diff --git a/frontend/taskdeck-web/src/store/board/boardCrudStore.ts b/frontend/taskdeck-web/src/store/board/boardCrudStore.ts
index d3f7b558f..2126563d4 100644
--- a/frontend/taskdeck-web/src/store/board/boardCrudStore.ts
+++ b/frontend/taskdeck-web/src/store/board/boardCrudStore.ts
@@ -20,7 +20,18 @@ export function createBoardCrudActions(state: BoardState, helpers: BoardHelpers)
     try {
       state.loading.value = true
       state.error.value = null
-      state.boards.value = await boardsApi.getBoards(search, includeArchived)
+      const freshBoards = await boardsApi.getBoards(search, includeArchived)
+      state.boards.value = freshBoards
+
+      // Preserve selection guard: only update activeBoardId if there is no
+      // current selection or the previously-selected board is no longer in the
+      // refreshed list (e.g. it was deleted). This prevents polling/subscription
+      // refreshes from resetting the user's active board to the first item.
+      const currentId = state.activeBoardId.value
+      const stillExists = currentId !== null && freshBoards.some((b) => b.id === currentId)
+      if (!stillExists) {
+        state.activeBoardId.value = freshBoards[0]?.id ?? null
+      }
     } catch (e: unknown) {
       helpers.handleApiError(e, 'Failed to fetch boards')
       throw e
@@ -117,6 +128,11 @@ export function createBoardCrudActions(state: BoardState, helpers: BoardHelpers)
       // Remove from boards list
       state.boards.value = state.boards.value.filter((b) => b.id !== boardId)
 
+      // Clear activeBoardId if the deleted board was the active selection
+      if (state.activeBoardId.value === boardId) {
+        state.activeBoardId.value = state.boards.value[0]?.id ?? null
+      }
+
       // Clear current board if it's the one being deleted
       if (state.currentBoard.value && state.currentBoard.value.id === boardId) {
         state.currentBoard.value = null
diff --git a/frontend/taskdeck-web/src/store/board/boardState.ts b/frontend/taskdeck-web/src/store/board/boardState.ts
index 3c77a4829..fe18f4519 100644
--- a/frontend/taskdeck-web/src/store/board/boardState.ts
+++ b/frontend/taskdeck-web/src/store/board/boardState.ts
@@ -20,6 +20,7 @@ export interface CardFilters {
 
 export function createBoardState() {
   const boards = ref<Board[]>([])
+  const activeBoardId = ref<string | null>(null)
   const currentBoard = ref<BoardDetail | null>(null)
   const currentBoardCards = ref<Card[]>([])
   const currentBoardLabels = ref<Label[]>([])
@@ -38,6 +39,7 @@ export function createBoardState() {
 
   return {
     boards,
+    activeBoardId,
     currentBoard,
     currentBoardCards,
     currentBoardLabels,
diff --git a/frontend/taskdeck-web/src/store/boardStore.ts b/frontend/taskdeck-web/src/store/boardStore.ts
index ae21fcdf6..3fac35233 100644
--- a/frontend/taskdeck-web/src/store/boardStore.ts
+++ b/frontend/taskdeck-web/src/store/boardStore.ts
@@ -38,6 +38,7 @@ export const useBoardStore = defineStore('board', () => {
   return {
     // State
     boards: state.boards,
+    activeBoardId: state.activeBoardId,
     currentBoard: state.currentBoard,
     currentBoardCards: state.currentBoardCards,
     currentBoardLabels: state.currentBoardLabels,
diff --git a/frontend/taskdeck-web/src/tests/store/boardStore.spec.ts b/frontend/taskdeck-web/src/tests/store/boardStore.spec.ts
index 739168470..ea4723de1 100644
--- a/frontend/taskdeck-web/src/tests/store/boardStore.spec.ts
+++ b/frontend/taskdeck-web/src/tests/store/boardStore.spec.ts
@@ -698,4 +698,86 @@ describe('boardStore', () => {
       expect(store.loading).toBe(false)
     })
   })
+
+  describe('activeBoardId — preserveSelection guard', () => {
+    const boardA: Board = {
+      id: 'board-a',
+      name: 'Board A',
+      description: '',
+      isArchived: false,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+      columns: [],
+    }
+
+    const boardB: Board = {
+      id: 'board-b',
+      name: 'Board B',
+      description: '',
+      isArchived: false,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+      columns: [],
+    }
+
+    it('sets activeBoardId to first board on initial fetchBoards when no prior selection', async () => {
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardA, boardB])
+
+      await store.fetchBoards()
+
+      expect(store.activeBoardId).toBe('board-a')
+    })
+
+    it('preserves activeBoardId across fetchBoards when selected board still exists', async () => {
+      // First load — sets selection to boardA (first item)
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardA, boardB])
+      await store.fetchBoards()
+      expect(store.activeBoardId).toBe('board-a')
+
+      // User selects boardB
+      store.activeBoardId = 'board-b'
+
+      // Poll cycle returns boards in a different order — boardB is still present
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardB, boardA])
+      await store.fetchBoards()
+
+      // Selection must NOT flip back to boardB (now first) or boardA
+      expect(store.activeBoardId).toBe('board-b')
+    })
+
+    it('falls back to first board when the selected board is removed from the list', async () => {
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardA, boardB])
+      await store.fetchBoards()
+      store.activeBoardId = 'board-b'
+
+      // boardB has been deleted on the server
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardA])
+      await store.fetchBoards()
+
+      expect(store.activeBoardId).toBe('board-a')
+    })
+
+    it('sets activeBoardId to null when no boards remain after refresh', async () => {
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardA])
+      await store.fetchBoards()
+      store.activeBoardId = 'board-a'
+
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([])
+      await store.fetchBoards()
+
+      expect(store.activeBoardId).toBeNull()
+    })
+
+    it('clears activeBoardId when the active board is deleted', async () => {
+      vi.mocked(boardsApi.getBoards).mockResolvedValue([boardA, boardB])
+      await store.fetchBoards()
+      store.activeBoardId = 'board-a'
+
+      vi.mocked(boardsApi.deleteBoard).mockResolvedValue()
+      await store.deleteBoard('board-a')
+
+      // activeBoardId should fall back to the remaining board
+      expect(store.activeBoardId).toBe('board-b')
+    })
+  })
 })