metadata may be a JSON string (e.g. '{"source": "doc1", "tags": ["a"]}')
or a JSON object — both are accepted. On parse failure an empty dict is
stored instead and a warning is returned alongside the result. If
collection is given, the memory is stored there (created automatically
if missing; default: the server-configured collection).

filter is an optional payload filter, as a JSON string or object (e.g.
'{"tags": ["x"]}' — only items whose tags field contains "x").
List values use MatchAny, scalars use exact match, and multiple
conditions are AND-ed. On parse failure the search runs without a filter
and a warning is returned alongside the results.
If collection is given, the search runs there (default: the
server-configured collection).

If point_id does not exist, an error is returned (existence is checked
first). When text is given, it is re-embedded and overwrites the stored
text; when text is None the existing text and vector are kept. When
metadata is given (JSON string or object), the payload metadata is
replaced entirely; when left empty ("") the existing metadata is kept.
Passing both text=None and an empty metadata is an error (nothing to
update).
If collection is given, the update happens there.

If point_id does not exist, an error is returned (existence is checked
first). If collection is given, the deletion happens there (default: the
server-configured collection).