fix: detect titles and bells in byte writes, skip OSC terminators

lib/terminal.test.ts

@@ -241,6 +241,41 @@ describe('Terminal', () => {
 
       term.dispose();
     });
+
+    test('onBell fires on a bell character in bytes', async () => {
+      const term = await createIsolatedTerminal();
+      term.open(container!);
+
+      let bellFired = false;
+      term.onBell(() => {
+        bellFired = true;
+      });
+
+      term.write(new Uint8Array([0x61, 0x07]));
+
+      expect(bellFired).toBe(true);
+
+      term.dispose();
+    });
+
+    test('onBell does not fire on the BEL that ends an OSC sequence', async () => {
+      const term = await createIsolatedTerminal();
+      term.open(container!);
+
+      let bells = 0;
+      term.onBell(() => {
+        bells++;
+      });
+
+      term.write('\x1b]2;title\x07');
+      term.write(new TextEncoder().encode('\x1b]8;;https://example.com\x07link\x1b]8;;\x07'));
+      expect(bells).toBe(0);
+
+      term.write('\x1b]2;title\x07\x07');
+      expect(bells).toBe(1);
+
+      term.dispose();
+    });
   });
 
   describe('Writing', () => {
@@ -1021,6 +1056,23 @@ describe('onTitleChange event', () => {
       expect(receivedTitle).toBe('Title with ST');
       term.dispose();
     });
+
+    test('should fire when the sequence is written as bytes', async () => {
+      const term = await createIsolatedTerminal({ cols: 80, rows: 24 });
+      // Using shared container from beforeEach
+      if (!container) return;
+      term.open(container!);
+
+      let receivedTitle = '';
+      term.onTitleChange((title) => {
+        receivedTitle = title;
+      });
+
+      term.write(new TextEncoder().encode('\x1b]2;Bytes · Title\x07'));
+
+      expect(receivedTitle).toBe('Bytes · Title');
+      term.dispose();
+    });
   });
 });
 

lib/terminal.ts

@@ -38,6 +38,11 @@ import { CanvasRenderer } from './renderer';
 import { SelectionManager } from './selection-manager';
 import type { ILink, ILinkProvider } from './types';
 
+/** An OSC sequence with its BEL or ST terminator. */
+const OSC_SEQUENCE = /\x1b\][^\x07\x1b]*(?:\x07|\x1b\\)/g;
+
+const utf8Decoder = new TextDecoder();
+
 // ============================================================================
 // Terminal Class
 // ============================================================================
@@ -566,11 +571,18 @@ export class Terminal implements ITerminalCore {
     // These need to be sent back to the PTY via onData
     this.processTerminalResponses();
 
-    // Check for bell character (BEL, \x07)
-    // WASM doesn't expose bell events, so we detect it in the data stream
-    if (typeof data === 'string' && data.includes('\x07')) {
-      this.bellEmitter.fire();
-    } else if (data instanceof Uint8Array && data.includes(0x07)) {
+    // WASM doesn't expose bell or title events, so we detect them in the data
+    // stream. Bytes are only decoded when they hold a BEL or an OSC sequence.
+    const text =
+      typeof data === 'string'
+        ? data
+        : data.includes(0x07) || hasOscStart(data)
+          ? utf8Decoder.decode(data)
+          : '';
+
+    // Check for bell character (BEL, \x07), skipping the BEL that ends an OSC
+    // sequence (titles, hyperlinks, clipboard)
+    if (text.includes('\x07') && text.replace(OSC_SEQUENCE, '').includes('\x07')) {
       this.bellEmitter.fire();
     }
 
@@ -584,8 +596,8 @@ export class Terminal implements ITerminalCore {
 
     // Check for title changes (OSC 0, 1, 2 sequences)
     // This is a simplified implementation - Ghostty WASM may provide this
-    if (typeof data === 'string' && data.includes('\x1b]')) {
-      this.checkForTitleChange(data);
+    if (text.includes('\x1b]')) {
+      this.checkForTitleChange(text);
     }
 
     // Call callback if provided
@@ -1914,3 +1926,11 @@ export class Terminal implements ITerminalCore {
     return this.wasmTerm!.hasMouseTracking();
   }
 }
+
+/** Whether bytes contain ESC ] (the start of an OSC sequence). */
+function hasOscStart(data: Uint8Array): boolean {
+  for (let i = data.indexOf(0x1b); i !== -1; i = data.indexOf(0x1b, i + 1)) {
+    if (data[i + 1] === 0x5d) return true;
+  }
+  return false;
+}