Debug an XR Blocks app

Follow one red → cause → green thread. Preserve the failing observation until one proved cause explains it, then make that same observation pass.

1. Freeze the failure contract

Record the exact entry, launch command and URL, target form factor, expected result, observed result, first known failure, and whether the user requested a diagnosis or a repair. Snapshot the existing worktree and treat unrelated changes as user-owned.

Choose one observable check for the failure: a build error, rejected import, uncaught exception, missing first frame, wrong event field, incorrect state, resource that survives teardown, or simulator/device mismatch.

Complete this step when one exact check is reproducibly red and the allowed mutation scope is explicit.