feat: add discord reaction tool

src/discord/monitor.ts

@@ -44,6 +44,7 @@ type DiscordHistoryEntry = {
   sender: string;
   body: string;
   timestamp?: number;
+  messageId?: string;
 };
 
 export async function monitorDiscordProvider(opts: MonitorDiscordOpts = {}) {
@@ -122,6 +123,7 @@ export async function monitorDiscordProvider(opts: MonitorDiscordOpts = {}) {
           sender: message.member?.displayName ?? message.author.tag,
           body: baseText,
           timestamp: message.createdTimestamp,
+          messageId: message.id,
         });
         while (history.length > historyLimit) history.shift();
         guildHistories.set(message.channelId, history);
@@ -196,11 +198,12 @@ export async function monitorDiscordProvider(opts: MonitorDiscordOpts = {}) {
       const fromLabel = isDirectMessage
         ? buildDirectLabel(message)
         : buildGuildLabel(message);
+      const textWithId = `${text}\n[discord message id: ${message.id} channel: ${message.channelId}]`;
       let combinedBody = formatAgentEnvelope({
         surface: "Discord",
         from: fromLabel,
         timestamp: message.createdTimestamp,
-        body: text,
+        body: textWithId,
       });
       let shouldClearHistory = false;
       if (!isDirectMessage) {
@@ -215,7 +218,7 @@ export async function monitorDiscordProvider(opts: MonitorDiscordOpts = {}) {
                 surface: "Discord",
                 from: fromLabel,
                 timestamp: entry.timestamp,
-                body: `${entry.sender}: ${entry.body}`,
+                body: `${entry.sender}: ${entry.body} [id:${entry.messageId ?? "unknown"} channel:${message.channelId}]`,
               }),
             )
             .join("\n");

src/discord/send.ts

@@ -29,6 +29,11 @@ export type DiscordSendResult = {
   channelId: string;
 };
 
+export type DiscordReactOpts = {
+  token?: string;
+  rest?: REST;
+};
+
 function resolveToken(explicit?: string) {
   const cfgToken = loadConfig().discord?.token;
   const token = normalizeDiscordToken(
@@ -42,6 +47,16 @@ function resolveToken(explicit?: string) {
   return token;
 }
 
+function normalizeReactionEmoji(raw: string) {
+  const trimmed = raw.trim();
+  if (!trimmed) {
+    throw new Error("emoji required");
+  }
+  const customMatch = trimmed.match(/^<a?:([^:>]+):(\d+)>$/);
+  const identifier = customMatch ? `${customMatch[1]}:${customMatch[2]}` : trimmed;
+  return encodeURIComponent(identifier);
+}
+
 function parseRecipient(raw: string): DiscordRecipient {
   const trimmed = raw.trim();
   if (!trimmed) {
@@ -164,3 +179,16 @@ export async function sendMessageDiscord(
     channelId: String(result.channel_id ?? channelId),
   };
 }
+
+export async function reactMessageDiscord(
+  channelId: string,
+  messageId: string,
+  emoji: string,
+  opts: DiscordReactOpts = {},
+) {
+  const token = resolveToken(opts.token);
+  const rest = opts.rest ?? new REST({ version: "10" }).setToken(token);
+  const encoded = normalizeReactionEmoji(emoji);
+  await rest.put(Routes.channelMessageReaction(channelId, messageId, encoded));
+  return { ok: true };
+}