Add resend mechanism for media

README.md

@@ -5,6 +5,8 @@ Flutter app for Search and Rescue operations over a [MeshCore](https://github.co
 ## Features
 
 - **Messaging** — send/receive messages to contacts and channels
+- **Voice messages** — push-to-talk voice over the mesh using [Codec2](https://github.com/drowe67/codec2) ultra-low-bitrate speech compression (700–3200 bps); fragments are streamed on demand via direct BLE links without requiring firmware changes
+- **Image messages** — send photos over the mesh as AVIF-compressed fragments; images are fetched on demand when the recipient taps the placeholder; configurable resolution (64 / 128 / 256 px), compression level, and colour/grayscale mode
 - **Contacts** — track team members, repeaters, and rooms with live telemetry
 - **SAR Markers** — drop emoji-coded location pins (person found, fire, staging area) via chat messages
 - **Map** — view team positions and markers on OpenStreetMap / topo / satellite; tiles cached for offline use
@@ -70,10 +72,12 @@ cd ios && pod deintegrate && pod install && cd ..
 
 | Platform | Permissions |
 |----------|-------------|
-| iOS | Bluetooth, Location (when in use) |
-| Android | `BLUETOOTH_SCAN`, `BLUETOOTH_CONNECT`, `ACCESS_FINE_LOCATION`, `INTERNET` |
+| iOS | Bluetooth, Location (when in use), Microphone (voice), Photo Library / Camera (images) |
+| Android | `BLUETOOTH_SCAN`, `BLUETOOTH_CONNECT`, `ACCESS_FINE_LOCATION`, `INTERNET`, `RECORD_AUDIO`, `READ_MEDIA_IMAGES` |
 
-## SAR Marker format
+## Wire protocols
+
+### SAR Marker
 
 ```
 S:<emoji>:<lat>,<lon>
@@ -81,6 +85,40 @@ S:<emoji>:<lat>,<lon>
 
 Examples: `S:🧑:46.0569,14.5058` · `S:🔥:46.057,14.506` · `S:🏕️:46.0571,14.506`
 
+### Voice messages (on-demand, direct contacts only)
+
+Control plane (text):
+
+```
+VE1:{sid}:{mode}:{total}:{durationMs}:{senderKey6}:{ts}:{ver}   ← envelope
+VR1:{sid}:a:{requesterKey6}:{ts}:{ver}                          ← fetch request
+```
+
+Data plane (binary via `cmdSendRawData` / `pushRawData`, ≤160 bytes/packet):
+
+```
+[0x56 'V'][sessionId:4B][mode:1B][idx:1B][total:1B][Codec2 frame...]
+```
+
+Codec2 modes: 700C / 1200 / 1300 / 1400 / 1600 / 2400 / 3200 bps.
+
+### Image messages (on-demand, direct contacts only)
+
+Control plane (text):
+
+```
+IE1:{sid}:{fmt}:{total}:{w}:{h}:{bytes}:{senderKey6}:{ts}:{ver}  ← envelope
+IR1:{sid}:a:{requesterKey6}:{ts}:{ver}                           ← fetch request
+```
+
+Data plane (binary via `cmdSendRawData` / `pushRawData`, ≤160 bytes/packet):
+
+```
+[0x49 'I'][sessionId:4B][fmt:1B][idx:1B][total:1B][AVIF fragment...]
+```
+
+Images are compressed to AVIF (configurable up to 256×256, grayscale by default). At 152 bytes of payload per fragment a typical image takes 7–20 fragments — comparable to a short voice clip.
+
 ## Architecture
 
 ```