The core "deadline" recipe: one palette pick puts down the core.send and core.on_event pair that ADR-0010 decision 1 spells (ADR-0005 clause 4C).

A clock interrupt on a group is two blocks, and which two and where is knowledge an author otherwise has to hold in their head:

• a core.send carrying the deadline event and a delay, at index 0 of the enclosing group's body - first, so the deadline starts when the group starts; and
• a core.on_event naming the same event, on that same group's interrupts rail.

Both halves are ordinary blocks of ordinary core types. The recipe is the knowledge of how they go together and nothing more: it adds no vocabulary, no row to ADR-0002 decision 10's table, and nothing a document holds that it could not have held before.

The event name is generated rather than asked for, and it is written twice by the recipe rather than twice by the author - which is the coupling ADR-0010 decision 5 records as the family rule, and the half of it that was most easily got wrong by hand. It is derived from the send block's own minted id, so two deadlines in one group never name the same event.

What it refuses, and why that is a refusal rather than a finding

The pair only means anything on a block with an interrupts rail, which in the core vocabulary is core.group and core.resumable_group and nothing else - core.sequence's moduledoc says so in terms. Armed anywhere else, insert/2 answers {:error, {:no_interrupts_slot, id}} and nothing is written, so there is no document for the view model to say anything about. A refused gesture is not a finding (clause 3C).

insert/2 is handed the armed position and the document and nothing else (clause 2C), so the enclosing block's declared slots are out of its reach - a palette is not one of its arguments. It reads the two core type names instead. That is core knowledge about core types inside a core recipe, not the editor learning what a block is called: a host whose own group type carries an interrupts rail registers its own recipe under this name, which is exactly what clause 1C's collision rule is for.