diff --git a/src/platform/auth/session/useSessionCookie.ts b/src/platform/auth/session/useSessionCookie.ts
index 49f6fec46e..1f1750f066 100644
--- a/src/platform/auth/session/useSessionCookie.ts
+++ b/src/platform/auth/session/useSessionCookie.ts
@@ -1,3 +1,5 @@
+import { createSingletonPromise } from '@vueuse/core'
+
 import { api } from '@/scripts/api'
 import { isCloud } from '@/platform/distribution/types'
 import { useFirebaseAuthStore } from '@/stores/firebaseAuthStore'
@@ -12,29 +14,17 @@ export const useSessionCookie = () => {
    * Called after login and on token refresh.
    */
   const createSession = async (): Promise<void> => {
-    if (!isCloud) return
+    if (!isCloud || logoutInProgress) return
 
-    const authStore = useFirebaseAuthStore()
-    const authHeader = await authStore.getAuthHeader()
-
-    if (!authHeader) {
-      throw new Error('No auth header available for session creation')
-    }
+    const promise = createSessionSingleton()
+    inFlightCreateSession = promise
 
-    const response = await fetch(api.apiURL('/auth/session'), {
-      method: 'POST',
-      credentials: 'include',
-      headers: {
-        ...authHeader,
-        'Content-Type': 'application/json'
+    try {
+      await promise
+    } finally {
+      if (inFlightCreateSession === promise) {
+        inFlightCreateSession = null
       }
-    })
-
-    if (!response.ok) {
-      const errorData = await response.json().catch(() => ({}))
-      throw new Error(
-        `Failed to create session: ${errorData.message || response.statusText}`
-      )
     }
   }
 
@@ -45,21 +35,90 @@ export const useSessionCookie = () => {
   const deleteSession = async (): Promise<void> => {
     if (!isCloud) return
 
+    logoutInProgress = true
+
+    try {
+      if (inFlightCreateSession) {
+        currentCreateController?.abort()
+        try {
+          await inFlightCreateSession
+        } catch (error: unknown) {
+          if (!isAbortError(error)) {
+            throw error
+          }
+        }
+      }
+
+      const response = await fetch(api.apiURL('/auth/session'), {
+        method: 'DELETE',
+        credentials: 'include'
+      })
+
+      if (!response.ok) {
+        const errorData = await response.json().catch(() => ({}))
+        throw new Error(
+          `Failed to delete session: ${
+            errorData.message || response.statusText
+          }`
+        )
+      }
+    } finally {
+      logoutInProgress = false
+      await createSessionSingleton.reset()
+    }
+  }
+
+  return {
+    createSession,
+    deleteSession
+  }
+}
+
+let inFlightCreateSession: Promise<void> | null = null
+let currentCreateController: AbortController | null = null
+let logoutInProgress = false
+
+const createSessionSingleton = createSingletonPromise(async () => {
+  const authStore = useFirebaseAuthStore()
+  const authHeader = await authStore.getAuthHeader()
+
+  if (!authHeader) {
+    throw new Error('No auth header available for session creation')
+  }
+
+  const controller = new AbortController()
+  currentCreateController = controller
+
+  try {
     const response = await fetch(api.apiURL('/auth/session'), {
-      method: 'DELETE',
-      credentials: 'include'
+      method: 'POST',
+      credentials: 'include',
+      signal: controller.signal,
+      headers: {
+        ...authHeader,
+        'Content-Type': 'application/json'
+      }
     })
 
     if (!response.ok) {
       const errorData = await response.json().catch(() => ({}))
       throw new Error(
-        `Failed to delete session: ${errorData.message || response.statusText}`
+        `Failed to create session: ${errorData.message || response.statusText}`
       )
     }
+  } catch (error: unknown) {
+    if (!isAbortError(error)) {
+      throw error
+    }
+  } finally {
+    if (currentCreateController === controller) {
+      currentCreateController = null
+    }
   }
+})
 
-  return {
-    createSession,
-    deleteSession
-  }
+const isAbortError = (error: unknown): boolean => {
+  if (!error || typeof error !== 'object') return false
+  const name = 'name' in error ? (error as { name?: string }).name : undefined
+  return name === 'AbortError'
 }
diff --git a/tests-ui/platform/auth/session/useSessionCookie.test.ts b/tests-ui/platform/auth/session/useSessionCookie.test.ts
new file mode 100644
index 0000000000..b25f1f64ed
--- /dev/null
+++ b/tests-ui/platform/auth/session/useSessionCookie.test.ts
@@ -0,0 +1,139 @@
+import { describe, expect, it, vi } from 'vitest'
+
+const makeSuccessResponse = () =>
+  new Response('{}', {
+    status: 200,
+    statusText: 'OK',
+    headers: { 'Content-Type': 'application/json' }
+  })
+
+type Deferred<T> = {
+  promise: Promise<T>
+  resolve: (value: T) => void
+  reject: (reason: unknown) => void
+}
+
+const createDeferred = <T>(): Deferred<T> => {
+  let resolve: (value: T) => void
+  let reject: (reason: unknown) => void
+
+  const promise = new Promise<T>((res, rej) => {
+    resolve = res
+    reject = rej
+  })
+
+  // @ts-expect-error initialized via closure assignments above
+  return { promise, resolve, reject }
+}
+
+const mockModules = async () => {
+  vi.resetModules()
+
+  const getAuthHeader = vi.fn(async () => ({ Authorization: 'Bearer token' }))
+
+  vi.doMock('@/scripts/api', () => ({
+    api: {
+      apiURL: vi.fn((path: string) => `/api${path}`)
+    }
+  }))
+
+  vi.doMock('@/platform/distribution/types', () => ({
+    isCloud: true
+  }))
+
+  vi.doMock('@/stores/firebaseAuthStore', () => ({
+    useFirebaseAuthStore: vi.fn(() => ({
+      getAuthHeader
+    }))
+  }))
+
+  const module = await import('@/platform/auth/session/useSessionCookie')
+  return { getAuthHeader, useSessionCookie: module.useSessionCookie }
+}
+
+describe('useSessionCookie', () => {
+  it('deduplicates in-flight session creation', async () => {
+    const { useSessionCookie, getAuthHeader } = await mockModules()
+
+    const postDeferred = createDeferred<Response>()
+
+    const fetchSpy = vi
+      .spyOn(globalThis, 'fetch')
+      .mockImplementation(() => postDeferred.promise)
+
+    const { createSession } = useSessionCookie()
+
+    const firstCall = createSession()
+    const secondCall = createSession()
+
+    await Promise.resolve()
+
+    expect(fetchSpy).toHaveBeenCalledTimes(1)
+    expect(getAuthHeader).toHaveBeenCalledTimes(1)
+
+    postDeferred.resolve(makeSuccessResponse())
+    await expect(firstCall).resolves.toBeUndefined()
+    await expect(secondCall).resolves.toBeUndefined()
+
+    fetchSpy.mockRestore()
+  })
+
+  it('aborts pending create on logout and skips new ones while logout is in progress', async () => {
+    const { useSessionCookie, getAuthHeader } = await mockModules()
+
+    const firstPostDeferred = createDeferred<Response>()
+    const deleteDeferred = createDeferred<Response>()
+
+    let capturedSignal: AbortSignal | undefined
+
+    const fetchSpy = vi.spyOn(globalThis, 'fetch')
+    fetchSpy
+      .mockImplementationOnce((_, init?: RequestInit) => {
+        capturedSignal = init?.signal as AbortSignal | undefined
+        return firstPostDeferred.promise
+      })
+      .mockImplementationOnce((_, init?: RequestInit) => {
+        expect(init?.method).toBe('DELETE')
+        return deleteDeferred.promise
+      })
+      .mockImplementation((_, init?: RequestInit) => {
+        if (init?.method === 'POST') {
+          return Promise.resolve(makeSuccessResponse())
+        }
+        return Promise.resolve(makeSuccessResponse())
+      })
+
+    const { createSession, deleteSession } = useSessionCookie()
+
+    const createPromise = createSession()
+
+    await Promise.resolve()
+
+    const logoutPromise = deleteSession()
+
+    await Promise.resolve()
+
+    expect(fetchSpy).toHaveBeenCalledTimes(1)
+    expect(capturedSignal?.aborted).toBe(true)
+
+    const abortError = new Error('aborted')
+    abortError.name = 'AbortError'
+    firstPostDeferred.reject(abortError)
+    await expect(createPromise).resolves.toBeUndefined()
+
+    await Promise.resolve()
+    expect(fetchSpy).toHaveBeenCalledTimes(2)
+    expect(getAuthHeader).toHaveBeenCalledTimes(1)
+
+    await expect(createSession()).resolves.toBeUndefined()
+    expect(fetchSpy).toHaveBeenCalledTimes(2)
+
+    deleteDeferred.resolve(makeSuccessResponse())
+    await expect(logoutPromise).resolves.toBeUndefined()
+
+    await expect(createSession()).resolves.toBeUndefined()
+    expect(fetchSpy).toHaveBeenCalledTimes(3)
+
+    fetchSpy.mockRestore()
+  })
+})