new client connection logic

- esp32 requests for image when ready to receive
- server serves initial image on request

pi/contents_server.py

@@ -17,6 +17,7 @@ Protocol:
 
 import argparse
 import asyncio
+import json
 import logging
 from datetime import datetime
 from pathlib import Path
@@ -68,17 +69,17 @@ async def handler(ws):
 
     configs = load_config(_config_path)
     img_idle = load_status_image(IMG_DIR / "idle.png")
+    current_img = img_idle
 
-    try:
-        await send_status_image(ws, img_idle)
+    alarms = [_prepare_alarm(entry) for entry in configs] if configs else []
 
-        if not configs:
+    async def alarm_ticker():
+        nonlocal current_img
+        if not alarms:
             log.info("No alarms configured — idling forever")
             await asyncio.Future()
             return
 
-        alarms = [_prepare_alarm(entry) for entry in configs]
-
         while True:
             for alarm in alarms:
                 if should_fire(alarm["config"]):
@@ -88,13 +89,28 @@ async def handler(ws):
                         alarm["last_fired"] = current_minute
                         log.info("Alarm firing: %s at %s",
                                  alarm["config"]["alarm_time"], current_minute)
-                        await send_status_image(ws, alarm["img"])
+                        current_img = alarm["img"]
+                        await send_status_image(ws, current_img)
                         await stream_alarm(ws, alarm["pcm"], alarm["sr"],
                                            alarm["ch"], alarm["bits"])
-                        await send_status_image(ws, img_idle)
+                        current_img = img_idle
+                        await send_status_image(ws, current_img)
 
             await asyncio.sleep(TICK_INTERVAL)
 
+    async def receiver():
+        async for msg in ws:
+            try:
+                data = json.loads(msg)
+            except (json.JSONDecodeError, TypeError):
+                continue
+            if data.get("type") == "request_image":
+                log.info("Client requested image — sending current (%d bytes)",
+                         len(current_img))
+                await send_status_image(ws, current_img)
+
+    try:
+        await asyncio.gather(alarm_ticker(), receiver())
     except websockets.exceptions.ConnectionClosed:
         log.info("Client disconnected: %s:%d", remote[0], remote[1])