Add configurable MQTT discovery prefix (fixes #12)

Users with a custom HA discovery prefix (e.g. 'discover') can now
configure it via UI or MQTT_DISCOVERY_PREFIX env var. Default remains
'homeassistant' for backward compatibility.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Dennis Braun

app/config.py

@@ -26,6 +26,7 @@
     "mqtt_user": "",
     "mqtt_password": "",
     "mqtt_topic_prefix": "docsight",
+    "mqtt_discovery_prefix": "homeassistant",
     "poll_interval": 900,
     "web_port": 8765,
     "history_days": 0,
@@ -50,6 +51,7 @@
     "mqtt_user": "MQTT_USER",
     "mqtt_password": "MQTT_PASSWORD",
     "mqtt_topic_prefix": "MQTT_TOPIC_PREFIX",
+    "mqtt_discovery_prefix": "MQTT_DISCOVERY_PREFIX",
     "poll_interval": "POLL_INTERVAL",
     "web_port": "WEB_PORT",
     "history_days": "HISTORY_DAYS",

app/i18n/de.json

@@ -114,6 +114,8 @@
   "username_opt": "Benutzername (optional)",
   "password_opt": "Passwort (optional)",
   "topic_prefix": "Topic-Prefix",
+  "discovery_prefix": "Discovery-Prefix",
+  "discovery_prefix_hint": "Standard: homeassistant. Nur aendern, wenn du es in HA angepasst hast.",
   "complete_setup": "Einrichtung abschliessen",
   "testing": "Teste...",
   "connected": "Verbunden",

app/i18n/en.json

@@ -114,6 +114,8 @@
   "username_opt": "Username (optional)",
   "password_opt": "Password (optional)",
   "topic_prefix": "Topic Prefix",
+  "discovery_prefix": "Discovery Prefix",
+  "discovery_prefix_hint": "Default: homeassistant. Only change if you customized it in HA.",
   "complete_setup": "Complete Setup",
   "testing": "Testing...",
   "connected": "Connected",

app/i18n/es.json

@@ -114,6 +114,8 @@
   "username_opt": "Usuario (opcional)",
   "password_opt": "Contraseña (opcional)",
   "topic_prefix": "Prefijo de topic",
+  "discovery_prefix": "Prefijo de descubrimiento",
+  "discovery_prefix_hint": "Predeterminado: homeassistant. Solo cambia si lo personalizaste en HA.",
   "complete_setup": "Completar configuración",
   "testing": "Probando...",
   "connected": "Conectado",

app/i18n/fr.json

@@ -114,6 +114,8 @@
   "username_opt": "Nom d'utilisateur (optionnel)",
   "password_opt": "Mot de passe (optionnel)",
   "topic_prefix": "Préfixe de topic",
+  "discovery_prefix": "Préfixe de découverte",
+  "discovery_prefix_hint": "Défaut : homeassistant. Ne changez que si vous l'avez personnalisé dans HA.",
   "complete_setup": "Terminer la configuration",
   "testing": "Test en cours...",
   "connected": "Connecté",

app/main.py

@@ -43,6 +43,7 @@ def polling_loop(config_mgr, storage, stop_event):
             user=mqtt_user,
             password=mqtt_password,
             topic_prefix=config["mqtt_topic_prefix"],
+            ha_prefix=config["mqtt_discovery_prefix"],
         )
         try:
             mqtt_pub.connect()

app/templates/settings.html

@@ -290,6 +290,11 @@ <h2>{{ t.general }}</h2>
                 <label for="mqtt_topic_prefix">{{ t.topic_prefix }}</label>
                 <input type="text" id="mqtt_topic_prefix" name="mqtt_topic_prefix" value="{{ config.mqtt_topic_prefix }}">
             </div>
+            <div class="form-row full">
+                <label for="mqtt_discovery_prefix">{{ t.discovery_prefix }}</label>
+                <input type="text" id="mqtt_discovery_prefix" name="mqtt_discovery_prefix" value="{{ config.mqtt_discovery_prefix }}" placeholder="homeassistant">
+                <span class="hint">{{ t.discovery_prefix_hint }}</span>
+            </div>
         </div>
         <div class="btn-row">
             <button type="button" class="btn btn-secondary" onclick="testMqtt()">{{ t.test_connection }}</button>

app/templates/setup.html

@@ -287,6 +287,11 @@ <h2>{{ t.mqtt_broker }}</h2>
                     <label for="mqtt_topic_prefix">{{ t.topic_prefix }}</label>
                     <input type="text" id="mqtt_topic_prefix" name="mqtt_topic_prefix" value="{{ config.mqtt_topic_prefix }}" placeholder="docsight">
                 </div>
+                <div class="form-row full">
+                    <label for="mqtt_discovery_prefix">{{ t.discovery_prefix }}</label>
+                    <input type="text" id="mqtt_discovery_prefix" name="mqtt_discovery_prefix" value="{{ config.mqtt_discovery_prefix }}" placeholder="homeassistant">
+                    <span class="hint">{{ t.discovery_prefix_hint }}</span>
+                </div>
             </div>
             <div class="btn-row">
                 <button type="button" class="btn btn-secondary" onclick="testMqtt()">{{ t.test_connection }}</button>