Android Pixel model paired with an OS version older than the device shipped with
br.android_model_os_predates · convicts
What it catches
MODEL <-> OS-VERSION coherence — a release-date bound, a NEW axis independent of the screen/DPR/GPU model rungs. A device physically CANNOT run an Android version OLDER than the one it SHIPPED with (Pixel 2 = Android 8, 3 = 9, 4 = 10, 5 = 11, 6 = 12, 7 = 13, 8/9 = 14). The model is already pinned across the 3-surface CH-UA-Model ratchet; getHighEntropyValues(['platformVersion']) is the real OS major version (Chromium derives it from the Android UA — GROUNDED: KS_DEVICE='Pixel 5' -> platformVersion 11, KS_DEVICE='Nexus 5' -> 6.0). So a pinned Pixel whose platformVersion major is BELOW its launch version is a randomizer or source-fork that paired a real model with an impossible OS. CONVICTING (w0.6). FP-SAFE: a device runs its launch OS or NEWER, so version < launch is physically impossible for that model; scoped to Pixels (deterministic launch dates). EXPERIMENTAL — the vanishing confound is a custom ROM running an OLDER Android on newer hardware (enthusiast, rare). GROUNDED LIVE: KS_DEVICE='Nexus 5' (platformVersion 6.0) + KS_FORGE_JS_MODEL='Pixel 5' (launch 11) FIRES android_model_os_predates (6 < 11); KS_DEVICE='Pixel 5' + KS_FORGE_JS_MODEL='Pixel 5' (platformVersion 11) does NOT fire (11 >= 11). Complements model<->screen/DPR: a coherent Android device must match its model on screen, DPR AND a possible OS version.
Signals it reads
browser.android_model_os_predates
How it fires
present
Bypassed by 10
Frontier evaders that reach the detector uncaught (scored only suspicious, defeating every convicting tell) — this check is not one that stops them. The red-team frontier this detection still has to convict.