# The controls Astra removed, and what a migration must preserve

Astra removed familiar sampling controls; a migration must preserve the task intention rather than silently translate unrelated settings.

Author: Retrivium editorial team
Language: en
Analysis published: 2026-11-03
Event date: 2026-09-03
Original announcement: https://developers.openai.com/api/docs/changelog
Canonical URL: https://retrivium.ai/retrospectives/astra-reasoning-control-compatibility/

A removed generation control is a compatibility event even when the new model is more capable. Astra's release made this visible for applications that treated reasoning and sampling settings as a universal configuration object shared by every model.

## The dated change was narrower than a universal recipe

The [September 3, 2026 changelog](https://developers.openai.com/api/docs/changelog) says Astra does not support the none reasoning level, custom temperature or top_p, or logprobs. Earlier [Responses architecture](https://developers.openai.com/blog/responses-api), published September 22, 2025, and [agent primitives](https://developers.openai.com/blog/skills-shell-tips), published February 11, 2026, had already expanded execution beyond a plain text completion. These sources describe an evolving interface, not one timeless parameter dictionary.

## Shared configuration can conceal different intentions

Suppose a routing service uses temperature to express three unrelated intentions: repeatable extraction, varied brainstorming and conservative operational decisions. Removing that field cannot be fixed meaningfully by inserting an arbitrary replacement reasoning value. The intentions were different before the migration, even if they shared one setting.

Extraction needs a valid output contract and checked fields. Brainstorming needs an evaluation of useful diversity. An operational decision needs explicit criteria and an escalation path. A single numeric control never established all of those properties.

## Silent omission makes the experiment ambiguous

A client wrapper might discard unsupported options automatically. That can prevent a request error while leaving operators unaware that the experiment changed. A dashboard still showing the old setting then describes an intention rather than the effective request.

Capture the actual serialized request and the selected model revision. If a wrapper transforms configuration, keep both its input and output available for inspection. The purpose is to identify the intervention being tested, not to preserve every obsolete option indefinitely.

## A useful compatibility fixture

Create representative cases for extraction, brainstorming and bounded decisions. Record what the old settings were supposed to achieve, then define observable acceptance criteria for each case. Run the supported Astra configuration without pretending that its reasoning effort has the same meaning as temperature.

Include malformed input and an ambiguous decision. A schema-valid answer can still extract the wrong field, and a confident choice can still require escalation. These cases distinguish configuration compatibility from the task properties the application actually needs.

## The practical consequence of the release

Parameter removal shifts responsibility toward explicit task contracts. It does not show that sampling controls were always unimportant or that the new configuration guarantees reproducibility. Those stronger conclusions require their own evidence.

Keep migration notes focused on effective requests, intended behavior and observed failures. That allows a later operator to explain why a previously familiar setting disappeared and what replaced its application-level purpose. The resulting configuration is smaller, but the reasoning behind it becomes more visible.

## Related reading

- [Changing an API contract](/journal/provider-api-contract-deprecation-migration/)
- [Structured-output migration checks](/journal/vllm-structured-backend-migration/)