Have ToJson() match the default formatter's escaping behavior

src/Seq.Syntax/Expressions/Runtime/RuntimeOperators.cs

@@ -14,6 +14,7 @@
 
 using System.Globalization;
 using System.Runtime.CompilerServices;
+using System.Text.Encodings.Web;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using Seq.Syntax.Expressions.Compilation.Linq;
@@ -25,6 +26,13 @@ namespace Seq.Syntax.Expressions.Runtime;
 
 static class RuntimeOperators
 {
+    static readonly JsonSerializerOptions ToJsonSerializerOptions = new()
+    {
+        // Avoids defense-in-depth encoding of HTML content chars/non-ASCII data, which renders the results unreadable
+        // for many non-Latin languages.
+        Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping
+    };
+
     internal static EvaluationResult ScalarBoolean(bool value)
     {
         return JsonValue.Create(value);
@@ -552,12 +560,10 @@ public static EvaluationResult UriEncode(string value)
     }
 
     public static EvaluationResult ToJson(JsonNode? value)
-    {
-        // Serializes over the *inserted* form of a typed scalar: `Values.Clone` degrades a level
-        // to its string moniker and rejects pre-encoded `unsafe()` output. Nodes nested within
-        // containers were already degraded when they were inserted.
+    { 
+        // `Values.Clone` handles the level wrapper type and rejects pre-encoded `unsafe()` output.
         var node = value is JsonValue ? Values.Clone(value) : value;
-        return JsonValue.Create(node?.ToJsonString() ?? "null");
+        return JsonValue.Create(node?.ToJsonString(ToJsonSerializerOptions) ?? "null");
     }
 
     public static EvaluationResult FromJson(string json)

src/Seq.Syntax/Templates/Rendering/JsonWriter.cs

@@ -45,13 +45,7 @@ public JsonWriter(TemplateOutputEncoder encoder)
         _null = encoder.GetRun(TemplateThemeStyle.Null);
         _scalar = encoder.GetRun(TemplateThemeStyle.Scalar);
     }
-
-    public void Format(JsonNode? value, TextWriter output)
-    {
-        var invisibleCharacterCount = 0;
-        Format(value, output, ref invisibleCharacterCount);
-    }
-
+
     public void Format(JsonNode? value, TextWriter output, ref int invisibleCharacterCount)
     {
         try

test/Seq.Syntax.Tests/Cases/expression-evaluation-cases.asv

@@ -350,6 +350,12 @@ tojson(undefined())                  ⇶ undefined()
 tojson([1, 'b', null])               ⇶ '[1,"b",null]'
 tojson({a: 1})                       ⇶ '{"a":1}'
 tojson(@Level)                       ⇶ '"Information"'
+// HTML-sensitive and non-ASCII characters are emitted literally rather than as `\uXXXX` escapes
+tojson('<a href="x">&</a>')          ⇶ '"<a href=\"x\">&</a>"'
+tojson('it''s 1+1')                  ⇶ '"it''s 1+1"'
+tojson('日本語 Ñandú')                ⇶ '"日本語 Ñandú"'
+tojson({'名前': '値'})                ⇶ '{"名前":"値"}'
+tojson(['<', '>', '&', '''', '+'])   ⇶ '["<",">","&","''","+"]'
 
 // JSON deserialization
 fromjson('{"a": [1, null, "x"]}')    ⇶ {a: [1, null, 'x']}