Field Notes
Essays from the implementation floor.
We build trust infrastructure for the agent era. These essays come out of that work: some technical, some philosophical, all honest about what we know and what we don't. Notes on verification, protocols, and agents, and on the larger questions underneath them: attention, agency, and what deserves protecting as AI changes how the world transacts. From the people building A.V.A.
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The Signature Base Visa Didn't Specify
A payments spec described its signature base in one sentence. Every implementer's answer passes their own tests. On finding the ambiguity, naming it in public, and asking for the test vector that settles it.