feat(web): prime group sessions with member roster

src/auto-reply/reply.ts

@@ -413,6 +413,25 @@ export async function getReplyFromConfig(
     isFirstTurnInSession && sessionCfg?.sessionIntro
       ? applyTemplate(sessionCfg.sessionIntro, sessionCtx)
       : "";
+  const groupIntro =
+    isFirstTurnInSession && sessionCtx.ChatType === "group"
+      ? (() => {
+          const subject = sessionCtx.GroupSubject?.trim();
+          const members = sessionCtx.GroupMembers?.trim();
+          const subjectLine = subject
+            ? `You are replying inside the WhatsApp group "${subject}".`
+            : "You are replying inside a WhatsApp group chat.";
+          const membersLine = members
+            ? `Group members: ${members}.`
+            : undefined;
+          return [subjectLine, membersLine]
+            .filter(Boolean)
+            .join(" ")
+            .concat(
+              " Address the specific sender noted in the message context.",
+            );
+        })()
+      : "";
   const bodyPrefix = reply?.bodyPrefix
     ? applyTemplate(reply.bodyPrefix, sessionCtx)
     : "";
@@ -430,6 +449,9 @@ export async function getReplyFromConfig(
   if (sessionIntro) {
     prefixedBodyBase = `${sessionIntro}\n\n${prefixedBodyBase}`;
   }
+  if (groupIntro) {
+    prefixedBodyBase = `${groupIntro}\n\n${prefixedBodyBase}`;
+  }
   if (abortedHint) {
     prefixedBodyBase = `${abortedHint}\n\n${prefixedBodyBase}`;
     if (sessionEntry && sessionStore && sessionKey) {

src/auto-reply/templating.ts

@@ -7,6 +7,11 @@ export type MsgContext = {
   MediaUrl?: string;
   MediaType?: string;
   Transcript?: string;
+  ChatType?: string;
+  GroupSubject?: string;
+  GroupMembers?: string;
+  SenderName?: string;
+  SenderE164?: string;
 };
 
 export type TemplateContext = MsgContext & {

src/web/auto-reply.ts

@@ -766,6 +766,11 @@ export async function monitorWebProvider(
           MediaPath: latest.mediaPath,
           MediaUrl: latest.mediaUrl,
           MediaType: latest.mediaType,
+          ChatType: latest.chatType,
+          GroupSubject: latest.groupSubject,
+          GroupMembers: latest.groupParticipants?.join(", "),
+          SenderName: latest.senderName,
+          SenderE164: latest.senderE164,
         },
         {
           onReplyStart: latest.sendComposing,

src/web/inbound.ts

@@ -39,6 +39,8 @@ export type WebInboundMessage = {
   senderJid?: string;
   senderE164?: string;
   senderName?: string;
+  groupSubject?: string;
+  groupParticipants?: string[];
   mentionedJids?: string[];
   selfJid?: string | null;
   selfE164?: string | null;
@@ -73,6 +75,33 @@ export async function monitorWebInbox(options: {
   const selfJid = sock.user?.id;
   const selfE164 = selfJid ? jidToE164(selfJid) : null;
   const seen = new Set<string>();
+  const groupMetaCache = new Map<
+    string,
+    { subject?: string; participants?: string[]; expires: number }
+  >();
+  const GROUP_META_TTL_MS = 5 * 60 * 1000; // 5 minutes
+
+  const getGroupMeta = async (jid: string) => {
+    const cached = groupMetaCache.get(jid);
+    if (cached && cached.expires > Date.now()) return cached;
+    try {
+      const meta = await sock.groupMetadata(jid);
+      const participants =
+        meta.participants
+          ?.map((p) => jidToE164(p.id) ?? p.id)
+          .filter(Boolean) ?? [];
+      const entry = {
+        subject: meta.subject,
+        participants,
+        expires: Date.now() + GROUP_META_TTL_MS,
+      };
+      groupMetaCache.set(jid, entry);
+      return entry;
+    } catch (err) {
+      logVerbose(`Failed to fetch group metadata for ${jid}: ${String(err)}`);
+      return { expires: Date.now() + GROUP_META_TTL_MS };
+    }
+  };
 
   sock.ev.on("messages.upsert", async (upsert) => {
     if (upsert.type !== "notify") return;
@@ -109,6 +138,13 @@ export async function monitorWebInbox(options: {
       const from = group ? remoteJid : jidToE164(remoteJid);
       // Skip if we still can't resolve an id to key conversation
       if (!from) continue;
+      let groupSubject: string | undefined;
+      let groupParticipants: string[] | undefined;
+      if (group) {
+        const meta = await getGroupMeta(remoteJid);
+        groupSubject = meta.subject;
+        groupParticipants = meta.participants;
+      }
 
       // Filter unauthorized senders early to prevent wasted processing
       // and potential session corruption from Bad MAC errors
@@ -197,6 +233,8 @@ export async function monitorWebInbox(options: {
           senderJid: participantJid,
           senderE164: senderE164 ?? undefined,
           senderName,
+          groupSubject,
+          groupParticipants,
           mentionedJids: mentionedJids ?? undefined,
           selfJid,
           selfE164,