Prevent self-directed agent messages

src/main/automation/automation-action-handlers.ts

@@ -155,6 +155,12 @@ function handleAgentNotification<K extends "notify_agent" | "send_message">({
     );
     return;
   }
+  if (channel === "direct" && toAgentId === fromAgentId) {
+    logger.info(
+      `[automation] Skipping rule "${rule.name}" - direct messages require two distinct participants`,
+    );
+    return;
+  }
 
   const dispatchResult = dispatchAgentMessage(
     { db, emitEvent, publishDomainChanged, wakeAgentIfPossible },

src/main/database/messages.ts

@@ -61,6 +61,9 @@ export function buildMessageMethods(
       if (channel === "direct" && !input.toAgentId) {
         throw new Error("Direct messages require a recipient.");
       }
+      if (channel === "direct" && input.toAgentId === input.fromAgentId) {
+        throw new Error("Direct messages require two distinct participants.");
+      }
       const senderKind = input.senderKind
         ?? (input.fromAgentId === BOARD_READER_ID ? "human" : "agent");
       const id = randomUUID();

src/main/messaging/dispatch.ts

@@ -53,6 +53,7 @@ export interface NormalizedAgentMessageInput {
 export interface MessageValidationError {
   code:
     | "DIRECT_MESSAGE_RECIPIENT_REQUIRED"
+    | "SELF_DIRECT_MESSAGE_FORBIDDEN"
     | "NON_DIRECT_MESSAGE_RECIPIENT_FORBIDDEN"
     | "INVALID_COMPANY_REFERENCE"
     | "CHANNEL_TARGET_REQUIRED"
@@ -147,6 +148,12 @@ export function validateAgentMessageInput(
       message: "Direct messages require a recipient agent.",
     };
   }
+  if (input.channel === "direct" && input.toAgentId === input.fromAgentId) {
+    return {
+      code: "SELF_DIRECT_MESSAGE_FORBIDDEN",
+      message: "Direct messages require two distinct participants.",
+    };
+  }
   if (input.channel !== "direct" && input.toAgentId) {
     return {
       code: "NON_DIRECT_MESSAGE_RECIPIENT_FORBIDDEN",