feat: send generated greeting when user joins via invite

After accepting a join request (onInvite) or joining a conversation
(/convos/join), trigger the normal reply pipeline with a system context
message so the agent generates a contextual introduction based on its
instructions. No new endpoints needed — greetings fire automatically
from the existing invite-accept and join handlers.

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

Author: saulmc

extensions/convos/index.ts

@@ -5,7 +5,7 @@ import * as path from "node:path";
 import { emptyPluginConfigSchema, renderQrPngBase64 } from "openclaw/plugin-sdk";
 import type { ConvosSDKClient } from "./src/sdk-client.js";
 import { resolveConvosAccount, type CoreConfig } from "./src/accounts.js";
-import { convosPlugin } from "./src/channel.js";
+import { convosPlugin, triggerGreeting } from "./src/channel.js";
 import { getClientForAccount } from "./src/outbound.js";
 import { getConvosRuntime, setConvosRuntime, setConvosSetupActive } from "./src/runtime.js";
 import { resolveConvosDbPath } from "./src/sdk-client.js";
@@ -446,6 +446,21 @@ const plugin = {
           }
 
           const result = await client.joinConversation(inviteUrl, name);
+
+          // Trigger a generated greeting in the background after joining.
+          if (result.status === "joined") {
+            triggerGreeting({
+              account,
+              conversationId: result.conversationId,
+              senderId: "system",
+              context:
+                "[System] You've just been added to a user's pre-existing chat. Introduce yourself concisely.",
+              runtime,
+            }).catch((err) => {
+              console.error("[convos-join] Greeting generation failed:", err);
+            });
+          }
+
           jsonResponse(res, 200, {
             conversationId: result.conversationId,
             status: result.status,
@@ -467,7 +482,8 @@ const plugin = {
         }
         try {
           const body = await readJsonBody(req);
-          const conversationId = typeof body.conversationId === "string" ? body.conversationId : undefined;
+          const conversationId =
+            typeof body.conversationId === "string" ? body.conversationId : undefined;
           const message = typeof body.message === "string" ? body.message : undefined;
           if (!conversationId || !message) {
             jsonResponse(res, 400, { error: "conversationId and message (strings) are required" });
@@ -505,7 +521,8 @@ const plugin = {
         }
         try {
           const body = await readJsonBody(req);
-          const conversationId = typeof body.conversationId === "string" ? body.conversationId : undefined;
+          const conversationId =
+            typeof body.conversationId === "string" ? body.conversationId : undefined;
           const name = typeof body.name === "string" ? body.name : undefined;
 
           if (!conversationId) {

extensions/convos/src/channel.ts

@@ -277,6 +277,10 @@ export const convosPlugin: ChannelPlugin<ResolvedConvosAccount> = {
         `[${account.accountId}] XMTP stateDir: ${stateDir}, cwd: ${process.cwd()}, dbPath: ${dbPath}`,
       );
 
+      // Track conversations that have already received a greeting so we
+      // only greet the first user who joins, not every subsequent invite.
+      const greetedConversations = new Set<string>();
+
       // Create SDK client with message handling
       const client = await ConvosSDKClient.create({
         privateKey: account.privateKey,
@@ -294,6 +298,22 @@ export const convosPlugin: ChannelPlugin<ResolvedConvosAccount> = {
           // TODO: Add policy-based handling
           log?.info(`[${account.accountId}] Auto-accepting invite request`);
           await inviteCtx.accept();
+
+          // Greet only the first user who joins each conversation.
+          if (!greetedConversations.has(inviteCtx.conversationId)) {
+            greetedConversations.add(inviteCtx.conversationId);
+            triggerGreeting({
+              account,
+              conversationId: inviteCtx.conversationId,
+              senderId: inviteCtx.joinerInboxId,
+              context:
+                "[System] You've just created this group and a user has just joined. Introduce yourself concisely.",
+              runtime,
+              log,
+            }).catch((err) => {
+              log?.error(`[${account.accountId}] Greeting generation failed: ${String(err)}`);
+            });
+          }
         },
       });
 
@@ -508,6 +528,31 @@ async function deliverConvosReply(params: {
   }
 }
 
+/**
+ * Trigger a generated greeting by feeding a synthetic system message through
+ * the normal reply pipeline. The agent will produce a contextual introduction
+ * based on its instructions / system prompt.
+ */
+export async function triggerGreeting(params: {
+  account: ResolvedConvosAccount;
+  conversationId: string;
+  senderId: string;
+  context: string;
+  runtime: PluginRuntime;
+  log?: RuntimeLogger;
+}): Promise<void> {
+  const { account, conversationId, senderId, context, runtime, log } = params;
+  const syntheticMsg: InboundMessage = {
+    conversationId,
+    messageId: `greeting-${Date.now()}`,
+    senderId,
+    senderName: "",
+    content: context,
+    timestamp: new Date(),
+  };
+  await handleInboundMessage(account, syntheticMsg, runtime, log);
+}
+
 /**
  * Stop SDK client for an account
  */