General Idea

Run one FileWatcher on the client, and sync changes client to server
Run one FileWatcher on the server, and sync changes server to client
Bootstrap the process, for now with an rsync of server to client
When a file changes, send path+time+data to other side
State machine of the file on each side?

Server-side should own the state machine of path/mtime/hash
If no client-side connection, server-side can cache changes since last client connect
When client connects, bring up to date

Need a state machine of the connection state:

Initialize
Get Server State

If overflow goto 1

Get Client State

If overlfow goto 1

Bring into sync
Watch server

If overflow goto 1

watch client

If overlfow goto 1

The steady-state (post initial sync) client side would be:

One thread listening for file changes (or overflow)
One thread listening for server changes
Central logic that, on each incoming Update, decides what to do

Then:

On change from server:
- Ensure server's mtime >= our mtime
  - If so, write file
  - If not, it's fine, we should have an incoming/outgoing Update to correct the server
On add/change from file system:
- Send file + mtime to server

Threads

Both sides should have:

One thread for inotify (FileWatcher)
- Writes to inbound queue
grpc thread(s) listening stream
- Writes to inbound queue
One thread diffing trees (SyncLogic)
- Writes to outbound queue
One thread putting updates on the wire