OTO
concepts · from ARCHITECTURE.md at v0.6.1

The shape of a fact

ComponentPayment APIcomponent.payment-api
When
as_of when it was recorded
valid_from · valid_to when it was true
status current · superseded · proposed · intended
Where from
source_doc · sources the documents that attest it
evidence the quote, and where in the document
What it says
summary · aliases · tags
attributes typed values the class declares
What replaced it
supersedes · superseded_by the chain a correction leaves behind
One node. Cyan is time, blue is provenance, indigo is meaning: every fact carries all three.

A node carries its type, label, aliases, summary, attributes, tags and sources, plus the temporal fields that make the graph bi-temporal:

Field Meaning
as_of when the fact was recorded
valid_from, valid_to when it was true in the world
status current, superseded, proposed or intended (asserted as a plan, not observed; never answers "what is")
supersedes, superseded_by the chain a correction leaves behind
source_doc, sources the documents or assertions that attest it
attributes typed values about the thing. A class may declare them in the vocabulary as "attributes": {"Claim": {"state": ["enum:open|closed", "..."]}} with types string, number, integer, boolean, date, list or enum. A present value must fit; a key nobody declared on a declaring class is reported, and refused under strict_attributes. Exported as datatype properties.
evidence where in the document: [{"doc", "where", "quote"}], shown on the entity page and in every answer
source_type document (default), human_assertion, or inference

A correction never overwrites. It adds a new node, marks the old one superseded, and links the two. oto curate check reports any changed value that lacks that record, a chain that does not point both ways, a date handoff that does not match, an edge outside its declared domain or range, and a fact citing a document that has since arrived as a new version and has not been re-attested against it. The engine answers with current facts by default and slices history on request.