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Radix documents the 11/12 APCA guarantee against a step 2 background only, not step 1. Correct the claim and the example (which used bg-sand-1), add the precise Lc 60 / Lc 90 targets and a source link, and note that step 1 is safe in practice but not part of the stated guarantee. Signed-off-by: Émile Ré <emile@probo.com>