#2350 mac docs: the two prompt opt-ins an M1 Max cannot run (measured)

Descripción

Recorded with the hardware they were measured on, per the measured-numbers rule, because neither can be fixed here: mm_gu3's fault is a threadgroup-count threshold of the cooperative-tensor path on this GPU (the fix shape would change the M5's register-operand GEMM), and router_route's race has no acquire atomic to fix it with on this Metal (device-scope atomics are relaxed-only, macOS 26.6). Both are opt-in and off by default; the engine's M1 defaults are the v2 expert GEMMs and the separate gemv + moe_route, which run on this box.

Measured on an M1 Max (macOS 26.6.2, Q2_0): mm_gu3 with 35 threadgroups passes and 40 faults (data-independent; the engine's tile 16x32x32 SG 4 and the v3 test's 190 tiles both fault). router_route's logits are bitwise gemv's, but two identical runs give different ids, weights and plan.

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