CS06 — Projections isolation

Date: 2026-10-11. Status: LOCAL_DONE. Scope: math pins, isolation proof, static guards — no route/schema/migration change, no VPS/APK. Head: maintained dev. Plan: phased plan. Rules: B-BR-CS06.

Proofs (actual)

• Display math: floor basis-point vectors incl. unanimous, splits, 1/9999 edges and 2^40 counts — shares never exceed the ratio, never 0% with votes, always within 0..10000.
• Dynamic isolation: full helpfulness lifecycle (cast, change, second voter, remove, rebuild) leaves community_current_prices, feedback_rating_stats and community_projection_inputs byte-identical (snapshot comparison around the lifecycle).
• Static isolation (build-failing pins): consensus/projection/feed/ vote/signal queries reference no helpfulness tables; helpfulness.sql references no rating/consensus/projection tables.
• 35-day audit freeze: no DELETE/TRUNCATE path against disputes, confirmations, helpfulness votes or observations in owned queries (media 24h lifecycle excepted, as designed). The 35-day horizon bounds ledger/media retention, never fact audit.

Checks

Unit module + helpfulness integration green; go build, go vet (incl. integration tags), gofmt -l, git diff --check clean; scan-secrets.sh passed.

Limits / owed

• Official star methodology stays independent (existing feedrating proof cited); social votes remain audit-only review inputs.
• Weighted-tally display work for mobile surfaces: CS08/CS11.

Next microtask: CS07 — benchmark and guardrails.