from acontext import AcontextClient

client = AcontextClient(api_key='sk_project_token')

# Patch message meta (adds/updates keys, use None to delete)
updated_meta = client.sessions.patch_message_meta(
    session_id='session-uuid',
    message_id='message-uuid',
    meta={'status': 'processed', 'old_key': None}  # None deletes the key
)
print(updated_meta)  # {'existing_key': 'value', 'status': 'processed'}

{
  "code": 123,
  "error": "<string>",
  "msg": "<string>",
  "data": {
    "meta": {}
  }
}