Reorder children for panel display order (Feature 03, task 3)

- ChildrenDao.reorder now requires a COMPLETE permutation of the
  children table: partial lists (missing an existing child), unknown
  ids and duplicates are rejected with ValueError before any write,
  inside the existing transaction and connection lock (check and
  write atomic). Empty list is the maximally partial reorder against
  a non-empty table; against an empty table it stays a no-op. The two
  DAO tests that encoded the old permissive semantics (silent no-op
  on empty/unknown) are updated to the new contract.
- children.py gains reorder_children: the Feature 09-facing wrapper,
  which additionally rejects non-integer ids up front (bools and
  floats would silently compare against stored integer ids at the SQL
  layer).
- Business tests: round-trip (active list returns new order), partial/
  unknown/duplicate/non-int rejections with order-unchanged proofs,
  empty-list rejection, and inactive children keeping positions in a
  whole-table permutation. Suite: 866 passed.

custom_components/nestquest/children.py

@@ -236,6 +236,30 @@ async def set_child_active(
     return updated
 
 
+async def reorder_children(
+    database: NestQuestDatabase, ordered_ids: list[int]
+) -> None:
+    """Rewrite the children's panel display order in one transaction.
+
+    ``ordered_ids`` must be a complete permutation of the children
+    table — every child id exactly once.  A partial list (missing an
+    existing child), an unknown id, or a duplicate is rejected with
+    ValueError before any write, so the current order survives a
+    rejected call.  The DAO enforces this inside its own transaction
+    (check and write are atomic under the connection lock); this
+    wrapper additionally rejects non-integer ids up front, since
+    ``bool`` and floats would silently compare against stored integer
+    ids at the SQL layer.
+    """
+    for child_id in ordered_ids:
+        if isinstance(child_id, bool) or not isinstance(child_id, int):
+            raise ValueError(
+                f"ordered_ids must contain only integer child ids, got "
+                f"{child_id!r}"
+            )
+    await ChildrenDao(database).reorder(ordered_ids)
+
+
 async def list_children(
     database: NestQuestDatabase, *, active_only: bool = False
 ) -> list[ChildRecord]:

custom_components/nestquest/dao_children.py

@@ -191,13 +191,20 @@ class ChildrenDao:
     async def reorder(self, ordered_ids: list[int]) -> None:
         """Persist a new sort order: ``ordered_ids[i]`` gets sort_order i.
 
+        The list must be a COMPLETE permutation of the children table:
+        every existing child id appears exactly once.  Partial lists
+        (missing an existing child) and unknown ids (naming a child
+        that does not exist) are rejected with ValueError BEFORE any
+        write, leaving the current order untouched — a silent partial
+        reorder would leave unlisted children with stale positions and
+        hide a caller bug.  Duplicate ids are rejected up front: they
+        cannot all hold distinct positions, and silently assigning the
+        last occurrence's index would hide a caller bug.
+
         Runs inside one transaction; positions are staged at offset
         -len (all negative, so any permutation of the same ids never
         collides mid-reorder under the wrapper's single-connection
-        serialization), then finalized 0..n-1.  Duplicate ids are
-        rejected up front: they cannot all hold distinct positions, and
-        silently assigning the last occurrence's index would hide a
-        caller bug.
+        serialization), then finalized 0..n-1.
 
         Concurrent reorder() calls on one connection are serialized by
         a connection-scoped asyncio lock (shared across every ChildrenDao
@@ -205,10 +212,10 @@ class ChildrenDao:
         transaction() rejects a second concurrent transaction with
         RuntimeError, so racing callers would crash instead of
         queueing.  The lock makes the second call wait, then run
-        against the first call's final state.
+        against the first call's final state — which also keeps the
+        completeness check honest: the re-read of the table happens
+        inside the same lock and transaction as the writes.
         """
-        if not ordered_ids:
-            return
         if len(set(ordered_ids)) != len(ordered_ids):
             raise ValueError(
                 "reorder() received duplicate child ids; every id must "
@@ -216,6 +223,29 @@ class ChildrenDao:
             )
         async with _connection_lock(self._database):
             async with self._database.transaction():
+                rows = await self._database.fetch_all(
+                    f"SELECT id FROM children"
+                )
+                existing = {row[0] for row in rows}
+                listed = set(ordered_ids)
+                missing = sorted(existing - listed)
+                unknown = sorted(listed - existing)
+                if missing or unknown:
+                    details = []
+                    if missing:
+                        details.append(
+                            f"missing child ids {missing} (a partial "
+                            "reorder would leave them with stale "
+                            "positions)"
+                        )
+                    if unknown:
+                        details.append(
+                            f"unknown child ids {unknown}"
+                        )
+                    raise ValueError(
+                        "reorder() must list every child exactly once; "
+                        + "; ".join(details)
+                    )
                 offset = len(ordered_ids)
                 await self._database.execute_many(
                     "UPDATE children SET sort_order = ? WHERE id = ?",