Add integration tests for reconnect scenarios

Test that initial_state provides full terminal state, multiple
sessions are independent, and the CSI 'T' artifact bug is fixed.

src/terminal.test.ts

@@ -164,4 +164,105 @@ describe("terminal", () => {
 
     disposeTerminal(term);
   });
+
+  describe("reconnect scenarios", () => {
+    test("initial_state provides full terminal state for reconnecting clients", async () => {
+      const term = createTerminal(80, 24);
+
+      // Simulate some output that a client missed
+      await writeSync(term, "Line 1\r\n");
+      await writeSync(term, "Line 2\r\n");
+      await writeSync(term, "\x1b[31mRed line\x1b[0m\r\n");
+
+      // Serialize the full state (as sent in initial_state event)
+      const html = serializeAsHTML(term);
+
+      // Verify all content is present
+      expect(html).toContain("Line 1");
+      expect(html).toContain("Line 2");
+      expect(html).toContain("Red line");
+
+      // Verify ANSI styling is preserved
+      expect(html).toMatch(/color|red|#[a-f0-9]{6}/i);
+
+      disposeTerminal(term);
+    });
+
+    test("multiple sessions have independent terminal emulators", async () => {
+      const term1 = createTerminal(80, 24);
+      const term2 = createTerminal(80, 24);
+
+      // Write different content to each
+      await writeSync(term1, "Session 1 output");
+      await writeSync(term2, "Session 2 output");
+
+      const html1 = serializeAsHTML(term1);
+      const html2 = serializeAsHTML(term2);
+
+      // Each should have only its own content
+      expect(html1).toContain("Session 1 output");
+      expect(html1).not.toContain("Session 2 output");
+      expect(html2).toContain("Session 2 output");
+      expect(html2).not.toContain("Session 1 output");
+
+      disposeTerminal(term1);
+      disposeTerminal(term2);
+    });
+
+    test("T artifact bug is fixed (CSI sequences with T final byte)", async () => {
+      const term = createTerminal(80, 24);
+
+      // CSI sequences ending in 'T' (scroll down) were leaking through as literal 'T'
+      // This was a bug in our old ANSI parser
+      await writeSync(term, "Before\x1b[1T"); // Scroll down 1 line
+      await writeSync(term, "After");
+
+      const html = serializeAsHTML(term);
+
+      // Should not contain literal 'T' from the escape sequence
+      // Only 'Before' and 'After' should be visible
+      expect(html).toContain("Before");
+      expect(html).toContain("After");
+
+      // Extract text content without HTML tags
+      const textContent = html
+        .replace(/<[^>]+>/g, "")
+        .replace(/&nbsp;/g, " ")
+        .trim();
+
+      // Should not have standalone 'T' characters
+      expect(textContent).not.toMatch(/\bT\b/);
+
+      disposeTerminal(term);
+    });
+
+    test("complex ANSI sequences don't leak artifacts", async () => {
+      const term = createTerminal(80, 24);
+
+      // Test various CSI final bytes that could leak as literals
+      await writeSync(term, "Start\r\n");
+      await writeSync(term, "\x1b[2J"); // Clear screen (J)
+      await writeSync(term, "\x1b[H"); // Cursor home (H)
+      await writeSync(term, "\x1b[K"); // Clear to end of line (K)
+      await writeSync(term, "\x1b[1T"); // Scroll down (T)
+      await writeSync(term, "\x1b[1S"); // Scroll up (S)
+      await writeSync(term, "Clean output");
+
+      const html = serializeAsHTML(term);
+
+      // Should only contain the actual text
+      expect(html).toContain("Clean output");
+
+      // Extract text without HTML
+      const textContent = html
+        .replace(/<[^>]+>/g, "")
+        .replace(/&nbsp;/g, " ")
+        .trim();
+
+      // Should not contain literal CSI final bytes
+      expect(textContent).not.toMatch(/[HJKTS](?!.*Clean)/);
+
+      disposeTerminal(term);
+    });
+  });
 });