CHW-2307 CoverageUnavailable

Default message: required signal coverage unavailable: a data source your deployment marked mandatory could not be evaluated for this package, so the request was refused rather than allowed unchecked; the missing sources are named in the reason field — retry once the source recovers, relax CHAINSAW_COVERAGE_REQUIRED, or set CHAINSAW_COVERAGE_MODE=warn to measure before enforcing
HTTP status: 403 (client)
Reason: COVERAGE_UNAVAILABLE

Problem. A download or publish returned 403 saying required signal coverage was unavailable. Nothing was found wrong with the package — the deployment could not finish looking. Cause. This deployment set CHAINSAW_COVERAGE_MODE=closed and listed one or more data sources in CHAINSAW_COVERAGE_REQUIRED. At least one of those sources could not be evaluated for this coordinate, and the configured CHAINSAW_COVERAGE_GRACE / CHAINSAW_COVERAGE_MAX_LEDGER_AGE window had lapsed, so the gate refused rather than allow unchecked. The missing sources are named in the response reason field. Fix. Prefer waiting for the source to recover — a refusal here means the control is working. If the outage is prolonged, either drop that source from CHAINSAW_COVERAGE_REQUIRED, fall back to CHAINSAW_COVERAGE_MODE=warn to keep measuring without refusing, or use CHAINSAW_COVERAGE_BREAK_GLASS for a single invocation (it logs loudly on every use). Off by default: a deployment that sets no CHAINSAW_COVERAGE_* variables can never see this code. On the server (proxy + publish) only the metadata-only sources are accepted here; requiring an artifact-bound source is refused at startup, not at request time. HTTP 403.