feat(headless): share immutable process content

src/AcDream.Headless/Configuration/HeadlessConfiguration.cs

@@ -16,6 +16,17 @@ internal sealed class HeadlessConfiguration
 internal sealed class HeadlessProcessSettings
 {
     public HeadlessPathOverrides Paths { get; init; } = new();
+
+    public HeadlessContentDescriptor? Content { get; init; }
+}
+
+internal sealed class HeadlessContentDescriptor
+{
+    [JsonRequired]
+    public string DatDirectory { get; init; } = string.Empty;
+
+    [JsonRequired]
+    public string PreparedAssetPath { get; init; } = string.Empty;
 }
 
 internal sealed class HeadlessSessionDescriptor

src/AcDream.Headless/Configuration/HeadlessConfigurationLoader.cs

@@ -52,6 +52,8 @@ internal static class HeadlessConfigurationLoader
                 "sessions must be an array.");
         }
 
+        ValidateContent(configuration.Process?.Content);
+
         var sessionIds = new HashSet<string>(StringComparer.Ordinal);
         var credentialReferences = new HashSet<string>(
             StringComparer.Ordinal);
@@ -83,6 +85,18 @@ internal static class HeadlessConfigurationLoader
         return configuration;
     }
 
+    private static void ValidateContent(HeadlessContentDescriptor? content)
+    {
+        if (content is null)
+            return;
+        if (string.IsNullOrWhiteSpace(content.DatDirectory)
+            || string.IsNullOrWhiteSpace(content.PreparedAssetPath))
+        {
+            throw new HeadlessConfigurationException(
+                "process.content requires non-empty datDirectory and preparedAssetPath.");
+        }
+    }
+
     private static void ValidateSession(HeadlessSessionDescriptor session)
     {
         if (session.Endpoint is null