An OpenAI account with auto-passthrough enabled (extra.openai_passthrough=true,
"replace auth only, allow all models") was still filtered out during account
selection when it had a non-empty credentials.model_mapping that did not list the
requested model. isOpenAICompatibleAccountEligibleForRequest calls
Account.IsModelSupported directly, and IsModelSupported only bypassed the mapping
whitelist for passthrough accounts when the mapping was empty. A leftover mapping
(common after switching an account from whitelist mode to passthrough) therefore
excluded the account -> zero candidates -> ErrNoAvailableAccounts, and the client
saw 404 "Model ... is not supported by any configured account in this group" even
though a direct account test with the same model succeeded (that path already
honored passthrough via isModelSupportedByAccount).
Fix: short-circuit passthrough at the top of Account.IsModelSupported, before the
model_mapping check, so it is consistent with isModelSupportedByAccount. Add a
regression test covering passthrough + non-empty leftover mapping.
Wesley Liddick