From 10b83d69c5f9d422fad26fa95023dce697fb3949 Mon Sep 17 00:00:00 2001
From: Joseph Doherty <dohejw01@gmail.com>
Date: Thu, 22 Oct 2026 17:30:50 -0400
Subject: [PATCH] perf(adminui): /scripts lists a projection and loads source
 per dialog (R04 P8)

The list loaded every script entity including SourceCode to render names and
hashes. ScriptListQueries projects {ScriptId, Name, Language, SourceHash} for
the list and fetches one script's source when its Source dialog opens, with a
generation guard against a superseded open.

Refs #745
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
---
 .../Components/Pages/Scripts.razor            | 49 +++++++++++----
 .../ScriptList/ScriptListQueries.cs           | 41 +++++++++++++
 .../ScriptList/ScriptListQueriesTests.cs      | 59 +++++++++++++++++++
 3 files changed, 138 insertions(+), 11 deletions(-)
 create mode 100644 src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/ScriptList/ScriptListQueries.cs
 create mode 100644 tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ScriptList/ScriptListQueriesTests.cs

diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Scripts.razor b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Scripts.razor
index a946dfec..219b5eaa 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Scripts.razor
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Scripts.razor
@@ -3,7 +3,7 @@
 @rendermode RenderMode.InteractiveServer
 @using Microsoft.EntityFrameworkCore
 @using ZB.MOM.WW.OtOpcUa.Configuration
-@using ZB.MOM.WW.OtOpcUa.Configuration.Entities
+@using ZB.MOM.WW.OtOpcUa.AdminUI.ScriptList
 @inject IDbContextFactory<OtOpcUaConfigDbContext> DbFactory
 
 <PageErrorBoundary>
@@ -89,13 +89,17 @@ else
                     <button type="button" class="btn-close" aria-label="Close" @onclick="CloseSource"></button>
                 </div>
                 <div class="modal-body">
-                    @if (src is not null)
+                    @if (src is null || (_sourceLoaded && _sourceCode is null))
                     {
-                        <pre class="mono small mb-0" style="background:var(--zebra-bg);padding:1rem;border-radius:4px;overflow:auto">@src.SourceCode</pre>
+                        <p class="text-muted mb-0">This script is no longer loaded.</p>
+                    }
+                    else if (!_sourceLoaded)
+                    {
+                        <p class="text-muted mb-0">Loading source…</p>
                     }
                     else
                     {
-                        <p class="text-muted mb-0">This script is no longer loaded.</p>
+                        <pre class="mono small mb-0" style="background:var(--zebra-bg);padding:1rem;border-radius:4px;overflow:auto">@_sourceCode</pre>
                     }
                 </div>
                 <div class="modal-footer">
@@ -108,30 +112,53 @@ else
 </PageErrorBoundary>
 
 @code {
-    private List<Script>? _rows;
+    // A projection without SourceCode (R04 P8); the source loads per dialog open.
+    private List<ScriptListRow>? _rows;
 
     // Only the id of the script whose source dialog is open — never the record itself, so a reload
     // that drops or replaces the row cannot leave a stale object on screen.
     private string? _sourceScriptId;
 
+    // The open dialog's source, fetched on open. _sourceGeneration discards a superseded fetch (the
+    // operator opened another row, or closed the dialog, while the first one was in flight).
+    private string? _sourceCode;
+    private bool _sourceLoaded;
+    private int _sourceGeneration;
+
     protected override async Task OnInitializedAsync()
     {
         await using var db = await DbFactory.CreateDbContextAsync();
-        _rows = await db.Scripts.AsNoTracking()
-            .OrderBy(s => s.Name)
-            .ToListAsync();
+        _rows = await ScriptListQueries.LoadRowsAsync(db);
     }
 
     /// <summary>Re-resolves the open dialog's script from the current list on every render. Drives
     /// the dialog's CONTENT only — never its existence (see the comment at the markup): a script
     /// that is no longer loaded renders a notice with the frame and Close still mounted.</summary>
-    private Script? FindSourceScript()
+    private ScriptListRow? FindSourceScript()
         => _sourceScriptId is null
             ? null
             : _rows?.FirstOrDefault(s => s.ScriptId == _sourceScriptId);
 
     // One dialog at a time: opening another row replaces the id.
-    private void ShowSource(string scriptId) => _sourceScriptId = scriptId;
+    private async Task ShowSource(string scriptId)
+    {
+        var generation = ++_sourceGeneration;
+        _sourceScriptId = scriptId;
+        _sourceCode = null;
+        _sourceLoaded = false;
 
-    private void CloseSource() => _sourceScriptId = null;
+        await using var db = await DbFactory.CreateDbContextAsync();
+        var source = await ScriptListQueries.LoadSourceAsync(db, scriptId);
+        if (generation != _sourceGeneration) return;
+        _sourceCode = source;
+        _sourceLoaded = true;
+    }
+
+    private void CloseSource()
+    {
+        _sourceGeneration++;
+        _sourceScriptId = null;
+        _sourceCode = null;
+        _sourceLoaded = false;
+    }
 }
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/ScriptList/ScriptListQueries.cs b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/ScriptList/ScriptListQueries.cs
new file mode 100644
index 00000000..8c832ce1
--- /dev/null
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/ScriptList/ScriptListQueries.cs
@@ -0,0 +1,41 @@
+using Microsoft.EntityFrameworkCore;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+
+namespace ZB.MOM.WW.OtOpcUa.AdminUI.ScriptList;
+
+/// <summary>One row of the <c>/scripts</c> list: everything the list renders, and nothing else.</summary>
+/// <param name="ScriptId">The script's logical id.</param>
+/// <param name="Name">The authored display name.</param>
+/// <param name="Language">The script language (e.g. <c>CSharp</c>).</param>
+/// <param name="SourceHash">The source hash shown abbreviated on the row.</param>
+public sealed record ScriptListRow(string ScriptId, string Name, string Language, string SourceHash);
+
+/// <summary>
+///     Queries behind the <c>/scripts</c> page. The list is a projection that leaves out
+///     <c>SourceCode</c> (R04 P8): loading every script's full source to render names and hashes made
+///     the page cost proportional to the total size of every script in the fleet. The source is fetched
+///     on demand, for one script, when its "Source" dialog opens.
+/// </summary>
+public static class ScriptListQueries
+{
+    /// <summary>Loads the list rows, ordered by name, without any script's source.</summary>
+    /// <param name="db">The config DB context.</param>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>The list rows.</returns>
+    public static Task<List<ScriptListRow>> LoadRowsAsync(OtOpcUaConfigDbContext db, CancellationToken ct = default) =>
+        db.Scripts.AsNoTracking()
+            .OrderBy(s => s.Name)
+            .Select(s => new ScriptListRow(s.ScriptId, s.Name, s.Language, s.SourceHash))
+            .ToListAsync(ct);
+
+    /// <summary>Loads one script's source, or null when the script no longer exists.</summary>
+    /// <param name="db">The config DB context.</param>
+    /// <param name="scriptId">The script's logical id.</param>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>The source code, or null.</returns>
+    public static Task<string?> LoadSourceAsync(OtOpcUaConfigDbContext db, string scriptId, CancellationToken ct = default) =>
+        db.Scripts.AsNoTracking()
+            .Where(s => s.ScriptId == scriptId)
+            .Select(s => (string?)s.SourceCode)
+            .FirstOrDefaultAsync(ct);
+}
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ScriptList/ScriptListQueriesTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ScriptList/ScriptListQueriesTests.cs
new file mode 100644
index 00000000..d97efb12
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ScriptList/ScriptListQueriesTests.cs
@@ -0,0 +1,59 @@
+using Microsoft.EntityFrameworkCore;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.AdminUI.ScriptList;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests.ScriptList;
+
+/// <summary>R04 P8: the <c>/scripts</c> list is a projection without source; source loads per dialog.</summary>
+[Trait("Category", "Unit")]
+public sealed class ScriptListQueriesTests
+{
+    private static OtOpcUaConfigDbContext NewDb(string name) =>
+        new(new DbContextOptionsBuilder<OtOpcUaConfigDbContext>().UseInMemoryDatabase(name).Options);
+
+    private static async Task<string> SeedAsync()
+    {
+        var name = Guid.NewGuid().ToString("N");
+        await using var db = NewDb(name);
+        db.Scripts.AddRange(
+            new Script { ScriptId = "s-b", Name = "Beta", SourceCode = "return 2;", SourceHash = "hb" },
+            new Script { ScriptId = "s-a", Name = "Alpha", SourceCode = "return 1;", SourceHash = "ha", Language = "CSharp" });
+        await db.SaveChangesAsync();
+        return name;
+    }
+
+    [Fact]
+    public async Task LoadRowsAsync_returns_name_ordered_rows_without_source()
+    {
+        var name = await SeedAsync();
+        await using var db = NewDb(name);
+
+        var rows = await ScriptListQueries.LoadRowsAsync(db);
+
+        rows.Select(r => r.ScriptId).ShouldBe(["s-a", "s-b"]);
+        rows[0].ShouldBe(new ScriptListRow("s-a", "Alpha", "CSharp", "ha"));
+        // The row type has no source member at all — the list cannot load it by accident.
+        typeof(ScriptListRow).GetProperty("SourceCode").ShouldBeNull();
+    }
+
+    [Fact]
+    public async Task LoadSourceAsync_returns_one_scripts_source_or_null_when_gone()
+    {
+        var name = await SeedAsync();
+        await using var db = NewDb(name);
+
+        (await ScriptListQueries.LoadSourceAsync(db, "s-b")).ShouldBe("return 2;");
+        (await ScriptListQueries.LoadSourceAsync(db, "missing")).ShouldBeNull();
+    }
+
+    [Fact]
+    public void Scripts_page_uses_the_projection()
+    {
+        var src = AdminUiSource.Read("Components", "Pages", "Scripts.razor");
+        src.ShouldContain("ScriptListQueries.LoadRowsAsync(");
+        src.ShouldNotContain("List<Script>");
+    }
+}