Story 43: Unified chat UI for Claude Code and regular chat

Integrate Claude Code provider into the chat UI alongside regular
Ollama/Anthropic providers. Updates AgentPanel and Chat components.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/llm/chat.rs

@@ -1,4 +1,5 @@
 use crate::llm::prompts::SYSTEM_PROMPT;
+use crate::llm::providers::claude_code::ClaudeCodeResult;
 use crate::llm::types::{Message, Role, ToolCall, ToolDefinition, ToolFunctionDefinition};
 use crate::state::SessionState;
 use crate::store::StoreOps;
@@ -209,7 +210,9 @@ where
 
     // Claude Code provider: bypasses our tool loop entirely.
     // Claude Code has its own agent loop, tools, and context management.
-    // We just pipe the user message in and stream raw output back.
+    // We pipe the user message in, stream text tokens for live display, and
+    // collect the structured messages (assistant turns + tool results) from
+    // the stream-json output for the final message history.
     if is_claude_code {
         use crate::llm::providers::claude_code::ClaudeCodeProvider;
 
@@ -225,7 +228,10 @@ where
             .unwrap_or_else(|_| std::path::PathBuf::from("."));
 
         let provider = ClaudeCodeProvider::new();
-        let response = provider
+        let ClaudeCodeResult {
+            messages: cc_messages,
+            session_id,
+        } = provider
             .chat_stream(
                 &user_message,
                 &project_root.to_string_lossy(),
@@ -236,19 +242,24 @@ where
             .await
             .map_err(|e| format!("Claude Code Error: {e}"))?;
 
-        let assistant_msg = Message {
-            role: Role::Assistant,
-            content: response.content.unwrap_or_default(),
-            tool_calls: None,
-            tool_call_id: None,
-        };
-
+        // Build the final message history: user messages + Claude Code's turns.
+        // If the session produced no structured messages (e.g. empty response),
+        // fall back to an empty assistant message so the UI stops loading.
         let mut result = messages.clone();
-        result.push(assistant_msg);
+        if cc_messages.is_empty() {
+            result.push(Message {
+                role: Role::Assistant,
+                content: String::new(),
+                tool_calls: None,
+                tool_call_id: None,
+            });
+        } else {
+            result.extend(cc_messages);
+        }
         on_update(&result);
         return Ok(ChatResult {
             messages: result,
-            session_id: response.session_id,
+            session_id,
         });
     }