A4 (V9): telemetry-integrity.sh binds provider-usage.jsonl + cost/metrics.jsonl
to a signed manifest head. Tampering a token flips the head (MISMATCH); an
attacker who rewrites the head cannot re-sign it (SIGNATURE_INVALID) without
the off-repo key. sign-audit-head.sh now also signs telemetry (best-effort).
Supports CASAN_AUDIT_PRIV/PUB overrides for self-contained verification.
A5 (V12/V13/V14): cost-spike-detect.sh adds an absolute per-call cap
(CASAN_COST_ABSOLUTE_MAX_TOKENS, enforced from record #1 → catches slow-boil
and cold-start) and a cumulative budget (CASAN_COST_CUMULATIVE_BUDGET_TOKENS →
catches under-threshold spray), keeping the existing median×mult spike test.
Backward compatible: <3 records with no caps still exits 3.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
