diff --git a/packages/vitest/src/runtime/moduleRunner/moduleRunner.ts b/packages/vitest/src/runtime/moduleRunner/moduleRunner.ts
index be655b57f8af..197023e09bba 100644
--- a/packages/vitest/src/runtime/moduleRunner/moduleRunner.ts
+++ b/packages/vitest/src/runtime/moduleRunner/moduleRunner.ts
@@ -168,23 +168,39 @@ export class VitestModuleRunner
     if (mod.meta && 'mockedModule' in mod.meta) {
       const mockedModule = mod.meta.mockedModule as MockedModule
       const mockId = this.mocker.getMockPath(mod.id)
-      // bypass mock and force "importActual" behavior when:
-      // - mock was removed by doUnmock (stale mockedModule in meta)
-      // - self-import: mock factory/file is importing the module it's mocking
-      const isStale = !this.mocker.getDependencyMock(mod.id)
+      const currentMock = this.mocker.getDependencyMock(mod.id)
+      if (!currentMock) {
+        const node = await this.fetchModule(injectQuery(url, '_vitest_original'))
+        return this._cachedRequest(node.url, node, callstack, metadata)
+      }
       const isSelfImport = callstack.includes(mockId)
         || callstack.includes(url)
-        || ('redirect' in mockedModule && callstack.includes(mockedModule.redirect))
-      if (isStale || isSelfImport) {
+        || ('redirect' in currentMock && callstack.includes(currentMock.redirect))
+      if (isSelfImport) {
         const node = await this.fetchModule(injectQuery(url, '_vitest_original'))
         return this._cachedRequest(node.url, node, callstack, metadata)
       }
-      mocked = await this.mocker.requestWithMockedModule(
-        url,
-        mod,
-        callstack,
-        mockedModule,
-      )
+      if (currentMock !== mockedModule) {
+        // Mock was replaced (e.g. manual → automock across test files with
+        // isolate:false). The module node's meta carries stale code (code: '')
+        // from the prior manual/redirect mock's fetchModule return. Re-fetch
+        // the actual module so requestWithMockedModule can evaluate real code.
+        const freshNode = await this.fetchModule(injectQuery(url, '_vitest_original'))
+        mocked = await this.mocker.requestWithMockedModule(
+          url,
+          freshNode,
+          callstack,
+          currentMock,
+        )
+      }
+      else {
+        mocked = await this.mocker.requestWithMockedModule(
+          url,
+          mod,
+          callstack,
+          currentMock,
+        )
+      }
     }
     else {
       mocked = await this.mocker.mockedRequest(url, mod, callstack)