autumn

name	autumn
description	Autumn billing in Epicenter: `autumn.config.ts`, `autumn-js` credit checks, `atmn` CLI, plan gates, and metered AI usage. Use when changing billing, pricing, credits, plan access, refunds, or usage events.
metadata	{"author":"epicenter","version":"1.2"}

Autumn Billing Integration Guide

Reference Repositories

• Autumn: Usage-based billing platform
• Autumn TypeScript SDK + CLI: autumn-js SDK and atmn CLI
• Autumn Docs

Upstream Grounding

When Autumn Product, ProductItem, Feature, Entitlement, Customer, CustomerProduct, pricing, credit checks, SDK calls, CLI behavior, or usage-event semantics affect correctness, use source-backed grounding before relying on memory. If DeepWiki MCP is available, ask a narrow question against useautumn/autumn; if it is unavailable or the repo is not indexed, use upstream source or official docs directly. For autumn-js SDK or atmn CLI behavior, verify against the installed package, useautumn/typescript, or official docs. Treat DeepWiki as orientation, then verify decisive details against local billing code, installed types, source, or official docs before changing code.

Skip DeepWiki for hosted-only Epicenter billing boundaries already documented in AGENTS.md and below.

---

When to Apply This Skill

Use this when you need to:

• Define or modify features, credit systems, or plans in autumn.config.ts.
• Add credit checks or usage tracking via the autumn-js SDK.
• Gate API endpoints behind billing (free tier limits, paid plan access).
• Push/pull billing config with the atmn CLI.
• Debug billing issues (insufficient credits, customer sync, refunds).

Domain Model Checks

• Use Autumn's current nouns precisely: Feature, Entitlement, Product, ProductItem, Price, Customer, and CustomerProduct.
• Validate ProductItem shapes before pushing config. Most failures come from invalid interval combinations, missing linked features, or price/reset variants that do not match the feature type.
• Decide fail-open versus fail-closed behavior for check() errors at each endpoint. AI credit charging should fail closed before expensive provider calls.
• If Stripe webhooks or CustomerProduct state transitions are touched, make the handler idempotent around retries.

---

Naming Conventions (CRITICAL)

All IDs use snake_case. This is Autumn's explicit convention.

Feature IDs should be descriptive (not abstract tier numbers) and ecosystem-scoped (not tied to a single app feature like "chat"). The metered features represent model cost tiers that any AI feature can consume.

// CORRECT: descriptive, ecosystem-scoped
feature({ id: 'ai_fast', ... })
feature({ id: 'ai_standard', ... })
feature({ id: 'ai_premium', ... })
plan({ id: 'pro', ... })
plan({ id: 'credit_top_up', ... })

// WRONG: tied to a single feature ("chat")
feature({ id: 'ai_chat_fast', ... })

// WRONG: abstract tier numbers (Autumn convention prefers descriptive)
feature({ id: 'ai_tier_1', ... })

// WRONG: kebab-case
feature({ id: 'ai-fast', ... })

---

Feature Types

Type	consumable	Use Case	Example
metered	true	Usage that resets periodically (messages, API calls)	AI model invocations
metered	false	Persistent allocation (seats, storage)	Team seats
credit_system	n/a	Pool that maps to metered features via creditSchema	AI credits
boolean	n/a	Feature flag on/off	Advanced analytics

Credit systems require linked metered features with consumable: true. Each linked feature has a creditCost defining how many credits one unit consumes.

export const aiUsage = feature({
  id: 'ai_usage',
  name: 'AI Usage',
  type: 'metered',
  consumable: true,
});

export const aiCredits = feature({
  id: 'ai_credits',
  name: 'AI Credits',
  type: 'credit_system',
  creditSchema: [
    { meteredFeatureId: 'ai_usage', creditCost: 1 },
  ],
});

Proportional Billing

Instead of multiple metered features with fixed creditCost per tier, use a single metered feature with creditCost: 1 and vary the requiredBalance at runtime.

This gives per-model cost precision without cluttering the Autumn dashboard with dozens of features.

How it works: Autumn's check() with sendEvent: true uses requiredBalance as the deduction amount. With creditCost: 1, passing requiredBalance: 5 deducts exactly 5 credits from the pool.

// Runtime cost table (in worker/billing/ai-model-pricing.ts, not autumn.config.ts)
const MODEL_CREDITS: Record<string, number> = {
  'gpt-4o-mini': 1,      // cheap model = 1 credit
  'claude-sonnet-4': 5,  // mid-range = 5 credits
  'claude-opus-4': 30,   // expensive = 30 credits
};

// Dynamic deduction
const credits = MODEL_CREDITS[model];
await autumn.check({
  customerId,
  featureId: 'ai_usage',      // single feature for all models
  requiredBalance: credits,    // varies per model
  sendEvent: true,
});

Refund on error: Use track({ featureId: 'ai_usage', value: -credits }) to refund the exact amount.

Blocking expensive models: Omit them from MODEL_CREDITS. Unknown models → getModelCredits() returns undefined → 400.

---

Plan Structure

Groups

Plans in the same group are mutually exclusive. Subscribing to a new plan in the same group replaces the old one. Autumn handles the Stripe subscription swap automatically.

• Upgrade (free → pro): Immediate swap with proration.
• Downgrade (pro → free): Scheduled for end of billing cycle.

Add-ons

Plans with addOn: true stack on top of any plan. No group conflict.

autoEnable

Plans with autoEnable: true are auto-assigned when a customer is created via customers.getOrCreate(). Use for free tiers. Only allowed on plans with no price.

Plan items: reset.interval vs price.interval

The intervals are mutually exclusive, not reset and price themselves. A PlanItem is one of three variants:

PlanItemWithReset: Has reset.interval. If price is also present, it CANNOT have price.interval. Use for free allocations that reset periodically, optionally with one-time overage pricing.

PlanItemWithPriceInterval: Has price.interval. CANNOT have reset. The price.interval determines BOTH the billing cycle AND when the included balance resets for consumable features. Use for paid plans with usage-based overage.

PlanItemNoReset: No reset. Use for continuous-use features like seats, or boolean features.

// Free plan: reset only, no price
// `reset.interval` controls when the 50 included credits refresh
item({ featureId: aiCredits.id, included: 50, reset: { interval: 'month' } })

// Paid plan: price.interval handles both billing AND reset
// The 2000 included credits reset monthly via `price.interval: 'month'`
// Overage beyond 2000 billed at $1/100 credits
item({
  featureId: aiCredits.id,
  included: 2000,
  price: { amount: 1, billingUnits: 100, billingMethod: 'usage_based', interval: 'month' },
})

Key insight: For paid plans, included + price.interval implies monthly reset. The included field's Zod description: "Balance resets to this each interval for consumable features." You do NOT need a separate reset field on paid plan items.

---

SDK: autumn-js

Initialization

import { Autumn } from 'autumn-js';

const autumn = new Autumn({ secretKey: env.AUTUMN_SECRET_KEY });

Stateless: safe to create per-request. No connection pooling needed.

Customer Sync (MUST be blocking)

await autumn.customers.getOrCreate({
  customerId: userId,
  name: userName ?? undefined,
  email: userEmail ?? undefined,
});

This call MUST be awaited (blocking). Autumn's /check endpoint does not auto-create customers. The customer must exist before any check() call.

Credit Check

const credits = getModelCredits(data.model);
const { allowed, balance } = await autumn.check({
  customerId: userId,
  featureId: 'ai_usage',
  requiredBalance: credits,
  sendEvent: true,
  properties: { model, provider },
});

if (!allowed) {
  // Return 402 with balance info
}

featureId is always 'ai_usage'. The credit cost varies per model via the dynamic requiredBalance.

Refund on Error

await autumn.track({
  customerId: userId,
  featureId: 'ai_usage',
  value: -credits,  // Negative value = refund
});

Use when the operation fails after credits were already deducted (e.g., AI stream errors). Typically pushed to an afterResponse queue to avoid blocking the error response.

---

CLI: atmn

Setup

bun x atmn login       # OAuth login, saves keys to .env
bun x atmn env         # Verify org and environment

Config File

autumn.config.ts at the project root. Defines features and plans using atmn builders:

import { feature, item, plan } from 'atmn';

Push/Pull

bun x atmn preview     # Dry run, shows what would change
bun x atmn push        # Push to sandbox (interactive confirmation)
bun x atmn push --prod # Push to production
bun x atmn push --yes  # Auto-confirm (for CI/CD)
bun x atmn pull        # Pull remote config, generate SDK types

Data Inspection

bun x atmn customers   # Browse customers
bun x atmn plans       # Browse plans
bun x atmn features    # Browse features
bun x atmn events      # Browse usage events

---

Environment & Secrets

Key	Environment	Prefix
AUTUMN_SECRET_KEY	Sandbox (test)	am_sk_test_...
AUTUMN_SECRET_KEY	Production	am_sk_prod_...

Use the same key name in both environments. Let your secrets manager (Infisical, etc.) swap the value per environment. Don't create separate key names for sandbox vs prod.

For Cloudflare Workers: wrangler secret put AUTUMN_SECRET_KEY

For local dev with Infisical: secrets are auto-injected via infisical run --env=dev --path=/api -- wrangler dev

---

Middleware Pattern (Cloudflare Workers + Hono)

Ensure Customer Exists

Run after authGuard, before any billing-gated routes:

app.use('/ai/*', async (c, next) => {
  const autumn = createAutumn(c.env);
  await autumn.customers.getOrCreate({
    customerId: c.var.user.id,
    name: c.var.user.name ?? undefined,
    email: c.var.user.email ?? undefined,
  });
  await next();
});

Why inline? Cloudflare Workers don't expose env at module scope. The Autumn client must be created inside the request handler.

Credit Gate in Handler

const credits = getModelCredits(data.model);
if (!credits) return c.json(error, 400);

const { allowed, balance } = await autumn.check({
  customerId: c.var.user.id,
  featureId: 'ai_usage',
  requiredBalance: credits,
  sendEvent: true,
});

if (!allowed) return c.json(error, 402);

---

Stripe Integration

• Sandbox: Built-in Stripe test account. No setup needed.
• Production: Connect via Dashboard → Integrations → Stripe (OAuth recommended).
• Autumn creates Stripe products/prices automatically when you atmn push.
• Autumn is the source of truth for customer state; Stripe handles payments.

---

Common Gotchas

1. getOrCreate must be awaited: Fire-and-forget will cause check() to fail with "customer not found."
2. featureId in check() is always 'ai_usage': The credit cost varies per model via dynamic requiredBalance, not featureId.
3. reset.interval and price.interval are mutually exclusive: not reset and price themselves. A PlanItemWithReset CAN have a price, but that price cannot have an interval. For paid plans, price.interval handles both billing and balance reset.
4. sendEvent: true deducts atomically: Don't call track() separately for the happy path. Only use track({ value: -1 }) for refunds.
5. All IDs are snake_case: Autumn's pricing agent convention. Don't use kebab-case.
6. autoEnable triggers on customer creation: Not on first check(). Ensure the middleware calls getOrCreate before checking.
7. Multiple keys per environment: Autumn supports multiple active secret keys for rotation. Generate a new key, update secrets, then revoke the old key.
8. Use proportional billing: One metered feature (ai_usage) with creditCost: 1 and dynamic requiredBalance per model. Per-model costs live in worker/billing/ai-model-pricing.ts, not autumn.config.ts. This avoids cluttering the dashboard with dozens of features.

---

Project Files

File	Purpose
apps/api/autumn.config.ts	Feature, credit system, and plan definitions
apps/api/worker/billing/autumn.ts	createAutumnClient(env) SDK adapter and provider error mapping
apps/api/worker/billing/ai-model-pricing.ts	Model string to proportional credit cost mapping
apps/api/worker/billing/service.ts	Billing domain operations, reservations, dashboard DTOs, and storage sync
apps/api/worker/billing/policies.ts	AI credit charging and asset storage billing policies
apps/api/worker/billing/routes.ts	/api/billing/* routes and billing auth mount
apps/api/worker/index.ts	Cloud Worker composition and billing policy wiring

---

Resources

• Autumn Docs
• Autumn Dashboard
• GitHub: Autumn
• GitHub: TypeScript SDK + CLI
• API Keys