feat: simplify assurance reports with progressive disclosure

docs/packaging/CORE_LOCAL_ASSURANCE_VIEWER.md

@@ -78,6 +78,25 @@ Control Plane. `casan view` remains the predictable Core single-project viewer.
 The UI shell itself is non-sensitive and may load without a token. All project
 metadata, evidence and exports require the session token.
 
+## Presentation and disclosure policy
+
+Reports use two information layers:
+
+1. the executive layer shows verdict, governed volume, reliability, latency,
+   evidence quality, decision findings and measured distributions;
+2. the technical layer preserves filters, provider counters, canonical paths,
+   event history, sanitized manifests and raw breakdown tables behind native
+   disclosure controls.
+
+The technical layer is collapsed by default in interactive viewers. It remains
+available for investigation and is included in print-ready export appendices.
+This is progressive disclosure, not evidence deletion.
+
+Every visual must be derived from the report contract. Missing token, cost,
+freshness or provenance values remain unavailable; the UI must not invent a
+zero, trend, governance verdict or maturity claim. Charts include visible
+labels and values so meaning does not depend on color alone.
+
 ## Production acceptance gate
 
 The Core viewer is releasable only when all of these pass: