A strict lane (the Portal's Fireworks :US models) rejects `reasoning` /
`reasoning_details` by name. The in-memory record stopped the 400 for the
rest of the process, but `hermes chat --resume` (or a gateway restart)
re-learned it with another 400 on its first request. The record now lives in
the session's model_config (same seam as the Anthropic rejected-thinking
fingerprints) and is loaded once per session_id. Still keyed by
(provider, host, model), so sibling models keep every carrier.
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