The line that matters
October 14, 2025 ended mainstream support for Windows 10 22H2. ESU extends specific channels for a fee; the free-traffic interpretation after EOL is: on ESU, in matrix; vanilla 22H2 rolled off. For per-account tools the practical update policy is the test floor: we measure against the version that receives updates, because an out-of-support OS can no longer assume any `explorer`-behavior constant.
What 'support floor' really declares
minimum supported build
the oldest OS the vendor tested at ship; lower works — unvalidated
maximum expected build
the newest OS with a gate run at ship; newer rolls into the next matrix pass
policy revision date
ProofTune prints one on every scan — the policy data version that decided
See how ProofTune's OS-reading uses the build, edition, and policy revision to say Supported/Conditional/Out the same way across reports — the screenshot logic from the readiness dashboard is in the docs, fully traceable from the same keypaths auditors already use.
ProofTune ProjectEngineering notes — every claim here names the bytes a real tool touches. Verify first, install second.