Citation tracking: Requirements and source contract

Requires every factual claim in a grounded answer to cite a retrieved authorized chunk, refuse or hedge unsupported statements, and inherit source ACLs so citations never expose hidden documents.

Package status: reference context ready for human review. The contract and test scenarios are complete, but no claim is made that an adopting implementation has passed them.

Decision

Every factual claim in a grounded question-answer response must cite at least one retrieved chunk the caller is authorized to see. When retrieval does not support a claim, the system refuses that claim or marks it as unsupported rather than inventing a source. Citation objects inherit the ACL of the underlying chunk; a user who cannot open a document never receives its identifier, snippet, or title as a citation.

Scope

• Grounded answers over an authorized retrieval set for a single authenticated principal.
• Claim segmentation, citation attachment, unsupported-claim handling, source-visibility redaction, and answer-level refusal.
• Backend answer contract consumed by any client that displays citations.

Outside this block

• Retrieval ranking, chunking strategy, or embedding model choice.
• Prompt-injection defenses for tool or instruction channels, which are a separate control.

Contract

• Each factual sentence or structured claim carries a non-empty citation_ids list whose members exist in the current retrieval set.
• A claim with empty support is omitted, replaced by an explicit hedge, or causes a full unsupported_answer refusal when the question requires that fact.
• Citation payloads include only fields the principal can already read: no hidden path, owner, or sibling-document leak.
• Citations are bound to chunk identifiers from this turn's retrieval, not to model-recalled URLs.
• The answer records grounding_status of cited, hedged, or refused for every claim the policy classified as factual.
• Regenerating the answer with the same retrieval set and policy version cannot introduce a new unsourced factual claim.

Implementation

• Classify claims after generation against the retrieval set using span overlap or an approved entailment check; do not trust model-reported citations.
• Strip any citation whose chunk ACL fails for the session identity before serialization.

Failure handling

• If citation validation fails after generation, do not stream the unsourced claim; hedge or refuse the turn.
• If a chunk is revoked between retrieval and render, drop its citations and re-evaluate remaining support.

Verification

• Fixture answers with planted unsupported claims must fail the contract checker.
• ACL tests use two principals on the same corpus and assert citation sets never cross.

The executable-looking examples in this package are fixtures and acceptance contracts. Run python tools/validate.py from the collection root to check package structure and metadata; then implement and execute the scenarios in the target repository.

Adoption assumptions

• Names and numeric values in example.yaml are an adoption profile, not universal defaults.
• The adopting team must map actors, data classes, error vocabulary, and ownership to its system.

References

• No external normative source is required; this package defines a project decision for grounded question answering.