fix(ssh): contain relay notification handler failures (#2463)

Co-authored-by: Orca <help@stably.ai>

src/main/ssh/ssh-channel-multiplexer.test.ts

@@ -229,6 +229,50 @@ describe('SshChannelMultiplexer', () => {
       expect(a).not.toHaveBeenCalled()
       expect(b).toHaveBeenCalledWith({ streamId: 7 })
     })
+
+    it('contains generic notification handler failures', () => {
+      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {})
+      const badHandler = vi.fn(() => {
+        throw new Error('subscriber exploded')
+      })
+      const goodHandler = vi.fn()
+      mux.onNotification(badHandler)
+      mux.onNotification(goodHandler)
+
+      expect(() =>
+        transport.dataCallbacks[0](makeNotificationFrame('pty.data', { id: 'pty-1' }, 1))
+      ).not.toThrow()
+
+      expect(badHandler).toHaveBeenCalled()
+      expect(goodHandler).toHaveBeenCalledWith('pty.data', { id: 'pty-1' })
+      expect(mux.isDisposed()).toBe(false)
+      expect(warnSpy).toHaveBeenCalledWith(
+        '[ssh-mux] Notification handler failed for pty.data: subscriber exploded'
+      )
+    })
+
+    it('contains method notification handler failures', () => {
+      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {})
+      const badHandler = vi.fn(() => {
+        throw new Error('stream consumer exploded')
+      })
+      const goodHandler = vi.fn()
+      mux.onNotificationByMethod('fs.streamChunk', badHandler)
+      mux.onNotificationByMethod('fs.streamChunk', goodHandler)
+
+      expect(() =>
+        transport.dataCallbacks[0](
+          makeNotificationFrame('fs.streamChunk', { streamId: 1, seq: 0, data: 'aGk=' }, 1)
+        )
+      ).not.toThrow()
+
+      expect(badHandler).toHaveBeenCalled()
+      expect(goodHandler).toHaveBeenCalledWith({ streamId: 1, seq: 0, data: 'aGk=' })
+      expect(mux.isDisposed()).toBe(false)
+      expect(warnSpy).toHaveBeenCalledWith(
+        '[ssh-mux] Method notification handler failed for fs.streamChunk: stream consumer exploded'
+      )
+    })
   })
 
   describe('keepalive', () => {

src/main/ssh/ssh-channel-multiplexer.ts

@@ -361,13 +361,33 @@ export class SshChannelMultiplexer {
     // collection and skips the next handler. Iterating a snapshot prevents that.
     const snapshot = Array.from(this.notificationHandlers)
     for (const handler of snapshot) {
-      handler(msg.method, params)
+      try {
+        handler(msg.method, params)
+      } catch (err) {
+        // Why: relay notifications arrive on the SSH stream callback; one
+        // bad subscriber must not escape as a main-process uncaught exception.
+        console.warn(
+          `[ssh-mux] Notification handler failed for ${msg.method}: ${
+            err instanceof Error ? err.message : String(err)
+          }`
+        )
+      }
     }
     const methodHandlers = this.methodNotificationHandlers.get(msg.method)
     if (methodHandlers && methodHandlers.size > 0) {
       const methodSnapshot = Array.from(methodHandlers)
       for (const handler of methodSnapshot) {
-        handler(params)
+        try {
+          handler(params)
+        } catch (err) {
+          // Why: file-stream and PTY listeners are per-method subscribers; keep
+          // the mux alive even if one consumer rejects a malformed notification.
+          console.warn(
+            `[ssh-mux] Method notification handler failed for ${msg.method}: ${
+              err instanceof Error ? err.message : String(err)
+            }`
+          )
+        }
       }
     }
   }