Reasoning: summary heading

Prefix untitled reasoning summaries with a heading and inject a catch-up summary delta when the stream omitted one.

What it does

This transform prefixes a non-empty reasoning summary with **{title}** and two newlines when the summary has no heading. It also injects a reasoning summary delta before NodeDone when that node never streamed a summary delta.

The transform does not move content. It does not change encrypted or source. Enable reasoning_content_to_summary earlier in the same response-phase chain if you need plaintext content copied into summary first.

Reference

Property	Value
Type ID	`reasoning_summary_heading`
Phase	`response`
Scopes	Provider, Global, API key

When to use

A Responses client hides untitled reasoning summaries, or it only renders live response.reasoning_summary_text.delta.
Place this rule after reasoning_content_to_summary when both rules are enabled.

Configuration

Option	Type	Required	Default	Description
`default_title`	string	No	`"Thinking"`	Heading used for the first live summary delta, and for complete summaries when `derive_title` is false. Empty values become `"Thinking"`.
`derive_title`	boolean	No	`false`	When true, complete summaries with no prior live heading use a title derived from the first sentence. Live deltas always use `default_title`.
`max_title_chars`	integer	No	`64`	Maximum Unicode scalars in a sanitized title. The value must be at least `1`.

Example rule

{
  "transform": "reasoning_summary_heading",
  "enabled": true,
  "phase": "response",
  "models": [
    "*"
  ],
  "config": {
    "default_title": "Thinking",
    "derive_title": false,
    "max_title_chars": 64
  }
}