Restore the storage-domain medium the file-root design replaced: the cache
opens the session_projcache domain (per-record layout — one document per
session under the json backend root) and checkpoint writes land through
the domain's write chain. Reads and writes now share ONE coherent state:
cachedSnapshot reads synchronously from the domain's in-memory tables,
and every write is durability-first-then-memory, so a read can never go
around the write chain to the medium. The hand-rolled write chains,
in-flight tracking, per-session file paths, owner-only file modes, and
the sqlite no-path special case are gone; Config.root is removed and the
domain's version stamp makes a checkpointRecord bump discard stale
sessions per record instead of rejecting the whole medium. The async
ripple of the old file read is reverted: api-proxy's listing column and
subagent's cold identity read go back to synchronous cachedSnapshot.
_Kerman
1201ecc828