Discord: add fetch message action

src/agents/tools/discord-actions-messaging.ts

@@ -5,6 +5,7 @@ import {
   deleteMessageDiscord,
   editMessageDiscord,
   fetchChannelPermissionsDiscord,
+  fetchMessageDiscord,
   fetchReactionsDiscord,
   listPinsDiscord,
   listThreadsDiscord,
@@ -53,6 +54,23 @@ function formatDiscordTimestamp(ts?: string | null): string | undefined {
   return `${yyyy}-${mm}-${dd}T${hh}:${min}${sign}${offsetH}:${offsetM}${tzSuffix}`;
 }
 
+function parseDiscordMessageLink(link: string) {
+  const normalized = link.trim();
+  const match = normalized.match(
+    /^(?:https?:\/\/)?(?:ptb\.|canary\.)?discord(?:app)?\.com\/channels\/(\d+)\/(\d+)\/(\d+)(?:\/?|\?.*)$/i,
+  );
+  if (!match) {
+    throw new Error(
+      "Invalid Discord message link. Expected https://discord.com/channels/<guildId>/<channelId>/<messageId>.",
+    );
+  }
+  return {
+    guildId: match[1],
+    channelId: match[2],
+    messageId: match[3],
+  };
+}
+
 export async function handleDiscordMessagingAction(
   action: string,
   params: Record<string, unknown>,
@@ -157,6 +175,28 @@ export async function handleDiscordMessagingAction(
       const permissions = await fetchChannelPermissionsDiscord(channelId);
       return jsonResult({ ok: true, permissions });
     }
+    case "fetchMessage": {
+      if (!isActionEnabled("messages")) {
+        throw new Error("Discord message reads are disabled.");
+      }
+      const messageLink = readStringParam(params, "messageLink");
+      let guildId = readStringParam(params, "guildId");
+      let channelId = readStringParam(params, "channelId");
+      let messageId = readStringParam(params, "messageId");
+      if (messageLink) {
+        const parsed = parseDiscordMessageLink(messageLink);
+        guildId = parsed.guildId;
+        channelId = parsed.channelId;
+        messageId = parsed.messageId;
+      }
+      if (!guildId || !channelId || !messageId) {
+        throw new Error(
+          "Discord message fetch requires guildId, channelId, and messageId (or a valid messageLink).",
+        );
+      }
+      const message = await fetchMessageDiscord(channelId, messageId);
+      return jsonResult({ ok: true, message, guildId, channelId, messageId });
+    }
     case "readMessages": {
       if (!isActionEnabled("messages")) {
         throw new Error("Discord message reads are disabled.");

src/agents/tools/discord-actions.ts

@@ -11,6 +11,7 @@ const messagingActions = new Set([
   "sticker",
   "poll",
   "permissions",
+  "fetchMessage",
   "readMessages",
   "sendMessage",
   "editMessage",

src/agents/tools/discord-schema.ts

@@ -35,6 +35,21 @@ export const DiscordToolSchema = Type.Union([
     action: Type.Literal("permissions"),
     channelId: Type.String(),
   }),
+  Type.Union([
+    Type.Object({
+      action: Type.Literal("fetchMessage"),
+      messageLink: Type.String(),
+      guildId: Type.Optional(Type.String()),
+      channelId: Type.Optional(Type.String()),
+      messageId: Type.Optional(Type.String()),
+    }),
+    Type.Object({
+      action: Type.Literal("fetchMessage"),
+      guildId: Type.String(),
+      channelId: Type.String(),
+      messageId: Type.String(),
+    }),
+  ]),
   Type.Object({
     action: Type.Literal("readMessages"),
     channelId: Type.String(),

src/discord/send.ts

@@ -903,6 +903,17 @@ export async function readMessagesDiscord(
   )) as APIMessage[];
 }
 
+export async function fetchMessageDiscord(
+  channelId: string,
+  messageId: string,
+  opts: DiscordReactOpts = {},
+): Promise<APIMessage> {
+  const rest = resolveDiscordRest(opts);
+  return (await rest.get(
+    Routes.channelMessage(channelId, messageId),
+  )) as APIMessage;
+}
+
 export async function editMessageDiscord(
   channelId: string,
   messageId: string,