The official DeepSeek Chat Completions endpoint rejects the generic
"minimal" effort token (issue #4514). The declared effort contract for
DeepSeek models now advertises the provider's real vocabulary
(low/medium/high/max/xhigh), defaults to "low", and aliases the generic
"minimal" preset onto "low" so the "flash" dialogue mode serializes a
value the endpoint accepts.
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>