* feat(transport): CompositeTransport for dual Meshtastic+MeshCore (Phase 4)
Adds CompositeTransport (transport: both) that fans broadcasts to both
meshes, sizes to min(children) for uniform messages, and routes DM
replies back over the originating mesh via a transport hint threaded from
the inbound MeshMessage. Per-child self-filtering; supervisor watchdog now
resolves the Meshtastic child inside the composite. Additive/optional
throughout; single-transport behavior unchanged.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* refactor(sizing): fixed universal mesh budget (mesh_max_chars=140)
Replace per-transport / min-of-active max_chars with a single fixed
universal constant (mesh_max_chars, default 140 = MeshCore LCD). Every
message is built once against one deterministic budget regardless of
which radios are connected; no runtime variance, no per-transport
retooling. Meshtastic sizing intentionally moves 200 -> 140.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Matt Johnson <mj@k7zvx.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Route all mesh message sizing (renderer, digest, reply chunker, NWS
one-packet fit) through the active transport's max_chars instead of
scattered literal 200s. Meshtastic pinned at 200 (byte-identical output);
MeshCore uses its configured ~140. Sets up uniform-to-smaller sizing for
the composite transport. No behavior change on the Meshtastic path.
Co-authored-by: Matt Johnson <mj@k7zvx.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
