fix(failover): do not trip targets on a gRPC message size limit

ResourceExhausted is retried and trips the target, which is right for a
rate limit or an out-of-memory backend. A payload over the gRPC message
cap is ResourceExhausted too, but every target rejects it the same way,
so it tripped the whole chain. Classify it as a request error.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

core/services/failover/classify.go

@@ -22,6 +22,11 @@ var requestErrorMarkers = []string{
 	"exceeds the available context size",
 	"is larger than the max context size",
 	"maximum context length",
+	// A payload over the gRPC message cap is ResourceExhausted too, but it
+	// is the request's size, not the target's load: every target has the
+	// same cap.
+	"larger than max",
+	"gRPC message limit exceeded",
 }
 
 // IsRetryable reports whether a failed attempt should move to the next

core/services/failover/classify_test.go

@@ -36,6 +36,10 @@ var _ = DescribeTable("IsRetryable",
 	Entry("cloud-proxy upstream 503", errors.New("cloud-proxy: upstream 503: no healthy nodes"), 0, true),
 	Entry("cloud-proxy upstream 429 stays 4xx", errors.New("cloud-proxy: upstream 429: slow down"), 0, false),
 	Entry("context overflow", errors.New("the request exceeds the available context size"), 0, false),
+	Entry("grpc received message over the size limit", grpcstatus.Error(codes.ResourceExhausted, "grpc: received message larger than max (60000000 vs. 52428800)"), 0, false),
+	Entry("grpc sent message over the size limit", grpcstatus.Error(codes.ResourceExhausted, "grpc: trying to send message larger than max (60000000 vs. 52428800)"), 0, false),
+	Entry("embeddings over the gRPC message limit", fmt.Errorf("conversation too long for per-token embeddings (gRPC message limit exceeded): %w",
+		grpcstatus.Error(codes.ResourceExhausted, "grpc: received message larger than max (1 vs. 0)")), 0, false),
 	Entry("dial error", errors.New("dial tcp 10.0.0.1:8080: connect: connection refused"), 0, true),
 )