Mirrors canary's `XObject::StashHandle` (xobject.h:253-256): on first
adoption of a guest dispatcher header, stamp +0x08 with the
kXObjSignature fourcc 'X','E','N','\0' and +0x0C with the stash handle
(here the guest pointer itself, since our shadow table is keyed by ptr).
Audit-023/024A documented divergence at addresses such as 0x828F4838
where canary stores "XEN\0" + handle but we left zeros. Lands as
canary-correctness restoration; cascade impact at -n 500M is nil per
the discipline gate (no sharp prediction tied to the writeback).
Lockstep determinism preserved: instructions=100000003,
imports=987516, swaps=2, draws=0 across 2 reruns.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>