feat(aisidebar): implement Ollama availability handling and graceful startup

- Add comprehensive Ollama connection error handling strategy
- Implement OllamaClient with non-blocking initialization and connection checks
- Create OllamaAvailabilityMonitor for periodic Ollama connection tracking
- Update design and requirements to support graceful Ollama unavailability
- Add new project structure for AI sidebar module with initial implementation
- Enhance error handling to prevent application crashes when Ollama is not running
- Prepare for future improvements in AI sidebar interaction and resilience

aisidebar/chat_widget.py

@@ -0,0 +1,192 @@
+import threading
+from ignis import widgets, app
+from gi.repository import GLib
+from .ollama_client import OllamaClient
+from .conversation_manager import ConversationManager
+
+
+class ChatWidget(widgets.Box):
+    """Chat interface widget with Ollama integration"""
+
+    def __init__(self):
+        self._conversation_manager = ConversationManager()
+        self._ollama_client = OllamaClient()
+        self._current_model = self._ollama_client.default_model
+
+        # Header with title and model
+        header_title = widgets.Label(
+            label="AI Sidebar",
+            halign="start",
+            css_classes=["title-2"],
+        )
+
+        model_name = self._current_model or "No local model detected"
+
+        self._model_label = widgets.Label(
+            label=f"Model: {model_name}",
+            halign="start",
+            css_classes=["dim-label"],
+        )
+
+        header_box = widgets.Box(
+            vertical=True,
+            spacing=4,
+            child=[header_title, self._model_label],
+        )
+
+        # Message list
+        self._message_list = widgets.Box(
+            vertical=True,
+            spacing=8,
+            hexpand=True,
+            vexpand=True,
+            valign="start",
+        )
+
+        # Scrolled window for messages
+        self._scroller = widgets.Scroll(
+            hexpand=True,
+            vexpand=True,
+            min_content_height=300,
+            child=self._message_list,
+        )
+
+        # Input entry
+        self._entry = widgets.Entry(
+            hexpand=True,
+            placeholder_text="Ask a question…",
+            on_accept=lambda x: self._on_submit(),
+        )
+
+        # Send button
+        self._send_button = widgets.Button(
+            label="Send",
+            on_click=lambda x: self._on_submit(),
+        )
+
+        # Input box
+        input_box = widgets.Box(
+            spacing=8,
+            hexpand=True,
+            child=[self._entry, self._send_button],
+        )
+
+        # Main container
+        super().__init__(
+            vertical=True,
+            spacing=12,
+            hexpand=True,
+            vexpand=True,
+            child=[header_box, self._scroller, input_box],
+            css_classes=["ai-sidebar-content"],
+        )
+
+        # Set margins
+        self.set_margin_top(16)
+        self.set_margin_bottom(16)
+        self.set_margin_start(16)
+        self.set_margin_end(16)
+
+        # Load initial messages
+        self._populate_initial_messages()
+
+    def _populate_initial_messages(self):
+        """Load conversation history"""
+        for message in self._conversation_manager.messages:
+            self._append_message(message["role"], message["content"], persist=False)
+
+        if not self._conversation_manager.messages:
+            self._append_message(
+                "assistant",
+                "Welcome! Ask a question to start a conversation.",
+                persist=True,
+            )
+
+    def _append_message(self, role: str, content: str, *, persist: bool = True):
+        """Add a message bubble to the chat"""
+        label_prefix = "You" if role == "user" else "Assistant"
+
+        message_label = widgets.Label(
+            label=f"{label_prefix}: {content}",
+            halign="start",
+            xalign=0.0,
+            wrap=True,
+            wrap_mode="word_char",  # Fixed: use underscore not hyphen
+            justify="left",
+        )
+
+        self._message_list.append(message_label)
+        self._scroll_to_bottom()
+
+        if persist and self._conversation_manager:
+            self._conversation_manager.append_message(role, content)
+
+    def _scroll_to_bottom(self):
+        """Scroll to the latest message"""
+        def _scroll():
+            adjustment = self._scroller.get_vadjustment()
+            if adjustment:
+                adjustment.set_value(adjustment.get_upper() - adjustment.get_page_size())
+            return False
+
+        GLib.idle_add(_scroll)
+
+    def _set_input_enabled(self, enabled: bool):
+        """Enable/disable input controls"""
+        self._entry.set_sensitive(enabled)
+        self._send_button.set_sensitive(enabled)
+
+    def _on_submit(self):
+        """Handle message submission"""
+        text = self._entry.text.strip()
+        if not text:
+            return
+
+        self._entry.text = ""
+        self._append_message("user", text, persist=True)
+        self._request_response()
+
+    def _request_response(self):
+        """Request AI response in background thread"""
+        model = self._current_model or self._ollama_client.default_model
+        if not model:
+            self._append_message(
+                "assistant",
+                "No Ollama models are available. Install a model to continue.",
+                persist=True,
+            )
+            return
+
+        history = self._conversation_manager.chat_messages
+        self._set_input_enabled(False)
+
+        def _worker(messages):
+            response = self._ollama_client.chat(model=model, messages=list(messages))
+            GLib.idle_add(self._handle_response, response, priority=GLib.PRIORITY_DEFAULT)
+
+        thread = threading.Thread(target=_worker, args=(history,), daemon=True)
+        thread.start()
+
+    def _handle_response(self, response):
+        """Handle AI response"""
+        self._set_input_enabled(True)
+
+        if not response:
+            self._append_message(
+                "assistant",
+                "The model returned an empty response.",
+                persist=True,
+            )
+            return False
+
+        role = response.get("role", "assistant")
+        content = response.get("content") or ""
+        if not content:
+            content = "[No content received from Ollama]"
+
+        self._append_message(role, content, persist=True)
+        return False
+
+    def focus_input(self):
+        """Focus the input entry"""
+        self._entry.grab_focus()