next.js

014e821c - improve disk read semantics around MustExist and AllowMissing (#99249)

improve disk read semantics around MustExist and AllowMissing (#99249) Ensure two concurrent reads of a missing task both observe it as missing: `AllowMissing` returns `None` for both, and `MustExist` panics for both, rather than letting one reader mistake an intermediate blank entry for a task. A missing requested Data or Meta key is conclusive; the restore path also avoids retrying that key in a busy loop. Add focused coverage for `task_pair`, `prepare_tasks`, missing categories, and restore races. Stacked on #99383, which removes suspended-operation serialization; this PR no longer filters persisted operations. <!-- fleet e2b0931e-5002-47b5-b5e1-3a96fbc88cab --> --------- Co-authored-by: vercel-fleet-prod[bot] <318278635+vercel-fleet-prod[bot]@users.noreply.github.com> Co-authored-by: Luke Sandberg <210140+lukesandberg@users.noreply.github.com>