diff --git a/backend/src/Taskdeck.Application/Services/BoardService.cs b/backend/src/Taskdeck.Application/Services/BoardService.cs
index 40fdcb838..9cad6347e 100644
--- a/backend/src/Taskdeck.Application/Services/BoardService.cs
+++ b/backend/src/Taskdeck.Application/Services/BoardService.cs
@@ -100,8 +100,12 @@ public async Task<Result<BoardDetailDto>> GetBoardDetailAsync(Guid id, Guid acti
 
         var detail = await GetBoardDetailAsync(id, cancellationToken);
         if (!detail.IsSuccess) return detail;
-        var writable = _authorizationService is null ? null : await _authorizationService.CanWriteBoardAsync(actingUserId, id);
-        return Result.Success(detail.Value with { CanWrite = writable is { IsSuccess: true, Value: true } });
+        var writable = _authorizationService is null
+            || (await _authorizationService.CanWriteBoardAsync(actingUserId, id)) is { IsSuccess: true, Value: true };
+        // No authorization service configured (CLI / unauthenticated composition) means no
+        // authorization is being enforced at all, so the caller can write — the same
+        // convention ListBoardsPaginatedAsync and EnsureBoardPermissionAsync follow.
+        return Result.Success(detail.Value with { CanWrite = writable });
     }
 
     /// <summary>
diff --git a/backend/tests/Taskdeck.Application.Tests/Services/BoardServiceTests.cs b/backend/tests/Taskdeck.Application.Tests/Services/BoardServiceTests.cs
index 1991e966d..4e40378da 100644
--- a/backend/tests/Taskdeck.Application.Tests/Services/BoardServiceTests.cs
+++ b/backend/tests/Taskdeck.Application.Tests/Services/BoardServiceTests.cs
@@ -588,6 +588,44 @@ public async Task CreateBoardAsync_ShouldStampCanWriteTrue_ForTheCreatingOwner()
         result.IsSuccess.Should().BeTrue();
         result.Value.CanWrite.Should().BeTrue();
     }
+    [Fact]
+    public async Task GetBoardDetailAsync_ShouldStampCanWriteTrue_WhenNoAuthorizationService()
+    {
+        // Null authorization (CLI / unauthenticated composition) means no enforcement,
+        // so detail must agree with the list stamp: the caller can write.
+        var board = TestDataBuilder.CreateBoard("Detail Board");
+        _boardRepoMock.Setup(r => r.GetByIdWithDetailsAsync(board.Id, default))
+            .ReturnsAsync(board);
+
+        var result = await _service.GetBoardDetailAsync(board.Id, Guid.NewGuid());
+
+        result.IsSuccess.Should().BeTrue();
+        result.Value.CanWrite.Should().BeTrue();
+    }
+
+    [Fact]
+    public async Task ListBoardsPaginatedAsync_ShouldStampCanWriteTrue_WhenNoAuthorizationService()
+    {
+        // Parity lock for the detail stamp above: with no authorization service every
+        // visible board is writable.
+        var actingUserId = Guid.NewGuid();
+        var boards = new[]
+        {
+            new Board("Board A", "desc", actingUserId),
+            new Board("Board B", "desc", actingUserId)
+        };
+        var boardIds = boards.Select(b => b.Id).ToList();
+        _boardRepoMock.Setup(r => r.SearchIdsAsync(null, false, default))
+            .ReturnsAsync(boardIds);
+        _boardRepoMock.Setup(r => r.GetByIdsAsync(It.IsAny<IEnumerable<Guid>>(), default))
+            .ReturnsAsync(boards);
+
+        var result = await _service.ListBoardsPaginatedAsync(actingUserId);
+
+        result.IsSuccess.Should().BeTrue();
+        result.Value.Items.Should().HaveCount(2);
+        result.Value.Items.Should().OnlyContain(b => b.CanWrite);
+    }
 
     #endregion
 }