> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# PCA: aggregate limits on disposition metrics: combined prompt length and enum choices

> The Write to draft endpoint now enforces two aggregate limits when the payload includes postCallAnalyticsConfig.dispositionMetrics:

The [Write to draft](/api-reference/voice-agents/agent-versioning-branches/update-draft) endpoint now enforces two aggregate limits when the payload includes `postCallAnalyticsConfig.dispositionMetrics`:

* **Combined `dispositionMetricPrompt` length**. The sum across all metrics must be ≤ 50,000 characters. Exceeding it returns `400` with `The combined disposition metric prompts can be at most 50000 characters.`
* **ENUM choices per metric**. Each `dispositionMetricType: ENUM` metric can have at most 20 `choices`. Exceeding it returns `400` with `Each enum metric can have at most 20 choices. Ones already over the limit can stay as they are, but can't grow any further. Remove the extra choices to save.`

Both limits are grandfathered: agents already over either limit can still save as long as the change does not make it worse (total prompt length does not grow, and no over-limit enum grows or gains new choices). No cap on the number of metrics or on any single prompt's length.

Source: [atoms-platform#3448](https://github.com/smallest-inc/atoms-platform/pull/3448).

> The Write to draft endpoint now enforces two aggregate limits when the payload includes postCallAnalyticsConfig.dispositionMetrics: