
 
     private void setActive(TerminalPane pane) {
@@ -293,7 +317,20 @@ final class Tab implements AutoCloseable {
     }
 
     TerminalPane createFloatingPane() {
-        TerminalPane pane = openPane(true);
+        return addFloating(openPane(true));
+    }
+
+    /**
+     * Opens a floating pane whose process runs {@code command} directly (auto-closing when it
+     * exits), rather than an interactive shell. Used for one-shot panes like the scrollback editor.
+     */
+    TerminalPane createFloatingPane(String command) {
+        double[] size = paneSize(true);
+        return addFloating(register(TerminalPane.createWithCommand(
+                config, metrics, this::markContentChanged, size[0], size[1], paneWorkingDirectory(), command)));
+    }
+
+    private TerminalPane addFloating(TerminalPane pane) {
         floating.add(pane);
         floatingVisible = true;
         setActive(pane);
@@ -332,22 +369,31 @@ final class Tab implements AutoCloseable {
     }
 
     private TerminalPane openPane(boolean asFloating) {
+        double[] size = paneSize(asFloating);
+        return register(TerminalPane.create(
+                config, metrics, this::markContentChanged, size[0], size[1], paneWorkingDirectory()));
+    }
+
+    private double[] paneSize(boolean asFloating) {
         double availHeight = lastHeight - lastTopInset;
-        double widthPx;
-        double heightPx;
         if (asFloating) {
-            widthPx = Math.max(420, lastWidth * 0.58);
+            return new double[] {Math.max(420, lastWidth * 0.58), Math.max(260, availHeight * 0.58)};
-            heightPx = Math.max(260, availHeight * 0.58);
-        } else {
-            // A new tiled pane joins the row, so each gets 1/(n+1) of the width.
-            widthPx = lastWidth / (tiled.size() + 1);
-            heightPx = availHeight;
         }
-        // Open the new pane in the active pane's working directory, so a split/new pane lands
+        // A new tiled pane joins the row, so each gets 1/(n+1) of the width.
-        // where the user currently is. With no active pane yet (the tab's first pane), fall back to
+        return new double[] {lastWidth / (tiled.size() + 1), availHeight};
-        // the directory this tab was opened in. null (cwd unknown) falls back to home downstream.
+    }
-        String workingDirectory = active != null ? active.currentWorkingDirectory() : initialWorkingDirectory;
+
-        return TerminalPane.create(config, metrics, this::markContentChanged, widthPx, heightPx, workingDirectory);
+    // Open a new pane in the active pane's working directory, so a split/new pane lands where the
+    // user currently is. With no active pane yet (the tab's first pane), fall back to the directory
+    // this tab was opened in. null (cwd unknown) falls back to home downstream.
+    private String paneWorkingDirectory() {
+        return active != null ? active.currentWorkingDirectory() : initialWorkingDirectory;
+    }
+
+    // Wire the pane's self-exit (process ended) back to the compositor so it gets reaped.
+    private TerminalPane register(TerminalPane pane) {
+        pane.setOnExit(() -> onPaneExit.accept(pane));
+        return pane;
     }
 
     private static boolean directionFilter(Direction direction, TerminalPane current, TerminalPane candidate) {

src/main/java/com/gregor/jprototerm/TerminalPane.java

@@ -12,6 +12,7 @@ import dev.jlibghostty.RenderStateSnapshot;
 import dev.jlibghostty.ScrollViewport;
 import dev.jlibghostty.Terminal;
 import dev.jlibghostty.TerminalOptions;
+import javafx.application.Platform;
 import javafx.scene.canvas.GraphicsContext;
 import javafx.scene.shape.Shape;
 
@@ -39,6 +40,10 @@ public final class TerminalPane implements AutoCloseable, RenderTarget {
     private final RenderState renderState = new RenderState();
     private RenderStateSnapshot cachedSnapshot;
     private ShellSession session;
+    // Run once (on the FX thread) when this pane's process exits on its own, so the owning tab can
+    // remove it. Set by the Tab that creates the pane; null until then.
+    private Runnable onExit;
+    private boolean exited;
     // Clip region for rendering (rect minus the panes covering this one), set at layout time;
     // null means clip to the plain bounds. See RenderTarget#clip().
     private Shape clip;
@@ -74,6 +79,27 @@ public final class TerminalPane implements AutoCloseable, RenderTarget {
      */
     public static TerminalPane create(AppConfig config, TerminalMetrics metrics, Runnable onContentChange,
             double widthPx, double heightPx, String workingDirectory) {
+        TerminalPane pane = newPane(config, metrics, onContentChange, widthPx, heightPx);
+        pane.attach(ShellSession.start(config.shell(), config.envOverride(), pane, pane.columns, pane.rows,
+                workingDirectory));
+        return pane;
+    }
+
+    /**
+     * Opens a pane whose process runs {@code command} directly (via {@code /bin/sh -c}) instead of
+     * an interactive shell. The pane auto-closes when the command exits. See
+     * {@link ShellSession#startCommand}.
+     */
+    public static TerminalPane createWithCommand(AppConfig config, TerminalMetrics metrics, Runnable onContentChange,
+            double widthPx, double heightPx, String workingDirectory, String command) {
+        TerminalPane pane = newPane(config, metrics, onContentChange, widthPx, heightPx);
+        pane.attach(ShellSession.startCommand(config.envOverride(), pane, pane.columns, pane.rows,
+                workingDirectory, command));
+        return pane;
+    }
+
+    private static TerminalPane newPane(AppConfig config, TerminalMetrics metrics, Runnable onContentChange,
+            double widthPx, double heightPx) {
         int columns = widthPx > 0 ? metrics.columnsFor(widthPx) : config.columns();
         int rows = heightPx > 0 ? metrics.rowsFor(heightPx) : config.rows();
         Terminal terminal = Ghostty.open(new TerminalOptions(columns, rows, config.maxScrollback()));
@@ -81,10 +107,31 @@ public final class TerminalPane implements AutoCloseable, RenderTarget {
         TerminalPane pane = new TerminalPane(terminal, metrics, config.kittyGraphics(), onContentChange,
                 new GhosttyTerminalRenderer(metrics), columns, rows);
         pane.refresh();
-        pane.attach(ShellSession.start(config.shell(), config.envOverride(), pane, columns, rows, workingDirectory));
         return pane;
     }
 
+    /** Sets the callback run when this pane's process exits on its own (see {@link #handleSessionExit}). */
+    public void setOnExit(Runnable onExit) {
+        this.onExit = onExit;
+    }
+
+    /**
+     * Called from the shell reader thread when the pty stream ends without us closing it (the
+     * process exited). Hops to the FX thread and fires {@link #onExit} once, so tab/compositor
+     * mutation happens on the thread that owns the layout.
+     */
+    void handleSessionExit() {
+        Platform.runLater(() -> {
+            if (exited) {
+                return;
+            }
+            exited = true;
+            if (onExit != null) {
+                onExit.run();
+            }
+        });
+    }
+
     private void attach(ShellSession session) {
         this.session = session;
         terminal.setPtyWriter(bytes -> {