It's a 15 second loop of audio history. If you didn't record the bit a minute ago, it's gone.

A short buffer is common with wake word audio processing.

mikeocool 4 hours ago | parent | next [-]

It also summarizes your full conversations.

	▲	nomel an hour ago \| parent [-]
		No, that part requires intent, where you have to turn it on with the button. It was in the demo. Regardless, you'll be mortified if you search the app store for software or Amazon for hardware devices that do this! You can still pick up voice recorders at Staples, actually (I was surprised to see they still sell them, and they have weeks of recording time now, along with transcription software).

You missed the additional feature launch where they listen to your entire life and give you transcriptions and summaries.

“Siri Recap”