The v7.0.0 entropy-scanner rule 18 suppressed every line whose pattern
matched  — regardless of the URL host or what the URL
carried. A markdown image URL pointing at a non-CDN host (or carrying a
secret-shaped token in its query string) would therefore mask a real
high-entropy credential.
Refactor:
* MARKDOWN_IMAGE now captures the full URL (was a host-only prefix
matcher), so rule 18 can inspect host and query.
* MARKDOWN_IMAGE_CDN_HOSTS allowlist constant covers cdn./images./
media./assets./static./*.cdn./*.amazonaws.com/{s3,cloudfront}/
*.cloudflare./*.fastly./*.akamaized./raw.githubusercontent.com/
*.imgix.net/*.cloudinary.com/.
* MARKDOWN_IMAGE_QUERY_SECRET catches secret-shaped query keys
(token, key, secret, password, api_key, access_token, auth) plus
well-known provider prefixes (AKIA, Bearer, sk_live_, ghp_, ghs_,
ghu_, gho_, ghr_, npm_).
* Rule 18 now suppresses iff (host matches CDN allowlist) AND
(query has no secret-shaped token). Anything else falls through
to entropy classification.
+4 tests in tests/scanners/entropy-context.test.mjs (29 → 33).
Existing rule 18 fixture (cdn.example.com, no secret query) still
suppresses, so no regression on the legitimate path.
Refs: Batch B Wave 5 / Step 13 / v7.2.0
critical-review-2026-04-20.md §E18
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