Backend: Add Anthropic/Claude provider integration

- Add anthropic.rs module with streaming support
- Convert between internal and Anthropic tool/message formats
- Add keyring dependency for secure API key storage
- Add API key management commands (get_exists, set)
- Auto-detect provider from model name (claude-* prefix)
- Support SSE streaming from Anthropic API
- Handle tool calling with Anthropic's format
- Add cancellation support for Anthropic streams

src-tauri/src/commands/chat.rs

@@ -1,4 +1,5 @@
 use crate::commands::{fs, search, shell};
+use crate::llm::anthropic::AnthropicProvider;
 use crate::llm::ollama::OllamaProvider;
 use crate::llm::prompts::SYSTEM_PROMPT;
 use crate::llm::types::{Message, Role, ToolCall, ToolDefinition, ToolFunctionDefinition};
@@ -23,6 +24,35 @@ pub async fn get_ollama_models(base_url: Option<String>) -> Result<Vec<String>,
     OllamaProvider::get_models(&url).await
 }
 
+#[tauri::command]
+pub async fn get_anthropic_api_key_exists() -> Result<bool, String> {
+    match keyring::Entry::new("living-spec-anthropic-api-key", "default") {
+        Ok(entry) => Ok(entry.get_password().is_ok()),
+        Err(e) => Err(format!("Failed to access keychain: {}", e)),
+    }
+}
+
+#[tauri::command]
+pub async fn set_anthropic_api_key(api_key: String) -> Result<(), String> {
+    let entry = keyring::Entry::new("living-spec-anthropic-api-key", "default")
+        .map_err(|e| format!("Failed to create keychain entry: {}", e))?;
+
+    entry
+        .set_password(&api_key)
+        .map_err(|e| format!("Failed to store API key: {}", e))?;
+
+    Ok(())
+}
+
+fn get_anthropic_api_key() -> Result<String, String> {
+    let entry = keyring::Entry::new("living-spec-anthropic-api-key", "default")
+        .map_err(|e| format!("Failed to access keychain: {}", e))?;
+
+    entry
+        .get_password()
+        .map_err(|_| "Anthropic API key not found. Please set your API key.".to_string())
+}
+
 #[tauri::command]
 pub async fn chat(
     app: AppHandle,
@@ -46,12 +76,13 @@ pub async fn chat(
         .clone()
         .unwrap_or_else(|| "http://localhost:11434".to_string());
 
-    if config.provider.as_str() != "ollama" {
+    // Determine provider from model name
+    let is_claude = config.model.starts_with("claude-");
+
+    if !is_claude && config.provider.as_str() != "ollama" {
         return Err(format!("Unsupported provider: {}", config.provider));
     }
 
-    let provider = OllamaProvider::new(base_url);
-
     // 2. Define Tools
     let tool_defs = get_tool_definitions();
     let tools = if config.enable_tools.unwrap_or(true) {
@@ -100,10 +131,22 @@ pub async fn chat(
         turn_count += 1;
 
         // Call LLM with streaming
-        let response = provider
-            .chat_stream(&app, &config.model, &current_history, tools, &mut cancel_rx)
-            .await
-            .map_err(|e| format!("LLM Error: {}", e))?;
+        let response = if is_claude {
+            // Use Anthropic provider
+            let api_key = get_anthropic_api_key()?;
+            let anthropic_provider = AnthropicProvider::new(api_key);
+            anthropic_provider
+                .chat_stream(&app, &config.model, &current_history, tools, &mut cancel_rx)
+                .await
+                .map_err(|e| format!("Anthropic Error: {}", e))?
+        } else {
+            // Use Ollama provider
+            let ollama_provider = OllamaProvider::new(base_url.clone());
+            ollama_provider
+                .chat_stream(&app, &config.model, &current_history, tools, &mut cancel_rx)
+                .await
+                .map_err(|e| format!("Ollama Error: {}", e))?
+        };
 
         // Process Response
         if let Some(tool_calls) = response.tool_calls {