Fix terminal Cmd+Backspace on macOS

apps/web/src/components/ThreadTerminalDrawer.tsx

@@ -28,7 +28,11 @@ import {
   resolveWrappedTerminalLinkRange,
   wrappedTerminalLinkRangeIntersectsBufferLine,
 } from "../terminal-links";
-import { isTerminalClearShortcut, terminalNavigationShortcutData } from "../keybindings";
+import {
+  isTerminalClearShortcut,
+  terminalDeleteShortcutData,
+  terminalNavigationShortcutData,
+} from "../keybindings";
 import {
   DEFAULT_THREAD_TERMINAL_HEIGHT,
   DEFAULT_THREAD_TERMINAL_ID,
@@ -407,6 +411,14 @@ export function TerminalViewport({
         return false;
       }
 
+      const deleteData = terminalDeleteShortcutData(event);
+      if (deleteData !== null) {
+        event.preventDefault();
+        event.stopPropagation();
+        void sendTerminalInput(deleteData, "Failed to delete terminal input");
+        return false;
+      }
+
       if (!isTerminalClearShortcut(event)) return true;
       event.preventDefault();
       event.stopPropagation();

apps/web/src/keybindings.test.ts

@@ -20,6 +20,7 @@ import {
   resolveShortcutCommand,
   shouldShowThreadJumpHints,
   shortcutLabelForCommand,
+  terminalDeleteShortcutData,
   terminalNavigationShortcutData,
   threadJumpCommandForIndex,
   threadJumpIndexFromCommand,
@@ -560,6 +561,34 @@ describe("isTerminalClearShortcut", () => {
   });
 });
 
+describe("terminalDeleteShortcutData", () => {
+  it("maps Cmd+Backspace on macOS to delete-to-line-start", () => {
+    assert.strictEqual(
+      terminalDeleteShortcutData(event({ key: "Backspace", metaKey: true }), "MacIntel"),
+      "\u0015",
+    );
+  });
+
+  it("ignores non-macOS platforms and modified variants", () => {
+    assert.isNull(terminalDeleteShortcutData(event({ key: "Backspace", metaKey: true }), "Linux"));
+    assert.isNull(
+      terminalDeleteShortcutData(
+        event({ key: "Backspace", metaKey: true, altKey: true }),
+        "MacIntel",
+      ),
+    );
+  });
+
+  it("ignores non-keydown events", () => {
+    assert.isNull(
+      terminalDeleteShortcutData(
+        event({ type: "keyup", key: "Backspace", metaKey: true }),
+        "MacIntel",
+      ),
+    );
+  });
+});
+
 describe("terminalNavigationShortcutData", () => {
   it("maps Option+Arrow on macOS to word movement", () => {
     assert.strictEqual(

apps/web/src/keybindings.ts

@@ -37,6 +37,7 @@ const TERMINAL_WORD_BACKWARD = "\u001bb";
 const TERMINAL_WORD_FORWARD = "\u001bf";
 const TERMINAL_LINE_START = "\u0001";
 const TERMINAL_LINE_END = "\u0005";
+const TERMINAL_DELETE_TO_LINE_START = "\u0015";
 const EVENT_CODE_KEY_ALIASES: Readonly<Record<string, readonly string[]>> = {
   BracketLeft: ["["],
   BracketRight: ["]"],
@@ -370,6 +371,28 @@ export function isTerminalClearShortcut(
   );
 }
 
+export function terminalDeleteShortcutData(
+  event: ShortcutEventLike,
+  platform = navigator.platform,
+): string | null {
+  if (event.type !== undefined && event.type !== "keydown") {
+    return null;
+  }
+
+  if (!isMacPlatform(platform)) {
+    return null;
+  }
+
+  const key = normalizeEventKey(event.key);
+  if (key !== "backspace") {
+    return null;
+  }
+
+  return event.metaKey && !event.ctrlKey && !event.altKey && !event.shiftKey
+    ? TERMINAL_DELETE_TO_LINE_START
+    : null;
+}
+
 export function terminalNavigationShortcutData(
   event: ShortcutEventLike,
   platform = navigator.platform,