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

backend/internal/service/model_not_found_error.go

@@ -0,0 +1,68 @@
+package service
+
+import (
+	"net/http"
+	"strings"
+)
+
+var upstreamModelNotFoundKeywords = []string{"model not found", "unknown model", "not found"}
+
+func isUpstreamModelNotFoundError(statusCode int, body []byte) bool {
+	if statusCode != http.StatusNotFound {
+		return false
+	}
+	normalized := normalizeModelNotFoundBody(body)
+	if normalized == "" || !strings.Contains(normalized, "model") {
+		return false
+	}
+	return containsModelNotFoundKeyword(normalized)
+}
+
+func isModelNotFoundError(statusCode int, body []byte) bool {
+	return isUpstreamModelNotFoundError(statusCode, body) || statusCode == http.StatusNotFound
+}
+
+// openAICodexPlanGatedModelPhrase matches the deterministic Codex 400 returned
+// when a ChatGPT OAuth account's plan cannot serve the requested model, e.g.
+// {"detail":"The 'gpt-5.6-sol' model is not supported when using Codex with a ChatGPT account."}
+// The phrase is compared against the normalized body (lowercased, "_"/"-"
+// folded to spaces), so it also matches the same message embedded in
+// error.message-style payloads.
+const openAICodexPlanGatedModelPhrase = "model is not supported when using codex"
+
+// isOpenAICodexPlanGatedModelError reports whether the upstream response is the
+// deterministic Codex rejection of a plan-gated model on a ChatGPT account.
+// Unlike transient failures, retrying the same account cannot succeed until the
+// account's plan changes, so callers should treat it like model-not-found and
+// cool the (account, model) pair down instead of re-selecting the account.
+func isOpenAICodexPlanGatedModelError(statusCode int, body []byte) bool {
+	if statusCode != http.StatusBadRequest {
+		return false
+	}
+	normalized := normalizeModelNotFoundBody(body)
+	if normalized == "" {
+		return false
+	}
+	return strings.Contains(normalized, openAICodexPlanGatedModelPhrase)
+}
+
+func containsModelNotFoundKeyword(normalizedBody string) bool {
+	if normalizedBody == "" {
+		return false
+	}
+	for _, keyword := range upstreamModelNotFoundKeywords {
+		if strings.Contains(normalizedBody, keyword) {
+			return true
+		}
+	}
+	return false
+}
+
+func normalizeModelNotFoundBody(body []byte) string {
+	if len(body) == 0 {
+		return ""
+	}
+	normalized := strings.ToLower(string(body))
+	normalized = strings.NewReplacer("_", " ", "-", " ", "\n", " ", "\r", " ", "\t", " ").Replace(normalized)
+	return strings.Join(strings.Fields(normalized), " ")
+}