A2A extensions

Extensions we publish to the A2A protocol. Each one is a versioned URI an agent card can declare, with the specification, its Markdown source and an extension.json published beside it.

• Learnables

  https://rsaxb.com/a2a/learnables/v1Version 1, 2026-08-17

  A2A lets an agent stop and ask a human. It does not say what happens to the answer. This extension does: an agent publishes what it can be taught, attaches a teachable proposal to a question, and absorbs the answer as a new immutable version of its knowledge.

  SpecificationMarkdownextension.jsonWhy: The answer died with the task

• Expectations

  https://rsaxb.com/a2a/expectations/v1Version 1, 2026-09-05

  Every state change in A2A is caused by something arriving. Nothing lets the passage of time cause one. This extension does: an agent states what it expects to happen next and by when, so a step that never happens becomes a task instead of a silence.

  SpecificationMarkdownextension.jsonWhy: Your agent cannot hear silence