Check facts extracted from documents

Use GND when a report, form, memo, or article needs to become structured facts that can be checked against domain rules. Keep two questions visible: “Do these facts satisfy the model?” and “Did the extraction faithfully capture the document?” A checker pass answers the first question; extraction fidelity needs its own evidence.

Prepare the extraction vocabulary

With an authored, supported non-temporal model, this contextual command emits the extraction bundle:

gnd extract model.orm.yaml --out artifacts

The bundle includes a shape-only JSON Schema projection, a constraint-blind verbalization, an applicability description, and an index that binds their digests and header template. It is produced offline. gnd extract does not read the source document or call a model provider.

gnd extract model.orm.yaml --out artifacts --guidelines also writes <stem>.guidelines.md: per fact type, its readings, the fact types played by the same object types, and per role the object type's description, reference mode and primitive. It stays constraint-blind; an external uniqueness that identifies an entity appears only as that entity's identification. A description is the modeller's prose and can restate a rule, and the guideline repeats descriptions, so read it as guidance about meaning, not as rules to enforce.

The extraction schema describes which facts and values can be represented. It deliberately does not tell an extractor how to rewrite facts to satisfy uniqueness, mandatory, or other domain rules. If a document describes an invalid application state, the extraction should preserve that state so the checker can reveal it.

Ask an agent to extract, then verify its output

In an agent session with the GND skills installed, explicitly select the extraction workflow. Example prompt; replace the named files with your own:

Use gnd-extract with model.orm.yaml and artifacts/ to extract report.md into
extracted.population.json. Preserve the document's facts, including facts
that violate the model. Write the required digest-bound extraction sidecar,
then run the verifier and explain its findings.

The skill treats the document as quoted data. Instructions, links, and code inside it are content to interpret, not commands to follow. The agent writes the population and its adjacent extraction sidecar. The sidecar records the model, document, projection, and population binding.

Given those completed artifacts, the contextual verification command is:

gnd verify model.orm.yaml extracted.population.json --artifacts artifacts --format json

Verification validates the handoff before checking the population. Missing, malformed, or stale sidecars produce input refusal at band 3. Read the extraction block and the semantic verdicts independently. If your population was authored directly and never extracted, explicitly use --no-extraction; the report records that the extraction path was skipped.

Bind important values to source spans

An anchored constraint checks whether populated role values have witnesses in a bound source document. The anchor sidecar names a fact occurrence, role, source span, and the necessary digests. Contextual snapshot command:

gnd check model.orm.yaml extracted.population.json --anchors extracted.population.anchors.json --document report.md --format json

A malformed binding is refused. An absent or unsuitable witness can be a failure or an unchecked result depending on the situation and modality. The matcher uses documented lexical normalization and explicit numeric/date recognizers; it does not infer arbitrary paraphrase equivalence. Source anchoring provides specific occurrence evidence, not a blanket truth claim. The sidecar format, including version 2's several anchors per role, is in the anchor sidecar reference.

Test a round trip without hiding failures

For an extraction evaluation, explicitly select gnd-render-doc to turn a known population into prose. That workflow preserves all applicable source facts, plants three kinds of distractors, and writes a document manifest. gnd doccheck checks that rendering contract. Then separately select gnd-extract to read the document back, and measure the retained round-trip cases with gnd fidelity.

These outputs remain different evidence: rendering completeness, extracted population checking, and measured fidelity. Saved extraction outputs or synthetic receipts are not evidence that a provider ran now.

See the extraction contract and rendering contract for exact sidecars, manifests, distractors, and failure semantics.