Address PR #19 review feedback round 2:

- Bounty.created_by_user_id is now non-optional (always required)
- Removed is_group from RoomData (negative room_id is self-documenting)
- Added room_id to TrackedBounty to track which room bounty was tracked from
- Added clarifying docstrings explaining TrackingData vs TrackedBounty
- Updated tests to match new model structure

core/models.py

@@ -1,53 +1,63 @@
 """Domain dataclasses for JIGAIDO bounty tracker."""
 
 from dataclasses import dataclass
-from typing import Optional
 
 
 @dataclass
 class Bounty:
-    """Bounty - used for both group and personal bounties.
+    """A bounty created by a user.
 
-    Use created_by_user_id to distinguish: if set, it's a group bounty
-    created by that user. If None, it's a personal/DM bounty.
+    The created_by_user_id field always refers to the user who created the bounty.
+    It does NOT indicate whether the bounty is a group or personal bounty.
     """
 
     id: int
-    text: Optional[str]
-    link: Optional[str]
-    due_date_ts: Optional[int]
+    text: str | None
+    link: str | None
+    due_date_ts: int | None
     created_at: int
-    created_by_user_id: Optional[int] = None
+    created_by_user_id: int
 
 
 @dataclass
 class TrackedBounty:
-    """A bounty that a user is tracking."""
+    """A bounty that a user is tracking.
+
+    Use TrackedBounty when you need to record that a user is tracking a specific
+    bounty from a specific room. The room_id indicates which room the bounty
+    was tracked from (useful when users can track bounties across multiple rooms).
+
+    For simple tracking lists, just use bounty_id and created_at.
+    """
 
     bounty_id: int
     created_at: int
+    room_id: int
 
 
 @dataclass
 class RoomData:
     """All data for a room (group or DM).
 
-    For groups: is_group=True, room_id is negative (Telegram group ID)
-    For DMs: is_group=False, room_id is the user_id (positive)
-    next_id is used to generate unique bounty IDs within this room.
+    The room_id can be negative for Telegram groups or positive for DMs.
+    The next_id field is used to generate unique bounty IDs within this room.
     """
 
     room_id: int
-    is_group: bool
     bounties: list[Bounty]
     next_id: int
 
 
 @dataclass
 class TrackingData:
-    """User tracking data within a group.
+    """User tracking state within a group.
 
-    group_id is the Telegram group ID (always negative).
+    TrackingData vs TrackedBounty:
+    - Use TrackingData to store ALL tracked bounties for a user in a specific group.
+      It contains the group_id, user_id, and a list of TrackedBounty entries.
+    - Use TrackedBounty to represent a single tracked bounty entry within that list.
+
+    TrackingData is the container, TrackedBounty is the item.
     """
 
     group_id: int