Port from Kilo-Org/kilocode#12508: a stray read-only state.db / -wal /
-shm (sudo run, restored backup, copied dotfiles) previously killed
SessionDB init with an opaque 'sqlite3.OperationalError: attempt to
write a readonly database' raised from deep inside _init_schema —
naming no file and no fix — and the obvious wrong 'fix' (deleting the
-wal) silently loses committed transactions.
New preflight_db_writability() runs before the first connection on both
DB open paths (SessionDB.__init__ and hermes_cli.kanban_db.connect):
- files inside the Hermes home tree are repaired with chmod u+rw (the
safe scope: Hermes owns them, and the OS makes chmod fail on files
the user doesn't own, which bounds the repair exactly);
- anything else (root-owned files, read-only mounts, custom paths)
fails fast with an error naming the exact file and the exact chmod
command, plus an explicit 'do NOT delete the -wal' warning;
- WAL sidecars are never deleted or truncated — once writable, the
normal open path checkpoints committed frames into the DB.
Proven live on main first: chmod 444 state.db -> SessionDB() raises the
opaque readonly error. With the fix: in-home DBs self-heal; out-of-home
DBs get the actionable message. Sabotage run confirms the integration
tests fail without the wiring (2 failed / 10 passed).
