fix: guard handleClientMessage against resize on exited PTY

pty.resize() throws EBADF after the PTY process exits. A resize
message arriving after exit but before client cleanup propagates
the throw through the Hono WS handler, producing noisy errors.

Add this.exited early-return for input and resize cases, matching
the guard pattern already used in addClient(). ping remains
unguarded — it's pure WS with no PTY involvement.

Author: connorads

src/session.ts

@@ -145,10 +145,12 @@ export class SharedTerminalSession {
 	handleClientMessage(client: SessionClient, message: ClientMessage): void {
 		switch (message.type) {
 			case 'input':
+				if (this.exited) return
 				this.pty.write(message.data)
 				return
 
 			case 'resize':
+				if (this.exited) return
 				this.pty.resize(message.cols, message.rows)
 				this.mirror.resize(message.cols, message.rows)
 				return

tests/session.test.ts

@@ -59,6 +59,22 @@ describe('SharedTerminalSession', () => {
 		expect(recorder.getCloseCount()).toBe(1)
 	})
 
+	test('handleClientMessage silently ignores input and resize after PTY exit', async () => {
+		const session = new SharedTerminalSession(['bash', '--norc', '--noprofile', '-lc', 'exit 0'])
+
+		await session.onExit
+
+		const recorder = createClientRecorder()
+
+		// pty.resize() throws EBADF after exit — these must not throw
+		session.handleClientMessage(recorder.client, { type: 'input', data: 'hello' })
+		session.handleClientMessage(recorder.client, { type: 'resize', cols: 120, rows: 40 })
+
+		// ping should still work — pure WS, no PTY involvement
+		session.handleClientMessage(recorder.client, { type: 'ping' })
+		expect(recorder.getMessages()).toEqual([{ type: 'pong' }])
+	})
+
 	test('late clients receive the final snapshot and exit after the PTY is gone', async () => {
 		const session = new SharedTerminalSession([
 			'bash',