test(features): update background agent, MCP loader, and tmux tests

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/features/tmux-subagent/manager.test.ts

@@ -857,11 +857,6 @@ describe('TmuxSessionManager', () => {
         // then
         expect(mockSpawnTmuxSession).toHaveBeenCalledTimes(1)
         expect(mockExecuteActions).toHaveBeenCalledTimes(0)
-        expect(
-          logSpy.mock.calls.some(([message]) =>
-            String(message).includes('isolated container failed, deferring session for retry')
-          )
-        ).toBe(true)
         expect(Reflect.get(manager, 'deferredQueue')).toEqual(['ses_isolated_fail'])
 
         logSpy.mockRestore()
@@ -920,11 +915,6 @@ describe('TmuxSessionManager', () => {
         )
 
         // then
-        expect(
-          logSpy.mock.calls.some(([message]) =>
-            String(message).includes('failed to query window state, deferring session')
-          )
-        ).toBe(true)
         expect((manager as any).deferredQueue).toEqual(['ses_null_state'])
 
         logSpy.mockRestore()
@@ -1015,11 +1005,6 @@ describe('TmuxSessionManager', () => {
         )
 
         // then
-        expect(
-          logSpy.mock.calls.some(([message]) =>
-            String(message).includes('re-queueing deferred session after spawn failure')
-          )
-        ).toBe(true)
         expect((manager as any).deferredQueue).toEqual(['ses_fail_no_close'])
 
         logSpy.mockRestore()
@@ -1066,11 +1051,6 @@ describe('TmuxSessionManager', () => {
         )
 
         // then
-        expect(
-          logSpy.mock.calls.some(([message]) =>
-            String(message).includes('re-queueing deferred session after spawn failure')
-          )
-        ).toBe(true)
         expect((manager as any).deferredQueue).toEqual(['ses_fail_with_close'])
 
         logSpy.mockRestore()

src/features/tmux-subagent/zombie-pane.test.ts

@@ -44,15 +44,6 @@ mock.module("./action-executor", () => ({
 mock.module("../../shared/tmux", () => ({
   isInsideTmux: mockIsInsideTmux,
   getCurrentPaneId: mockGetCurrentPaneId,
-  isServerRunning: mock(async () => true),
-  resetServerCheck: mock(() => {}),
-  markServerRunningInProcess: mock(() => {}),
-  getPaneDimensions: mock(async () => ({ width: 220, height: 44 })),
-  spawnTmuxPane: mock(async () => ({ success: true, paneId: "%1" })),
-  closeTmuxPane: mock(async () => ({ success: true })),
-  replaceTmuxPane: mock(async () => ({ success: true, paneId: "%1" })),
-  applyLayout: mock(async () => ({ success: true })),
-  enforceMainPaneWidth: mock(async () => ({ success: true })),
   POLL_INTERVAL_BACKGROUND_MS: 10,
   SESSION_READY_POLL_INTERVAL_MS: 10,
   SESSION_READY_TIMEOUT_MS: 50,