refactor(ui): skeleton dispatch for StreamLineFormatter rewrite

src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs

@@ -6,6 +6,7 @@ namespace ClaudeDo.Ui.Helpers;
 public class StreamLineFormatter
 {
     private const int MaxLength = 50_000;
+    private const int MaxArgChars = 120;
 
     public string? FormatLine(string line)
     {
@@ -22,73 +23,42 @@ public class StreamLineFormatter
         using (doc)
         {
             var root = doc.RootElement;
+            if (root.ValueKind != JsonValueKind.Object)
+                return null;
             if (!root.TryGetProperty("type", out var typeProp))
                 return null;
 
-            var type = typeProp.GetString();
-
-            switch (type)
+            return typeProp.GetString() switch
             {
-                case "stream_event":
-                    return FormatStreamEvent(root);
+                "system"    => FormatSystem(root),
+                "assistant" => FormatAssistant(root),
+                "user"      => FormatUser(root),
+                "result"    => FormatResult(root),
+                _           => null,
+            };
+        }
+    }
 
-                case "result":
+    private static string? FormatSystem(JsonElement root)
+    {
+        if (!root.TryGetProperty("subtype", out var subtypeProp))
+            return null;
+        return subtypeProp.GetString() switch
+        {
+            "api_retry" => "[Retrying API call...]\n",
+            _           => null,
+        };
+    }
+
+    private static string? FormatAssistant(JsonElement root) => null;
+
+    private static string? FormatUser(JsonElement root) => null;
+
+    private static string? FormatResult(JsonElement root)
+    {
         if (root.TryGetProperty("result", out var resultProp))
             return $"\n--- Result ---\n{resultProp.GetString()}\n";
         return null;
-
-                case "system":
-                    if (root.TryGetProperty("subtype", out var subtypeProp) &&
-                        subtypeProp.GetString() == "api_retry")
-                        return "\n[Retrying API call...]\n";
-                    return null;
-
-                default:
-                    return null;
-            }
-        }
-    }
-
-    private static string? FormatStreamEvent(JsonElement root)
-    {
-        if (!root.TryGetProperty("event", out var ev))
-            return null;
-        if (!ev.TryGetProperty("type", out var evTypeProp))
-            return null;
-
-        var evType = evTypeProp.GetString();
-
-        switch (evType)
-        {
-            case "content_block_delta":
-                if (!ev.TryGetProperty("delta", out var delta))
-                    return null;
-                if (!delta.TryGetProperty("type", out var deltaTypeProp))
-                    return null;
-                var deltaType = deltaTypeProp.GetString();
-                if (deltaType == "text_delta")
-                {
-                    return delta.TryGetProperty("text", out var textProp)
-                        ? textProp.GetString()
-                        : null;
-                }
-                return null; // input_json_delta and others → skip
-
-            case "content_block_stop":
-                return "\n";
-
-            case "content_block_start":
-                if (!ev.TryGetProperty("content_block", out var cb))
-                    return null;
-                if (cb.TryGetProperty("type", out var cbTypeProp) &&
-                    cbTypeProp.GetString() == "tool_use" &&
-                    cb.TryGetProperty("name", out var nameProp))
-                    return $"\n[Tool: {nameProp.GetString()}]\n";
-                return null;
-
-            default:
-                return null; // message_start, message_delta, etc.
-        }
     }
 
     public string FormatFile(string filePath)