Hot Reload agent improvements

Refactor agent code so that it can be shared with dotnet-watch implementation via a shared project.

Add new API applyHotReloadDeltas to apply updates.

Author: tmat

src/Components/Web.JS/dist/Release/blazor.server.js

@@ -97,10 +97,15 @@ async function startCore(components: RootComponentManager<WebAssemblyComponentDe
     }
   });
 
+  // obsolete:
   Blazor._internal.applyHotReload = (id: string, metadataDelta: string, ilDelta: string, pdbDelta: string | undefined, updatedTypes?: number[]) => {
     dispatcher.invokeDotNetStaticMethod('Microsoft.AspNetCore.Components.WebAssembly', 'ApplyHotReloadDelta', id, metadataDelta, ilDelta, pdbDelta, updatedTypes ?? null);
   };
 
+  Blazor._internal.applyHotReloadDeltas = (deltas: { moduleId: string, metadataDelta: string, ilDelta: string, pdbDelta: string, updatedTypes: number[] }[], loggingLevel: number) => {
+    return dispatcher.invokeDotNetStaticMethod('Microsoft.AspNetCore.Components.WebAssembly', 'ApplyHotReloadDeltas', deltas, loggingLevel);
+  };
+
   Blazor._internal.getApplyUpdateCapabilities = () => dispatcher.invokeDotNetStaticMethod('Microsoft.AspNetCore.Components.WebAssembly', 'GetApplyUpdateCapabilities');
 
   // Configure JS interop

src/Components/Web.JS/dist/Release/blazor.web.js

@@ -89,7 +89,11 @@ export interface IBlazor {
     }
 
     // APIs invoked by hot reload
+
+    // obsolete:
     applyHotReload?: (id: string, metadataDelta: string, ilDelta: string, pdbDelta: string | undefined, updatedTypes?: number[]) => void;
+
+    applyHotReloadDeltas?: (deltas: { moduleId: string, metadataDelta: string, ilDelta: string, pdbDelta: string, updatedTypes: number[] }[], loggingLevel: number) => {message: string, severity: number}[];
     getApplyUpdateCapabilities?: () => string;
     hotReloadApplied?: () => void;
   }

src/Components/Web.JS/dist/Release/blazor.webassembly.js

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.Extensions.HotReload;
+
+internal enum AgentMessageSeverity : byte
+{
+    Verbose = 0,
+    Warning = 1,
+    Error = 2,
+}

src/Components/Web.JS/src/Boot.WebAssembly.Common.ts

@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Linq;
+
+namespace Microsoft.Extensions.HotReload;
+
+internal sealed class AgentReporter
+{
+    private readonly List<(string message, AgentMessageSeverity severity)> _log = [];
+
+    public void Report(string message, AgentMessageSeverity severity)
+    {
+        _log.Add((message, severity));
+    }
+
+    public IReadOnlyCollection<(string message, AgentMessageSeverity severity)> GetAndClearLogEntries(ResponseLoggingLevel level)
+    {
+        lock (_log)
+        {
+            var filteredLog = (level != ResponseLoggingLevel.Verbose)
+                ? _log.Where(static entry => entry.severity != AgentMessageSeverity.Verbose)
+                : _log;
+
+            var log = filteredLog.ToArray();
+            _log.Clear();
+            return log;
+        }
+    }
+}