sessions_reply holds lines: a released v0.0.1-16 client refuses a new daemon's long reply as unreachable

open   by a73x

From the wall-is-the-layout branch (2026-09-02). sessions_reply now carries one '# holds NAME N' line per session (version-gated). A released v0.0.1-16 client sizes its receive buffer at sessions_text_max (1056 B) and a pre-holds dev build at 1101 B; either refuses a longer payload as Transport, so a NEW daemon with roughly fourteen or more 32-character session names reads 'unreachable' on an OLD wall until that wall upgrades. Documented in README's compat note and decisions.md; nothing to fix unless a bounded reply (holds lines only on request) is wanted.