diff --git a/src/platform/auth/workspace/workspaceConstants.ts b/src/platform/auth/workspace/workspaceConstants.ts
index cc28d1f47..b56c1644d 100644
--- a/src/platform/auth/workspace/workspaceConstants.ts
+++ b/src/platform/auth/workspace/workspaceConstants.ts
@@ -1,7 +1,10 @@
 export const WORKSPACE_STORAGE_KEYS = {
+  // sessionStorage keys (cleared on browser close)
   CURRENT_WORKSPACE: 'Comfy.Workspace.Current',
   TOKEN: 'Comfy.Workspace.Token',
-  EXPIRES_AT: 'Comfy.Workspace.ExpiresAt'
+  EXPIRES_AT: 'Comfy.Workspace.ExpiresAt',
+  // localStorage key (persists across browser sessions)
+  LAST_WORKSPACE_ID: 'Comfy.Workspace.LastWorkspaceId'
 } as const
 
 export const TOKEN_REFRESH_BUFFER_MS = 5 * 60 * 1000
diff --git a/src/platform/navigation/preservedQueryNamespaces.ts b/src/platform/navigation/preservedQueryNamespaces.ts
index 541f18869..f8fb0a50e 100644
--- a/src/platform/navigation/preservedQueryNamespaces.ts
+++ b/src/platform/navigation/preservedQueryNamespaces.ts
@@ -1,3 +1,4 @@
 export const PRESERVED_QUERY_NAMESPACES = {
-  TEMPLATE: 'template'
+  TEMPLATE: 'template',
+  INVITE: 'invite'
 } as const
diff --git a/src/platform/workspace/api/workspaceApi.ts b/src/platform/workspace/api/workspaceApi.ts
new file mode 100644
index 000000000..4ea581dfb
--- /dev/null
+++ b/src/platform/workspace/api/workspaceApi.ts
@@ -0,0 +1,334 @@
+import type { AxiosResponse } from 'axios'
+import axios from 'axios'
+
+import { t } from '@/i18n'
+import { api } from '@/scripts/api'
+import { useFirebaseAuthStore } from '@/stores/firebaseAuthStore'
+import type { AuthHeader } from '@/types/authTypes'
+
+// Types aligned with backend API
+export type WorkspaceType = 'personal' | 'team'
+export type WorkspaceRole = 'owner' | 'member'
+
+interface Workspace {
+  id: string
+  name: string
+  type: WorkspaceType
+}
+
+export interface WorkspaceWithRole extends Workspace {
+  role: WorkspaceRole
+}
+
+// Member type from API
+export interface Member {
+  id: string
+  name: string
+  email: string
+  joined_at: string
+}
+
+interface PaginationInfo {
+  offset: number
+  limit: number
+  total: number
+}
+
+interface ListMembersResponse {
+  members: Member[]
+  pagination: PaginationInfo
+}
+
+export interface ListMembersParams {
+  offset?: number
+  limit?: number
+}
+
+// Pending invite type from API
+export interface PendingInvite {
+  id: string
+  email: string
+  token: string
+  invited_at: string
+  expires_at: string
+}
+
+interface ListInvitesResponse {
+  invites: PendingInvite[]
+}
+
+interface CreateInviteRequest {
+  email: string
+}
+
+interface AcceptInviteResponse {
+  workspace_id: string
+  workspace_name: string
+}
+
+// Billing types (POST /api/billing/portal)
+interface BillingPortalRequest {
+  return_url: string
+}
+
+interface BillingPortalResponse {
+  billing_portal_url: string
+}
+
+interface CreateWorkspacePayload {
+  name: string
+}
+
+interface UpdateWorkspacePayload {
+  name: string
+}
+
+// API responses
+interface ListWorkspacesResponse {
+  workspaces: WorkspaceWithRole[]
+}
+
+// Token exchange types (POST /api/auth/token)
+interface ExchangeTokenRequest {
+  workspace_id: string
+}
+
+export interface ExchangeTokenResponse {
+  token: string
+  expires_at: string
+  workspace: Workspace
+  role: WorkspaceRole
+  permissions: string[]
+}
+
+export class WorkspaceApiError extends Error {
+  constructor(
+    message: string,
+    public readonly status?: number,
+    public readonly code?: string
+  ) {
+    super(message)
+    this.name = 'WorkspaceApiError'
+  }
+}
+
+const workspaceApiClient = axios.create({
+  headers: {
+    'Content-Type': 'application/json'
+  }
+})
+
+async function withAuth<T>(
+  request: (headers: AuthHeader) => Promise<AxiosResponse<T>>
+): Promise<T> {
+  const authHeader = await useFirebaseAuthStore().getAuthHeader()
+  if (!authHeader) {
+    throw new WorkspaceApiError(
+      t('toastMessages.userNotAuthenticated'),
+      401,
+      'NOT_AUTHENTICATED'
+    )
+  }
+  try {
+    const response = await request(authHeader)
+    return response.data
+  } catch (err) {
+    if (axios.isAxiosError(err)) {
+      const status = err.response?.status
+      const message = err.response?.data?.message ?? err.message
+      throw new WorkspaceApiError(message, status)
+    }
+    throw err
+  }
+}
+
+/**
+ * Wrapper that uses Firebase ID token directly (not workspace token).
+ * Used for token exchange where we need the Firebase token to get a workspace token.
+ */
+async function withFirebaseAuth<T>(
+  request: (headers: AuthHeader) => Promise<AxiosResponse<T>>
+): Promise<T> {
+  const firebaseToken = await useFirebaseAuthStore().getIdToken()
+  if (!firebaseToken) {
+    throw new WorkspaceApiError(
+      t('toastMessages.userNotAuthenticated'),
+      401,
+      'NOT_AUTHENTICATED'
+    )
+  }
+  const headers: AuthHeader = { Authorization: `Bearer ${firebaseToken}` }
+  try {
+    const response = await request(headers)
+    return response.data
+  } catch (err) {
+    if (axios.isAxiosError(err)) {
+      const status = err.response?.status
+      const message = err.response?.data?.message ?? err.message
+      const code =
+        status === 401
+          ? 'INVALID_FIREBASE_TOKEN'
+          : status === 403
+            ? 'ACCESS_DENIED'
+            : status === 404
+              ? 'WORKSPACE_NOT_FOUND'
+              : 'TOKEN_EXCHANGE_FAILED'
+      throw new WorkspaceApiError(message, status, code)
+    }
+    throw err
+  }
+}
+
+export const workspaceApi = {
+  /**
+   * List all workspaces the user has access to
+   * GET /api/workspaces
+   */
+  list: (): Promise<ListWorkspacesResponse> =>
+    withAuth((headers) =>
+      workspaceApiClient.get(api.apiURL('/workspaces'), { headers })
+    ),
+
+  /**
+   * Create a new workspace
+   * POST /api/workspaces
+   */
+  create: (payload: CreateWorkspacePayload): Promise<WorkspaceWithRole> =>
+    withAuth((headers) =>
+      workspaceApiClient.post(api.apiURL('/workspaces'), payload, { headers })
+    ),
+
+  /**
+   * Update workspace name
+   * PATCH /api/workspaces/:id
+   */
+  update: (
+    workspaceId: string,
+    payload: UpdateWorkspacePayload
+  ): Promise<WorkspaceWithRole> =>
+    withAuth((headers) =>
+      workspaceApiClient.patch(
+        api.apiURL(`/workspaces/${workspaceId}`),
+        payload,
+        { headers }
+      )
+    ),
+
+  /**
+   * Delete a workspace (owner only)
+   * DELETE /api/workspaces/:id
+   */
+  delete: (workspaceId: string): Promise<void> =>
+    withAuth((headers) =>
+      workspaceApiClient.delete(api.apiURL(`/workspaces/${workspaceId}`), {
+        headers
+      })
+    ),
+
+  /**
+   * Leave the current workspace.
+   * POST /api/workspace/leave
+   */
+  leave: (): Promise<void> =>
+    withAuth((headers) =>
+      workspaceApiClient.post(api.apiURL('/workspace/leave'), null, { headers })
+    ),
+
+  /**
+   * List workspace members (paginated).
+   * GET /api/workspace/members
+   */
+  listMembers: (params?: ListMembersParams): Promise<ListMembersResponse> =>
+    withAuth((headers) =>
+      workspaceApiClient.get(api.apiURL('/workspace/members'), {
+        headers,
+        params
+      })
+    ),
+
+  /**
+   * Remove a member from the workspace.
+   * DELETE /api/workspace/members/:userId
+   */
+  removeMember: (userId: string): Promise<void> =>
+    withAuth((headers) =>
+      workspaceApiClient.delete(api.apiURL(`/workspace/members/${userId}`), {
+        headers
+      })
+    ),
+
+  /**
+   * List pending invites for the workspace.
+   * GET /api/workspace/invites
+   */
+  listInvites: (): Promise<ListInvitesResponse> =>
+    withAuth((headers) =>
+      workspaceApiClient.get(api.apiURL('/workspace/invites'), { headers })
+    ),
+
+  /**
+   * Create an invite for the workspace.
+   * POST /api/workspace/invites
+   */
+  createInvite: (payload: CreateInviteRequest): Promise<PendingInvite> =>
+    withAuth((headers) =>
+      workspaceApiClient.post(api.apiURL('/workspace/invites'), payload, {
+        headers
+      })
+    ),
+
+  /**
+   * Revoke a pending invite.
+   * DELETE /api/workspace/invites/:inviteId
+   */
+  revokeInvite: (inviteId: string): Promise<void> =>
+    withAuth((headers) =>
+      workspaceApiClient.delete(api.apiURL(`/workspace/invites/${inviteId}`), {
+        headers
+      })
+    ),
+
+  /**
+   * Accept a workspace invite.
+   * POST /api/invites/:token/accept
+   */
+  acceptInvite: (token: string): Promise<AcceptInviteResponse> =>
+    withAuth((headers) =>
+      workspaceApiClient.post(api.apiURL(`/invites/${token}/accept`), null, {
+        headers
+      })
+    ),
+
+  /**
+   * Exchange Firebase JWT for workspace-scoped Cloud JWT.
+   * POST /api/auth/token
+   *
+   * Uses Firebase ID token directly (not getAuthHeader) since we're
+   * exchanging it for a workspace-scoped token.
+   */
+  exchangeToken: (workspaceId: string): Promise<ExchangeTokenResponse> =>
+    withFirebaseAuth((headers) =>
+      workspaceApiClient.post(
+        api.apiURL('/auth/token'),
+        { workspace_id: workspaceId } satisfies ExchangeTokenRequest,
+        { headers }
+      )
+    ),
+
+  /**
+   * Access the billing portal for the current workspace.
+   * POST /api/billing/portal
+   *
+   * Uses workspace-scoped token to get billing portal URL.
+   */
+  accessBillingPortal: (returnUrl?: string): Promise<BillingPortalResponse> =>
+    withAuth((headers) =>
+      workspaceApiClient.post(
+        api.apiURL('/billing/portal'),
+        {
+          return_url: returnUrl ?? window.location.href
+        } satisfies BillingPortalRequest,
+        { headers }
+      )
+    )
+}
diff --git a/src/platform/workspace/services/sessionManager.ts b/src/platform/workspace/services/sessionManager.ts
new file mode 100644
index 000000000..c26859a75
--- /dev/null
+++ b/src/platform/workspace/services/sessionManager.ts
@@ -0,0 +1,148 @@
+import { WORKSPACE_STORAGE_KEYS } from '@/platform/auth/workspace/workspaceConstants'
+
+/**
+ * Session manager for workspace context.
+ * Handles sessionStorage operations and page reloads for workspace switching.
+ */
+export const sessionManager = {
+  /**
+   * Get the current workspace ID from sessionStorage
+   */
+  getCurrentWorkspaceId(): string | null {
+    try {
+      return sessionStorage.getItem(WORKSPACE_STORAGE_KEYS.CURRENT_WORKSPACE)
+    } catch {
+      return null
+    }
+  },
+
+  /**
+   * Set the current workspace ID in sessionStorage
+   */
+  setCurrentWorkspaceId(workspaceId: string): void {
+    try {
+      sessionStorage.setItem(
+        WORKSPACE_STORAGE_KEYS.CURRENT_WORKSPACE,
+        workspaceId
+      )
+    } catch {
+      console.warn('Failed to set workspace ID in sessionStorage')
+    }
+  },
+
+  /**
+   * Clear the current workspace ID from sessionStorage
+   */
+  clearCurrentWorkspaceId(): void {
+    try {
+      sessionStorage.removeItem(WORKSPACE_STORAGE_KEYS.CURRENT_WORKSPACE)
+    } catch {
+      console.warn('Failed to clear workspace ID from sessionStorage')
+    }
+  },
+
+  /**
+   * Get the last workspace ID from localStorage (cross-session persistence)
+   */
+  getLastWorkspaceId(): string | null {
+    try {
+      return localStorage.getItem(WORKSPACE_STORAGE_KEYS.LAST_WORKSPACE_ID)
+    } catch {
+      return null
+    }
+  },
+
+  /**
+   * Persist the last workspace ID to localStorage
+   */
+  setLastWorkspaceId(workspaceId: string): void {
+    try {
+      localStorage.setItem(
+        WORKSPACE_STORAGE_KEYS.LAST_WORKSPACE_ID,
+        workspaceId
+      )
+    } catch {
+      console.warn('Failed to persist last workspace ID to localStorage')
+    }
+  },
+
+  /**
+   * Clear the last workspace ID from localStorage
+   */
+  clearLastWorkspaceId(): void {
+    try {
+      localStorage.removeItem(WORKSPACE_STORAGE_KEYS.LAST_WORKSPACE_ID)
+    } catch {
+      console.warn('Failed to clear last workspace ID from localStorage')
+    }
+  },
+
+  /**
+   * Get the workspace token and expiry from sessionStorage
+   */
+  getWorkspaceToken(): { token: string; expiresAt: number } | null {
+    try {
+      const token = sessionStorage.getItem(WORKSPACE_STORAGE_KEYS.TOKEN)
+      const expiresAtStr = sessionStorage.getItem(
+        WORKSPACE_STORAGE_KEYS.EXPIRES_AT
+      )
+      if (!token || !expiresAtStr) return null
+
+      const expiresAt = parseInt(expiresAtStr, 10)
+      if (isNaN(expiresAt)) return null
+
+      return { token, expiresAt }
+    } catch {
+      return null
+    }
+  },
+
+  /**
+   * Store the workspace token and expiry in sessionStorage
+   */
+  setWorkspaceToken(token: string, expiresAt: number): void {
+    try {
+      sessionStorage.setItem(WORKSPACE_STORAGE_KEYS.TOKEN, token)
+      sessionStorage.setItem(
+        WORKSPACE_STORAGE_KEYS.EXPIRES_AT,
+        expiresAt.toString()
+      )
+    } catch {
+      console.warn('Failed to set workspace token in sessionStorage')
+    }
+  },
+
+  /**
+   * Clear the workspace token from sessionStorage
+   */
+  clearWorkspaceToken(): void {
+    try {
+      sessionStorage.removeItem(WORKSPACE_STORAGE_KEYS.TOKEN)
+      sessionStorage.removeItem(WORKSPACE_STORAGE_KEYS.EXPIRES_AT)
+    } catch {
+      console.warn('Failed to clear workspace token from sessionStorage')
+    }
+  },
+
+  /**
+   * Switch workspace and reload the page.
+   * Clears the old workspace token before reload so fresh token is fetched.
+   * Code after calling this won't execute (page is gone).
+   */
+  switchWorkspaceAndReload(workspaceId: string): void {
+    this.clearWorkspaceToken()
+    this.setCurrentWorkspaceId(workspaceId)
+    this.setLastWorkspaceId(workspaceId)
+    window.location.reload()
+  },
+
+  /**
+   * Clear workspace context and reload (e.g., after deletion).
+   * Falls back to personal workspace on next boot.
+   */
+  clearAndReload(): void {
+    this.clearWorkspaceToken()
+    this.clearCurrentWorkspaceId()
+    window.location.reload()
+  }
+}