A provider-qualified model string (@provider:model) is deliberately kept
intact for internal routing (#1253), but three places on the way to the
Hermes gateway mishandled it:
* _clean_session_model_provider returned the whole "provider:model"
value as the provider, so the gateway saw a provider named
"ollama-cloud:deepseek-v4-flash" -> "Unknown provider".
* _session_model_state_from_request extracted the provider correctly
but left the full "@provider:model" string as the model value.
* both gateway request builders sent that string verbatim as
body["model"], which the upstream provider API 404'd on.
Rather than add positional colon-split heuristics, route all three
through config._parse_provider_qualified_model_id() -- the existing
shared grammar that already distinguishes a multi-segment custom
provider ID (custom:<slug>, custom:<host>:<port>) from a model segment
carrying its own colon tag (:free, :0731). A positional split cannot
tell those two shapes apart, so any single split direction breaks the
other; the shared parser is the only thing that gets both right.
_split_provider_qualified_model now delegates to that parser too, which
fixes the same class of truncation at all of its call sites in routes.py
instead of only the two reported ones, and guarantees the provider used
for the routing decision matches the model sent in the request.
Fixes#6722
dss539
eda1ddd6f3