WSv2 egress relays upstream events verbatim without the HTTP-path
namespace restore, so flattening requests that take the WSv2 branch
would surface flattened tool names the client cannot match. Resolve
the WS transport decision before flattening and skip flattening only
when the request will actually go WSv2 (passthrough accounts return
via HTTP before the WSv2 branch and still flatten).
Also check all type assertions in responses_namespace_test.go to
satisfy golangci-lint errcheck.
Resolve conflict in openai_gateway_passthrough.go streaming path: keep
main's normalizeCompletedImageGenerationStatus normalization ahead of
this branch's namespace restore block, mirroring the established order
in openai_gateway_response_handling.go.
The snapshot taken before dispatching the OAuth response handler still used
raw c.Writer.Size(), while handleOpenAIImagesOAuthResponseError compares it
against the keepalive-adjusted size. From the second failover round on, the
previous round's heartbeat bytes made the raw snapshot positive while the
adjusted size stayed -1, so a retryable upstream error was misjudged as
'response already written': the failover was swallowed and the client got a
committed 200 with a whitespace-only body.
Snapshot now uses OpenAIImagesJSONKeepaliveAdjustedWrittenSize, matching the
comparison side. Regression test simulates a prior-round heartbeat before
ForwardImages and asserts the retryable error still converts to
UpstreamFailoverError (verified red without the fix, green with it).
Treat a non-empty messages dispatch model as a caller-approved fallback after account-level mapping, without reclassifying the requested Claude family.\n\nAdd Fable forwarding and endpoint boundary regression coverage.\n\nFixes #4177
OpenAI OAuth (ChatGPT) accounts deterministically reject plan-gated
models with 400 "The 'X' model is not supported when using Codex with
a ChatGPT account". Account selection had no capability filtering for
this, so the scheduler kept picking the same account for the same model
forever; every attempt burned an upstream call and surfaced to clients
as a retryable 502, sustaining client retry storms.
Treat this 400 like upstream model-not-found: mark the (account, model)
pair via SetModelRateLimit (30min cooldown) so
IsSchedulableForModelWithContext skips the account for that model
during selection, and return true so the in-flight request fails over
to another account through the existing UpstreamFailoverError path.
shaw