From 3a67fe81b49832651665afd83db6b1e1ffb3b10e Mon Sep 17 00:00:00 2001
From: Mika Kuns <mika.kuns@fb-tuning.de>
Date: Tue, 21 Apr 2026 15:08:35 +0200
Subject: [PATCH] feat(ui): render assistant tool_use blocks with per-tool args

---
 .../Helpers/StreamLineFormatter.cs            | 93 ++++++++++++++++++-
 1 file changed, 92 insertions(+), 1 deletion(-)

diff --git a/src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs b/src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs
index 1990bed..3e86556 100644
--- a/src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs
+++ b/src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs
@@ -95,7 +95,8 @@ public class StreamLineFormatter
                     break;
 
                 case "tool_use":
-                    // Filled in by a later task.
+                    sb.Append(FormatToolUse(block));
+                    sb.Append('\n');
                     break;
 
                 case "thinking":
@@ -128,6 +129,96 @@ public class StreamLineFormatter
         return null;
     }
 
+    private static string FormatToolUse(JsonElement block)
+    {
+        var name = block.TryGetProperty("name", out var nameProp)
+            ? nameProp.GetString() ?? "?"
+            : "?";
+
+        JsonElement input = default;
+        var hasInput = block.TryGetProperty("input", out input)
+                       && input.ValueKind == JsonValueKind.Object;
+
+        var label = name;
+        if (hasInput && (name == "Task" || name == "Agent"))
+        {
+            var sub = GetStr(input, "subagent_type");
+            if (!string.IsNullOrEmpty(sub))
+                label = $"{name}: {sub}";
+        }
+
+        string? arg = hasInput ? BuildToolArg(name, input) : null;
+
+        return string.IsNullOrEmpty(arg)
+            ? $"[{label}]"
+            : $"[{label}] {arg}";
+    }
+
+    private static string? BuildToolArg(string toolName, JsonElement input)
+    {
+        switch (toolName)
+        {
+            case "Read":
+            case "Write":
+            case "Edit":
+            case "NotebookEdit":
+                return Basename(GetStr(input, "file_path"));
+
+            case "Bash":
+            case "PowerShell":
+            {
+                var cmd = GetStr(input, "command");
+                return string.IsNullOrEmpty(cmd) ? null : "$ " + Truncate(cmd, MaxArgChars);
+            }
+
+            case "Grep":
+            {
+                var p = GetStr(input, "pattern");
+                return string.IsNullOrEmpty(p) ? null : $"\"{Truncate(p, MaxArgChars)}\"";
+            }
+
+            case "Glob":
+                return Truncate(GetStr(input, "pattern"), MaxArgChars);
+
+            case "Task":
+            case "Agent":
+                return Truncate(GetStr(input, "description"), MaxArgChars);
+
+            case "WebFetch":
+                return GetStr(input, "url");
+
+            case "WebSearch":
+            {
+                var q = GetStr(input, "query");
+                return string.IsNullOrEmpty(q) ? null : $"\"{Truncate(q, MaxArgChars)}\"";
+            }
+
+            case "TodoWrite":
+                return null;
+
+            default:
+                return null;
+        }
+    }
+
+    private static string? GetStr(JsonElement obj, string name)
+        => obj.TryGetProperty(name, out var p) && p.ValueKind == JsonValueKind.String
+            ? p.GetString()
+            : null;
+
+    private static string Basename(string? path)
+    {
+        if (string.IsNullOrEmpty(path)) return "";
+        var i = path.LastIndexOfAny(new[] { '/', '\\' });
+        return i < 0 ? path : path[(i + 1)..];
+    }
+
+    private static string Truncate(string? s, int max)
+    {
+        if (string.IsNullOrEmpty(s)) return "";
+        return s.Length <= max ? s : s[..max] + "…";
+    }
+
     public string FormatFile(string filePath)
     {
         var sb = new StringBuilder();