# `zappier/billing/credit`

**Package:** `zappier`  
**Source:** `packages/zappier/src/billing/credit.ts`  
**Lines:** 20

## What this module is

Implementation module in `zappier`. The tables below are extracted from the source (signatures + JSDoc).

## Exports

`BilledSummary`, `applyMonthlyCredit`

## Types / interfaces / classes

| Kind | Name |
|------|------|
| interface | `BilledSummary` |

## Functions

| Name | Parameters | Param types (JSDoc) | Returns | Calls (same file / helpers) |
|------|------------|---------------------|---------|-----------------------------|
| `applyMonthlyCredit` | `summary: UsageSummary,
  tier: TierConfig,` | — | `unknown` | see Call graph |

## What it imports / requires

- `../pricing`
- `../usage`

## Call graph (identifiers invoked)

`applyMonthlyCredit`, `min`

Each identifier is a call site in this file. Follow the import list to see the defining module; open that module’s MD for parameter and return types.

## Return values (how to read this)

- HTTP route handlers return Express `res.json(...)` bodies (see route docs).
- Zapier `perform` functions return a **single object** (creates) or an **array** (triggers/searches).
- Pricing functions return integer **cents** on `Quote.totalCents`.