OfficialCost is built on one rule: every published value traces to stored evidence. Nothing is invented, estimated by a model, or hand-edited without a source.
Source registry → legal review → collection (official APIs / CSV / pages) → raw evidence stored immutably in object storage → deterministic extraction → normalization → fact candidate → confidence scoring → verification → publication.
Each fact links to one or more evidence records, each tied to a registered source. Facts are immutable and versioned: a changed value creates a new version and supersedes the old one, so the full history is auditable.
Values gain confidence when independent, high-trust sources agree. Disagreements above a variance threshold open a conflict for review rather than silently averaging.
A page is only published when it clears coverage, confidence, and knowledge-density thresholds. Pages below the bar return 404 rather than show thin content.
Related: source methodology · confidence scoring.