feat: agent brain (ollama) and chat ui

.living_spec/specs/functional/AI_INTEGRATION.md

@@ -0,0 +1,29 @@
+# Functional Spec: AI Integration
+
+## 1. Provider Abstraction
+The system uses a pluggable architecture for LLMs. The `ModelProvider` interface abstracts:
+*   **Generation:** Sending prompt + history + tools to the model.
+*   **Parsing:** Extracting text content vs. tool calls from the raw response.
+
+## 2. Ollama Implementation
+*   **Endpoint:** `http://localhost:11434/api/chat`
+*   **JSON Protocol:**
+    *   Request: `{ model: "name", messages: [...], stream: false, tools: [...] }`
+    *   Response: Standard Ollama JSON with `message.tool_calls`.
+*   **Fallback:** If the specific local model doesn't support native tool calling, we may need a fallback system prompt approach, but for this story, we assume a tool-capable model (like `llama3.1` or `mistral-nemo`).
+
+## 3. Chat Loop (Backend)
+The `chat` command acts as the **Agent Loop**:
+1.  Frontend sends: `User Message`.
+2.  Backend appends to `SessionState.history`.
+3.  Backend calls `OllamaProvider`.
+4.  **If Text Response:** Return text to Frontend.
+5.  **If Tool Call:**
+    *   Backend executes the Tool (using the Core Tools from Story #2).
+    *   Backend appends `ToolResult` to history.
+    *   Backend *re-prompts* Ollama with the new history (recursion).
+    *   Repeat until Text Response or Max Turns reached.
+
+## 4. Frontend State
+*   **Settings:** Store `llm_provider` ("ollama"), `ollama_model` ("llama3.2"), `ollama_base_url`.
+*   **Chat:** Display the conversation. Tool calls should be visible as "System Events" (e.g., collapsed accordions).

.living_spec/specs/tech/STACK.md

@@ -78,6 +78,8 @@ To support both Remote and Local models, the system implements a `ModelProvider`
     *   `walkdir`: Simple directory traversal.
     *   `tokio`: Async runtime.
     *   `reqwest`: For LLM API calls (if backend-initiated).
+    *   `uuid`: For unique message IDs.
+    *   `chrono`: For timestamps.
     *   `tauri-plugin-dialog`: Native system dialogs.
 *   **JavaScript:**
     *   `@tauri-apps/api`: Tauri Bridge.