Physical AI receipts

What exists in the lab today

• Interactive demo at /demo/robot: three simulated warehouse-robot decisions (mode, actuation, override), browser offline verify, tamper the outcome. Toggle demo fixture key vs lab edge key.
• Lab edge-signer in the product repo (edge-signer/): sign a physical_* stream, verify with published aqta-verify-receipt, tamper must fail (./scripts/smoke.sh). ESP32 firmware dumps the same receipts over USB serial for host verify. Optional desktop exhibit: Cannon (companion shell around the brick; stagecraft only; not the deep-tech claim).
• Published convention ATTESTATION-v1-physical: same twelve-field envelope; event class in policy_applied (physical_mode, physical_override, physical_actuation).

That is substrate-independence as a lab primitive. Same receipt format as software Seal. Not a claim that Seal ships robots.

Same receipt. Different substrate.

The Ed25519 signature that clears a model call in a bank workflow can clear a machine decision at the edge: a mode change, a human override, an actuation command an investigator cares about. Verified offline with the same open verifier, against a published key the checking party pins for themselves.

We sign what was decided. We never claim the decision was right. That boundary is the product, and it is what keeps Act II out of rings we cannot win.

Identity registries answer who. Seal answers what.

Machine identity schemes (for example national humanoid robot digital ID registries that assign a unique code per unit) prove which machine is in the room. They do not prove what it decided under which checks, and they do not give a hostile third party an offline cryptographic check of a specific act.

Those registries are complementary to Seal, not competitors and not customers by fiat. Seal owns the decision-record half: what was cleared, under which rules, checkable offline.

What we sign (and what we refuse)

• Investigator events: mode changes, overrides, consequential actuation commands. Not 1 kHz servo ticks.
• Off the hot path: sign, buffer, sync when connected. Cloud round-trips in a real-time loop are a non-starter.
• Same ATTESTATION-v1 envelope. Detail in a hashed preimage. Related: Receipt identity.