Thesis
Agents get write access to proposals, never to truth.
Existing agent primitives either append or retrieve. None can detect that two things are both asserted and cannot both be true. Datum adds authority tiers, declarative constraints and supersession, and gives agents three tools, read, check and propose, but never commit.
01 · Argument
Supersession is the primitive nobody has.
Version control handles change. Canon needs deliberate change to what was previously true, with both states still meaningful: a retcon in narrative, an amendment in policy, a superseded decision record in engineering. A supersession marks the old claim superseded, never deletes it, and raises no conflict. That is what separates intent from error.
Evidence
A threat model names ten attacks, and three are still open.
Corroboration collusion, provenance forgery and supersession abuse remain open against v0.2 and carry into v0.3 as normative work. A conformance suite covers six levels, from read to federation, and a mock adapter is required to fail the upper levels by design.
Diagram · Four tools, one trust boundary
datum.read, datum.check and datum.propose are open to agents. datum.commit needs an authorized principal and rejects any unresolved blocking violation. Extraction from prose to claims is a pluggable adapter, and machine-extracted claims default to proposed, never binding.
“Agents get write access to proposals, never to truth.”
“Low drift at low coverage is not conformance. It is ignorance.”
Tension
Collapsing duplicate proposals makes corroboration look like consensus.
The spec counts fifty agents proposing one fact as one proposal with fifty corroborations, and treats the count as signal. The threat model identifies that as a weakness: colluding sources amplify each other. The planned fix is lineage-weighted corroboration in v0.3.
Implication
Rights holders and licensees can share one canon with asymmetric rights.
Federation separates the right to read from the right to supersede. That is the workflow PDF style guides and approval emails carry today, and the spec names it as the commercial surface.
Companion documents
The threat model, the GREATGAME benchmark specification and the conformance suite sit in the same public repository, under Apache-2.0 and CC-BY.