Add CalDAV calendar integration, LLM-suggested tags, and settings refinements

- CalDAV integration: per-user calendar config, create/list/search events
  via caldav library, LLM tools for calendar operations from chat
- LLM-suggested tags: new tag_suggestions service prompts LLM with existing
  tags and note content to suggest 3-5 relevant tags; exposed via API
  endpoints (suggest-tags, append-tag); integrated into editor views
  (suggest button + clickable pills) and chat tool calls (pills in
  ToolCallCard with one-click apply)
- Settings/model UI refinements, generation task improvements

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

src/fabledassistant/services/llm.py

@@ -8,6 +8,7 @@ from typing import Literal
 import httpx
 
 from fabledassistant.config import Config
+from fabledassistant.services.caldav import is_caldav_configured
 from fabledassistant.services.notes import get_note, search_notes_for_context
 from fabledassistant.services.settings import get_setting
 
@@ -79,9 +80,10 @@ async def stream_chat(
     options: dict | None = None,
 ) -> AsyncGenerator[str, None]:
     """Stream chat completion from Ollama, yielding content chunks."""
-    payload: dict = {"model": model, "messages": messages, "stream": True}
+    merged_options = {"num_ctx": 16384}
     if options:
-        payload["options"] = options
+        merged_options.update(options)
+    payload: dict = {"model": model, "messages": messages, "stream": True, "options": merged_options}
     async with httpx.AsyncClient(timeout=httpx.Timeout(1800.0, connect=30.0, read=300.0)) as client:
         async with client.stream(
             "POST",
@@ -119,7 +121,17 @@ async def stream_chat_with_tools(
     ChatChunk(type="tool_calls") is yielded. Always ends with
     ChatChunk(type="done").
     """
-    payload: dict = {"model": model, "messages": messages, "stream": True}
+    options: dict = {"num_ctx": 16384}
+    # Disable thinking mode for models like qwen3 — it interferes with tool calling
+    if tools:
+        options["num_predict"] = 4096
+    payload: dict = {
+        "model": model,
+        "messages": messages,
+        "stream": True,
+        "options": options,
+        "think": False,
+    }
     if tools:
         payload["tools"] = tools
     async with httpx.AsyncClient(timeout=httpx.Timeout(1800.0, connect=30.0, read=300.0)) as client:
@@ -129,6 +141,7 @@ async def stream_chat_with_tools(
             json=payload,
         ) as resp:
             resp.raise_for_status()
+            accumulated_tool_calls: list[dict] = []
             async for line in resp.aiter_lines():
                 if not line.strip():
                     continue
@@ -140,11 +153,22 @@ async def stream_chat_with_tools(
                 if chunk:
                     yield ChatChunk(type="content", content=chunk)
 
-                # Check for tool calls on done
+                # Collect tool calls from any message (some models
+                # emit them before the done flag)
+                tc = msg.get("tool_calls")
+                if tc:
+                    accumulated_tool_calls.extend(tc)
+
                 if data.get("done"):
-                    tool_calls = msg.get("tool_calls")
-                    if tool_calls:
-                        yield ChatChunk(type="tool_calls", tool_calls=tool_calls)
+                    if accumulated_tool_calls:
+                        logger.info(
+                            "Ollama returned %d tool call(s): %s",
+                            len(accumulated_tool_calls),
+                            json.dumps(accumulated_tool_calls)[:500],
+                        )
+                        yield ChatChunk(type="tool_calls", tool_calls=accumulated_tool_calls)
+                    else:
+                        logger.debug("Ollama done with no tool calls")
                     yield ChatChunk(type="done")
                     break
 
@@ -220,14 +244,19 @@ async def build_context(
     from datetime import date as date_type
     assistant_name = await get_setting(user_id, "assistant_name", "Fable")
     today = date_type.today().isoformat()
+    has_caldav = await is_caldav_configured(user_id)
+    date_guidance = "For relative dates like 'Friday' or 'next week', resolve them to YYYY-MM-DD format."
+    if has_caldav:
+        date_guidance += " For calendar events, use ISO 8601 datetime format (e.g. 2025-01-15T14:00:00)."
+
     system_parts = [
         f"You are a helpful assistant named {assistant_name}, integrated into a note-taking and task-tracking app called Fabled Assistant. "
         "Help users with their notes, tasks, and general questions. "
         "When note context is provided, use it to give relevant answers. "
         f"Today's date is {today}. "
-        "You have tools available to create tasks, create notes, and search the user's notes. "
-        "Use them when the user asks you to create, add, or find tasks and notes. "
-        "For relative dates like 'Friday' or 'next week', resolve them to YYYY-MM-DD format."
+        "When the user asks you to create, add, or find something, use the provided tool functions. "
+        "Do not describe or write out function calls as text — actually invoke the tools. "
+        f"{date_guidance}"
     ]
 
     context_meta: dict = {