Check if user has enough credits before responding with AI generated content

packages/ai-bot/lib/ai-billing.ts

@@ -0,0 +1,95 @@
+import {
+  getCurrentActiveSubscription,
+  getUserByMatrixUserId,
+  spendCredits,
+  sumUpCreditsLedger,
+} from '@cardstack/billing/billing-queries';
+import { PgAdapter, TransactionManager } from '@cardstack/postgres';
+import { logger, retry } from '@cardstack/runtime-common';
+import * as Sentry from '@sentry/node';
+
+let log = logger('ai-bot');
+
+export async function saveUsageCost(
+  pgAdapter: PgAdapter,
+  matrixUserId: string,
+  generationId: string,
+) {
+  try {
+    // Generation data is sometimes not immediately available, so we retry a couple of times until we are able to get the cost
+    let costInUsd = await retry(() => fetchGenerationCost(generationId), {
+      retries: 10,
+      delayMs: 500,
+    });
+
+    let creditsConsumed = Math.round(costInUsd / 0.001);
+
+    let user = await getUserByMatrixUserId(pgAdapter, matrixUserId);
+
+    // This check is for the transition period where we don't have subscriptions fully rolled out yet.
+    // When we have assurance that all users who use the bot have subscriptions, we can remove this subscription check.
+    let subscription = await getCurrentActiveSubscription(pgAdapter, user!.id);
+    if (!subscription) {
+      log.info(
+        `user ${matrixUserId} has no subscription, skipping credit usage tracking`,
+      );
+      return Promise.resolve();
+    }
+
+    if (!user) {
+      throw new Error(
+        `should not happen: user with matrix id ${matrixUserId} not found in the users table`,
+      );
+    }
+
+    let txManager = new TransactionManager(pgAdapter);
+
+    await txManager.withTransaction(async () => {
+      await spendCredits(pgAdapter, user!.id, creditsConsumed);
+
+      // TODO: send a signal to the host app to update credits balance displayed in the UI
+    });
+  } catch (err) {
+    log.error(
+      `Failed to track AI usage (matrixUserId: ${matrixUserId}, generationId: ${generationId}):`,
+      err,
+    );
+    Sentry.captureException(err);
+    // Don't throw, because we don't want to crash the bot over this
+  }
+}
+
+export async function getAvailableCredits(
+  pgAdapter: PgAdapter,
+  matrixUserId: string,
+) {
+  let user = await getUserByMatrixUserId(pgAdapter, matrixUserId);
+
+  if (!user) {
+    throw new Error(
+      `should not happen: user with matrix id ${matrixUserId} not found in the users table`,
+    );
+  }
+
+  let availableCredits = await sumUpCreditsLedger(pgAdapter, {
+    userId: user.id,
+  });
+
+  return availableCredits;
+}
+
+async function fetchGenerationCost(generationId: string) {
+  let response = await (
+    await fetch(`https://openrouter.ai/api/v1/generation?id=${generationId}`, {
+      headers: {
+        Authorization: `Bearer ${process.env.OPENROUTER_API_KEY}`,
+      },
+    })
+  ).json();
+
+  if (response.error && response.error.includes('not found')) {
+    return null;
+  }
+
+  return response.data.total_cost;
+}

packages/ai-bot/lib/matrix.ts

@@ -145,7 +145,7 @@ function getErrorMessage(error: any): string {
     return `OpenAI error: ${error.name} - ${error.message}`;
   }
   if (typeof error === 'string') {
-    return `Unknown error: ${error}`;
+    return error;
   }
-  return `Unknown error`;
+  return 'Unknown error';
 }

packages/ai-bot/lib/send-response.ts

@@ -133,7 +133,7 @@ export class Responder {
     }
   }
 
-  async onError(error: OpenAIError) {
+  async onError(error: OpenAIError | string) {
     Sentry.captureException(error);
     return await sendError(
       this.client,

packages/ai-bot/main.ts

@@ -25,20 +25,43 @@
 import type { MatrixEvent as DiscreteMatrixEvent } from 'https://cardstack.com/base/matrix-event';
 import * as Sentry from '@sentry/node';
 
+import { getAvailableCredits, saveUsageCost } from './lib/ai-billing';
+import { PgAdapter } from '@cardstack/postgres';
+import {
+  getUserByMatrixUserId,
+  sumUpCreditsLedger,
+} from '@cardstack/billing/billing-queries';
+
 let log = logger('ai-bot');
 
+let trackAiUsageCostPromises = new Map<string, Promise<void>>();
+
 class Assistant {
   private openai: OpenAI;
   private client: MatrixClient;
+  pgAdapter: PgAdapter;
   id: string;
 
   constructor(client: MatrixClient, id: string) {
     this.openai = new OpenAI({
-      baseURL: 'https://openrouter.ai/api/v1', // We use openrouter so that we can track usage cost in $
+      baseURL: 'https://openrouter.ai/api/v1',
       apiKey: process.env.OPENROUTER_API_KEY,
     });
     this.id = id;
     this.client = client;
+    this.pgAdapter = new PgAdapter();
+  }
+
+  async trackAiUsageCost(matrixUserId: string, generationId: string) {
+    if (trackAiUsageCostPromises.has(matrixUserId)) {
+      return;
+    }
+    trackAiUsageCostPromises.set(
+      matrixUserId,
+      saveUsageCost(this.pgAdapter, matrixUserId, generationId).finally(() => {
+        trackAiUsageCostPromises.delete(matrixUserId);
+      }),
+    );
   }
 
   getResponse(history: DiscreteMatrixEvent[]) {
@@ -133,6 +156,7 @@
     async function (event, room, toStartOfTimeline) {
       try {
         let eventBody = event.getContent().body;
+        let senderMatrixUserId = event.getSender()!;
         if (!room) {
           return;
         }
@@ -150,15 +174,15 @@
           return; // don't respond to card fragments, we just gather these in our history
         }
 
-        if (event.getSender() === aiBotUserId) {
+        if (senderMatrixUserId === aiBotUserId) {
           return;
         }
         log.info(
           '(%s) (Room: "%s" %s) (Message: %s %s)',
           event.getType(),
           room?.name,
           room?.roomId,
-          event.getSender(),
+          senderMatrixUserId,
           eventBody,
         );
 
@@ -177,18 +201,47 @@
         }
 
         const responder = new Responder(client, room.roomId);
-        await responder.initialize();
-
         if (historyError) {
-          responder.finalize(
+          return responder.finalize(
             'There was an error processing chat history. Please open another session.',
           );
-          return;
         }
 
+        await responder.initialize();
+
+        // Do not generate new responses if previous ones' cost is still being reported
+        let pendingCreditsConsumptionPromise = trackAiUsageCostPromises.get(
+          senderMatrixUserId!,
+        );
+        if (pendingCreditsConsumptionPromise) {
+          try {
+            await pendingCreditsConsumptionPromise;
+          } catch (e) {
+            log.error(e);
+            return responder.onError(
+              'There was an error saving your Boxel credits usage. Try again or contact support if the problem persists.',
+            );
+          }
+        }
+
+        let availableCredits = await getAvailableCredits(
+          assistant.pgAdapter,
+          senderMatrixUserId,
+        );
+
+        let minimumCredits = 10;
+
+        if (availableCredits < minimumCredits) {
+          return responder.onError(
+            `You need a minimum of ${minimumCredits} credits to continue using the AI bot. Please upgrade to a larger plan, or top up your account.`,
+          );
+        }
+
+        let generationId: string | undefined;
         const runner = assistant
           .getResponse(history)
           .on('chunk', async (chunk, _snapshot) => {
+            generationId = chunk.id;
             await responder.onChunk(chunk);
           })
           .on('content', async (_delta, snapshot) => {
@@ -200,9 +253,18 @@
           .on('error', async (error) => {
             await responder.onError(error);
           });
-        // We also need to catch the error when getting the final content
-        let finalContent = await runner.finalContent().catch(responder.onError);
-        await responder.finalize(finalContent);
+
+        let finalContent;
+        try {
+          finalContent = await runner.finalContent();
+          await responder.finalize(finalContent);
+        } catch (error) {
+          await responder.onError(error);
+        } finally {
+          if (generationId) {
+            assistant.trackAiUsageCost(senderMatrixUserId, generationId);
+          }
+        }
 
         if (shouldSetRoomTitle(eventList, aiBotUserId, event)) {
           return await assistant.setTitle(room.roomId, history, event);

packages/ai-bot/package.json

@@ -1,7 +1,9 @@
 {
   "name": "@cardstack/ai-bot",
   "dependencies": {
-    "@cardstack/runtime-common": "workspace:^",
+    "@cardstack/runtime-common": "workspace:*",
+    "@cardstack/postgres": "workspace:*",
+    "@cardstack/billing": "workspace:*",
     "@sentry/node": "^8.31.0",
     "@types/node": "^18.18.5",
     "@types/stream-chain": "^2.0.1",
@@ -21,7 +23,7 @@
   },
   "scripts": {
     "lint": "eslint . --cache --ext ts",
-    "start": "NODE_NO_WARNINGS=1 ts-node --transpileOnly main",
+    "start": "NODE_NO_WARNINGS=1 PGDATABASE=boxel PGPORT=5435 ts-node --transpileOnly main",
     "test": "NODE_NO_WARNINGS=1 qunit --require ts-node/register/transpile-only tests/index.ts",
     "get-chat": "NODE_NO_WARNINGS=1 ts-node --transpileOnly scripts/get_chat.ts"
   },

packages/billing/billing-queries.ts

@@ -472,3 +472,67 @@ export async function expireRemainingPlanAllowanceInSubscriptionCycle(
     subscriptionCycleId,
   });
 }
+
+export async function spendCredits(
+  dbAdapter: DBAdapter,
+  userId: string,
+  creditsToSpend: number,
+) {
+  let subscription = await getCurrentActiveSubscription(dbAdapter, userId);
+  if (!subscription) {
+    throw new Error('active subscription not found');
+  }
+  let subscriptionCycle = await getMostRecentSubscriptionCycle(
+    dbAdapter,
+    subscription.id,
+  );
+  if (!subscriptionCycle) {
+    throw new Error('subscription cycle not found');
+  }
+  let availablePlanAllowanceCredits = await sumUpCreditsLedger(dbAdapter, {
+    creditType: [
+      'plan_allowance',
+      'plan_allowance_used',
+      'plan_allowance_expired',
+    ],
+    userId,
+  });
+
+  if (availablePlanAllowanceCredits >= creditsToSpend) {
+    await addToCreditsLedger(dbAdapter, {
+      userId,
+      creditAmount: -creditsToSpend,
+      creditType: 'plan_allowance_used',
+      subscriptionCycleId: subscriptionCycle.id,
+    });
+  } else {
+    // If user does not have enough plan allowance credits to cover the spend, try to also use extra credits
+    let availableExtraCredits = await sumUpCreditsLedger(dbAdapter, {
+      creditType: ['extra_credit', 'extra_credit_used'],
+      userId,
+    });
+    let planAllowanceToSpend = availablePlanAllowanceCredits; // Spend all plan allowance credits first
+    let extraCreditsToSpend = creditsToSpend - planAllowanceToSpend;
+    if (extraCreditsToSpend > availableExtraCredits) {
+      extraCreditsToSpend = availableExtraCredits;
+    }
+
+    if (planAllowanceToSpend > 0) {
+      await addToCreditsLedger(dbAdapter, {
+        userId,
+        creditAmount: -planAllowanceToSpend,
+        creditType: 'plan_allowance_used',
+        subscriptionCycleId: subscriptionCycle.id,
+      });
+    }
+
+    if (extraCreditsToSpend > 0) {
+      await addToCreditsLedger(dbAdapter, {
+        userId,
+        creditAmount: -extraCreditsToSpend,
+        creditType: 'extra_credit_used',
+        subscriptionCycleId: subscriptionCycle.id,
+      });
+    }
+  }
+}

packages/billing/stripe-webhook-handlers/checkout-session-completed.ts

@@ -1,6 +1,8 @@
 import { type DBAdapter } from '@cardstack/runtime-common';
 import {
   addToCreditsLedger,
+  getCurrentActiveSubscription,
+  getMostRecentSubscriptionCycle,
   getUserByStripeId,
   insertStripeEvent,
   markStripeEventAsProcessed,
@@ -50,11 +52,27 @@ export async function handleCheckoutSessionCompleted(
         );
       }
 
+      let subscription = await getCurrentActiveSubscription(dbAdapter, user.id);
+      if (!subscription) {
+        throw new Error(
+          `User ${user.id} has no subscription, cannot add extra credits`,
+        );
+      }
+      let subscriptionCycle = await getMostRecentSubscriptionCycle(
+        dbAdapter,
+        subscription!.id,
+      );
+      if (!subscriptionCycle) {
+        throw new Error(
+          `User ${user.id} has no subscription cycle, cannot add extra credits`,
+        );
+      }
+
       await addToCreditsLedger(dbAdapter, {
         userId: user.id,
         creditAmount: creditReloadAmount,
         creditType: 'extra_credit',
-        subscriptionCycleId: null,
+        subscriptionCycleId: subscriptionCycle.id,
       });
     }
   });

packages/billing/stripe-webhook-handlers/index.ts

@@ -124,9 +124,6 @@ export default async function stripeWebhookHandler(
 
   let type = event.type;
 
-  // For adding extra credits, we should listen for charge.succeeded, and for
-  // subsciptions, we should listen for invoice.payment_succeeded (I discovered this when I was
-  // testing which webhooks arrive for both types of payments)
   switch (type) {
     // These handlers should eventually become jobs which workers will process asynchronously
     case 'invoice.payment_succeeded':