Collapse tool-call chat rows into a single live status line

Each round of a multi-tool-call chain used to append a new "Calling: X"
message, so a long tool chain stacked up a growing list of rows in the
transcript. Replaced with a transient status line under the thinking
indicator that updates in place each round; once the response
completes, the whole chain collapses into one expandable summary
message ("Used N tool calls") instead of N separate ones.

oAI/Views/Main/ChatView.swift

@@ -53,7 +53,7 @@ struct ChatView: View {
 
                         // Processing indicator
                         if viewModel.isGenerating && viewModel.messages.last?.isStreaming != true {
-                            ProcessingIndicator()
+                            ProcessingIndicator(toolActivity: viewModel.currentToolActivity)
                                 .padding(.horizontal)
                         }
 
@@ -156,30 +156,43 @@ struct ChatView: View {
 }
 
 struct ProcessingIndicator: View {
+    /// Current tool round's status (e.g. "🔧 Calling: read_file"), replaced in place each round
+    /// rather than the chat accumulating a new row per round — see ChatViewModel.currentToolActivity.
+    let toolActivity: String?
     @State private var animating = false
     @State private var thinkingText = ThinkingVerbs.random()
 
     var body: some View {
-        HStack(spacing: 8) {
-            Text(thinkingText)
-                .font(.system(size: 14, weight: .medium))
-                .foregroundColor(.confabSecondary)
+        VStack(alignment: .leading, spacing: 4) {
+            HStack(spacing: 8) {
+                Text(thinkingText)
+                    .font(.system(size: 14, weight: .medium))
+                    .foregroundColor(.confabSecondary)
 
-            HStack(spacing: 4) {
-                ForEach(0..<3) { index in
-                    Circle()
-                        .fill(Color.confabSecondary)
-                        .frame(width: 6, height: 6)
-                        .scaleEffect(animating ? 1.0 : 0.5)
-                        .animation(
-                            .easeInOut(duration: 0.6)
-                                .repeatForever()
-                                .delay(Double(index) * 0.2),
-                            value: animating
-                        )
+                HStack(spacing: 4) {
+                    ForEach(0..<3) { index in
+                        Circle()
+                            .fill(Color.confabSecondary)
+                            .frame(width: 6, height: 6)
+                            .scaleEffect(animating ? 1.0 : 0.5)
+                            .animation(
+                                .easeInOut(duration: 0.6)
+                                    .repeatForever()
+                                    .delay(Double(index) * 0.2),
+                                value: animating
+                            )
+                    }
                 }
             }
+
+            if let toolActivity {
+                Text(toolActivity)
+                    .font(.system(size: 12))
+                    .foregroundColor(.confabSecondary.opacity(0.75))
+                    .transition(.opacity)
+            }
         }
+        .animation(.easeInOut(duration: 0.15), value: toolActivity)
         .padding(.horizontal, 16)
         .padding(.vertical, 12)
         .background(Color.confabSecondary.opacity(0.05))