fix(app): a focused terminal no longer shows a tall browser caret at its left edge

app/e2e/terminal-keys.spec.ts

@@ -48,3 +48,20 @@ for (const renderer of ["ghostty", "xterm"] as const) {
     await expect.poll(() => sent(page)).toBe("\x1b[13;2u\x1bb\x1bf\x01\x05\x15\r");
   });
 }
+
+// ghostty-web makes the terminal's host contenteditable and focuses it, so
+// without caret-color the browser blinks its own caret, the canvas's height,
+// at the left edge beside the terminal's cursor.
+test("ghostty: a focused terminal shows no browser caret", async ({ app }) => {
+  mockOnly("the shell is on the mock's gpu box");
+  await app.open({ prefs: { terminal: { renderer: "ghostty" } } });
+  const page = app.page;
+  await openShell(page);
+  const caret = () =>
+    page.evaluate(() => {
+      const a = document.activeElement as HTMLElement | null;
+      const host = a?.closest<HTMLElement>("[contenteditable=true]");
+      return host ? getComputedStyle(host).caretColor : "no editable host";
+    });
+  await expect.poll(caret).toBe("rgba(0, 0, 0, 0)");
+});

app/src/lib/terminal.ts

@@ -523,6 +523,10 @@ async function createGhostty(host: HTMLElement, colors: TerminalColors, prefs: T
     hung.stop();
     delete (t as { focus?: unknown }).focus;
   }
+  // open() makes the host contenteditable and focus() focuses the host, so
+  // the browser blinked its own text caret there, as tall as the canvas, at
+  // the terminal's left edge. The terminal draws its own cursor.
+  host.style.caretColor = "transparent";
   keepLastColumn(t);
   oneReadPerFrame(t);
   const frames = drawOnDemand(t, host, prefs.cursorBlink);

docs/changelog.mdx

@@ -10,14 +10,18 @@ upgrades with `berth upgrade BOX`, or by running the
 again.
 
 ## Unreleased
-
+- **No more tall blinking bar at a terminal's left edge.** With the Ghostty
+  renderer, a focused terminal showed the browser's own text cursor down its
+  whole height, next to the terminal's real cursor. Only the real one shows
+  now.
 - **A box newer than the app is no longer called outdated.** An older
   Shipyard used to offer to update a box that already ran a newer release,
   and *Update all* (or updating boxes automatically) would put its older
   `berthd` on it. Now a newer box is left alone, and `berth upgrade` refuses
   to downgrade one unless you pass `--force`. This works once both the app
   and the box are on this release or later.
 
+
 ## v0.3.22
 
 - **Mac terminal keys work in terminals.** ⇧↵ starts a new line in Claude