feat(rulebook): service layer — Topic CRUD

src/fabledassistant/services/rulebooks.py

@@ -108,3 +108,106 @@ async def find_rulebook_by_title(
             )
         )
         return result.scalar_one_or_none()
+
+
+# ── Topic CRUD ──────────────────────────────────────────────────────────
+
+from fabledassistant.models.rulebook import RulebookTopic
+
+
+async def _assert_rulebook_owned(session, rulebook_id: int, user_id: int) -> None:
+    """Raise ValueError if rulebook doesn't exist or isn't owned by user.
+    Centralizes ownership check used by all topic/rule operations.
+    """
+    result = await session.execute(
+        select(Rulebook).where(
+            Rulebook.id == rulebook_id,
+            Rulebook.owner_user_id == user_id,
+        )
+    )
+    if result.scalar_one_or_none() is None:
+        raise ValueError(f"rulebook {rulebook_id} not found")
+
+
+async def create_topic(
+    rulebook_id: int, user_id: int, title: str,
+    description: str = "", order_index: int = 0,
+) -> RulebookTopic:
+    async with async_session() as session:
+        await _assert_rulebook_owned(session, rulebook_id, user_id)
+        topic = RulebookTopic(
+            rulebook_id=rulebook_id,
+            title=title,
+            description=description or None,
+            order_index=order_index,
+        )
+        session.add(topic)
+        await session.commit()
+        await session.refresh(topic)
+        return topic
+
+
+async def list_topics(rulebook_id: int, user_id: int) -> list[RulebookTopic]:
+    async with async_session() as session:
+        await _assert_rulebook_owned(session, rulebook_id, user_id)
+        result = await session.execute(
+            select(RulebookTopic)
+            .where(RulebookTopic.rulebook_id == rulebook_id)
+            .order_by(RulebookTopic.order_index, RulebookTopic.title)
+        )
+        return list(result.scalars().all())
+
+
+async def get_topic(topic_id: int, user_id: int) -> Optional[RulebookTopic]:
+    """Get a topic, scoped via the rulebook owner."""
+    async with async_session() as session:
+        result = await session.execute(
+            select(RulebookTopic)
+            .join(Rulebook, RulebookTopic.rulebook_id == Rulebook.id)
+            .where(
+                RulebookTopic.id == topic_id,
+                Rulebook.owner_user_id == user_id,
+            )
+        )
+        return result.scalar_one_or_none()
+
+
+async def update_topic(
+    topic_id: int, user_id: int, **fields,
+) -> Optional[RulebookTopic]:
+    async with async_session() as session:
+        result = await session.execute(
+            select(RulebookTopic)
+            .join(Rulebook, RulebookTopic.rulebook_id == Rulebook.id)
+            .where(
+                RulebookTopic.id == topic_id,
+                Rulebook.owner_user_id == user_id,
+            )
+        )
+        topic = result.scalar_one_or_none()
+        if topic is None:
+            return None
+        allowed = {"title", "description", "order_index"}
+        for key, value in fields.items():
+            if key in allowed and value is not None:
+                setattr(topic, key, value)
+        await session.commit()
+        await session.refresh(topic)
+        return topic
+
+
+async def delete_topic(topic_id: int, user_id: int) -> None:
+    async with async_session() as session:
+        result = await session.execute(
+            select(RulebookTopic)
+            .join(Rulebook, RulebookTopic.rulebook_id == Rulebook.id)
+            .where(
+                RulebookTopic.id == topic_id,
+                Rulebook.owner_user_id == user_id,
+            )
+        )
+        topic = result.scalar_one_or_none()
+        if topic is None:
+            return
+        await session.delete(topic)
+        await session.commit()