> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nozle.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Credit Systems and Rates

> Create a credit catalog and exact metric conversion rates

Create Credit Systems and rates in the Nozle dashboard. Rails owns this configuration, organization scoping, auditing, and version history.

## Rate formula

```text theme={null}
credits required = metric units × credit_amount / metric_amount
```

All amounts are exact decimals. API requests and responses use strings, such as `"2.500000000000"`, to avoid binary floating-point loss.

## Mapping rules

* the metric and Credit System must belong to the same organization;
* only `consumable=true` metrics are eligible;
* Phase 1 accepts `count_agg` and direct-field `sum_agg` metrics;
* amounts must be finite and positive;
* a rate edit closes the previous effective version and creates a new one;
* historical operations retain the exact rate snapshot they used.

A metric with any rate history is configuration-locked: its code and metering definition cannot be changed or soft-deleted, and `consumable` must remain true.

If one metric has multiple active mappings, integrations must select a Credit System explicitly unless configuration provides one deterministic mapping. Nozle does not silently fall back between pools based on current balance.