The detour helper from PR #34 (used by the metadata hook and PR #389's two geometry hooks) wrote a 16-byte
branch + literal in two steps while game threads may run the function (installation is retried from
xrPollEvent). Each hook now publishes a single aligned release-atomic AArch64 B to a stub within +-128 MiB;
the trampoline replays the one verified instruction and returns to entry+4. Every mprotect is checked;
failures before publication free the stub and trampoline and leave the function untouched; no stub in range =
no hook. Adapter artifacts rebuilt by us (the PR's binary isn't shipped).