A configured root that already exists as a file or unreadable directory cannot host cwd buckets, but the backend previously mounted and deferred that deterministic configuration error until a later list or write.
Probe the resolved root while the plugin loads, surface every error except ENOENT, and keep an absent root valid for lazy first materialization. Document the timing contract, regenerate the config catalog, and pin the non-directory case at the load boundary.
JSONL discovered a log by the requested session id but later routed repair and append from the parsed header. A log selected for session A could therefore declare session B and redirect mutation to B.
Validate the requested id and exact header-derived cwd-bucket path before returning a stored prefix, reject duplicate ids across buckets, and repeat the id/cwd guards in the coordinator before repair or state publication. Collapse the redundant loadLive hook into loadStored while retaining the existing bucket layout and one-live-writer topology, avoiding flat-layout churn and a locator generic that SQLite and test backends do not need.
