Add shared table context state

docs/tables_frontend_overhaul_implementation_plan.md

@@ -55,6 +55,7 @@ It is intentionally implementation-focused:
 | 2026-03-21 | P2.3 | Completed | Added a shared `RecentTablesState` service backed by browser storage, centralized the recents storage key, and started recording successful table visits from the `Tables` page so later omnibox and rail work has real shared data. |
 | 2026-03-21 | P2.4 | Completed | Added a shared `PinnedTablesState` service with browser persistence, centralized the pin storage key, initialized pin state in the `Tables` page, and added a first live pin/unpin action plus pinned status chips so later omnibox and navigation work have real saved pins to consume. |
 | 2026-03-21 | P2.5 | Completed | Added shared table-context URL types and a serializer, registered the serializer centrally, and started round-tripping table context through `/tables` and `/tools/diagnostics` so direct links restore the selected table and diagnostic cell context instead of relying only on local storage defaults. |
+| 2026-03-21 | P2.8 | Completed | Added a shared `TableContextState` service on top of browser storage and the URL serializer, moved the `Tables` page off page-local table selection persistence, and switched diagnostics to the same restore/persist/build-URI flow so table context logic now lives in shared frontend state instead of being reinvented per page. |
 
 ### Lessons Learned
 
@@ -79,6 +80,7 @@ It is intentionally implementation-focused:
 - Shared browser-backed state becomes more useful once one real page writes to it immediately. Recording recents from `Tables` now keeps later omnibox work from being blocked on synthetic placeholder data.
 - Shared pinned-state services also need one live writer early. A minimal pin/unpin affordance in the current `Tables` page is enough to validate persistence before the larger navigation surfaces consume pins.
 - URL serializers only pay off when wired into real pages. Using the shared serializer in both `Tables` and diagnostics now gives the project one verified round-trip path before the larger table-context service lands.
+- The serializer alone is not the reusable boundary. The maintainable seam is a shared context-state helper that owns restore, persist, normalization, and URI-building conventions while pages keep only workflow-specific selection logic.
 
 ## Target Outcomes
 
@@ -373,7 +375,7 @@ Establish the shared shell, tokens, typography, and theme system that every dest
 | `P2.5` | Completed | Shared table-context URLs now parse and serialize through one helper and are consumed by `/tables` and `/tools/diagnostics`. |
 | `P2.6` | Pending | The shell omnibox is still a placeholder trigger. |
 | `P2.7` | Pending | Shared primitives for chips, tabs, drawers, and inspector sections are not extracted yet. |
-| `P2.8` | Pending | Table-selection logic still lives inside individual pages. |
+| `P2.8` | Completed | Table-context restore, persistence, normalization, and URI building now flow through one shared state service used by `Tables` and diagnostics. |
 
 ### Goal
 

src/RolemasterDb.App/Components/Pages/Tables.razor

@@ -5,11 +5,10 @@
 @using System.Diagnostics.CodeAnalysis
 @using System.Linq
 @inject NavigationManager NavigationManager
-@inject IJSRuntime JSRuntime
 @inject LookupService LookupService
 @inject RolemasterDb.App.Frontend.AppState.PinnedTablesState PinnedTablesState
 @inject RolemasterDb.App.Frontend.AppState.RecentTablesState RecentTablesState
-@inject RolemasterDb.App.Frontend.AppState.TableContextUrlSerializer TableContextUrlSerializer
+@inject RolemasterDb.App.Frontend.AppState.TableContextState TableContextState
 
 <PageTitle>Critical Tables</PageTitle>
 
@@ -82,6 +81,10 @@
     {
         <p class="muted">No critical tables are available yet.</p>
     }
+    else if (!hasResolvedStoredTableSelection)
+    {
+        <p class="muted">Restoring table context...</p>
+    }
     else if (isDetailLoading)
     {
         <p class="muted">Loading the selected table...</p>
@@ -227,7 +230,7 @@
 }
 
 @code {
-    private const string SelectedTableStorageKey = "rolemaster.tables.selectedTable";
+    private const string ContextDestination = "tables";
     private LookupReferenceData? referenceData;
     private CriticalTableDetail? tableDetail;
     private string selectedTableSlug = string.Empty;
@@ -285,9 +288,8 @@
     {
         selectedTableSlug = tableSlug;
         isTableMenuOpen = false;
-        await PersistSelectedTableAsync(tableSlug);
         await LoadTableDetailAsync();
-        SyncTableContextUrl();
+        await PersistAndSyncTableContextAsync();
     }
 
     private async Task LoadTableDetailAsync()
@@ -336,35 +338,26 @@
 
         if (!hasResolvedStoredTableSelection && referenceData?.CriticalTables.Count > 0)
         {
-            try
+            var initialContext = await TableContextState.RestoreAsync(
-            {
+                NavigationManager.Uri,
-                var routeContext = TableContextUrlSerializer.Parse(NavigationManager.Uri);
+                ContextDestination,
-                var storedTableSlug = await JSRuntime.InvokeAsync<string?>("localStorage.getItem", SelectedTableStorageKey);
+                referenceData.CriticalTables,
+                RolemasterDb.App.Frontend.AppState.TableContextMode.Reference);
+
             hasResolvedStoredTableSelection = true;
 
-                var resolvedTableSlug = ResolveSelectedTableSlug(routeContext.TableSlug ?? storedTableSlug);
+            var resolvedTableSlug = initialContext.TableSlug ?? string.Empty;
             if (string.IsNullOrWhiteSpace(selectedTableSlug) ||
                 !string.Equals(resolvedTableSlug, selectedTableSlug, StringComparison.OrdinalIgnoreCase))
             {
                 selectedTableSlug = resolvedTableSlug;
                 await LoadTableDetailAsync();
-                    await PersistSelectedTableAsync(selectedTableSlug);
+                await PersistAndSyncTableContextAsync();
-                    SyncTableContextUrl();
                 await InvokeAsync(StateHasChanged);
                 return;
             }
 
-                if (!string.Equals(storedTableSlug, selectedTableSlug, StringComparison.OrdinalIgnoreCase))
+            await PersistAndSyncTableContextAsync();
-                {
-                    await PersistSelectedTableAsync(selectedTableSlug);
-                }
-
-                SyncTableContextUrl();
-            }
-            catch (InvalidOperationException)
-            {
-                // During prerender localStorage is unavailable. Retry after interactive render.
-            }
         }
     }
 
@@ -781,46 +774,6 @@
     private string GetSelectedTableLabel() =>
         SelectedTableReference?.Label ?? "Select a table";
 
-    private string ResolveSelectedTableSlug(string? storedTableSlug)
-    {
-        if (referenceData is null || referenceData.CriticalTables.Count == 0)
-        {
-            return string.Empty;
-        }
-
-        if (!string.IsNullOrWhiteSpace(storedTableSlug) &&
-            referenceData.CriticalTables.Any(item => string.Equals(item.Key, storedTableSlug, StringComparison.OrdinalIgnoreCase)))
-        {
-            return storedTableSlug;
-        }
-
-        return referenceData.CriticalTables.First().Key;
-    }
-
-    private Task PersistSelectedTableAsync(string tableSlug) =>
-        JSRuntime.InvokeVoidAsync("localStorage.setItem", SelectedTableStorageKey, tableSlug).AsTask();
-
-    private void SyncTableContextUrl()
-    {
-        if (string.IsNullOrWhiteSpace(selectedTableSlug))
-        {
-            return;
-        }
-
-        var targetUri = TableContextUrlSerializer.BuildRelativeUri(
-            "/tables",
-            new RolemasterDb.App.Frontend.AppState.TableContextSnapshot(
-                TableSlug: selectedTableSlug,
-                Mode: RolemasterDb.App.Frontend.AppState.TableContextMode.Reference));
-
-        if (string.Equals(NavigationManager.ToBaseRelativePath(NavigationManager.Uri), targetUri.TrimStart('/'), StringComparison.Ordinal))
-        {
-            return;
-        }
-
-        NavigationManager.NavigateTo(targetUri, replace: true);
-    }
-
     private Task TogglePinnedTableAsync()
     {
         if (SelectedTableReference is not { } selectedTable)
@@ -849,6 +802,25 @@
             selectedTable.CurationPercentage);
     }
 
+    private async Task PersistAndSyncTableContextAsync()
+    {
+        var snapshot = BuildCurrentTableContext();
+        await TableContextState.PersistAsync(ContextDestination, snapshot);
+
+        var targetUri = TableContextState.BuildUri("/tables", snapshot);
+        if (string.Equals(NavigationManager.ToBaseRelativePath(NavigationManager.Uri), targetUri.TrimStart('/'), StringComparison.Ordinal))
+        {
+            return;
+        }
+
+        NavigationManager.NavigateTo(targetUri, replace: true);
+    }
+
+    private RolemasterDb.App.Frontend.AppState.TableContextSnapshot BuildCurrentTableContext() =>
+        new(
+            TableSlug: selectedTableSlug,
+            Mode: RolemasterDb.App.Frontend.AppState.TableContextMode.Reference);
+
     private string GetTableOptionCssClass(CriticalTableReference table)
     {
         var classes = new List<string>();

src/RolemasterDb.App/Components/Tools/DiagnosticsPageContent.razor

@@ -3,7 +3,7 @@
 @using System.Linq
 @inject NavigationManager NavigationManager
 @inject LookupService LookupService
-@inject RolemasterDb.App.Frontend.AppState.TableContextUrlSerializer TableContextUrlSerializer
+@inject RolemasterDb.App.Frontend.AppState.TableContextState TableContextState
 
 <section class="panel diagnostics-page tooling-surface">
     <header class="diagnostics-page-header">
@@ -21,6 +21,10 @@
     {
         <p class="muted">No critical tables are available yet.</p>
     }
+    else if (!hasInitializedContext)
+    {
+        <p class="muted">Restoring diagnostic context...</p>
+    }
     else
     {
         <div class="diagnostics-selector-grid">
@@ -160,15 +164,33 @@
     private bool isDiagnosticsLoading;
     private string? detailError;
     private string? diagnosticsError;
+    private bool hasInitializedContext;
 
     private bool isBusy => isDetailLoading || isDiagnosticsLoading;
+    private string ContextDestination => "tools.diagnostics";
 
     protected override async Task OnInitializedAsync()
     {
         referenceData = await LookupService.GetReferenceDataAsync();
-        var routeContext = TableContextUrlSerializer.Parse(NavigationManager.Uri);
+    }
-        selectedTableSlug = ResolveSelectedTableSlug(routeContext.TableSlug);
+
-        await LoadTableDetailAsync(routeContext);
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (!firstRender || hasInitializedContext || referenceData?.CriticalTables.Count is not > 0)
+        {
+            return;
+        }
+
+        var initialContext = await TableContextState.RestoreAsync(
+            NavigationManager.Uri,
+            ContextDestination,
+            referenceData.CriticalTables,
+            RolemasterDb.App.Frontend.AppState.TableContextMode.Diagnostics);
+
+        selectedTableSlug = initialContext.TableSlug ?? string.Empty;
+        hasInitializedContext = true;
+        await LoadTableDetailAsync(initialContext);
+        await InvokeAsync(StateHasChanged);
     }
 
     private async Task HandleTableChanged(ChangeEventArgs args)
@@ -181,7 +203,7 @@
     {
         selectedRollBand = args.Value?.ToString() ?? string.Empty;
         ResolveSelectedCell();
-        SyncRouteContext();
+        await PersistAndSyncRouteContextAsync();
         await LoadSelectedCellDiagnosticsAsync();
     }
 
@@ -189,7 +211,7 @@
     {
         selectedGroupKey = NormalizeOptionalText(args.Value?.ToString());
         ResolveSelectedCell();
-        SyncRouteContext();
+        await PersistAndSyncRouteContextAsync();
         await LoadSelectedCellDiagnosticsAsync();
     }
 
@@ -197,7 +219,7 @@
     {
         selectedColumnKey = args.Value?.ToString() ?? string.Empty;
         ResolveSelectedCell();
-        SyncRouteContext();
+        await PersistAndSyncRouteContextAsync();
         await LoadSelectedCellDiagnosticsAsync();
     }
 
@@ -238,7 +260,7 @@
                 ResolveSelectedCell();
             }
 
-            SyncRouteContext();
+            await PersistAndSyncRouteContextAsync();
             await LoadSelectedCellDiagnosticsAsync();
         }
         catch (Exception exception)
@@ -370,7 +392,7 @@
             }
 
             diagnosticsModel = CriticalCellEditorModel.FromResponse(response);
-            SyncRouteContext();
+            await PersistAndSyncRouteContextAsync();
         }
         catch (Exception exception)
         {
@@ -385,39 +407,24 @@
     private static string? NormalizeOptionalText(string? value) =>
         string.IsNullOrWhiteSpace(value) ? null : value.Trim();
 
-    private string ResolveSelectedTableSlug(string? tableSlug)
+    private async Task PersistAndSyncRouteContextAsync()
-    {
-        if (referenceData is null || referenceData.CriticalTables.Count == 0)
-        {
-            return string.Empty;
-        }
-
-        if (!string.IsNullOrWhiteSpace(tableSlug) &&
-            referenceData.CriticalTables.Any(item => string.Equals(item.Key, tableSlug, StringComparison.OrdinalIgnoreCase)))
-        {
-            return tableSlug;
-        }
-
-        return referenceData.CriticalTables.First().Key;
-    }
-
-    private void SyncRouteContext()
     {
         if (string.IsNullOrWhiteSpace(selectedTableSlug))
         {
             return;
         }
 
-        var targetUri = TableContextUrlSerializer.BuildRelativeUri(
+        var snapshot = new RolemasterDb.App.Frontend.AppState.TableContextSnapshot(
-            "/tools/diagnostics",
-            new RolemasterDb.App.Frontend.AppState.TableContextSnapshot(
             TableSlug: selectedTableSlug,
             GroupKey: selectedGroupKey,
             ColumnKey: selectedColumnKey,
             RollBand: selectedRollBand,
             ResultId: selectedCell?.ResultId,
-                Mode: RolemasterDb.App.Frontend.AppState.TableContextMode.Diagnostics));
+            Mode: RolemasterDb.App.Frontend.AppState.TableContextMode.Diagnostics);
 
+        await TableContextState.PersistAsync(ContextDestination, snapshot);
+
+        var targetUri = TableContextState.BuildUri("/tools/diagnostics", snapshot);
         if (string.Equals(NavigationManager.ToBaseRelativePath(NavigationManager.Uri), targetUri.TrimStart('/'), StringComparison.Ordinal))
         {
             return;

src/RolemasterDb.App/Frontend/AppState/BrowserStorageKeys.cs

@@ -5,4 +5,7 @@ public static class BrowserStorageKeys
     public const string ThemeMode = "rolemaster.theme.mode";
     public const string PinnedTables = "rolemaster.tables.pinned";
     public const string RecentTables = "rolemaster.tables.recent";
+
+    public static string TableContext(string destination) =>
+        $"rolemaster.tables.context.{destination}";
 }

src/RolemasterDb.App/Frontend/AppState/TableContextState.cs

@@ -0,0 +1,82 @@
+using System.Text.Json;
+using RolemasterDb.App.Features;
+
+namespace RolemasterDb.App.Frontend.AppState;
+
+public sealed class TableContextState(
+    BrowserStorageService browserStorage,
+    TableContextUrlSerializer serializer)
+{
+    private static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web);
+
+    public async Task<TableContextSnapshot> RestoreAsync(
+        string currentUri,
+        string destination,
+        IReadOnlyList<CriticalTableReference> availableTables,
+        TableContextMode defaultMode)
+    {
+        var routeContext = serializer.Parse(currentUri);
+        if (!string.IsNullOrWhiteSpace(routeContext.TableSlug))
+        {
+            return Normalize(routeContext, availableTables, defaultMode);
+        }
+
+        try
+        {
+            var storedValue = await browserStorage.GetItemAsync(BrowserStorageKeys.TableContext(destination));
+            if (!string.IsNullOrWhiteSpace(storedValue))
+            {
+                var storedContext = JsonSerializer.Deserialize<TableContextSnapshot>(storedValue, SerializerOptions);
+                if (storedContext is not null)
+                {
+                    return Normalize(storedContext, availableTables, defaultMode);
+                }
+            }
+        }
+        catch (InvalidOperationException)
+        {
+            // JS interop is unavailable during prerender. Fall back to route/default context.
+        }
+        catch (JsonException)
+        {
+            // Ignore malformed storage payloads and fall back to route/default context.
+        }
+
+        return Normalize(routeContext, availableTables, defaultMode);
+    }
+
+    public Task PersistAsync(string destination, TableContextSnapshot context)
+    {
+        var serialized = JsonSerializer.Serialize(context, SerializerOptions);
+        return browserStorage.SetItemAsync(BrowserStorageKeys.TableContext(destination), serialized).AsTask();
+    }
+
+    public string BuildUri(string basePath, TableContextSnapshot context) =>
+        serializer.BuildRelativeUri(basePath, context);
+
+    public string ResolveTableSlug(IReadOnlyList<CriticalTableReference> availableTables, string? preferredSlug)
+    {
+        if (availableTables.Count == 0)
+        {
+            return string.Empty;
+        }
+
+        if (!string.IsNullOrWhiteSpace(preferredSlug) &&
+            availableTables.Any(item => string.Equals(item.Key, preferredSlug, StringComparison.OrdinalIgnoreCase)))
+        {
+            return preferredSlug;
+        }
+
+        return availableTables[0].Key;
+    }
+
+    private TableContextSnapshot Normalize(
+        TableContextSnapshot context,
+        IReadOnlyList<CriticalTableReference> availableTables,
+        TableContextMode defaultMode) =>
+        context with
+        {
+            TableSlug = ResolveTableSlug(availableTables, context.TableSlug),
+            Mode = context.Mode ?? defaultMode
+        };
+}

src/RolemasterDb.App/Program.cs

@@ -15,6 +15,7 @@ builder.Services.AddScoped<LookupService>();
 builder.Services.AddScoped<BrowserStorageService>();
 builder.Services.AddScoped<PinnedTablesState>();
 builder.Services.AddScoped<RecentTablesState>();
+builder.Services.AddScoped<TableContextState>();
 builder.Services.AddSingleton<TableContextUrlSerializer>();
 builder.Services.AddScoped<ThemeState>();