Brain flywheel 8: brain-health report — the brain measures itself #1687

Problem — The brain has no KPIs: nobody knows claims-created vs applied, time-to-distill, backlog trends, or refutation rate, so improvement is unmeasurable.
Approach — A monthly notturno job that renders the health report from pass receipts: created vs adopted, time-to-distill, pending backlog trends, refutation rate, schema compliance — published as a dated brief.

Acceptance Criteria

• The report renders all five KPI families from pass receipts, no ad-hoc recomputation
• KPIs are computed over claim/ job state, not hand-entered numbers
• The report lands as a dated brief in the briefs area and is idempotent per period
• A fixture period produces fixture-pinned numbers (the report is testable)

Testing Decisions

Fixture receipts + fixture claims → pinned KPI assertions; extends slice 6's receipt surfaces.

Key Decisions

The report measures, never acts. Numbers carry provenance to the receipts that produced them.

Source

Part of #1679. Vault spec spec-20261002-090500-company-brain-flywheel. Depends on the slice-6 job receipts existing.

Notes

Slice 8 of 9 — blocked by 6.