feat(text.json): JsonObject helpers + migrate 3 pragma'd callers off Newtonsoft (#83)

src/Fallout.Common/CI/GitHubActions/GitHubActions.Client.cs

@@ -5,8 +5,8 @@
 
 using System.Linq;
 using System.Net.Http;
+using System.Text.Json.Nodes;
 using System.Threading.Tasks;
-using Newtonsoft.Json.Linq;
 using Fallout.Common.Utilities;
 using Fallout.Common.Utilities.Net;
 
@@ -22,16 +22,14 @@ await _httpClient.Value
             .GetResponseAsync();
     }
 
-    private JObject GetJobDetails(long runId)
+    private JsonObject GetJobDetails(long runId)
     {
         var response = _httpClient.Value
             .CreateRequest(HttpMethod.Get, $"repos/{Repository}/actions/runs/{runId}/jobs")
             .GetResponse()
             .AssertSuccessfulStatusCode();
 
-#pragma warning disable CS0618 // GetBodyAsJson(JObject) retires in v11; migrate to GetBodyAsJsonObject + System.Text.Json.Nodes.JsonObject access patterns then.
-        return response.GetBodyAsJson().GetAwaiter().GetResult()
-#pragma warning restore CS0618
+        return response.GetBodyAsJsonObject().GetAwaiter().GetResult()
             .GetChildren("jobs")
             .Single(x => x.GetPropertyStringValue("name") == Job);
     }

src/Fallout.Common/Tools/Mastodon/MastodonTasks.cs

@@ -9,6 +9,7 @@
 using System.Net.Http;
 using System.Threading.Tasks;
 using Fallout.Common.Tooling;
+using Fallout.Common.Utilities;
 using Fallout.Common.Utilities.Net;
 
 namespace Fallout.Common.Tools.Mastodon;
@@ -37,10 +38,8 @@ async Task<string> PostMediaFile(string file)
                     .AddStreamContent("file", stream, Path.GetFileName(file)))
                 .GetResponseAsync();
 
-#pragma warning disable CS0618 // GetBodyAsJson(JObject) retires in v11; migrate to GetBodyAsJsonObject + System.Text.Json.Nodes.JsonObject access patterns then.
-            var json = await response.GetBodyAsJson();
-#pragma warning restore CS0618
-            return json["id"].NotNull().ToString();
+            var json = await response.GetBodyAsJsonObject();
+            return json.GetPropertyStringValue("id");
         }
 
         var mediaTasks = status.MediaFiles.Select(PostMediaFile).ToArray();

src/Fallout.Common/Tools/Slack/SlackTasks.cs

@@ -51,9 +51,7 @@ public static async Task<string> SendOrUpdateSlackMessage(Configure<SlackMessage
             .WithJsonContent(message)
             .GetResponseAsync();
 
-#pragma warning disable CS0618 // GetBodyAsJson(JObject) retires in v11; migrate to GetBodyAsJsonObject + System.Text.Json.Nodes.JsonObject access patterns then.
-        var jobject = await response.GetBodyAsJson();
-#pragma warning restore CS0618
+        var jobject = await response.GetBodyAsJsonObject();
         var error = jobject.GetPropertyValueOrNull<string>("error");
         Assert.True(error == null, error);
 

src/Fallout.Utilities.Text.Json/JsonObject.GetChildren.cs

@@ -0,0 +1,31 @@
+// Copyright 2026 Maintainers of Fallout.
+// Originally based on NUKE by Matthias Koch and contributors.
+// Distributed under the MIT License.
+// https://github.com/ChrisonSimtian/Fallout/blob/main/LICENSE
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.Json.Nodes;
+
+namespace Fallout.Common.Utilities;
+
+public static partial class JsonNodeExtensions
+{
+    /// <summary>
+    /// Reads property <paramref name="name"/> as a <see cref="JsonArray"/> and returns its elements typed as <typeparamref name="T"/>.
+    /// </summary>
+    public static IEnumerable<T> GetChildren<T>(this JsonObject jsonObject, string name)
+        where T : JsonNode
+    {
+        var array = jsonObject[name] as JsonArray;
+        return array?.OfType<T>() ?? Enumerable.Empty<T>();
+    }
+
+    /// <summary>
+    /// Reads property <paramref name="name"/> as a <see cref="JsonArray"/> of <see cref="JsonObject"/> children.
+    /// </summary>
+    public static IEnumerable<JsonObject> GetChildren(this JsonObject jsonObject, string name)
+    {
+        return jsonObject.GetChildren<JsonObject>(name);
+    }
+}

src/Fallout.Utilities.Text.Json/JsonObject.GetPropertyValue.cs

@@ -0,0 +1,43 @@
+// Copyright 2026 Maintainers of Fallout.
+// Originally based on NUKE by Matthias Koch and contributors.
+// Distributed under the MIT License.
+// https://github.com/ChrisonSimtian/Fallout/blob/main/LICENSE
+
+using System.Text.Json.Nodes;
+
+namespace Fallout.Common.Utilities;
+
+public static partial class JsonNodeExtensions
+{
+    /// <summary>
+    /// Reads property <paramref name="name"/> as <typeparamref name="T"/>, returning <c>default</c> if absent.
+    /// </summary>
+    public static T GetPropertyValueOrNull<T>(this JsonObject jsonObject, string name)
+    {
+        return jsonObject[name] is JsonNode node ? node.GetValue<T>() : default;
+    }
+
+    /// <summary>
+    /// Reads property <paramref name="name"/> as <typeparamref name="T"/>, throwing if absent.
+    /// </summary>
+    public static T GetPropertyValue<T>(this JsonObject jsonObject, string name)
+    {
+        return jsonObject[name].NotNull($"Property '{name}' not found").GetValue<T>();
+    }
+
+    /// <summary>
+    /// Reads property <paramref name="name"/> as a nested <see cref="JsonObject"/>, throwing if absent.
+    /// </summary>
+    public static JsonObject GetPropertyValue(this JsonObject jsonObject, string name)
+    {
+        return jsonObject[name].NotNull($"Property '{name}' not found").AsObject();
+    }
+
+    /// <summary>
+    /// Reads property <paramref name="name"/> as a string, throwing if absent.
+    /// </summary>
+    public static string GetPropertyStringValue(this JsonObject jsonObject, string name)
+    {
+        return jsonObject.GetPropertyValue<string>(name);
+    }
+}