fix: unlike not supported — wallmood is idempotent SET, not toggle (v0.4.5)

Extensive FW_DEBUG=1 testing revealed:
- wallmood with moodType=STAR is an idempotent SET operation, not a toggle
- Tested: all moodType variations, moodStarShortcut param, 9 alternative
  endpoints — none could remove a like
- Service Worker in the web app prevents intercepting the real unlike payload
- like=False now returns a clear error; like=True continues to work correctly
- SPEC.md updated with full investigation notes and ruled-out approaches

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

src/mcp_familywall/server.py

@@ -478,22 +478,36 @@ def delete_task(task_id: str) -> str:
 
 @mcp.tool()
 def like_post(post_id: str, like: bool = True) -> str:
-    """Like or unlike a wall post/activity.
+    """Like a wall post/activity with a STAR mood.
+
+    Note: Unlike (like=False) is not yet supported. The Family Wall API offers
+    no discoverable endpoint or parameter to remove a like. Passing like=False
+    returns an error without making any API call.
 
     Args:
         post_id: Wall post ID from get_activities (e.g. ``wall/23431854_31119189``).
-        like: ``True`` to like the post, ``False`` to unlike.
+        like: Must be ``True``. ``False`` is reserved for future unlike support.
 
     Returns:
         JSON success indicator or an error message.
     """
-    # wallmood toggles the STAR mood on a wall post (same endpoint for like/unlike).
+    # Unlike is not yet supported: extensive FW_DEBUG=1 testing showed that
+    # wallmood with moodType="STAR" is an idempotent SET operation (not a toggle).
+    # Tested and ruled out: moodType variations ("NONE", "REMOVE", "DELETE", ""),
+    # moodStarShortcut parameter, and alternative endpoints (all return 502).
+    # See SPEC.md for full investigation notes.
+    if not like:
+        return json.dumps(
+            {"error": "Unlike is not yet supported. The unlike mechanism is unknown."},
+            ensure_ascii=False,
+            indent=2,
+        )
+
     # Verified via FW_DEBUG=1:
     #   - Parameter 'wall_message_id': post ID as returned by get_activities
-    #   - Parameter 'moodType': "STAR" (Family Wall's internal like type)
-    #   - Response a00.r.r: full wall message object with moodMap showing current state
-    # The endpoint is a toggle — calling it again removes the mood.
-    # 'like=False' relies on this toggle behaviour (call again to undo).
+    #   - Parameter 'moodType': "STAR" (Family Wall's internal like type; "LIKE" is silently
+    #     mapped to "STAR" server-side — use "STAR" directly)
+    #   - Response a00.r.r: full wall message object with moodMap showing resulting state
     params: dict[str, Any] = {
         "wall_message_id": post_id,
         "moodType": "STAR",
@@ -504,7 +518,7 @@ def like_post(post_id: str, like: bool = True) -> str:
     except RuntimeError as exc:
         return f"Error: {exc}"
 
-    # Extract moodMap from response to determine actual resulting state.
+    # Extract moodMap from the response to confirm the like was recorded.
     try:
         wall_obj = data["a00"]["r"]["r"]
         if not isinstance(wall_obj, dict):
@@ -518,8 +532,7 @@ def like_post(post_id: str, like: bool = True) -> str:
             indent=2,
         )
 
-    # Determine whether the post is now liked by checking if any entry in
-    # moodMap contains "STAR" (the server-side representation of a like).
+    # Confirm the STAR is present in moodMap (server-side representation of a like).
     now_liked = any("STAR" in moods for moods in mood_map.values())
 
     return json.dumps(