Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/service/openai_routing_hint.go

@@ -0,0 +1,128 @@
+package service
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
+	"github.com/tidwall/gjson"
+	"go.uber.org/zap"
+	"golang.org/x/net/http/httpguts"
+)
+
+const openAICodexRoutingHintHeader = "x-codex-routing-hint"
+
+// setOpenAICodexRoutingHint mirrors the Codex backend routing-hint contract for
+// OpenAI OAuth requests. The request model must already be the final upstream
+// slug and serviceTier must already reflect any local policy rewrite/filter.
+func setOpenAICodexRoutingHint(headers http.Header, account *Account, model string, serviceTier string) {
+	if headers == nil {
+		return
+	}
+
+	// The routing hint is gateway-owned. Strip every spelling before deciding
+	// whether to synthesize it so API-key/provider credential paths cannot pass
+	// through a caller- or account-override-supplied hint. http.Header.Del only
+	// removes the canonical map key; inbound maps can contain raw lowercase keys.
+	deleteOpenAIHeaderEqualFold(headers, openAICodexRoutingHintHeader)
+	if account == nil || !account.IsOpenAIOAuth() {
+		return
+	}
+
+	model = strings.TrimSpace(model)
+	if model == "" || strings.ContainsAny(model, ";=") {
+		return
+	}
+
+	// Codex treats "default" as an explicit standard-routing sentinel, not as a
+	// service tier sent to the backend. Fast follows the gateway's existing
+	// canonicalization and therefore becomes "priority"; flex stays "flex".
+	canonicalTier := normalizedOpenAIServiceTierValue(serviceTier)
+	// This backport has no Codex model-catalog snapshot with which to validate
+	// arbitrary tier ids. Keep the hint to the two effective tiers Codex itself
+	// selects; default, missing, and other gateway-compatible API values remain
+	// model-only rather than expanding the ChatGPT routing protocol here.
+	switch canonicalTier {
+	case OpenAIFastTierPriority, OpenAIFastTierFlex:
+	default:
+		canonicalTier = ""
+	}
+
+	hint := "model=" + model
+	if canonicalTier != "" {
+		hint += ";tier=" + canonicalTier
+	}
+	if !httpguts.ValidHeaderFieldValue(hint) {
+		return
+	}
+	headers.Set(openAICodexRoutingHintHeader, hint)
+}
+
+func deleteOpenAIHeaderEqualFold(headers http.Header, name string) {
+	if headers == nil {
+		return
+	}
+	name = strings.TrimSpace(name)
+	for key := range headers {
+		if strings.EqualFold(strings.TrimSpace(key), name) {
+			delete(headers, key)
+		}
+	}
+}
+
+func setOpenAICodexRoutingHintFromBody(headers http.Header, account *Account, body []byte) {
+	fields := gjson.GetManyBytes(body, "model", "service_tier")
+	setOpenAICodexRoutingHint(headers, account, fields[0].String(), fields[1].String())
+}
+
+// logOpenAIRoutingDiagnostics records only gateway-derived routing state. In
+// particular, it deliberately does not include any header values, tokens, or
+// credentials because these diagnostics run on authentication-bearing paths.
+func logOpenAIRoutingDiagnostics(
+	ctx context.Context,
+	account *Account,
+	transport string,
+	model string,
+	serviceTier string,
+	hintGenerated bool,
+	wsAffinityDecision string,
+) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	accountID := int64(0)
+	if account != nil {
+		accountID = account.ID
+	}
+
+	logger.FromContext(ctx).Debug("openai routing decision",
+		zap.String("component", "service.openai_routing"),
+		zap.String("transport", strings.TrimSpace(transport)),
+		zap.Int64("account_id", accountID),
+		zap.String("final_model", strings.TrimSpace(model)),
+		zap.String("final_service_tier", normalizedOpenAIServiceTierValue(serviceTier)),
+		zap.Bool("routing_hint_generated", hintGenerated),
+		zap.String("ws_affinity_decision", strings.TrimSpace(wsAffinityDecision)),
+	)
+}
+
+func logOpenAIRoutingDiagnosticsFromBody(
+	ctx context.Context,
+	account *Account,
+	transport string,
+	headers http.Header,
+	body []byte,
+	wsAffinityDecision string,
+) {
+	fields := gjson.GetManyBytes(body, "model", "service_tier")
+	logOpenAIRoutingDiagnostics(
+		ctx,
+		account,
+		transport,
+		fields[0].String(),
+		fields[1].String(),
+		strings.TrimSpace(headers.Get(openAICodexRoutingHintHeader)) != "",
+		wsAffinityDecision,
+	)
+}