fix: harden message hook session/group context and add integration coverage (#9859) (thanks @Drickon)

docs/automation/hooks.md

@@ -299,6 +299,30 @@ Message events include rich context about the message:
   accountId?: string,     // Provider account ID
   conversationId?: string, // Chat/conversation ID
   messageId?: string,     // Message ID returned by the provider
+  isGroup?: boolean,      // Whether this outbound message belongs to a group/channel context
+  groupId?: string,       // Group/channel identifier for correlation with message:received
+}
+
+// message:transcribed context
+{
+  body?: string,          // Raw inbound body before enrichment
+  bodyForAgent?: string,  // Enriched body visible to the agent
+  transcript: string,     // Audio transcript text
+  channelId: string,      // Channel (e.g., "telegram", "whatsapp")
+  conversationId?: string,
+  messageId?: string,
+}
+
+// message:preprocessed context
+{
+  body?: string,          // Raw inbound body
+  bodyForAgent?: string,  // Final enriched body after media/link understanding
+  transcript?: string,    // Transcript when audio was present
+  channelId: string,      // Channel (e.g., "telegram", "whatsapp")
+  conversationId?: string,
+  messageId?: string,
+  isGroup?: boolean,
+  groupId?: string,
 }
 ```