feat(billing): 火山方舟视频计费 - 支持真实 Token 预授权与结算

Refs #228

Co-authored-by: MasterChiefCN <49179444+MasterChiefCN@users.noreply.github.com>

backend/internal/service/finance_token_test.go

@@ -0,0 +1,85 @@
+package service
+
+import (
+	"testing"
+
+	"infinite-canvas/backend/internal/model"
+)
+
+func TestSupportsTokenBillingForVolcengineArkVideo(t *testing.T) {
+	if !supportsTokenBilling("text", model.ChannelInterfaceChatCompletion) {
+		t.Fatal("text protocol should support Token billing")
+	}
+	if !supportsTokenBilling("video", model.ChannelInterfaceVolcengineArkVideo) {
+		t.Fatal("Volcengine Ark video should support Token billing")
+	}
+	if supportsTokenBilling("video", model.ChannelInterfaceNewAPIVideo) {
+		t.Fatal("video protocols without a final usage contract must not support Token billing")
+	}
+}
+
+func TestEstimateArkVideoTokensUsesPixelFrameEstimate(t *testing.T) {
+	estimate := estimateArkVideoTokens(map[string]any{
+		"config": map[string]any{
+			"model": "doubao-seedance-1-5-pro", "videoSeconds": "5", "vquality": "720", "size": "16:9",
+		},
+	})
+	// 1280*720*(5*24+1)/1024 = 108900，预授权再保留 10% 余量。
+	if estimate.InputTokens != 0 || estimate.OutputTokens != 119790 {
+		t.Fatalf("estimateArkVideoTokens() = %#v", estimate)
+	}
+}
+
+func TestEstimateArkVideoTokensIncludesUnknownReferenceVideo(t *testing.T) {
+	estimate := estimateArkVideoTokens(map[string]any{
+		"config": map[string]any{
+			"model": "doubao-seedance-2-0", "videoSeconds": "5", "vquality": "720p", "size": "16:9",
+		},
+		"referenceVideos": []any{map[string]any{"id": "video-1"}},
+	})
+	if estimate.OutputTokens != 477180 {
+		t.Fatalf("estimateArkVideoTokens() = %#v", estimate)
+	}
+}
+
+func TestEstimateArkVideoTokensCapsReferenceDuration(t *testing.T) {
+	estimate := estimateArkVideoTokens(map[string]any{
+		"config": map[string]any{
+			"model": "doubao-seedance-2-0", "videoSeconds": "5", "vquality": "720p", "size": "16:9",
+		},
+		"referenceVideos": []any{map[string]any{"id": "video-1", "durationMs": int64(60_000)}},
+	})
+	if estimate.OutputTokens != 477180 {
+		t.Fatalf("estimateArkVideoTokens() = %#v", estimate)
+	}
+}
+
+func TestTokenEstimateAmountAllowsVideoOutputOnly(t *testing.T) {
+	amount, err := tokenEstimateAmount(&model.ChannelModel{OutputTokenPriceMicrocredits: 16_000_000}, tokenBillingEstimate{OutputTokens: 119790}, 10_000)
+	if err != nil {
+		t.Fatalf("tokenEstimateAmount() error = %v", err)
+	}
+	if amount != 1_916_640 {
+		t.Fatalf("tokenEstimateAmount() = %d", amount)
+	}
+}
+
+func TestEnrichAPICallLogReadsArkVideoUsage(t *testing.T) {
+	log := &model.ApiCallLog{Capability: "video", Path: "/api/v3/contents/generations/tasks/cgt-test"}
+	(&Service{}).EnrichAPICallLog(log, []byte(`{"id":"cgt-test","status":"succeeded","usage":{"completion_tokens":108900,"total_tokens":108900}}`))
+	if !log.UsageAvailable || log.InputTokens != 0 || log.OutputTokens != 108900 {
+		t.Fatalf("EnrichAPICallLog() = %#v", log)
+	}
+
+	fallback := &model.ApiCallLog{Capability: "video", Path: "/api/v3/contents/generations/tasks/cgt-test"}
+	(&Service{}).EnrichAPICallLog(fallback, []byte(`{"usage":{"total_tokens":35800}}`))
+	if !fallback.UsageAvailable || fallback.OutputTokens != 35800 {
+		t.Fatalf("EnrichAPICallLog() total_tokens fallback = %#v", fallback)
+	}
+
+	missing := &model.ApiCallLog{Capability: "video", Path: "/api/v3/contents/generations/tasks/cgt-test"}
+	(&Service{}).EnrichAPICallLog(missing, []byte(`{"usage":{}}`))
+	if missing.UsageAvailable {
+		t.Fatalf("EnrichAPICallLog() accepted empty Ark usage: %#v", missing)
+	}
+}