some guard rails

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

@@ -55,7 +55,7 @@ public record AppConfig(
         AppConfig defaults = defaults();
         Path path = configPath();
         if (!Files.isRegularFile(path)) {
-            writeDefaultConfig(path, defaults);
+            save(path, defaults);
             return defaults;
         }
 
@@ -195,10 +195,6 @@ public record AppConfig(
         return Map.copyOf(parsed);
     }
 
-    private static void writeDefaultConfig(Path path, AppConfig defaults) {
-        save(path, defaults);
-    }
-
     private static void save(Path path, AppConfig config) {
         try {
             Path parent = path.getParent();
@@ -340,15 +336,7 @@ public record AppConfig(
     }
 
     private static int intValue(TomlTable table, String key, int fallback) {
-        TomlPrimitive primitive = primitive(table, key);
-        if (primitive == null) {
-            return fallback;
-        }
-        try {
-            return primitive.asInteger();
-        } catch (RuntimeException ex) {
-            return fallback;
-        }
+        return (int) longValue(table, key, fallback);
     }
 
     private static long longValue(TomlTable table, String key, long fallback) {

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

@@ -114,7 +114,7 @@ public final class Compositor {
     public void setFont(String family, double size) {
         metrics.setFont(family, size);
         paneContentVersion.clear();
-        lastWidth = -1.0; // force a redraw on the next frame
+        layoutVersion++; // recomposite with the new metrics on the next frame
     }
 
     // ---- Tabs and panes -------------------------------------------------------------
@@ -123,8 +123,9 @@ public final class Compositor {
         return tabs.isEmpty();
     }
 
+    /** The active pane of the current tab, or {@code null} when no tab is left. */
     public TerminalPane activePane() {
-        return currentTab().activePane();
+        return isEmpty() ? null : currentTab().activePane();
     }
 
     public void navigate(Direction direction) {
@@ -134,29 +135,11 @@ public final class Compositor {
     }
 
     public void toggleFloating() {
-        if (isEmpty()) {
-            return;
-        }
-        currentTab().toggleFloating();
-        layoutVersion++;
+        mutateCurrentTab(() -> currentTab().toggleFloating());
     }
 
     public void createPane() {
-        if (isEmpty()) {
-            return;
-        }
-        currentTab().createPane();
-        layoutVersion++;
-    }
-
-    /** Opens a new floating pane, makes it active, and returns it (null when no tab exists). */
-    public TerminalPane openFloatingPane() {
-        if (isEmpty()) {
-            return null;
-        }
-        TerminalPane pane = currentTab().createFloatingPane();
-        layoutVersion++;
-        return pane;
+        mutateCurrentTab(() -> currentTab().createPane());
     }
 
     /**
@@ -173,26 +156,25 @@ public final class Compositor {
     }
 
     public void nextFloatingPane() {
-        if (isEmpty()) {
-            return;
-        }
-        currentTab().nextFloatingPane();
-        layoutVersion++;
+        mutateCurrentTab(() -> currentTab().nextFloatingPane());
     }
 
     public void toggleActiveFloating() {
+        mutateCurrentTab(() -> currentTab().toggleActiveFloating());
+    }
+
+    // Run a structural change on the current tab and bump the layout version so the next frame
+    // recomposites. No-op when no tab is left.
+    private void mutateCurrentTab(Runnable change) {
         if (isEmpty()) {
             return;
         }
-        currentTab().toggleActiveFloating();
+        change.run();
         layoutVersion++;
     }
 
     public void closeActivePane() {
-        if (isEmpty()) {
-            return;
-        }
-        TerminalPane active = currentTab().activePane();
+        TerminalPane active = activePane();
         if (active != null) {
             closePane(active);
         }
@@ -230,7 +212,8 @@ public final class Compositor {
     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();
+        TerminalPane active = activePane();
+        String workingDirectory = active != null ? active.currentWorkingDirectory() : null;
         tabs.add(new Tab(config, metrics, workingDirectory, this::closePane));
         currentTabIndex = tabs.size() - 1;
         layoutVersion++;
@@ -470,11 +453,11 @@ public final class Compositor {
     private void handleMouseReleased(MouseEvent event) {
         TerminalPane pane = paneAt(event.getX(), event.getY());
         if (pane == null) {
-            pane = activePane();
+            pane = activePane(); // released outside every pane (e.g. mid-drag): route to the active one
         }
 
         MouseButton button = pressedButton == MouseButton.UNKNOWN ? mouseButton(event) : pressedButton;
-        MouseTarget target = mouseTarget(pane);
+        MouseTarget target = pane == null ? null : mouseTarget(pane);
         if (target != null) {
             send(pane, target, MouseInput.release(button, localX(event.getX(), pane, target), localY(event.getY(), pane, target), modifiers(event)), false, event);
         }
@@ -485,7 +468,10 @@ public final class Compositor {
     private void handleMouseDragged(MouseEvent event) {
         TerminalPane pane = paneAt(event.getX(), event.getY());
         if (pane == null) {
-            pane = activePane();
+            pane = activePane(); // dragged outside every pane: route to the active one
+        }
+        if (pane == null) {
+            return;
         }
 
         MouseButton button = pressedButton == MouseButton.UNKNOWN ? mouseButton(event) : pressedButton;

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

@@ -9,6 +9,7 @@ import java.nio.channels.ServerSocketChannel;
 import java.nio.channels.SocketChannel;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.LinkOption;
 import java.nio.file.Path;
 import java.nio.file.attribute.PosixFilePermissions;
 
@@ -23,6 +24,11 @@ import java.nio.file.attribute.PosixFilePermissions;
  * (mode 0700), so only the owning user can connect.
  */
 public final class Daemon {
+    // One request is a single line holding a filesystem path; anything bigger is bogus.
+    private static final int MAX_REQUEST_BYTES = 4096;
+    // The accept loop is single-threaded, so a client that stalls must not wedge the daemon.
+    private static final long READ_TIMEOUT_NANOS = 5_000_000_000L;
+
     private Daemon() {
     }
 
@@ -31,9 +37,9 @@ public final class Daemon {
         Path socket = socketPath();
         try {
             Files.createDirectories(socket.getParent());
-            trySecureDir(socket.getParent());
+            secureDir(socket.getParent());
         } catch (IOException ex) {
-            System.err.println("jprototerm: cannot create socket dir " + socket.getParent() + ": " + ex.getMessage());
+            System.err.println("jprototerm: cannot secure socket dir " + socket.getParent() + ": " + ex.getMessage());
             return;
         }
 
@@ -107,25 +113,48 @@ public final class Daemon {
             manager.openWindow(workingDirectory == null || workingDirectory.isBlank()
                     ? null
                     : workingDirectory.trim());
+            connection.configureBlocking(true);
             connection.write(ByteBuffer.wrap("OK\n".getBytes(StandardCharsets.UTF_8)));
         }
     }
 
+    // Reads the request line non-blocking with a deadline and a size cap: the accept loop is
+    // single-threaded, so a client that stalls or never sends a newline must fail the connection
+    // (an IOException logged by run()) rather than wedge the daemon or grow the buffer unbounded.
     private static String readLine(SocketChannel channel) throws IOException {
+        channel.configureBlocking(false);
+        long deadline = System.nanoTime() + READ_TIMEOUT_NANOS;
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         ByteBuffer buffer = ByteBuffer.allocate(4096);
-        while (channel.read(buffer) != -1) {
-            buffer.flip();
-            while (buffer.hasRemaining()) {
-                byte b = buffer.get();
-                if (b == '\n') {
-                    return out.toString(StandardCharsets.UTF_8);
+        while (true) {
+            int n = channel.read(buffer);
+            if (n > 0) {
+                buffer.flip();
+                while (buffer.hasRemaining()) {
+                    byte b = buffer.get();
+                    if (b == '\n') {
+                        return out.toString(StandardCharsets.UTF_8);
+                    }
+                    out.write(b);
+                    if (out.size() > MAX_REQUEST_BYTES) {
+                        throw new IOException("request line too long");
+                    }
+                }
+                buffer.clear();
+            } else if (n == -1) {
+                return out.size() == 0 ? null : out.toString(StandardCharsets.UTF_8);
+            } else {
+                if (System.nanoTime() >= deadline) {
+                    throw new IOException("request timed out");
+                }
+                try {
+                    Thread.sleep(5);
+                } catch (InterruptedException ex) {
+                    Thread.currentThread().interrupt();
+                    throw new IOException("interrupted while reading request");
                 }
-                out.write(b);
             }
-            buffer.clear();
         }
-        return out.size() == 0 ? null : out.toString(StandardCharsets.UTF_8);
     }
 
     private static Path socketPath() {
@@ -136,11 +165,19 @@ public final class Daemon {
         return dir.resolve("daemon.sock");
     }
 
-    private static void trySecureDir(Path dir) {
+    // Make the socket dir private, and refuse to use it if it is not ours. The /tmp fallback
+    // path is predictable, so another user could have pre-created it (the classic /tmp race);
+    // binding a socket inside a directory someone else owns would hand them control of it.
+    private static void secureDir(Path dir) throws IOException {
         try {
             Files.setPosixFilePermissions(dir, PosixFilePermissions.fromString("rwx------"));
-        } catch (IOException | UnsupportedOperationException ignored) {
-            // Best effort: XDG_RUNTIME_DIR is already user-private; the /tmp fallback we try to lock.
+        } catch (UnsupportedOperationException ignored) {
+            return; // not a POSIX filesystem: nothing more we can check
+        }
+        String owner = Files.getOwner(dir, LinkOption.NOFOLLOW_LINKS).getName();
+        String user = System.getProperty("user.name");
+        if (!owner.equals(user)) {
+            throw new IOException(dir + " is owned by '" + owner + "', not '" + user + "'");
         }
     }
 }

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

@@ -18,7 +18,6 @@ import javafx.scene.image.Image;
 import javafx.scene.image.PixelFormat;
 import javafx.scene.image.PixelBuffer;
 import javafx.scene.image.WritableImage;
-import javafx.scene.paint.Color;
 
 import java.io.ByteArrayInputStream;
 import java.nio.IntBuffer;
@@ -40,19 +39,17 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
     private static final int DIRTY_PARTIAL = 1;
     private static final int DIRTY_FULL = 2;
 
-    private static final Color DEFAULT_FOREGROUND = Color.rgb(225, 229, 235);
-    private static final Color SELECTED_BACKGROUND = Color.rgb(52, 92, 140);
+    // All colors are packed ARGB ints (alpha always 0xff): the software backbuffer never needs
+    // a javafx Color, so cells go straight from RenderColor to the pixel format.
+    private static final int DEFAULT_FOREGROUND = 0xffe1e5eb; // rgb(225, 229, 235)
+    private static final int SELECTED_BACKGROUND = 0xff345c8c; // rgb(52, 92, 140)
     // The default cell background (used for cells with no explicit bg, and as the foreground
     // for reverse-video cells whose background is the terminal default).
-    private static final Color PANE_BACKGROUND = Color.rgb(9, 10, 12);
-    private static final Color ACTIVE_BORDER = Color.rgb(87, 166, 255);
-    private static final Color INACTIVE_BORDER = Color.rgb(52, 57, 65);
-    private static final Color CURSOR_FILL = Color.rgb(225, 229, 235, 0.28);
-
-    // A full-screen redraw asks for one Color per cell; most cells share a handful of colors,
-    // so cache them by packed RGB instead of allocating a Color each time. Bounded so a
-    // truecolor gradient can't grow it without limit.
-    private static final Map<Integer, Color> COLOR_CACHE = new HashMap<>();
+    private static final int PANE_BACKGROUND = 0xff090a0c; // rgb(9, 10, 12)
+    private static final int ACTIVE_BORDER = 0xff57a6ff; // rgb(87, 166, 255)
+    private static final int INACTIVE_BORDER = 0xff343941; // rgb(52, 57, 65)
+    // Block cursor: DEFAULT_FOREGROUND blended at 28% alpha by fillRectAlpha.
+    private static final int CURSOR_FILL_ALPHA = 71;
 
     private final TerminalMetrics metrics;
     // Decoded kitty images for this renderer's pane (kitty graphics state is per-terminal).
@@ -131,16 +128,12 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
 
     // Effective background colour of a cell as it is drawn (reverse video swaps fg/bg, an
     // unset colour falls back to the defaults).
-    private static Color cellBackgroundColor(RenderCell cell) {
-        if (cell.inverse()) {
-            var fg = cell.foreground();
-            return fg.isPresent() ? toFxColor(fg.get()) : DEFAULT_FOREGROUND;
-        }
-        var bg = cell.background();
-        return bg.isPresent() ? toFxColor(bg.get()) : PANE_BACKGROUND;
+    private static int cellBackgroundColor(RenderCell cell) {
+        int override = cellBackgroundOverride(cell);
+        return override != 0 ? override : PANE_BACKGROUND;
     }
 
-    private static Color rowEdgeBackground(RenderRow row, boolean firstCell) {
+    private static int rowEdgeBackground(RenderRow row, boolean firstCell) {
         List<RenderCell> cells = row.cells();
         if (cells.isEmpty()) {
             return PANE_BACKGROUND;
@@ -148,41 +141,28 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
         return cellBackgroundColor(firstCell ? cells.get(0) : cells.get(cells.size() - 1));
     }
 
-    // Background override for a cell: null means the pane default background already covers it.
-    private static Color cellBackgroundOverride(RenderCell cell) {
+    // Background override for a cell: 0 means the pane default background already covers it
+    // (real colors always carry 0xff alpha, so 0 is never a valid color).
+    private static int cellBackgroundOverride(RenderCell cell) {
         if (cell.inverse()) {
             var fg = cell.foreground();
-            return fg.isPresent() ? toFxColor(fg.get()) : DEFAULT_FOREGROUND;
+            return fg.isPresent() ? packArgb(fg.get()) : DEFAULT_FOREGROUND;
         }
-        var bgOpt = cell.background();
-        Color bg = bgOpt.isPresent() ? toFxColor(bgOpt.get()) : null;
-        return bg;
+        var bg = cell.background();
+        return bg.isPresent() ? packArgb(bg.get()) : 0;
     }
 
-    private static Color cellForegroundColor(RenderCell cell) {
-        var fgOpt = cell.foreground();
-        var bgOpt = cell.background();
-        Color fg = fgOpt.isPresent() ? toFxColor(fgOpt.get()) : DEFAULT_FOREGROUND;
-        Color bg = bgOpt.isPresent() ? toFxColor(bgOpt.get()) : null;
-
+    private static int cellForegroundColor(RenderCell cell) {
         if (cell.inverse()) {
-            return (bg != null) ? bg : PANE_BACKGROUND;
+            var bg = cell.background();
+            return bg.isPresent() ? packArgb(bg.get()) : PANE_BACKGROUND;
         }
-        return fg;
+        var fg = cell.foreground();
+        return fg.isPresent() ? packArgb(fg.get()) : DEFAULT_FOREGROUND;
     }
 
-    private static Color toFxColor(RenderColor color) {
-        int key = (color.red() << 16) | (color.green() << 8) | color.blue();
-        Color cached = COLOR_CACHE.get(key);
-        if (cached != null) {
-            return cached;
-        }
-        if (COLOR_CACHE.size() >= 4096) {
-            COLOR_CACHE.clear();
-        }
-        Color created = Color.rgb(color.red(), color.green(), color.blue());
-        COLOR_CACHE.put(key, created);
-        return created;
+    private static int packArgb(RenderColor color) {
+        return 0xff000000 | (color.red() << 16) | (color.green() << 8) | color.blue();
     }
 
     // ---- Kitty graphics --------------------------------------------------------------
@@ -474,7 +454,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
         private void paintFull(GraphicsContext gc, RenderStateSnapshot snapshot,
                 double px, double py, double paneWidth, double paneHeight, boolean active) {
             ensure(paneWidth, paneHeight);
-            fillRect(0, 0, width, height, argbPre(PANE_BACKGROUND));
+            fillRect(0, 0, width, height, PANE_BACKGROUND);
             if (snapshot != null) {
                 paintSnapshot(snapshot);
                 drawCursor(snapshot);
@@ -574,11 +554,6 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
                     return;
                 }
             }
-            if (repaintedRowHasCursor(newCursorRow, repainted)
-                    && !repaintCursorRow(snapshot, newCursorRow, repainted)) {
-                paintFullOrShifted(gc, target.snapshotFull(), px, py, paneWidth, paneHeight, active);
-                return;
-            }
             lastCursor = cursor;
             if (needsCursorDraw) {
                 drawCursor(snapshot);
@@ -601,10 +576,6 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             return true;
         }
 
-        private boolean repaintedRowHasCursor(int rowIndex, boolean[] repainted) {
-            return rowIndex >= 0 && rowIndex < repainted.length && repainted[rowIndex];
-        }
-
         private RenderRow rowByIndex(RenderStateSnapshot snapshot, int rowIndex) {
             for (RenderRow row : snapshot.renderRows()) {
                 if (row.row() == rowIndex) {
@@ -737,7 +708,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             // per-strip fillRect calls don't touch, so mark the full content band for upload.
             markDirtyRows(top, top + contentHeight);
             if (dy == 0 || Math.abs(dy) >= contentHeight) {
-                fillRect(0, top, width, contentHeight, argbPre(PANE_BACKGROUND));
+                fillRect(0, top, width, contentHeight, PANE_BACKGROUND);
                 return;
             }
 
@@ -748,7 +719,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
                 for (int y = 0; y < copyHeight; y++) {
                     System.arraycopy(pixels, (srcY + y) * width, pixels, (dstY + y) * width, width);
                 }
-                fillRect(0, top + copyHeight, width, -dy, argbPre(PANE_BACKGROUND));
+                fillRect(0, top + copyHeight, width, -dy, PANE_BACKGROUND);
             } else {
                 int srcY = top;
                 int dstY = top + dy;
@@ -756,7 +727,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
                 for (int y = copyHeight - 1; y >= 0; y--) {
                     System.arraycopy(pixels, (srcY + y) * width, pixels, (dstY + y) * width, width);
                 }
-                fillRect(0, top, width, dy, argbPre(PANE_BACKGROUND));
+                fillRect(0, top, width, dy, PANE_BACKGROUND);
             }
         }
 
@@ -767,8 +738,8 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             }
             int top = contentTop();
             int contentBottom = top + snapshot.rows() * lineHeight();
-            fillRect(0, 0, width, top, argbPre(rowEdgeBackground(rows.get(0), true)));
-            fillRect(0, contentBottom, width, height - contentBottom, argbPre(rowEdgeBackground(rows.get(rows.size() - 1), true)));
+            fillRect(0, 0, width, top, rowEdgeBackground(rows.get(0), true));
+            fillRect(0, contentBottom, width, height - contentBottom, rowEdgeBackground(rows.get(rows.size() - 1), true));
             for (RenderRow row : rows) {
                 paintRow(row);
             }
@@ -777,13 +748,13 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
         private void paintRow(RenderRow row) {
             int rowTop = contentTop() + (row.row() * lineHeight());
             int rowHeight = lineHeight();
-            fillRect(0, rowTop, width, rowHeight, argbPre(PANE_BACKGROUND));
+            fillRect(0, rowTop, width, rowHeight, PANE_BACKGROUND);
             if (row.row() == 0) {
-                fillRect(0, 0, width, contentTop(), argbPre(rowEdgeBackground(row, true)));
+                fillRect(0, 0, width, contentTop(), rowEdgeBackground(row, true));
             }
             if (row.row() == rowHashes.length - 1) {
                 int bottom = contentTop() + (rowHashes.length * lineHeight());
-                fillRect(0, bottom, width, height - bottom, argbPre(rowEdgeBackground(row, true)));
+                fillRect(0, bottom, width, height - bottom, rowEdgeBackground(row, true));
             }
             paintRowSidePadding(row, rowTop, rowHeight);
             paintRowBackgrounds(row, rowTop, rowHeight);
@@ -797,31 +768,30 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             }
             int left = contentLeft();
             int contentRight = left + (cells.size() * cellWidth());
-            fillRect(0, rowTop, left, rowHeight, argbPre(rowEdgeBackground(row, true)));
-            fillRect(contentRight, rowTop, width - contentRight, rowHeight, argbPre(rowEdgeBackground(row, false)));
+            fillRect(0, rowTop, left, rowHeight, rowEdgeBackground(row, true));
+            fillRect(contentRight, rowTop, width - contentRight, rowHeight, rowEdgeBackground(row, false));
         }
 
         private void paintRowBackgrounds(RenderRow row, int rowTop, int rowHeight) {
-            int cellWidth = cellWidth();
-            Color runBackground = null;
+            int runBackground = 0;
             int runStartColumn = 0;
             int previousColumn = -1;
             for (RenderCell cell : row.cells()) {
                 if (cell.kittyPlaceholder().isPresent()) {
                     flushBackground(runBackground, runStartColumn, previousColumn, rowTop, rowHeight);
-                    runBackground = null;
+                    runBackground = 0;
                     previousColumn = -1;
                     continue;
                 }
 
-                Color bg = cell.selected() ? SELECTED_BACKGROUND : cellBackgroundOverride(cell);
-                if (bg == null) {
+                int bg = cell.selected() ? SELECTED_BACKGROUND : cellBackgroundOverride(cell);
+                if (bg == 0) {
                     flushBackground(runBackground, runStartColumn, previousColumn, rowTop, rowHeight);
-                    runBackground = null;
+                    runBackground = 0;
                     previousColumn = -1;
                     continue;
                 }
-                if (runBackground == null || bg != runBackground || cell.column() != previousColumn + 1) {
+                if (bg != runBackground || cell.column() != previousColumn + 1) {
                     flushBackground(runBackground, runStartColumn, previousColumn, rowTop, rowHeight);
                     runBackground = bg;
                     runStartColumn = cell.column();
@@ -831,12 +801,12 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             flushBackground(runBackground, runStartColumn, previousColumn, rowTop, rowHeight);
         }
 
-        private void flushBackground(Color background, int startColumn, int endColumn, int rowTop, int rowHeight) {
-            if (background == null || endColumn < startColumn) {
+        private void flushBackground(int background, int startColumn, int endColumn, int rowTop, int rowHeight) {
+            if (background == 0 || endColumn < startColumn) {
                 return;
             }
             fillRect(contentLeft() + (startColumn * cellWidth()), rowTop,
-                    (endColumn - startColumn + 1) * cellWidth(), rowHeight, argbPre(background));
+                    (endColumn - startColumn + 1) * cellWidth(), rowHeight, background);
         }
 
         private void paintRowText(RenderRow row, int rowTop) {
@@ -847,8 +817,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
                     continue;
                 }
                 GlyphCache.Glyph glyph = metrics.glyphCache().glyph(cell.text());
-                int color = rgb(cellForegroundColor(cell));
-                blitGlyph(glyph, x0 + (cell.column() * cellWidth), rowTop, color);
+                blitGlyph(glyph, x0 + (cell.column() * cellWidth), rowTop, cellForegroundColor(cell));
             }
         }
 
@@ -907,13 +876,13 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             saveCursorUnder(x, y, cw, lh);
             RenderCursorStyle style = snapshot.cursorStyle();
             if (style == RenderCursorStyle.BAR) {
-                fillRect(x, y + 2, 1, Math.max(1, lh - 4), argbPre(DEFAULT_FOREGROUND));
+                fillRect(x, y + 2, 1, Math.max(1, lh - 4), DEFAULT_FOREGROUND);
             } else if (style == RenderCursorStyle.UNDERLINE) {
-                fillRect(x + 1, y + lh - 2, Math.max(1, cw - 2), 1, argbPre(DEFAULT_FOREGROUND));
+                fillRect(x + 1, y + lh - 2, Math.max(1, cw - 2), 1, DEFAULT_FOREGROUND);
             } else if (style == RenderCursorStyle.BLOCK) {
-                fillRectAlpha(x, y + 1, Math.max(1, cw - 1), Math.max(1, lh - 2), CURSOR_FILL);
+                fillRectAlpha(x, y + 1, Math.max(1, cw - 1), Math.max(1, lh - 2), DEFAULT_FOREGROUND, CURSOR_FILL_ALPHA);
             } else {
-                strokeRect(x, y + 1, Math.max(1, cw - 1), Math.max(1, lh - 2), argbPre(DEFAULT_FOREGROUND), 1);
+                strokeRect(x, y + 1, Math.max(1, cw - 1), Math.max(1, lh - 2), DEFAULT_FOREGROUND, 1);
             }
         }
 
@@ -957,7 +926,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
         }
 
         private void drawBorder(boolean active) {
-            strokeRect(0, 0, width, height, argbPre(active ? ACTIVE_BORDER : INACTIVE_BORDER), active ? 2 : 1);
+            strokeRect(0, 0, width, height, active ? ACTIVE_BORDER : INACTIVE_BORDER, active ? 2 : 1);
         }
 
         private void strokeRect(int x, int y, int w, int h, int color, int lineWidth) {
@@ -974,9 +943,7 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
             }
         }
 
-        private void fillRectAlpha(int x, int y, int w, int h, Color color) {
-            int alpha = (int) Math.round(color.getOpacity() * 255.0);
-            int rgb = rgb(color);
+        private void fillRectAlpha(int x, int y, int w, int h, int rgb, int alpha) {
             int red = (rgb >> 16) & 0xff;
             int green = (rgb >> 8) & 0xff;
             int blue = rgb & 0xff;
@@ -1082,21 +1049,6 @@ final class GhosttyTerminalRenderer extends TerminalRenderer {
         return hash * 0x100000001b3L;
     }
 
-    private static int rgb(Color color) {
-        int red = (int) Math.round(color.getRed() * 255.0);
-        int green = (int) Math.round(color.getGreen() * 255.0);
-        int blue = (int) Math.round(color.getBlue() * 255.0);
-        return (red << 16) | (green << 8) | blue;
-    }
-
-    private static int argbPre(Color color) {
-        int alpha = (int) Math.round(color.getOpacity() * 255.0);
-        int red = (int) Math.round(color.getRed() * alpha);
-        int green = (int) Math.round(color.getGreen() * alpha);
-        int blue = (int) Math.round(color.getBlue() * alpha);
-        return (alpha << 24) | (red << 16) | (green << 8) | blue;
-    }
-
     // A kitty image is immutable for a given (id, number); re-transmitting under the same id
     // changes the number (and the snapshot below evicts stale entries by id anyway). So the
     // identity + dimensions + payload length are enough to key the decoded-image cache, and

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

@@ -29,6 +29,11 @@ final class GlyphCache {
     record Glyph(int width, int height, byte[] alpha) {
     }
 
+    // Bounds the atlas so pathological glyph diversity (e.g. a dump of distinct CJK/emoji cells)
+    // can't grow it without limit; on overflow it clears and rebuilds on demand, like any
+    // metrics change.
+    private static final int MAX_GLYPHS = 4096;
+
     private final TerminalMetrics metrics;
     private final Map<String, Glyph> glyphs = new HashMap<>();
     // The metrics snapshot the cached glyphs were rasterized for; a mismatch clears the cache.
@@ -43,7 +48,16 @@ final class GlyphCache {
 
     Glyph glyph(String text) {
         ensureCurrent();
-        return glyphs.computeIfAbsent(text, this::renderGlyph);
+        Glyph cached = glyphs.get(text);
+        if (cached != null) {
+            return cached;
+        }
+        if (glyphs.size() >= MAX_GLYPHS) {
+            glyphs.clear();
+        }
+        Glyph rendered = renderGlyph(text);
+        glyphs.put(text, rendered);
+        return rendered;
     }
 
     // Drop the rasterized masks if the font/cell geometry changed since they were built. Cheap to

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

@@ -5,17 +5,19 @@ import javafx.scene.input.KeyEvent;
 
 import java.util.Locale;
 
-public record KeyBinding(boolean alt, boolean control, boolean shift, KeyCode code) {
+public record KeyBinding(boolean alt, boolean control, boolean shift, boolean meta, KeyCode code) {
     public static KeyBinding parse(String value) {
         boolean alt = false;
         boolean control = false;
         boolean shift = false;
+        boolean meta = false;
         KeyCode code = null;
 
         for (String part : value.split("\\+")) {
             String token = part.trim().toUpperCase(Locale.ROOT);
             switch (token) {
-                case "ALT", "META" -> alt = true;
+                case "ALT" -> alt = true;
+                case "META", "SUPER" -> meta = true;
                 case "CTRL", "CONTROL" -> control = true;
                 case "SHIFT" -> shift = true;
                 default -> code = keyCode(token);
@@ -25,13 +27,14 @@ public record KeyBinding(boolean alt, boolean control, boolean shift, KeyCode co
         if (code == null) {
             throw new IllegalArgumentException("Key binding has no key code: " + value);
         }
-        return new KeyBinding(alt, control, shift, code);
+        return new KeyBinding(alt, control, shift, meta, code);
     }
 
     public boolean matches(KeyEvent event) {
         return event.isAltDown() == alt
                 && event.isControlDown() == control
                 && event.isShiftDown() == shift
+                && event.isMetaDown() == meta
                 && event.getCode() == code;
     }
 
@@ -44,6 +47,9 @@ public record KeyBinding(boolean alt, boolean control, boolean shift, KeyCode co
         if (alt) {
             builder.append("ALT+");
         }
+        if (meta) {
+            builder.append("META+");
+        }
         if (shift) {
             builder.append("SHIFT+");
         }

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

@@ -317,6 +317,10 @@ public final class LinuxPty implements AutoCloseable {
     }
 
     private void closeMaster() {
+        // Note: closing the master fd does NOT wake a reader thread blocked in read() on it —
+        // the reader unblocks via EOF when the child exits and the slave end closes. The signal
+        // here usually does that; if the child ignores it, the SIGKILL escalation in reap()
+        // guarantees it shortly after.
         callKill(pid, closeSignal);
         callInt(CLOSE, masterFd);
     }

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

@@ -22,8 +22,11 @@ final class StartupTiming {
     private StartupTiming() {
     }
 
-    /** Records a phase boundary, printing the delta since the previous mark and since JVM start. */
-    static void mark(String phase) {
+    /**
+     * Records a phase boundary, printing the delta since the previous mark and since JVM start.
+     * Synchronized because marks come from both the launcher thread and the FX thread.
+     */
+    static synchronized void mark(String phase) {
         if (!ENABLED) {
             return;
         }
@@ -38,7 +41,7 @@ final class StartupTiming {
      * Records the first rendered frame exactly once, then becomes a no-op. Safe and cheap to call
      * from the render loop every frame (it only ever touches FX-thread state).
      */
-    static void firstFrame() {
+    static synchronized void firstFrame() {
         if (!ENABLED || firstFrameSeen) {
             return;
         }

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

@@ -18,6 +18,14 @@ import java.util.stream.Stream;
  * return whether they actually changed anything so it can bump its layout version.
  */
 final class Tab implements AutoCloseable {
+    // Floating-pane sizing policy: a fraction of the tab's size with a floor so panes stay
+    // usable in small windows, cascaded diagonally per pane, kept off the window edge.
+    private static final double FLOATING_SIZE_FRACTION = 0.58;
+    private static final double FLOATING_MIN_WIDTH = 420.0;
+    private static final double FLOATING_MIN_HEIGHT = 260.0;
+    private static final double FLOATING_CASCADE_OFFSET = 28.0;
+    private static final double FLOATING_EDGE_MARGIN = 12.0;
+
     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
@@ -86,15 +94,24 @@ final class Tab implements AutoCloseable {
         }
         List<TerminalPane> ordered = new ArrayList<>(tiled.size() + floating.size());
         ordered.addAll(tiled);
+        ordered.addAll(floatingOrder());
+        return List.copyOf(ordered);
+    }
+
+    // Floating panes bottom-to-top: insertion order, with the active pane moved to the top.
+    // Single source of the stacking order, so the clips assigned in assignClips() always match
+    // the compositing order in panes().
+    private List<TerminalPane> floatingOrder() {
+        List<TerminalPane> order = new ArrayList<>(floating.size());
         for (TerminalPane pane : floating) {
             if (pane != active) {
-                ordered.add(pane);
+                order.add(pane);
             }
         }
         if (floating.contains(active)) {
-            ordered.add(active); // active floating pane on top
+            order.add(active);
         }
-        return List.copyOf(ordered);
+        return order;
     }
 
     boolean isActive(TerminalPane pane) {
@@ -133,13 +150,15 @@ final class Tab implements AutoCloseable {
             tiled.get(i).bounds(i * tileWidth, topInset, tileWidth, availHeight);
         }
 
-        double floatingWidth = Math.max(420, width * 0.58);
-        double floatingHeight = Math.max(260, availHeight * 0.58);
+        double floatingWidth = Math.max(FLOATING_MIN_WIDTH, width * FLOATING_SIZE_FRACTION);
+        double floatingHeight = Math.max(FLOATING_MIN_HEIGHT, availHeight * FLOATING_SIZE_FRACTION);
         for (int i = 0; i < floating.size(); i++) {
-            double offset = i * 28.0;
+            double offset = i * FLOATING_CASCADE_OFFSET;
             floating.get(i).bounds(
-                    Math.min(width - floatingWidth - 12.0, ((width - floatingWidth) / 2.0) + offset),
-                    Math.min(height - floatingHeight - 12.0, topInset + ((availHeight - floatingHeight) / 2.0) + offset),
+                    Math.min(width - floatingWidth - FLOATING_EDGE_MARGIN,
+                            ((width - floatingWidth) / 2.0) + offset),
+                    Math.min(height - floatingHeight - FLOATING_EDGE_MARGIN,
+                            topInset + ((availHeight - floatingHeight) / 2.0) + offset),
                     floatingWidth,
                     floatingHeight);
         }
@@ -154,27 +173,18 @@ final class Tab implements AutoCloseable {
     // every pane clips to its plain bounds.
     private void assignClips() {
         if (!floatingVisible || floating.isEmpty()) {
-            tiled.forEach(pane -> pane.setClip(null));
-            floating.forEach(pane -> pane.setClip(null));
+            allPanes().forEach(pane -> pane.setClip(null));
             return;
         }
 
-        // Floating panes bottom-to-top, matching panes(): insertion order, active pane on top.
-        List<TerminalPane> order = new ArrayList<>(floating.size());
-        for (TerminalPane pane : floating) {
-            if (pane != active) {
-                order.add(pane);
-            }
-        }
-        if (floating.contains(active)) {
-            order.add(active);
-        }
-
-        // Walk top-to-bottom, accumulating the union of the panes above each one.
+        // Walk the floating stack top-to-bottom, accumulating the union of the panes above
+        // each one. The topmost pane has nothing above it and keeps an unclipped bounds.
+        List<TerminalPane> order = floatingOrder();
         Shape above = null;
         for (int i = order.size() - 1; i >= 0; i--) {
-            Rectangle rect = rectOf(order.get(i));
-            order.get(i).setClip(above == null ? null : Shape.subtract(rect, above));
+            TerminalPane pane = order.get(i);
+            Rectangle rect = rectOf(pane);
+            pane.setClip(above == null ? null : Shape.subtract(rect, above));
             above = (above == null) ? rect : Shape.union(above, rect);
         }
 
@@ -259,12 +269,6 @@ final class Tab implements AutoCloseable {
         }
     }
 
-    void closeActivePane() {
-        if (active != null) {
-            closePane(active);
-        }
-    }
-
     /**
      * 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
@@ -329,8 +333,8 @@ final class Tab implements AutoCloseable {
         }
     }
 
-    TerminalPane createFloatingPane() {
-        return addFloating(openPane(true));
+    private void createFloatingPane() {
+        addFloating(openPane(true));
     }
 
     /**
@@ -390,7 +394,9 @@ final class Tab implements AutoCloseable {
     private double[] paneSize(boolean asFloating) {
         double availHeight = lastHeight - lastTopInset;
         if (asFloating) {
-            return new double[] {Math.max(420, lastWidth * 0.58), Math.max(260, availHeight * 0.58)};
+            return new double[] {
+                    Math.max(FLOATING_MIN_WIDTH, lastWidth * FLOATING_SIZE_FRACTION),
+                    Math.max(FLOATING_MIN_HEIGHT, availHeight * FLOATING_SIZE_FRACTION)};
         }
         // A new tiled pane joins the row, so each gets 1/(n+1) of the width.
         return new double[] {lastWidth / (tiled.size() + 1), availHeight};

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

@@ -18,6 +18,7 @@ import javafx.scene.shape.Shape;
 
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Supplier;
 
 /**
  * One terminal: owns its ghostty {@link Terminal}, the {@link ShellSession}/pty driving it,
@@ -80,8 +81,8 @@ 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, config.closeSignalNumber()));
+        attachOrShowError(pane, () -> ShellSession.start(config.shell(), config.envOverride(), pane,
+                pane.columns, pane.rows, workingDirectory, config.closeSignalNumber()));
         return pane;
     }
 
@@ -93,11 +94,23 @@ public final class TerminalPane implements AutoCloseable, RenderTarget {
     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, config.closeSignalNumber()));
+        attachOrShowError(pane, () -> ShellSession.startCommand(config.envOverride(), pane,
+                pane.columns, pane.rows, workingDirectory, command, config.closeSignalNumber()));
         return pane;
     }
 
+    // Start the pane's process, but never let a spawn failure (e.g. a bad `shell` in config)
+    // propagate and crash window/pane creation. ShellSession has already written the error into
+    // the pane, so the pane opens showing it; with no session attached it is inert (sends are
+    // dropped) and the user closes it with the close-pane key.
+    private static void attachOrShowError(TerminalPane pane, Supplier<ShellSession> start) {
+        try {
+            pane.attach(start.get());
+        } catch (RuntimeException ex) {
+            System.err.println("jprototerm: " + ex.getMessage());
+        }
+    }
+
     private static TerminalPane newPane(AppConfig config, TerminalMetrics metrics, Runnable onContentChange,
             double widthPx, double heightPx) {
         int columns = widthPx > 0 ? metrics.columnsFor(widthPx) : config.columns();

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

@@ -41,34 +41,28 @@ abstract class TerminalRenderer {
     void release() {
     }
 
-    protected static void clipRect(GraphicsContext gc, double x, double y, double width, double height) {
-        gc.beginPath();
-        gc.rect(x, y, width, height);
-        gc.clip();
-    }
-
     /**
      * Clip to {@code region} if given (the pane's rect minus the panes covering it, computed by
      * {@code Shape.subtract} at layout), otherwise to the plain rect. The region is a rectilinear
      * path, so it replays onto the canvas as move/line/close segments.
      */
     protected static void clip(GraphicsContext gc, double x, double y, double width, double height, Shape region) {
-        if (region == null) {
-            clipRect(gc, x, y, width, height);
-            return;
-        }
-        var elements = ((Path) region).getElements();
         gc.beginPath();
-        if (elements.isEmpty()) {
-            gc.rect(x, y, 0.0, 0.0); // fully covered: clip to nothing
-        }
-        for (PathElement element : elements) {
-            if (element instanceof MoveTo moveTo) {
-                gc.moveTo(moveTo.getX(), moveTo.getY());
-            } else if (element instanceof LineTo lineTo) {
-                gc.lineTo(lineTo.getX(), lineTo.getY());
-            } else if (element instanceof ClosePath) {
-                gc.closePath();
+        if (region == null) {
+            gc.rect(x, y, width, height);
+        } else {
+            var elements = ((Path) region).getElements();
+            if (elements.isEmpty()) {
+                gc.rect(x, y, 0.0, 0.0); // fully covered: clip to nothing
+            }
+            for (PathElement element : elements) {
+                if (element instanceof MoveTo moveTo) {
+                    gc.moveTo(moveTo.getX(), moveTo.getY());
+                } else if (element instanceof LineTo lineTo) {
+                    gc.lineTo(lineTo.getX(), lineTo.getY());
+                } else if (element instanceof ClosePath) {
+                    gc.closePath();
+                }
             }
         }
         gc.clip();

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

@@ -20,7 +20,9 @@ import javafx.stage.Stage;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 
 /**
  * One top-level terminal window: its own {@link Stage}, {@link Compositor}, config/metrics, render
@@ -34,6 +36,9 @@ final class TerminalWindow {
     private final Compositor compositor;
     private final Stage stage;
     private final AnimationTimer renderLoop;
+    // Key-bound actions by their config keybinding name, checked in this order on each key press
+    // (the keys must match AppConfig's keybinding keys).
+    private final Map<String, Runnable> keyActions = new LinkedHashMap<>();
     private AppConfig config;
     private boolean closed;
 
@@ -51,6 +56,23 @@ final class TerminalWindow {
         // The last pane closing closes this window (not the JVM); see teardown().
         compositor.setOnEmpty(this::teardown);
 
+        keyActions.put("navigate_left", () -> compositor.navigate(Direction.LEFT));
+        keyActions.put("navigate_down", () -> compositor.navigate(Direction.DOWN));
+        keyActions.put("navigate_up", () -> compositor.navigate(Direction.UP));
+        keyActions.put("navigate_right", () -> compositor.navigate(Direction.RIGHT));
+        keyActions.put("toggle_floating", compositor::toggleFloating);
+        keyActions.put("new_pane", compositor::createPane);
+        keyActions.put("next_floating", compositor::nextFloatingPane);
+        keyActions.put("promote_floating", compositor::toggleActiveFloating);
+        // Closing the last pane closes this window, via the compositor's onEmpty hook.
+        keyActions.put("close_pane", compositor::closeActivePane);
+        keyActions.put("new_tab", compositor::newTab);
+        keyActions.put("previous_tab", compositor::previousTab);
+        keyActions.put("next_tab", compositor::nextTab);
+        keyActions.put("open_font_selector", this::openFontSelector);
+        keyActions.put("open_scrollback", this::openScrollbackInEditor);
+        keyActions.put("paste", this::pasteFromClipboard);
+
         StackPane root = new StackPane(compositor.canvas(), compositor.imageOverlay());
         compositor.canvas().widthProperty().bind(root.widthProperty());
         compositor.canvas().heightProperty().bind(root.heightProperty());
@@ -107,59 +129,17 @@ final class TerminalWindow {
     }
 
     private void handlePressed(KeyEvent event) {
-        if (config.keybindings().get("navigate_left").matches(event)) {
-            compositor.navigate(Direction.LEFT);
-            event.consume();
-        } else if (config.keybindings().get("navigate_down").matches(event)) {
-            compositor.navigate(Direction.DOWN);
-            event.consume();
-        } else if (config.keybindings().get("navigate_up").matches(event)) {
-            compositor.navigate(Direction.UP);
-            event.consume();
-        } else if (config.keybindings().get("navigate_right").matches(event)) {
-            compositor.navigate(Direction.RIGHT);
-            event.consume();
-        } else if (config.keybindings().get("toggle_floating").matches(event)) {
-            compositor.toggleFloating();
-            event.consume();
-        } else if (config.keybindings().get("new_pane").matches(event)) {
-            compositor.createPane();
-            event.consume();
-        } else if (config.keybindings().get("next_floating").matches(event)) {
-            compositor.nextFloatingPane();
-            event.consume();
-        } else if (config.keybindings().get("promote_floating").matches(event)) {
-            compositor.toggleActiveFloating();
-            event.consume();
-        } else if (config.keybindings().get("close_pane").matches(event)) {
-            // Closing the last pane closes this window, via the compositor's onEmpty hook.
-            compositor.closeActivePane();
-            event.consume();
-        } else if (config.keybindings().get("new_tab").matches(event)) {
-            compositor.newTab();
-            event.consume();
-        } else if (config.keybindings().get("previous_tab").matches(event)) {
-            compositor.previousTab();
-            event.consume();
-        } else if (config.keybindings().get("next_tab").matches(event)) {
-            compositor.nextTab();
-            event.consume();
-        } else if (config.keybindings().get("open_font_selector").matches(event)) {
-            openFontSelector();
-            event.consume();
-        } else if (config.keybindings().get("open_scrollback").matches(event)) {
-            openScrollbackInEditor();
-            event.consume();
-        } else if (config.keybindings().get("paste").matches(event)) {
-            pasteFromClipboard();
-            event.consume();
-        } else {
-            String encoded = KeyEncoder.encode(event);
-            if (encoded != null) {
-                compositor.activePane().send(encoded);
+        for (Map.Entry<String, Runnable> action : keyActions.entrySet()) {
+            if (config.keybindings().get(action.getKey()).matches(event)) {
+                action.getValue().run();
                 event.consume();
+                return;
             }
         }
+        String encoded = KeyEncoder.encode(event);
+        if (encoded != null) {
+            sendToActivePane(encoded, event);
+        }
     }
 
     private void handleTyped(KeyEvent event) {
@@ -169,15 +149,25 @@ final class TerminalWindow {
 
         String text = event.getCharacter();
         if (text != null && !text.isEmpty() && text.charAt(0) >= 0x20 && text.charAt(0) != 0x7f) {
-            compositor.activePane().send(text);
+            sendToActivePane(text, event);
+        }
+    }
+
+    // Key handlers run on every keystroke, including any that race the window's teardown, so
+    // tolerate the no-pane-left state instead of assuming one exists.
+    private void sendToActivePane(String text, KeyEvent event) {
+        TerminalPane active = compositor.activePane();
+        if (active != null) {
+            active.send(text);
             event.consume();
         }
     }
 
     private void pasteFromClipboard() {
+        TerminalPane active = compositor.activePane();
         Clipboard clipboard = Clipboard.getSystemClipboard();
-        if (clipboard.hasString()) {
-            compositor.activePane().paste(clipboard.getString());
+        if (active != null && clipboard.hasString()) {
+            active.paste(clipboard.getString());
         }
     }
 
@@ -225,17 +215,22 @@ final class TerminalWindow {
     }
 
     private void openScrollbackInEditor() {
+        // Capture the active pane's scrollback before opening the floating pane, since that
+        // makes the new pane active.
+        TerminalPane active = compositor.activePane();
+        if (active == null) {
+            return;
+        }
         try {
-            // Capture the active pane's scrollback before opening the floating pane, since that
-            // makes the new pane active.
             Path file = Files.createTempFile("jprototerm-scrollback-", ".txt");
-            Files.writeString(file, compositor.activePane().scrollbackText());
-            file.toFile().deleteOnExit();
+            Files.writeString(file, active.scrollbackText());
 
             // Run the editor as the floating pane's process (via /bin/sh -c) rather than typing the
             // command into an interactive shell. The command runs deterministically from the start
-            // — no shell startup/rc race — and the pane auto-closes when the editor exits.
-            compositor.openFloatingPane(scrollbackEditorCommand(file));
+            // — no shell startup/rc race — and the pane auto-closes when the editor exits. The
+            // trailing rm removes the file (which holds terminal contents) when the editor exits;
+            // deleteOnExit would leak files for the JVM's whole lifetime in daemon mode.
+            compositor.openFloatingPane(scrollbackEditorCommand(file) + "; rm -f " + shellQuote(file.toString()));
         } catch (IOException ex) {
             System.err.println("Could not open scrollback in editor: " + ex.getMessage());
         }