feat(ui): extract CosplayerGrid to isolate grid re-renders from SortFilterBar

- Create CosplayerGrid.razor child component that manages its own data loading,
  pagination, infinite scroll via cosplayerObserver, and empty state
- Cosplayers.razor now only holds header/SortFilterBar/form state
- Filter param changes trigger reload via OnParametersSetAsync
- LoadVersion parameter allows parent to trigger grid reload
- Remove OnFilterChanged no-op handler - grid handles reloads via params

MilkStream.Client/Components/Pages/Cosplayers.razor

@@ -5,114 +5,58 @@
 @using Butter.Types
 @using MilkStream.Client
 @using Microsoft.Extensions.Options
-@using Microsoft.JSInterop
 @using MilkStream.Client.Components.Layout
 @using MilkStream.Client.Components.Shared
 @using MilkStream.Client.Services
 @using System.Globalization
-@implements IAsyncDisposable
+@implements IDisposable
 
 @inject PersonService         personService
 @inject LoginService          loginService
 @inject IOptions<ServiceOptions> serviceOptions
 @inject NavigationManager     navigationManager
-@inject IJSRuntime            jsRuntime
 
 <PageTitle>Cosplayers</PageTitle>
 
-@if (isLoading) {
-    <LoadSpinner/>
-} else {
-    <div class="d-flex align-items-center justify-content-between mb-3 px-2 flex-wrap gap-2">
-        <h4 class="m-0"><i class="bi bi-people"></i> Cosplayers</h4>
-        <div class="d-flex gap-2 flex-shrink-0 flex-wrap align-items-center">
-            @if (IsAdminOrCurator) {
-                if (cosplayerSelectMode) {
-                    <button class="btn btn-danger btn-sm" @onclick="DeleteSelectedCosplayers" disabled="@(selectedCosplayerIds.Count == 0)">
-                        <i class="bi bi-trash"></i> Delete @selectedCosplayerIds.Count
-                    </button>
-                    <button class="btn btn-secondary btn-sm" @onclick="() => { cosplayerSelectMode = false; selectedCosplayerIds.Clear(); }">
-                        Done
-                    </button>
-                } else {
-                    <button class="btn btn-secondary btn-sm" @onclick="() => cosplayerSelectMode = true">
-                        <i class="bi bi-check2-square"></i> Select
-                    </button>
-                }
-                <button class="btn btn-primary btn-sm" @onclick="OpenCreateForm">
-                    <i class="bi bi-plus-circle"></i> New Cosplayer
+<div class="d-flex align-items-center justify-content-between mb-3 px-2 flex-wrap gap-2">
+    <h4 class="m-0"><i class="bi bi-people"></i> Cosplayers</h4>
+    <div class="d-flex gap-2 flex-shrink-0 flex-wrap align-items-center">
+        @if (IsAdminOrCurator) {
+            if (cosplayerSelectMode) {
+                <button class="btn btn-danger btn-sm" @onclick="DeleteSelectedCosplayers" disabled="@(selectedCosplayerIds.Count == 0)">
+                    <i class="bi bi-trash"></i> Delete @selectedCosplayerIds.Count
+                </button>
+                <button class="btn btn-secondary btn-sm" @onclick="() => { cosplayerSelectMode = false; selectedCosplayerIds.Clear(); }">
+                    Done
+                </button>
+            } else {
+                <button class="btn btn-secondary btn-sm" @onclick="() => cosplayerSelectMode = true">
+                    <i class="bi bi-check2-square"></i> Select
                 </button>
             }
-        </div>
-    </div>
-
-    <SortFilterBar SearchQuery="@searchQuery"
-                   SearchQueryChanged="@((string? v) => searchQuery = v)"
-                   SortBy="@sortBy"
-                   SortByChanged="@((string? v) => sortBy = v)"
-                   SortAsc="@sortAsc"
-                   SortAscChanged="@((bool v) => sortAsc = v)"
-                   SortOptions="@sortOptions"
-                   OnFilterChanged="@OnFilterChanged" />
-
-    @if (people.Count == 0 && !hasMore) {
-        <EmptyState Variant="warning" Title="No media available">
-            @if (loginService.IsLoggedIn) {
-                <p>There are no cosplayers yet.</p>
-            } else {
-                <p>There is no public media available. Logging in <i>might</i> make more content visible.</p>
-            }
-        </EmptyState>
-    } else {
-        <div class="cosplayers-grid">
-            @foreach (var person in people) {
-            <div class="cosplayer-card @(cosplayerSelectMode ? "cosplayer-card-select" : "")" @key="person.Id"
-                 @onclick="() => HandleCardClick(person.Id)"
-                 @onclick:preventDefault="true">
-                @if (person.ProfileAssetId.HasValue) {
-                    var cx1 = person.ProfileCropX ?? 50;
-                    var cy1 = person.ProfileCropY ?? 50;
-                    var zoom1 = person.ProfileCropZoom ?? 0.6f;
-                    <div class="cosplayer-card-img-wrap">
-                        <img src="@ThumbUrl(person.ProfileAssetId.Value)" alt=""
-                             class="cosplayer-card-img"
-                             style="width: calc(100% / @zoom1.ToString(CultureInfo.InvariantCulture)); transform: translate(calc(-@cx1.ToString(CultureInfo.InvariantCulture) * 1%), calc(-@cy1.ToString(CultureInfo.InvariantCulture) * 1%))"
-                             onerror="this.style.display='none';this.nextElementSibling.style.display='flex'" />
-                        <div class="cosplayer-card-fallback" style="display:none">
-                            <i class="bi bi-person-circle"></i>
-                        </div>
-                    </div>
-                } else {
-                    <div class="cosplayer-card-img-wrap">
-                        <div class="cosplayer-card-fallback">
-                            <i class="bi bi-person-circle"></i>
-                        </div>
-                    </div>
-                }
-                <div class="cosplayer-card-info">
-                    <span class="cosplayer-card-name">@person.Name</span>
-                    <span class="cosplayer-card-count">@person.TotalAlbums albums</span>
-                </div>
-                @if (cosplayerSelectMode) {
-                    <div class="cosplayer-card-check">
-                        @if (selectedCosplayerIds.Contains(person.Id)) {
-                            <i class="bi bi-check-circle-fill text-danger"></i>
-                        } else {
-                            <i class="bi bi-circle text-white"></i>
-                        }
-                    </div>
-                }
-            </div>
+            <button class="btn btn-primary btn-sm" @onclick="OpenCreateForm">
+                <i class="bi bi-plus-circle"></i> New Cosplayer
+            </button>
         }
     </div>
+</div>
 
-    @if (isLoadingMore) {
-        <LoadSpinner/>
-    }
+<SortFilterBar SearchQuery="@searchQuery"
+               SearchQueryChanged="@((string? v) => searchQuery = v)"
+               SortBy="@sortBy"
+               SortByChanged="@((string? v) => sortBy = v)"
+               SortAsc="@sortAsc"
+               SortAscChanged="@((bool v) => sortAsc = v)"
+               SortOptions="@sortOptions" />
 
-    <div @ref="sentinelRef" class="masonry-sentinel"></div>
-    }
-}
+<CosplayerGrid SearchQuery="@searchQuery"
+               SortBy="@sortBy"
+               SortAsc="@sortAsc"
+               SelectionMode="@cosplayerSelectMode"
+               SelectedIds="@selectedCosplayerIds"
+               OnCardClicked="@NavigateToPerson"
+               OnToggleSelection="@ToggleCosplayerSelection"
+               LoadVersion="@loadVersion" />
 
 @if (showCreateForm) {
     <PersonForm Show="true"
@@ -122,24 +66,15 @@
 }
 
 @code {
-    List<PersonPreviewDto> people = [];
-    bool isLoading = true;
-    bool isLoadingMore;
-    bool hasMore = true;
-    int currentPage = 0;
-    string token = string.Empty;
-    string apiBase => serviceOptions.Value.BaseUrl.TrimEnd('/');
-    string TokenParam => string.IsNullOrEmpty(token) ? "" : $"?token={token}";
-    bool IsAdminOrCurator => loginService.LoggedUser?.AccessLevel is EAccessLevel.Admin or EAccessLevel.Curator;
     bool showCreateForm;
     bool cosplayerSelectMode;
     HashSet<Guid> selectedCosplayerIds = [];
-    ElementReference sentinelRef;
-    DotNetObjectReference<Cosplayers>? dotNetRef;
+    bool IsAdminOrCurator => loginService.LoggedUser?.AccessLevel is EAccessLevel.Admin or EAccessLevel.Curator;
 
     string? searchQuery;
     string? sortBy;
     bool sortAsc = true;
+    int loadVersion;
     Dictionary<string, string> sortOptions = new()
     {
         ["Name"] = "name",
@@ -149,122 +84,41 @@
 
     protected override async Task OnInitializedAsync() {
         loginService.LoggedUserChanged += OnLoggedUserChanged;
-        loginService.AuthInfoChanged += OnAuthInfoChanged;
-        token = loginService.AuthInfo?.Token ?? string.Empty;
-
-        if (!loginService.IsLoggedIn) {
-            isLoading = false;
-            return;
-        }
-
-        await LoadFirstPage();
-    }
-
-    protected override async Task OnAfterRenderAsync(bool firstRender) {
-        if (people.Count > 0 && dotNetRef == null) {
-            dotNetRef = DotNetObjectReference.Create(this);
-            await jsRuntime.InvokeVoidAsync(
-                "cosplayerObserver.observeBottom", sentinelRef, dotNetRef
-            );
-        }
-    }
-
-    async Task LoadFirstPage() {
-        isLoading = true;
-        var items = await personService.GetAllAsync(0, 30, searchQuery, sortBy, sortAsc);
-        if (items?.Count > 0) {
-            people = items;
-            currentPage = 1;
-        }
-        hasMore = items?.Count == 30;
-        isLoading = false;
-    }
-
-    [JSInvokable]
-    public async Task LoadMoreCosplayers() {
-        if (isLoadingMore || !hasMore) return;
-        isLoadingMore = true;
-        StateHasChanged();
-
-        var items = await personService.GetAllAsync(currentPage, 30, searchQuery, sortBy, sortAsc);
-        if (items?.Count > 0) {
-            people.AddRange(items);
-            currentPage++;
-        }
-        hasMore = items?.Count == 30;
-        isLoadingMore = false;
-        StateHasChanged();
-    }
-
-    async Task OnFilterChanged() {
-        people.Clear();
-        currentPage = 0;
-        hasMore = true;
-        // Dispose old observer so it re-attaches after re-render
-        if (dotNetRef != null) {
-            await jsRuntime.InvokeVoidAsync("cosplayerObserver.dispose");
-            dotNetRef.Dispose();
-            dotNetRef = null;
-        }
-        await LoadFirstPage();
-        StateHasChanged();
     }
 
     void OnLoggedUserChanged(object? _, UserInfoDto? _2) => StateHasChanged();
 
-    void OnAuthInfoChanged(object? _, AuthInfo? info) {
-        token = info?.Token ?? string.Empty;
-    }
-
-    public async ValueTask DisposeAsync() {
-        loginService.LoggedUserChanged -= OnLoggedUserChanged;
-        loginService.AuthInfoChanged -= OnAuthInfoChanged;
-        if (dotNetRef != null) {
-            await jsRuntime.InvokeVoidAsync("cosplayerObserver.dispose");
-            dotNetRef.Dispose();
-        }
-    }
-
     void NavigateToPerson(Guid id) {
         navigationManager.NavigateTo($"/cosplayer/{id}");
     }
 
-    void HandleCardClick(Guid id) {
-        if (cosplayerSelectMode) ToggleCosplayerSelection(id);
-        else NavigateToPerson(id);
-    }
-
-    string ThumbUrl(Guid id) => $"{apiBase}/api/media/thumb/{id}{TokenParam}";
-
-    void OpenCreateForm() {
-        showCreateForm = true;
-    }
-
-    async Task HandleFormSaved() {
-        showCreateForm = false;
-        people.Clear();
-        currentPage = 0;
-        hasMore = true;
-        await LoadFirstPage();
-    }
-
-    void CloseForm() {
-        showCreateForm = false;
-    }
-
     void ToggleCosplayerSelection(Guid id) {
         if (selectedCosplayerIds.Contains(id)) selectedCosplayerIds.Remove(id);
         else selectedCosplayerIds.Add(id);
     }
 
+    void OpenCreateForm() {
+        showCreateForm = true;
+    }
+
+    async Task HandleFormSaved() {
+        showCreateForm = false;
+        loadVersion++;
+    }
+
+    void CloseForm() {
+        showCreateForm = false;
+    }
+
     async Task DeleteSelectedCosplayers() {
         foreach (var id in selectedCosplayerIds.ToList())
             await personService.DeletePersonAsync(id);
         selectedCosplayerIds.Clear();
         cosplayerSelectMode = false;
-        people.Clear();
-        currentPage = 0;
-        hasMore = true;
-        await LoadFirstPage();
+        loadVersion++;
+    }
+
+    public void Dispose() {
+        loginService.LoggedUserChanged -= OnLoggedUserChanged;
     }
 }

MilkStream.Client/Components/Shared/CosplayerGrid.razor

@@ -0,0 +1,190 @@
+@using Butter.Dtos.Person
+@using Butter.Types
+@using Microsoft.Extensions.Options
+@using Microsoft.JSInterop
+@using MilkStream.Client
+@using MilkStream.Client.Components.Layout
+@using MilkStream.Client.Services
+@using System.Globalization
+@implements IAsyncDisposable
+
+@inject PersonService personService
+@inject LoginService loginService
+@inject IOptions<ServiceOptions> serviceOptions
+@inject IJSRuntime jsRuntime
+
+@if (isLoading) {
+    <LoadSpinner/>
+} else if (people.Count == 0 && !hasMore) {
+    <EmptyState Variant="warning" Title="No media available">
+        @if (loginService.IsLoggedIn) {
+            <p>There are no cosplayers yet.</p>
+        } else {
+            <p>There is no public media available. Logging in <i>might</i> make more content visible.</p>
+        }
+    </EmptyState>
+} else {
+    <div class="cosplayers-grid">
+        @foreach (var person in people) {
+            <div class="cosplayer-card @(SelectionMode ? "cosplayer-card-select" : "")" @key="person.Id"
+                 @onclick="() => HandleCardClick(person.Id)"
+                 @onclick:preventDefault="true">
+                @if (person.ProfileAssetId.HasValue) {
+                    var cx1 = person.ProfileCropX ?? 50;
+                    var cy1 = person.ProfileCropY ?? 50;
+                    var zoom1 = person.ProfileCropZoom ?? 0.6f;
+                    <div class="cosplayer-card-img-wrap">
+                        <img src="@ThumbUrl(person.ProfileAssetId.Value)" alt=""
+                             class="cosplayer-card-img"
+                             style="width: calc(100% / @zoom1.ToString(CultureInfo.InvariantCulture)); transform: translate(calc(-@cx1.ToString(CultureInfo.InvariantCulture) * 1%), calc(-@cy1.ToString(CultureInfo.InvariantCulture) * 1%))"
+                             onerror="this.style.display='none';this.nextElementSibling.style.display='flex'" />
+                        <div class="cosplayer-card-fallback" style="display:none">
+                            <i class="bi bi-person-circle"></i>
+                        </div>
+                    </div>
+                } else {
+                    <div class="cosplayer-card-img-wrap">
+                        <div class="cosplayer-card-fallback">
+                            <i class="bi bi-person-circle"></i>
+                        </div>
+                    </div>
+                }
+                <div class="cosplayer-card-info">
+                    <span class="cosplayer-card-name">@person.Name</span>
+                    <span class="cosplayer-card-count">@person.TotalAlbums albums</span>
+                </div>
+                @if (SelectionMode) {
+                    <div class="cosplayer-card-check">
+                        @if (SelectedIds.Contains(person.Id)) {
+                            <i class="bi bi-check-circle-fill text-danger"></i>
+                        } else {
+                            <i class="bi bi-circle text-white"></i>
+                        }
+                    </div>
+                }
+            </div>
+        }
+    </div>
+
+    @if (isLoadingMore) {
+        <LoadSpinner/>
+    }
+
+    <div @ref="sentinelRef" class="masonry-sentinel"></div>
+}
+
+@code {
+    [Parameter] public string? SearchQuery { get; set; }
+    [Parameter] public string? SortBy { get; set; }
+    [Parameter] public bool SortAsc { get; set; } = true;
+    [Parameter] public bool SelectionMode { get; set; }
+    [Parameter] public HashSet<Guid> SelectedIds { get; set; } = [];
+    [Parameter] public EventCallback<Guid> OnCardClicked { get; set; }
+    [Parameter] public EventCallback<Guid> OnToggleSelection { get; set; }
+    [Parameter] public int LoadVersion { get; set; }
+
+    List<PersonPreviewDto> people = [];
+    int currentPage = 0;
+    bool hasMore = true;
+    bool isLoading = true;
+    bool isLoadingMore;
+    ElementReference sentinelRef;
+    DotNetObjectReference<CosplayerGrid>? dotNetRef;
+
+    int? _prevLoadVersion;
+    string? _prevSearch;
+    string? _prevSortBy;
+    bool _prevSortAsc;
+    string _token = string.Empty;
+    string _apiBase => serviceOptions.Value.BaseUrl.TrimEnd('/');
+    string TokenParam => string.IsNullOrEmpty(_token) ? "" : $"?token={_token}";
+
+    protected override void OnInitialized() {
+        loginService.AuthInfoChanged += OnAuthInfoChanged;
+        _token = loginService.AuthInfo?.Token ?? string.Empty;
+    }
+
+    protected override async Task OnParametersSetAsync() {
+        bool filterChanged = _prevLoadVersion != LoadVersion
+            || _prevSearch != SearchQuery
+            || _prevSortBy != SortBy
+            || _prevSortAsc != SortAsc;
+
+        _prevLoadVersion = LoadVersion;
+        _prevSearch = SearchQuery;
+        _prevSortBy = SortBy;
+        _prevSortAsc = SortAsc;
+
+        if (filterChanged)
+            await Reload();
+    }
+
+    protected override async Task OnAfterRenderAsync(bool firstRender) {
+        if (people.Count > 0 && dotNetRef == null) {
+            dotNetRef = DotNetObjectReference.Create(this);
+            await jsRuntime.InvokeVoidAsync(
+                "cosplayerObserver.observeBottom", sentinelRef, dotNetRef
+            );
+        }
+    }
+
+    async Task Reload() {
+        await DisposeObserver();
+        people.Clear();
+        currentPage = 0;
+        hasMore = true;
+        isLoading = true;
+        StateHasChanged();
+
+        var items = await personService.GetAllAsync(0, 30, SearchQuery, SortBy, SortAsc);
+        if (items?.Count > 0) {
+            people = items;
+            currentPage = 1;
+        }
+        hasMore = items?.Count == 30;
+        isLoading = false;
+    }
+
+    [JSInvokable]
+    public async Task LoadMoreCosplayers() {
+        if (isLoadingMore || !hasMore) return;
+        isLoadingMore = true;
+        StateHasChanged();
+
+        var items = await personService.GetAllAsync(currentPage, 30, SearchQuery, SortBy, SortAsc);
+        if (items?.Count > 0) {
+            people.AddRange(items);
+            currentPage++;
+        }
+        hasMore = items?.Count == 30;
+        isLoadingMore = false;
+        StateHasChanged();
+    }
+
+    void HandleCardClick(Guid id) {
+        if (SelectionMode) {
+            OnToggleSelection.InvokeAsync(id);
+        } else {
+            OnCardClicked.InvokeAsync(id);
+        }
+    }
+
+    string ThumbUrl(Guid id) => $"{_apiBase}/api/media/thumb/{id}{TokenParam}";
+
+    void OnAuthInfoChanged(object? _, AuthInfo? info) {
+        _token = info?.Token ?? string.Empty;
+    }
+
+    async Task DisposeObserver() {
+        if (dotNetRef != null) {
+            await jsRuntime.InvokeVoidAsync("cosplayerObserver.dispose");
+            dotNetRef.Dispose();
+            dotNetRef = null;
+        }
+    }
+
+    public async ValueTask DisposeAsync() {
+        loginService.AuthInfoChanged -= OnAuthInfoChanged;
+        await DisposeObserver();
+    }
+}