Backend efficiency & consistency pass

- Rewrite get_all_tags() with SQL unnest instead of loading all notes
- Consolidate convert_note_to_task/convert_task_to_note to single-session ops
- Add search_notes_for_context() with single OR-keyword query for build_context()
- Drop selectinload from list_conversations(), use correlated subquery for message_count
- Add set_settings_batch() for single-transaction multi-setting upserts
- Extract get_installed_models() shared helper into services/llm.py
- Delete services/tasks.py pass-through wrapper; routes/tasks.py imports from services.notes
- Add B-tree indexes on notes.title and conversations.updated_at (migration 0007)
- Add logging to services/notes.py, services/chat.py, services/settings.py
- Safe Conversation.to_dict() when messages relationship is not loaded

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

alembic/versions/0007_add_title_and_updated_at_indexes.py

@@ -0,0 +1,23 @@
+"""add title and updated_at indexes
+
+Revision ID: 0007
+Revises: 0006
+Create Date: 2026-02-11 00:00:00.000000
+"""
+
+from alembic import op
+
+revision = "0007"
+down_revision = "0006"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.execute("CREATE INDEX IF NOT EXISTS ix_notes_title ON notes (title)")
+    op.execute("CREATE INDEX IF NOT EXISTS ix_conversations_updated_at ON conversations (updated_at)")
+
+
+def downgrade() -> None:
+    op.execute("DROP INDEX IF EXISTS ix_notes_title")
+    op.execute("DROP INDEX IF EXISTS ix_conversations_updated_at")

src/fabledassistant/models/conversation.py

@@ -1,6 +1,7 @@
 from datetime import datetime, timezone
 
 from sqlalchemy import DateTime, ForeignKey, Index, Integer, Text
+from sqlalchemy import inspect
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from fabledassistant.models import Base
@@ -27,12 +28,21 @@ class Conversation(Base):
         order_by="Message.created_at",
     )
 
+    __table_args__ = (
+        Index("ix_conversations_updated_at", "updated_at"),
+    )
+
     def to_dict(self) -> dict:
+        # Use loaded messages if available, otherwise 0
+        if "messages" in inspect(self).dict:
+            msg_count = len(self.messages) if self.messages else 0
+        else:
+            msg_count = 0
         return {
             "id": self.id,
             "title": self.title,
             "model": self.model,
-            "message_count": len(self.messages) if self.messages else 0,
+            "message_count": msg_count,
             "created_at": self.created_at.isoformat(),
             "updated_at": self.updated_at.isoformat(),
         }

src/fabledassistant/models/note.py

@@ -46,6 +46,7 @@ class Note(Base):
     __table_args__ = (
         Index("ix_notes_tags", "tags", postgresql_using="gin"),
         Index("ix_notes_status", "status"),
+        Index("ix_notes_title", "title"),
     )
 
     @property

src/fabledassistant/routes/chat.py

@@ -29,7 +29,7 @@ async def list_conversations_route():
     offset = request.args.get("offset", 0, type=int)
     conversations, total = await list_conversations(limit=limit, offset=offset)
     return jsonify({
-        "conversations": [c.to_dict() for c in conversations],
+        "conversations": conversations,
         "total": total,
     })
 
@@ -180,7 +180,7 @@ async def chat_status_route():
             resp.raise_for_status()
             result["ollama"] = "available"
             data = resp.json()
-            model_names = [m["name"] for m in data.get("models", [])]
+            model_names = {m["name"] for m in data.get("models", [])}
             # Match with or without :latest tag
             if default_model in model_names or f"{default_model}:latest" in model_names:
                 result["model"] = "ready"

src/fabledassistant/routes/settings.py

@@ -1,29 +1,11 @@
-import httpx
 from quart import Blueprint, jsonify, request
 
-from fabledassistant.config import Config
-from fabledassistant.services.settings import get_all_settings, set_setting
+from fabledassistant.services.llm import get_installed_models
+from fabledassistant.services.settings import get_all_settings, set_settings_batch
 
 settings_bp = Blueprint("settings", __name__, url_prefix="/api/settings")
 
 
-async def _get_installed_models() -> set[str]:
-    """Return set of installed Ollama model names, with and without :latest."""
-    try:
-        async with httpx.AsyncClient(timeout=5.0) as client:
-            resp = await client.get(f"{Config.OLLAMA_URL}/api/tags")
-            resp.raise_for_status()
-            data = resp.json()
-            names: set[str] = set()
-            for m in data.get("models", []):
-                name = m["name"]
-                names.add(name)
-                names.add(name.replace(":latest", ""))
-            return names
-    except Exception:
-        return set()
-
-
 @settings_bp.route("", methods=["GET"])
 async def get_settings_route():
     settings = await get_all_settings()
@@ -38,11 +20,10 @@ async def update_settings_route():
 
     if "default_model" in data:
         model = str(data["default_model"])
-        installed = await _get_installed_models()
+        installed = await get_installed_models()
         if installed and model not in installed:
             return jsonify({"error": f"Model '{model}' is not installed"}), 400
 
-    for key, value in data.items():
-        await set_setting(key, str(value))
+    await set_settings_batch({k: str(v) for k, v in data.items()})
     settings = await get_all_settings()
     return jsonify(settings)

src/fabledassistant/routes/tasks.py

@@ -3,12 +3,12 @@ from datetime import date
 from quart import Blueprint, jsonify, request
 
 from fabledassistant.models.note import TaskPriority, TaskStatus
-from fabledassistant.services.tasks import (
-    create_task,
-    delete_task,
-    get_task,
-    list_tasks,
-    update_task,
+from fabledassistant.services.notes import (
+    create_note,
+    delete_note,
+    get_note,
+    list_notes,
+    update_note,
 )
 from fabledassistant.utils.tags import extract_tags
 
@@ -26,9 +26,10 @@ async def list_tasks_route():
     limit = request.args.get("limit", 50, type=int)
     offset = request.args.get("offset", 0, type=int)
 
-    tasks, total = await list_tasks(
+    tasks, total = await list_notes(
         q=q,
         tags=tag or None,
+        is_task=True,
         status=status,
         priority=priority,
         sort=sort,
@@ -54,7 +55,7 @@ async def create_task_route():
         TaskPriority(data["priority"]).value if "priority" in data else TaskPriority.none.value
     )
 
-    task = await create_task(
+    task = await create_note(
         title=data.get("title", ""),
         body=body,
         status=status,
@@ -67,7 +68,7 @@ async def create_task_route():
 
 @tasks_bp.route("/<int:task_id>", methods=["GET"])
 async def get_task_route(task_id: int):
-    task = await get_task(task_id)
+    task = await get_note(task_id)
     if task is None:
         return jsonify({"error": "Task not found"}), 404
     return jsonify(task.to_dict())
@@ -95,7 +96,7 @@ async def update_task_route(task_id: int):
     if "body" in fields:
         fields["tags"] = extract_tags(fields["body"])
 
-    task = await update_task(task_id, **fields)
+    task = await update_note(task_id, **fields)
     if task is None:
         return jsonify({"error": "Task not found"}), 404
     return jsonify(task.to_dict())
@@ -113,7 +114,7 @@ async def patch_task_status(task_id: int):
     except ValueError:
         return jsonify({"error": f"Invalid status: {status_val}"}), 400
 
-    task = await update_task(task_id, status=status_val)
+    task = await update_note(task_id, status=status_val)
     if task is None:
         return jsonify({"error": "Task not found"}), 404
     return jsonify(task.to_dict())
@@ -121,7 +122,7 @@ async def patch_task_status(task_id: int):
 
 @tasks_bp.route("/<int:task_id>", methods=["DELETE"])
 async def delete_task_route(task_id: int):
-    deleted = await delete_task(task_id)
+    deleted = await delete_note(task_id)
     if not deleted:
         return jsonify({"error": "Task not found"}), 404
     return "", 204

src/fabledassistant/services/chat.py

@@ -1,3 +1,4 @@
+import logging
 from datetime import datetime, timezone
 
 from sqlalchemy import func, select
@@ -8,6 +9,8 @@ from fabledassistant.models.conversation import Conversation, Message
 from fabledassistant.services.llm import generate_completion
 from fabledassistant.services.notes import create_note
 
+logger = logging.getLogger(__name__)
+
 
 async def create_conversation(title: str = "", model: str = "") -> Conversation:
     async with async_session() as session:
@@ -35,20 +38,40 @@ async def get_conversation(conversation_id: int) -> Conversation | None:
 
 async def list_conversations(
     limit: int = 50, offset: int = 0
-) -> tuple[list[Conversation], int]:
+) -> tuple[list[dict], int]:
     async with async_session() as session:
         total = await session.scalar(
             select(func.count(Conversation.id))
         ) or 0
 
+        # Subquery for message count — avoids loading all messages
+        msg_count = (
+            select(func.count(Message.id))
+            .where(Message.conversation_id == Conversation.id)
+            .correlate(Conversation)
+            .scalar_subquery()
+        )
+
         result = await session.execute(
-            select(Conversation)
-            .options(selectinload(Conversation.messages))
+            select(Conversation, msg_count.label("message_count"))
             .order_by(Conversation.updated_at.desc())
             .limit(limit)
             .offset(offset)
         )
-        conversations = list(result.scalars().all())
+
+        conversations = []
+        for row in result.all():
+            conv = row[0]
+            d = {
+                "id": conv.id,
+                "title": conv.title,
+                "model": conv.model,
+                "message_count": row[1],
+                "created_at": conv.created_at.isoformat(),
+                "updated_at": conv.updated_at.isoformat(),
+            }
+            conversations.append(d)
+
         return conversations, total
 
 
@@ -149,6 +172,7 @@ async def summarize_conversation_as_note(
         {"role": "user", "content": "\n\n".join(conv_text)},
     ]
 
+    logger.info("Summarizing conversation %d with model %s", conversation_id, model)
     summary = await generate_completion(prompt_messages, model)
 
     title = conv.title or "Conversation Summary"

src/fabledassistant/services/llm.py

@@ -6,7 +6,7 @@ from collections.abc import AsyncGenerator
 import httpx
 
 from fabledassistant.config import Config
-from fabledassistant.services.notes import get_note, list_notes
+from fabledassistant.services.notes import get_note, search_notes_for_context
 from fabledassistant.services.settings import get_setting
 
 logger = logging.getLogger(__name__)
@@ -23,18 +23,32 @@ STOP_WORDS = frozenset({
 })
 
 
-async def ensure_model(model: str) -> None:
-    """Check if model exists in Ollama, pull if missing."""
+async def get_installed_models() -> set[str]:
+    """Return set of installed Ollama model names (with and without :latest)."""
     try:
         async with httpx.AsyncClient(timeout=10.0) as client:
             resp = await client.get(f"{Config.OLLAMA_URL}/api/tags")
             resp.raise_for_status()
             data = resp.json()
-            names = {m["name"] for m in data.get("models", [])}
-            # Check both with and without :latest tag
-            if model in names or f"{model}:latest" in names:
-                logger.info("Model '%s' already available", model)
-                return
+            names: set[str] = set()
+            for m in data.get("models", []):
+                name = m["name"]
+                names.add(name)
+                if name.endswith(":latest"):
+                    names.add(name.removesuffix(":latest"))
+            return names
+    except Exception:
+        logger.warning("Failed to fetch installed Ollama models")
+        return set()
+
+
+async def ensure_model(model: str) -> None:
+    """Check if model exists in Ollama, pull if missing."""
+    try:
+        installed = await get_installed_models()
+        if model in installed or f"{model}:latest" in installed:
+            logger.info("Model '%s' already available", model)
+            return
     except Exception:
         logger.warning("Failed to check Ollama models, attempting pull anyway")
 
@@ -172,39 +186,29 @@ async def build_context(
                 f"--- End Note ---"
             )
 
-    # Search notes by keywords from user message — search per keyword
-    # individually and deduplicate to get OR-style matching (any keyword hit
-    # is relevant context).  Collect up to 3 unique notes.
+    # Search notes by keywords from user message — single OR query
     keywords = _extract_keywords(user_message)
     if keywords:
-        seen_ids: set[int] = set()
-        snippets: list[str] = []
-        for kw in keywords[:5]:
-            if len(snippets) >= 3:
-                break
-            try:
-                notes, _ = await list_notes(q=kw, limit=3)
-                for n in notes:
-                    if n.id in seen_ids:
-                        continue
-                    if current_note_id and n.id == current_note_id:
-                        continue
-                    if n.id in exclude_set:
-                        continue
-                    seen_ids.add(n.id)
-                    body_preview = n.body[:2000] if n.body else ""
-                    snippets.append(f"- {n.title}: {body_preview}")
-                    context_meta["auto_notes"].append({"id": n.id, "title": n.title})
-                    if len(snippets) >= 3:
-                        break
-            except Exception:
-                continue
-        if snippets:
-            system_parts.append(
-                "\n\n--- Related Notes ---\n"
-                + "\n".join(snippets)
-                + "\n--- End Related Notes ---"
+        search_exclude = set(exclude_set)
+        if current_note_id:
+            search_exclude.add(current_note_id)
+        try:
+            notes = await search_notes_for_context(
+                keywords, exclude_ids=search_exclude or None, limit=3
             )
+            snippets: list[str] = []
+            for n in notes:
+                body_preview = n.body[:2000] if n.body else ""
+                snippets.append(f"- {n.title}: {body_preview}")
+                context_meta["auto_notes"].append({"id": n.id, "title": n.title})
+            if snippets:
+                system_parts.append(
+                    "\n\n--- Related Notes ---\n"
+                    + "\n".join(snippets)
+                    + "\n--- End Related Notes ---"
+                )
+        except Exception:
+            logger.warning("Failed to search notes for context", exc_info=True)
 
     # Fetch URL content from user message
     urls = _find_urls(user_message)

src/fabledassistant/services/notes.py

@@ -1,3 +1,4 @@
+import logging
 from datetime import date, datetime, timezone
 
 from sqlalchemy import func, or_, select, text
@@ -5,6 +6,8 @@ from sqlalchemy import func, or_, select, text
 from fabledassistant.models import async_session
 from fabledassistant.models.note import Note, TaskPriority, TaskStatus
 
+logger = logging.getLogger(__name__)
+
 
 async def create_note(
     title: str = "",
@@ -148,34 +151,69 @@ async def delete_note(note_id: int) -> bool:
 
 async def get_all_tags(q: str | None = None) -> list[str]:
     async with async_session() as session:
-        all_tags: set[str] = set()
-
-        result = await session.execute(select(Note))
-        for obj in result.scalars():
-            if obj.tags:
-                all_tags.update(obj.tags)
+        result = await session.execute(
+            text("SELECT DISTINCT unnest(tags) AS tag FROM notes WHERE tags != '{}'")
+        )
+        all_tags = [row[0] for row in result.fetchall()]
 
         if q:
             q_lower = q.lower()
-            all_tags = {t for t in all_tags if q_lower in t.lower()}
+            all_tags = [t for t in all_tags if q_lower in t.lower()]
 
         return sorted(all_tags)
 
 
 async def convert_note_to_task(note_id: int) -> Note:
-    note = await get_note(note_id)
-    if note is None:
-        raise ValueError("Note not found")
-    updated = await update_note(note_id, status=TaskStatus.todo.value, priority=TaskPriority.none.value)
-    return updated
+    async with async_session() as session:
+        note = await session.get(Note, note_id)
+        if note is None:
+            logger.warning("convert_note_to_task: note %d not found", note_id)
+            raise ValueError("Note not found")
+        note.status = TaskStatus.todo.value
+        note.priority = TaskPriority.none.value
+        note.updated_at = datetime.now(timezone.utc)
+        await session.commit()
+        await session.refresh(note)
+        logger.info("Converted note %d to task", note_id)
+        return note
 
 
 async def convert_task_to_note(note_id: int) -> Note:
-    note = await get_note(note_id)
-    if note is None:
-        raise ValueError("Note not found")
-    updated = await update_note(note_id, status=None, priority=None, due_date=None)
-    return updated
+    async with async_session() as session:
+        note = await session.get(Note, note_id)
+        if note is None:
+            logger.warning("convert_task_to_note: note %d not found", note_id)
+            raise ValueError("Note not found")
+        note.status = None
+        note.priority = None
+        note.due_date = None
+        note.updated_at = datetime.now(timezone.utc)
+        await session.commit()
+        await session.refresh(note)
+        logger.info("Converted task %d to note", note_id)
+        return note
+
+
+async def search_notes_for_context(
+    keywords: list[str],
+    exclude_ids: set[int] | None = None,
+    limit: int = 3,
+) -> list[Note]:
+    """Search notes by keywords with OR logic. Optimized for context building — no count query."""
+    async with async_session() as session:
+        keyword_filters = []
+        for kw in keywords:
+            escaped = kw.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")
+            pattern = f"%{escaped}%"
+            keyword_filters.append(or_(Note.title.ilike(pattern), Note.body.ilike(pattern)))
+
+        query = select(Note).where(or_(*keyword_filters))
+        if exclude_ids:
+            query = query.where(Note.id.notin_(exclude_ids))
+        query = query.order_by(Note.updated_at.desc()).limit(limit)
+
+        result = await session.execute(query)
+        return list(result.scalars().all())
 
 
 async def get_backlinks(note_id: int) -> list[dict]:

src/fabledassistant/services/settings.py

@@ -1,8 +1,12 @@
+import logging
+
 from sqlalchemy import select
 
 from fabledassistant.models import async_session
 from fabledassistant.models.setting import Setting
 
+logger = logging.getLogger(__name__)
+
 
 async def get_setting(key: str, default: str = "") -> str:
     async with async_session() as session:
@@ -22,6 +26,20 @@ async def set_setting(key: str, value: str) -> None:
         await session.commit()
 
 
+async def set_settings_batch(settings: dict[str, str]) -> None:
+    """Update multiple settings in a single transaction."""
+    async with async_session() as session:
+        for key, value in settings.items():
+            result = await session.execute(select(Setting).where(Setting.key == key))
+            setting = result.scalar_one_or_none()
+            if setting:
+                setting.value = value
+            else:
+                session.add(Setting(key=key, value=value))
+        await session.commit()
+    logger.info("Batch-updated %d settings", len(settings))
+
+
 async def get_all_settings() -> dict[str, str]:
     async with async_session() as session:
         result = await session.execute(select(Setting))

src/fabledassistant/services/tasks.py

@@ -1,63 +0,0 @@
-from datetime import date
-
-from fabledassistant.models.note import Note, TaskPriority, TaskStatus
-from fabledassistant.services.notes import (
-    create_note,
-    delete_note,
-    get_note,
-    list_notes,
-    update_note,
-)
-
-
-async def create_task(
-    title: str = "",
-    body: str = "",
-    status: str = TaskStatus.todo.value,
-    priority: str = TaskPriority.none.value,
-    due_date: date | None = None,
-    tags: list[str] | None = None,
-) -> Note:
-    return await create_note(
-        title=title,
-        body=body,
-        tags=tags,
-        status=status,
-        priority=priority,
-        due_date=due_date,
-    )
-
-
-async def get_task(task_id: int) -> Note | None:
-    return await get_note(task_id)
-
-
-async def list_tasks(
-    q: str | None = None,
-    tags: list[str] | None = None,
-    status: str | None = None,
-    priority: str | None = None,
-    sort: str = "updated_at",
-    order: str = "desc",
-    limit: int = 50,
-    offset: int = 0,
-) -> tuple[list[Note], int]:
-    return await list_notes(
-        q=q,
-        tags=tags,
-        is_task=True,
-        status=status,
-        priority=priority,
-        sort=sort,
-        order=order,
-        limit=limit,
-        offset=offset,
-    )
-
-
-async def update_task(task_id: int, **fields: object) -> Note | None:
-    return await update_note(task_id, **fields)
-
-
-async def delete_task(task_id: int) -> bool:
-    return await delete_note(task_id)

summary.md

@@ -12,7 +12,7 @@
 >    Include file-level details in the commit body when the change is non-trivial.
 
 ## Last Updated
-2026-02-10 — Phase 4.7: Styling consistency pass — design tokens, header alignment, standardized UI
+2026-02-11 — Phase 4.8: Backend efficiency & consistency pass
 
 ## Project Overview
 Fabled Assistant is a self-hosted note-taking and task-tracking application with
@@ -127,11 +127,11 @@ for AI-assisted features.
 - Auto-create via `get_or_create_note_by_title()` for wikilink clicks
 - `to_dict()` returns: `id`, `title`, `body`, `tags`, `parent_id`, `status`,
   `priority`, `due_date`, `is_task`, `created_at`, `updated_at`
-- Indexes: GIN on tags, B-tree on status
+- Indexes: GIN on tags, B-tree on status, B-tree on title
 
 ### Task ≡ Note with task attributes
-- No separate tasks table. The `services/tasks.py` module is a thin wrapper
-  around `services/notes.py` that passes `is_task=True` for listing and
+- No separate tasks table. `routes/tasks.py` imports directly from
+  `services/notes.py` with `is_task=True` for listing and
   defaults `status='todo'`, `priority='none'` for creation.
 - "Convert to task" = `update_note(id, status='todo', priority='none')`
 - "Convert to note" = `update_note(id, status=None, priority=None, due_date=None)`
@@ -140,13 +140,15 @@ for AI-assisted features.
 ### Settings
 - `key` (text PK), `value` (text)
 - Key-value store for app-wide settings (assistant name, default model, etc.)
-- CRUD via `services/settings.py`: `get_setting(key, default)`, `set_setting(key, value)`, `get_all_settings()`
+- CRUD via `services/settings.py`: `get_setting(key, default)`, `set_setting(key, value)`, `set_settings_batch(dict)`, `get_all_settings()`
 
 ### Conversations
 - `id` (int PK), `title` (str), `model` (str), `created_at`, `updated_at`
 - Has many messages (cascade delete)
 - Title auto-generated from first user message if not set
+- Index on `updated_at` for list ordering
 - `to_dict()` returns: `id`, `title`, `model`, `message_count`, `created_at`, `updated_at`
+- `list_conversations()` uses a subquery for `message_count` instead of eager-loading all messages
 
 ### Messages
 - `id` (int PK), `conversation_id` (FK to conversations, CASCADE), `role` (str: system/user/assistant),
@@ -171,7 +173,8 @@ fabledassistant/
 │       ├── 0003_task_note_companion.py # Data migration: create companion notes for existing tasks
 │       ├── 0004_merge_tasks_into_notes.py # Add task columns to notes, migrate data, drop tasks table
 │       ├── 0005_add_chat_tables.py    # Conversations + messages tables with FKs and indexes
-│       └── 0006_add_settings_table.py # Settings key-value table
+│       ├── 0006_add_settings_table.py # Settings key-value table
+│       └── 0007_add_title_and_updated_at_indexes.py # B-tree indexes on notes.title and conversations.updated_at
 ├── src/
 │   └── fabledassistant/
 │       ├── __init__.py
@@ -187,14 +190,13 @@ fabledassistant/
 │       │   ├── api.py           # /api blueprint with /health endpoint
 │       │   ├── chat.py          # /api/chat blueprint: conversations CRUD, SSE message streaming, save/summarize as note, models list/pull/delete, status check
 │       │   ├── notes.py         # /api/notes CRUD + /by-title + /resolve-title + /convert-to-task + /convert-to-note + /backlinks
-│       │   ├── tasks.py         # /api/tasks CRUD + PATCH status (thin wrappers, accepts body not description)
+│       │   ├── tasks.py         # /api/tasks CRUD + PATCH status (imports directly from services.notes, accepts body not description)
 │       │   └── settings.py      # /api/settings GET/PUT — app-wide settings
 │       ├── services/
-│       │   ├── notes.py         # CRUD, is_task filter, status/priority filters, convert_note_to_task, convert_task_to_note, get_backlinks
-│       │   ├── tasks.py         # Thin wrappers around notes.py (create_task, list_tasks with is_task=True, etc.)
-│       │   ├── llm.py           # Ollama interaction: ensure_model, stream_chat, generate_completion, fetch_url_content, build_context (keyword extraction, note search with 5 keywords + 2000-char previews, exclude_note_ids support, returns (messages, context_meta) tuple, URL fetching, configurable assistant name)
-│       │   ├── chat.py          # Conversation CRUD, add_message, save_response_as_note, summarize_conversation_as_note
-│       │   └── settings.py      # Settings CRUD: get_setting, set_setting, get_all_settings
+│       │   ├── notes.py         # CRUD, is_task filter, status/priority filters, convert_note_to_task, convert_task_to_note, get_backlinks, search_notes_for_context (OR-keyword search), get_all_tags (SQL unnest)
+│       │   ├── llm.py           # Ollama interaction: get_installed_models (shared helper), ensure_model, stream_chat, generate_completion, fetch_url_content, build_context (keyword extraction, single OR-query note search, exclude_note_ids support, returns (messages, context_meta) tuple, URL fetching, configurable assistant name)
+│       │   ├── chat.py          # Conversation CRUD (list uses subquery count), add_message, save_response_as_note, summarize_conversation_as_note
+│       │   └── settings.py      # Settings CRUD: get_setting, set_setting, set_settings_batch, get_all_settings
 │       ├── utils/
 │       │   ├── __init__.py
 │       │   └── tags.py          # extract_tags() — regex #tag extraction, skips code fences
@@ -301,7 +303,7 @@ container startup.
 
 ### Migration Chain
 ```
-0001_create_notes_table.py  →  0002_create_tasks_table.py  →  0003_task_note_companion.py  →  0004_merge_tasks_into_notes.py  →  0005_add_chat_tables.py  →  0006_add_settings_table.py
+0001_create_notes_table.py  →  0002_create_tasks_table.py  →  0003_task_note_companion.py  →  0004_merge_tasks_into_notes.py  →  0005_add_chat_tables.py  →  0006_add_settings_table.py  →  0007_add_title_and_updated_at_indexes.py
 ```
 
 ### How Migrations Run
@@ -481,6 +483,18 @@ When adding a new migration, follow these conventions:
 - [x] **Focus-visible states:** Global `focus-visible` rule with `--focus-ring` shadow on inputs, textareas, selects, buttons
 - [x] **Modal overlays:** Replaced hardcoded `rgba(0,0,0,0.5)` with `var(--color-overlay)` across all components
 
+### Phase 4.8 — Backend Efficiency & Consistency Pass ✓
+- [x] **`get_all_tags()` SQL rewrite:** Replaced O(n) Python-side tag extraction with single `SELECT DISTINCT unnest(tags)` query
+- [x] **`list_conversations()` subquery count:** Replaced `selectinload(Conversation.messages)` with correlated subquery for `message_count`, avoiding loading all messages for list view
+- [x] **Removed `services/tasks.py`:** Eliminated 64-line pass-through service; `routes/tasks.py` imports directly from `services.notes`
+- [x] **Consolidated convert functions:** `convert_note_to_task()` and `convert_task_to_note()` now use single session (was 3 DB round trips)
+- [x] **Batch settings updates:** New `set_settings_batch()` does all upserts in single transaction (was one transaction per setting)
+- [x] **Shared `get_installed_models()`:** Extracted duplicate Ollama model-listing logic from 3 locations into `services/llm.py`
+- [x] **`search_notes_for_context()`:** New function does single OR-keyword query (was up to 5 sequential `list_notes()` calls each with count query)
+- [x] **Logging:** Added `logger = logging.getLogger(__name__)` to `services/notes.py`, `services/chat.py`, `services/settings.py`
+- [x] **Database indexes:** Added B-tree indexes on `notes.title` (for `get_note_by_title` + backlinks) and `conversations.updated_at` (for list ordering)
+- [x] **Safe `Conversation.to_dict()`:** Handles case where messages relationship is not loaded
+
 ### Phase 5 — Polish & Production Hardening
 - [ ] Authentication (single-user or multi-user, TBD)
 - [ ] Docker Swarm production stack (secrets, volumes, networking)
@@ -506,7 +520,7 @@ When adding a new migration, follow these conventions:
 - Authentication model: single-user (password-only) vs multi-user?
 
 ## Current Status
-**Phase:** Phase 4.7 complete. Styling consistency pass with design tokens and standardized UI.
+**Phase:** Phase 4.8 complete. Backend efficiency & consistency pass.
 - Full note-taking and task-tracking CRUD with markdown, wikilinks, backlinks, tags
 - Unified note/task model (a task is a note with `status IS NOT NULL`)
 - LLM chat via Ollama with SSE streaming responses