fix(billing): keep billing a request whose period start moved forward before its first charge

apps/sim/app/api/billing/update-cost/route.test.ts

@@ -1050,6 +1050,23 @@ describe('POST /api/billing/update-cost — mid-run usage gate', () => {
 
       expect(body.usageExceeded).toBe(false)
     })
+
+    it('keeps the exceeded verdict with the plan-upgrade card when the card read outlasts the callback budget', async () => {
+      billingPlanMockFns.mockGetHighestPrioritySubscription.mockImplementation(async () => {
+        await sleep(1500)
+        return { plan: 'pro' }
+      })
+      const startedAt = Date.now()
+
+      const body = await (await POST(directCallback())).json()
+
+      expect(body).toMatchObject({
+        success: true,
+        usageExceeded: true,
+        usageUpgrade: { action: 'upgrade_plan' },
+      })
+      expect(Date.now() - startedAt).toBeLessThan(1400)
+    })
   })
 
   describe('a run that outlives its billing period', () => {

apps/sim/app/api/billing/update-cost/route.ts

@@ -85,7 +85,8 @@ function invalidBillingProtocolResponse(requestId: string, span: Span): NextResp
  * steady-state steps cost no ledger read. The charge is
  * already recorded when this runs; a gate that cannot answer reports not-exceeded and leaves the
  * refusal to the next step or re-check rather than ending a paying run on a database blip,
- * and so does a read that outlasts {@link USAGE_STANDING_TIMEOUT_MS}.
+ * and so does a verdict read that outlasts {@link USAGE_STANDING_TIMEOUT_MS}. An exceeded
+ * verdict always pauses the run; a card read past that budget falls back to the plan-upgrade card.
  */
 async function readUsageStanding(
   userId: string,
@@ -98,9 +99,10 @@ async function readUsageStanding(
       ? () => readMidRunAccountUsageVerdict(accountDecision)
       : null
   if (!isHosted || !readVerdict) return { usageExceeded: false }
+  const deadlineAt = Date.now() + USAGE_STANDING_TIMEOUT_MS
   let verdict: MidRunUsageVerdict
   try {
-    verdict = await withinDeadline(readVerdict, Date.now() + USAGE_STANDING_TIMEOUT_MS)
+    verdict = await withinDeadline(readVerdict, deadlineAt)
   } catch {
     logger.warn('Usage standing read outlasted the callback budget; answering not exceeded')
     return { usageExceeded: false }
@@ -110,7 +112,12 @@ async function readUsageStanding(
   if (verdict.status !== 'exceeded') return { usageExceeded: false }
   return {
     usageExceeded: true,
-    usageUpgrade: await resolveUsageUpgradePayload(userId, billingAttribution, verdict.scope),
+    usageUpgrade: await resolveUsageUpgradePayload(
+      userId,
+      billingAttribution,
+      verdict.scope,
+      deadlineAt
+    ),
   }
 }
 

apps/sim/lib/billing/core/usage-log.integration.ts

@@ -502,6 +502,32 @@ describe('Cumulative billing with PostgreSQL', () => {
       expect(await stampedWindowTotal(resetStart, resetEnd)).toBeCloseTo(0.6, 9)
     })
 
+    it('keeps billing a request whose period start moved forward before its first charge', async () => {
+      const resetStart = new Date('2025-09-15T00:00:00.000Z')
+      const resetEnd = new Date('2025-10-15T00:00:00.000Z')
+      await setSubscriptionWindow(resetStart, resetEnd)
+
+      expect(await charge(0.4)).toMatchObject({ billed: true, total: 0.4 })
+      expect(await charge(1)).toMatchObject({
+        billed: true,
+        total: 1,
+        billingPeriod: { start: resetStart, end: resetEnd },
+      })
+      expect(await ledgerRows()).toEqual([{ event_key: usage(0).eventKey, cost: '1' }])
+      expect(await stampedWindowTotal(resetStart, resetEnd)).toBeCloseTo(1, 9)
+    })
+
+    it('refuses a request admitted after the period its first charge was stamped with', async () => {
+      await setSubscriptionPeriod(0)
+      await charge(0.4)
+
+      await expect(charge(1, { start: periods[1], end: periods[2] })).rejects.toMatchObject({
+        name: CumulativeUsageContextMismatchError.name,
+        mismatchedFields: ['billing period'],
+      })
+      expect(await ledgerRows()).toEqual([{ event_key: usage(0).eventKey, cost: '0.4' }])
+    })
+
     it('holds an early period-start move until an in-flight top-up commits', async () => {
       const start = new Date(Date.now() - 24 * 60 * 60 * 1000)
       const end = new Date(Date.now() + 30 * 24 * 60 * 60 * 1000)

apps/sim/lib/billing/core/usage-log.ts

@@ -696,7 +696,10 @@ function assertCumulativeUsageLedgerBinding(
     workspaceId?: string
     billingContext: BillingContext
     eventKey: string
-    /** A request whose first charge landed after its period closed is stamped with a later one. */
+    /**
+     * A request whose first charge landed after its period closed, or after an anchor reset moved
+     * its start forward, is stamped with a later one.
+     */
     allowLaterPeriod?: boolean
   }
 ): void {
@@ -717,10 +720,11 @@ function assertCumulativeUsageLedgerBinding(
   const samePeriod =
     existing.billingPeriodStart?.getTime() === frozenPeriod.start.getTime() &&
     existing.billingPeriodEnd?.getTime() === frozenPeriod.end.getTime()
+  // The same forward-only rule that rolls a charge into a new period row.
   const laterPeriod =
     expected.allowLaterPeriod === true &&
     existing.billingPeriodStart !== null &&
-    existing.billingPeriodStart.getTime() >= frozenPeriod.end.getTime()
+    existing.billingPeriodStart.getTime() > frozenPeriod.start.getTime()
   if (!samePeriod && !laterPeriod) {
     mismatchedFields.push('billing period')
   }

apps/sim/lib/billing/usage-upgrade.ts

@@ -8,6 +8,7 @@ import type {
 import { getHighestPrioritySubscription } from '@/lib/billing/core/plan'
 import { isEnterprise, isPaid } from '@/lib/billing/plan-helpers'
 import { isOrgScopedSubscription } from '@/lib/billing/subscriptions/utils'
+import { withinDeadline } from '@/lib/core/utils/deadline'
 
 const logger = createLogger('UsageUpgrade')
 
@@ -22,12 +23,14 @@ const MEMBER_CAP_MESSAGE =
  * increase for a paid one, with copy naming who can raise an organization's limit. A member
  * over the cap their organization set gets copy naming who can raise that cap. An attributed
  * run reads the plan from its admission snapshot without a query; otherwise the actor's current
- * subscription decides, and a failed lookup falls back to the plan-upgrade card.
+ * subscription decides, and a lookup that fails or outlasts `deadlineAt` falls back to the
+ * plan-upgrade card.
  */
 export async function resolveUsageUpgradePayload(
   userId: string,
   billingAttribution?: BillingAttributionSnapshot,
-  scope?: AttributedUsageLimitsResult['scope']
+  scope?: AttributedUsageLimitsResult['scope'],
+  deadlineAt?: number
 ): Promise<UsageUpgradePayload> {
   if (scope === 'member') {
     return { reason: 'usage_limit', action: 'increase_limit', message: MEMBER_CAP_MESSAGE }
@@ -39,7 +42,9 @@ export async function resolveUsageUpgradePayload(
       plan = billingAttribution.payerSubscription?.plan
       orgScoped = billingAttribution.billingEntity.type === 'organization'
     } else {
-      const subscription = await getHighestPrioritySubscription(userId)
+      const subscription = await (deadlineAt === undefined
+        ? getHighestPrioritySubscription(userId)
+        : withinDeadline(() => getHighestPrioritySubscription(userId), deadlineAt))
       plan = subscription?.plan
       orgScoped = isOrgScopedSubscription(subscription, userId)
     }