A catch with persistent file stores

What conclusions in particular? This topic has covered a lot of ground - not all of it pertinent.

The graceful shutdown design note is related to how a flow can be stopped cleanly - without dropping messages that are already 'inflight' within the flow. That is all predicated on the runtime being allowed to shutdown cleanly.

The context file store already does flush to disk when the runtime is being shutdown cleanly.

There is a separate issue over whether the runtime is being allowed to shutdown cleanly or not, depending on the many ways people chose to run it - nodemon, systemd, pm2... etc etc.