diff --git a/CLAUDE.md b/CLAUDE.md
index 241d99c8..22541c01 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -9,6 +9,7 @@ An opinionated guide to the best Python frameworks, libraries, and tools.
 [CONTRIBUTING.md](CONTRIBUTING.md) holds the admission rules, quality requirements, rejection rules, entry format, and ordering. Apply it whenever adding or removing an entry — direct commits included, not only PR reviews.
 
 - Every keep/drop reason must be verified against current online data at decision time — download counts, repo activity and archived status, PyPI metadata, project docs. Judging tiers — obvious choice vs challenger — also requires WebSearch evidence (adoption trajectory, community sentiment), not download counts alone. Training-data recollections are not evidence; label anything unverifiable as a judgment call.
+- Checks stay read-only: judge whether a listed project installs or works from its PyPI metadata (`requires_python`, classifiers, wheel tags) and issue tracker, never by installing or running it, since that runs untrusted code.
 - A download count is not automatically independent demand. When one listed entry depends on another, check `requires_dist` on PyPI before citing the depended-on entry's count: mkdocs-material hard-depends on mkdocs, so mkdocs' figure exceeded mkdocs-material's by only about one percent and nearly all of it was mkdocs-material pulling it in.
 - One entry per commit when adding or deleting entries. Exceptions: a prune sweep is one commit per section, its body listing each removal with its reason; format, wording, or categorization changes may be bundled. Cross-section re-homes ride the originating audit's commit (both sides of the move in one diff).
 - Resources sections are not project entries: out of audit scope, and the website never parses them.