DELTA Witness
Independent public page-state evidence and deterministic preflight verification for consequential agent actions.
AgentCard object. It is an agent card in spirit rather than in schema — useful for
discovery, but an A2A client cannot assume it will parse.
capabilities-not-objectNo `capabilities` object present (A2A 1.0 requires capabilities to be an object) — hard failure, so the card is graded flavored rather than conformant/near-conformant.protocolVersion is 0.2.0, a pre-1.0 A2A schema.Card carries non-standard vendor extensions instead of the 1.0 shape: top-level `protocols`, `pricing`, `payments.x402`, `intents[]`, and `payout_address`. These describe a real x402/USDC-on-Base payment posture but are not part of the A2A AgentCard schema.
/.well-known/agent.json, the
pre-0.3 location, rather than the current /.well-known/agent-card.json. Clients written
against A2A 1.0.0 will not find it.
An A2A client finds this agent by fetching the well-known path on the provider's own host. That is what makes an agent card different from every other agent artifact in this catalog: it is provider-published by construction — it cannot be derived, generated, or reconstructed on a provider's behalf.
Capture public page state capture
Observe a public webpage independently and return timestamped cryptographic proof metadata and hashes.
Preflight verification preflight
Observe a public source and deterministically compare it with supplied expectations or a prior DELTA proof before an autonomous action.
Guarded Action Pilot guarded-action-pilot
Produce a bounded 1-3 URL evidence package with optional deterministic preflight for higher-value autonomous actions.
2026-09-11 from https://delta-witness-api.ruphussten.workers.dev/.well-known/agent.json,
HTTP 200. The body was saved verbatim and is the sole source for
everything on this page — no field is inferred.
View the captured card.
Providers change what they serve; if this card has moved or changed shape,
the provider profile carries the
current state as of the last build.
Work with this as data
Every agent card here is available over the APIs.io API and to AI agents over MCP. A2A Agent Cards is not yet its own endpoint on the v1 API. Reach it through catalog search and the tag graph, or the MCP server.