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

backend/internal/service/gateway_billing_header_test.go

@@ -0,0 +1,67 @@
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSyncBillingHeaderVersion(t *testing.T) {
+	tests := []struct {
+		name      string
+		body      string
+		userAgent string
+		wantSub   string // substring expected in result
+		unchanged bool   // expect body to remain the same
+	}{
+		{
+			name:      "replaces cc_version preserving message-derived suffix",
+			body:      `{"system":[{"type":"text","text":"x-anthropic-billing-header: cc_version=2.1.81.df2; cc_entrypoint=cli; cch=00000;"},{"type":"text","text":"You are Claude Code.","cache_control":{"type":"ephemeral"}}],"messages":[]}`,
+			userAgent: "claude-cli/2.1.22 (external, cli)",
+			wantSub:   "cc_version=2.1.22.df2",
+		},
+		{
+			name:      "no billing header in system",
+			body:      `{"system":[{"type":"text","text":"You are Claude Code."}],"messages":[]}`,
+			userAgent: "claude-cli/2.1.22",
+			unchanged: true,
+		},
+		{
+			name:      "no system field",
+			body:      `{"messages":[]}`,
+			userAgent: "claude-cli/2.1.22",
+			unchanged: true,
+		},
+		{
+			name:      "user-agent without version",
+			body:      `{"system":[{"type":"text","text":"x-anthropic-billing-header: cc_version=2.1.81; cc_entrypoint=cli; cch=00000;"}],"messages":[]}`,
+			userAgent: "Mozilla/5.0",
+			unchanged: true,
+		},
+		{
+			name:      "empty user-agent",
+			body:      `{"system":[{"type":"text","text":"x-anthropic-billing-header: cc_version=2.1.81; cc_entrypoint=cli; cch=00000;"}],"messages":[]}`,
+			userAgent: "",
+			unchanged: true,
+		},
+		{
+			name:      "version already matches",
+			body:      `{"system":[{"type":"text","text":"x-anthropic-billing-header: cc_version=2.1.22; cc_entrypoint=cli; cch=00000;"}],"messages":[]}`,
+			userAgent: "claude-cli/2.1.22",
+			unchanged: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := syncBillingHeaderVersion([]byte(tt.body), tt.userAgent)
+			if tt.unchanged {
+				assert.Equal(t, tt.body, string(result), "body should remain unchanged")
+			} else {
+				assert.Contains(t, string(result), tt.wantSub)
+				// Ensure old semver is gone
+				assert.NotContains(t, string(result), "cc_version=2.1.81")
+			}
+		})
+	}
+}