feat(api-ai): persist usage logs

apps/api/src/ai/ai.service.ts

@@ -15,7 +15,12 @@ import { PrismaService } from "../prisma/prisma.service";
 import { AiProviderRegistryService } from "./ai-provider-registry.service";
 import { AiChatDto } from "./dto/ai-chat.dto";
 import { UpsertAiProviderBindingDto } from "./dto/upsert-ai-provider-binding.dto";
-import { AiResolvedRouteCandidate, AiRouteAttempt, AiRouteFailureError } from "./ai.types";
+import {
+  AiResolvedRouteCandidate,
+  AiRouteAttempt,
+  AiRouteFailureError,
+  AiUsageMetrics
+} from "./ai.types";
 
 type AiBindingSummary = {
   id: string;
@@ -198,6 +203,7 @@ export class AiService {
       }
 
       const executor = this.aiProviderRegistryService.getExecutor(entry.candidate.channel);
+      const startedAt = Date.now();
 
       try {
         const result = await executor.execute(entry.candidate, {
@@ -205,6 +211,7 @@ export class AiService {
           message: dto.message,
           sessionId: dto.sessionId ?? null
         });
+        const latencyMs = Date.now() - startedAt;
 
         attempts.push({
           channel: result.channel,
@@ -214,6 +221,16 @@ export class AiService {
           reasonCode: null,
           reasonMessage: null
         });
+        await this.recordUsageLog({
+          userId,
+          channel: result.channel,
+          providerName: result.providerName,
+          model: result.model,
+          usage: result.usage,
+          latencyMs,
+          success: true,
+          errorCode: null
+        });
 
         return {
           channel: result.channel,
@@ -224,8 +241,19 @@ export class AiService {
           attempts
         };
       } catch (error) {
+        const latencyMs = Date.now() - startedAt;
         const failureAttempt = this.toFailureAttempt(entry.candidate, error);
         attempts.push(failureAttempt);
+        await this.recordUsageLog({
+          userId,
+          channel: failureAttempt.channel,
+          providerName: failureAttempt.providerName,
+          model: failureAttempt.model,
+          usage: null,
+          latencyMs,
+          success: false,
+          errorCode: failureAttempt.reasonCode
+        });
         this.logger.warn(
           `AI 通道降级：channel=${failureAttempt.channel} provider=${failureAttempt.providerName ?? "unknown"} code=${failureAttempt.reasonCode ?? "UNKNOWN"} message=${failureAttempt.reasonMessage ?? "unknown"}`
         );
@@ -464,4 +492,35 @@ export class AiService {
 
     return `${secret.slice(0, 4)}***${secret.slice(-2)}`;
   }
+
+  private async recordUsageLog(input: {
+    userId: string;
+    channel: AiChannel;
+    providerName: string | null;
+    model: string | null;
+    usage: AiUsageMetrics | null;
+    latencyMs: number;
+    success: boolean;
+    errorCode: string | null;
+  }): Promise<void> {
+    try {
+      await this.prismaService.aiUsageLog.create({
+        data: {
+          userId: input.userId,
+          channel: input.channel,
+          providerName: input.providerName,
+          model: input.model,
+          promptTokens: input.usage?.promptTokens ?? 0,
+          completionTokens: input.usage?.completionTokens ?? 0,
+          totalTokens: input.usage?.totalTokens ?? 0,
+          latencyMs: input.latencyMs,
+          success: input.success,
+          errorCode: input.errorCode
+        }
+      });
+    } catch (error) {
+      const message = error instanceof Error ? error.message : "未知错误";
+      this.logger.warn(`写入 AI 使用日志失败：${message}`);
+    }
+  }
 }

apps/api/src/ai/ai.types.ts

@@ -24,9 +24,16 @@ export type AiChatResult = {
   model: string | null;
   content: string;
   sessionId: string | null;
+  usage: AiUsageMetrics | null;
   raw: unknown;
 };
 
+export type AiUsageMetrics = {
+  promptTokens: number;
+  completionTokens: number;
+  totalTokens: number;
+};
+
 export type AiRouteAttempt = {
   channel: AiChannel;
   providerName: string | null;

apps/api/src/ai/providers/astrbot.provider.ts

@@ -133,6 +133,7 @@ export class AstrbotProvider implements AiChannelExecutor {
       model: candidate.model,
       content,
       sessionId,
+      usage: this.extractUsage(events),
       raw: events
     };
   }
@@ -248,4 +249,39 @@ export class AstrbotProvider implements AiChannelExecutor {
 
     return fallback;
   }
+
+  private extractUsage(events: Array<Record<string, unknown>>): AiChatResult["usage"] {
+    for (const event of events) {
+      if (this.readString(event["type"]) !== "agent_stats") {
+        continue;
+      }
+
+      const data = this.asRecord(event["data"]);
+      const tokenUsage = this.asRecord(data?.["token_usage"]);
+      if (!tokenUsage) {
+        continue;
+      }
+
+      const promptTokens =
+        (this.readNumber(tokenUsage["input_other"]) ?? 0) +
+        (this.readNumber(tokenUsage["input_cached"]) ?? 0);
+      const completionTokens = this.readNumber(tokenUsage["output"]) ?? 0;
+
+      return {
+        promptTokens,
+        completionTokens,
+        totalTokens: promptTokens + completionTokens
+      };
+    }
+
+    return null;
+  }
+
+  private asRecord(value: unknown): Record<string, unknown> | null {
+    return typeof value === "object" && value !== null ? (value as Record<string, unknown>) : null;
+  }
+
+  private readNumber(value: unknown): number | null {
+    return typeof value === "number" && Number.isFinite(value) ? value : null;
+  }
 }

apps/api/src/ai/providers/openai-compatible.provider.ts

@@ -105,6 +105,7 @@ export class OpenAiCompatibleProvider implements AiChannelExecutor {
       model: this.extractModel(payload) ?? candidate.model,
       content,
       sessionId: input.sessionId,
+      usage: this.extractUsage(payload),
       raw: payload
     };
   }
@@ -176,6 +177,31 @@ export class OpenAiCompatibleProvider implements AiChannelExecutor {
     return payload["model"];
   }
 
+  private extractUsage(payload: unknown): AiChatResult["usage"] {
+    if (!this.isRecord(payload)) {
+      return null;
+    }
+
+    const usage = payload["usage"];
+    if (!this.isRecord(usage)) {
+      return null;
+    }
+
+    const promptTokens = this.readNumber(usage["prompt_tokens"]);
+    const completionTokens = this.readNumber(usage["completion_tokens"]);
+    const totalTokens = this.readNumber(usage["total_tokens"]);
+
+    if (promptTokens === null && completionTokens === null && totalTokens === null) {
+      return null;
+    }
+
+    return {
+      promptTokens: promptTokens ?? 0,
+      completionTokens: completionTokens ?? 0,
+      totalTokens: totalTokens ?? (promptTokens ?? 0) + (completionTokens ?? 0)
+    };
+  }
+
   private extractErrorMessage(payload: unknown, fallback: string): string {
     if (!this.isRecord(payload)) {
       return fallback;
@@ -200,4 +226,8 @@ export class OpenAiCompatibleProvider implements AiChannelExecutor {
 
     return fallback;
   }
+
+  private readNumber(value: unknown): number | null {
+    return typeof value === "number" && Number.isFinite(value) ? value : null;
+  }
 }