Companion: keep a message log on the radio so multiple clients (phone + desktop) can each sync it

[UnoViper420]

Problem

A companion radio can only be used comfortably from one app. Contacts and channels live on the radio, so every client sees them, but message history doesn't:

• Messages that arrive while no client is connected wait in the companion's offline queue, and the first client to connect drains it. Whichever device connects next gets those messages; the others never see them.
• Messages I send only exist in the app I sent them from.
• Only one client can be connected at a time, so switching between my phone and the desktop app is routine, and each switch leaves the histories further apart.

The result is that my phone and Mac each show a partial conversation. For a messaging device, that's the biggest friction I've hit.

Setup: Elecrow ThinkNode M1 (nRF52840), Companion BLE firmware v1.17.1-d929643 (built 14-Aug-2026), MeshCore app on iOS and macOS.

Use cases

• Phone when out, desktop app at home.
• A household sharing one home node.
• Reconnecting after a few hours and seeing everything that happened, on whichever device you pick up.

Proposal

1. Persistent message log on the companion: a ring buffer of the last N messages (DMs and channel messages, including ones the companion sent), stored in flash, with N configurable.
2. Sequence numbers: each log entry gets an increasing sequence number.
3. "Sync since" command: a client asks for everything after the last sequence number it has seen, and the radio sends those entries. Each client keeps its own cursor, so syncing is no longer destructive and every client can catch up independently.
4. Backward compatible: keep the existing queue behavior for older apps, and add the new command alongside it.

Considerations

• Flash wear: ring buffer and batched writes. Some nRF52 boards have external QSPI flash, and ESP32 boards generally have more room.
• Privacy: messages would be stored on the device. Make the log optional, or let users clear it, much like contacts are already stored on the radio.
• No over-the-air change: this only affects the companion ↔ client protocol, not the mesh.

I'm not sure what the technical limitations are, but long term it feels like this would take MeshCore from POP to IMAP.

Thanks for all of the hard work the community has put into this, I am pretty new to it and have fallen in love.