fix(api/billing): stop falling back to ACUC when Autumn check fails (firecrawl#3631)

Autumn is the source of truth for credits and ACUC accounting has
diverged for many teams (e.g. teams showing negative remaining_credits
in ACUC while being current in Autumn). The previous code ran both
checks in parallel and silently fell back to ACUC whenever Autumn
returned null on error, producing spurious 402s.

The middleware now consults Autumn only and fails open on transient
Autumn failures, matching the behavior of browser.ts and
scrape-browser.ts.

Co-authored-by: firecrawl-spring[bot] <254786068+firecrawl-spring[bot]@users.noreply.github.com>

Author: firecrawl-spring[bot]

apps/api/src/routes/shared.ts

@@ -10,7 +10,6 @@ import { RateLimiterMode } from "../types";
 import { authenticateUser } from "../controllers/auth";
 import { createIdempotencyKey } from "../services/idempotency/create";
 import { validateIdempotencyKey } from "../services/idempotency/validate";
-import { checkTeamCredits } from "../services/billing/credit_billing";
 import { isUrlBlocked } from "../scraper/WebScraper/utils/blocklist";
 import { logger } from "../lib/logger";
 import {
@@ -120,32 +119,27 @@ export function checkCreditsMiddleware(
       }
 
       const requestedCredits = minimum ?? 1;
-      const useAutumnCheck = !!req.auth.org_id;
-
-      const autumnProperties = {
-        source: "checkCreditsMiddleware",
-        path: req.path,
-      };
-      const [legacyCheck, autumnResult] = await Promise.all([
-        checkTeamCredits(req.acuc ?? null, req.auth.team_id, requestedCredits),
-        useAutumnCheck
-          ? autumnService.checkCredits({
-              teamId: req.auth.team_id,
-              value: requestedCredits,
-              properties: autumnProperties,
-            })
-          : null,
-      ]);
-      let { success, remainingCredits, chunk } = legacyCheck;
-
-      if (autumnResult !== null) {
-        success = autumnResult.allowed;
-        remainingCredits = autumnResult.remaining;
-      }
 
-      if (chunk) {
-        req.acuc = chunk;
+      const autumnResult = await autumnService.checkCredits({
+        teamId: req.auth.team_id,
+        value: requestedCredits,
+        properties: {
+          source: "checkCreditsMiddleware",
+          path: req.path,
+        },
+      });
+
+      // Autumn is the source of truth for credits. If it's unavailable
+      // (returns null), fail open — matches the behavior in browser.ts /
+      // scrape-browser.ts and avoids turning an Autumn outage into a
+      // customer outage.
+      if (autumnResult === null) {
+        req.account = { remainingCredits: Infinity };
+        return next();
       }
+
+      const success = autumnResult.allowed;
+      const remainingCredits = autumnResult.remaining;
       req.account = { remainingCredits };
       if (!success) {
         if (