ADR-009: Immutable observations and conservative current-price projection

Status: Adopted algorithm proposal; calibrate before pilot. Date: 2026-09-28. Scope: planned platform; implementation evidence required by roadmap gates.

Context

Latest-write-wins and paid trust are vulnerable and misleading. Reads must remain cheap.

Decision

Append observations/decisions, separate votes/disputes, one eligible vote/contributor/key, exact-price groups, deterministic versioned consensus with freshness. Query indexed projection and enforce expiry at read time. Payment excluded structurally. Separate validation state, availability, freshness and confidence.

Alternatives

Mutable station price field; most recent request wins; paid weight; full event sourcing/CQRS infrastructure.

Consequences

Eventual consistency and conservative unknown/disputed outputs. Sybil resistance requires quotas/evidence/review. Full policy and golden examples in COMMUNITY_PRICING_SPEC; tuning changes policy version.

Validation and follow-up

Use the owning tasks in ROADMAP, specifications in docs index and decision log. Record tested policy/tool versions before marking a release gate complete.