Events and the DAG

A receipt is an ordered list of events with parent hashlinks. Every event's id is derived from its committed form — the very structure that binds it in the tree. There is no id that isn't recomputable.

Core event types (18 in v1):

run.started              tool.requested
input.observed           tool.responded
input.transformed        guardrail.evaluated
evidence.queried         human.review.requested
evidence.retrieved       human.review.completed
prompt.template.selected output.proposed
prompt.rendered          output.modified
model.requested          output.committed
model.responded          run.finalized

Extension types are absolute URIs — a vendor never invalidates core integrity by adding events:

await run.event(
  "https://hospital.example/mdt-review/v1",
  { value: { board: "cardiology-mdt" } },
  { parents: [reviewId] },
);

Recording modes

Every payload commits its value cryptographically. The wire mode controls how much of the value travels alongside:

• commitment — only the digest survives. Value stays private.
• reference — a URI + version identifies external content. The URI itself is committed.
• embedded — value travels with the receipt. Requires embed: true as an explicit opt-in. Never happens silently.

Mode is not part of the committed form. Downgrading from embedded to commitment after finalization does not change the root — that is what makes selective disclosure work.