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A2A binding
Carry AQP as an A2A extension linked to tasks, messages, and artifacts.
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An A2A Agent Card advertises https://agentqueryprotocol.com/extensions/2026-07-30/a2a and declares whether it can request, respond to, collect, or relay AQP objects.
Request
A server agent attaches a canonical QueryRequest as a structured-data Part on a Message or Artifact. The subject should include the A2A contextId, taskId, and, when applicable, artifactId.
Response
The respondent agent sends a new Message or Task containing the canonical response. When the collector is a separate A2A agent, the query provides its discovery location and a scoped capability.
Continuation
A receipt carrying nextQuery creates a new Message or Task in the same context. A mediated human approval is marked as a human response; decline terminates the gated chain.
Task lineage
A completed A2A task remains immutable. Answers, corrections, and refinements therefore create new messages or tasks in the same context and reference the original task rather than mutating it.