feat(ui): render user tool_result blocks as one-line summaries

src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs

@@ -120,7 +120,100 @@ public class StreamLineFormatter
         return true;
     }
 
-    private static string? FormatUser(JsonElement root) => null;
+    private static string? FormatUser(JsonElement root)
+    {
+        if (!TryGetContentArray(root, out var content))
+            return null;
+
+        var sb = new StringBuilder();
+        foreach (var block in content.EnumerateArray())
+        {
+            if (block.ValueKind != JsonValueKind.Object) continue;
+            if (!block.TryGetProperty("type", out var blockTypeProp)) continue;
+            if (blockTypeProp.GetString() != "tool_result") continue;
+
+            var summary = BuildToolResultSummary(root, block);
+            if (!string.IsNullOrEmpty(summary))
+            {
+                sb.Append("→ ");
+                sb.Append(summary);
+                sb.Append('\n');
+            }
+        }
+
+        return sb.Length == 0 ? null : sb.ToString();
+    }
+
+    private static string BuildToolResultSummary(JsonElement root, JsonElement block)
+    {
+        var isError = block.TryGetProperty("is_error", out var errProp)
+                      && errProp.ValueKind == JsonValueKind.True;
+
+        var contentText = ResolveContentText(block);
+
+        if (isError)
+        {
+            var msg = FirstNonEmptyLine(contentText);
+            return string.IsNullOrEmpty(msg) ? "error" : $"error: {Truncate(msg, MaxArgChars)}";
+        }
+
+        // tool_use_result.file.numLines shortcut for Read-style results
+        if (root.TryGetProperty("tool_use_result", out var tur)
+            && tur.ValueKind == JsonValueKind.Object
+            && tur.TryGetProperty("file", out var file)
+            && file.ValueKind == JsonValueKind.Object
+            && file.TryGetProperty("numLines", out var nl)
+            && nl.ValueKind == JsonValueKind.Number
+            && nl.TryGetInt32(out var lines))
+        {
+            return $"{lines} lines";
+        }
+
+        if (string.IsNullOrWhiteSpace(contentText))
+            return "ok";
+
+        var first = FirstNonEmptyLine(contentText);
+        return Truncate(first, MaxArgChars);
+    }
+
+    private static string ResolveContentText(JsonElement block)
+    {
+        if (!block.TryGetProperty("content", out var c))
+            return "";
+
+        if (c.ValueKind == JsonValueKind.String)
+            return c.GetString() ?? "";
+
+        if (c.ValueKind == JsonValueKind.Array)
+        {
+            var sb = new StringBuilder();
+            foreach (var part in c.EnumerateArray())
+            {
+                if (part.ValueKind != JsonValueKind.Object) continue;
+                if (!part.TryGetProperty("type", out var pt)) continue;
+                if (pt.GetString() != "text") continue;
+                if (part.TryGetProperty("text", out var t) && t.ValueKind == JsonValueKind.String)
+                {
+                    if (sb.Length > 0) sb.Append('\n');
+                    sb.Append(t.GetString());
+                }
+            }
+            return sb.ToString();
+        }
+
+        return "";
+    }
+
+    private static string FirstNonEmptyLine(string s)
+    {
+        if (string.IsNullOrEmpty(s)) return "";
+        foreach (var raw in s.Split('\n'))
+        {
+            var line = raw.TrimEnd('\r').Trim();
+            if (line.Length > 0) return line;
+        }
+        return "";
+    }
 
     private static string? FormatResult(JsonElement root)
     {