feat: support inbound files across all channels

src/channels/slack/slack-api.mjs

@@ -1,3 +1,4 @@
+import { fetchFileStream } from '../shared/file-download.mjs';
 import { fetchImageBuffer, ImagePromptError } from '../shared/image-prompt.mjs';
 
 const DEFAULT_BASE_URL = 'https://slack.com/api/';
@@ -232,6 +233,18 @@ export class SlackApi {
     });
   }
 
+  async fileInfo({ fileId, signal } = {}) {
+    const value = await this.#request('files.info', {
+      tokenKind: 'bot',
+      signal,
+      body: { file: slackId(fileId, 'file id') },
+    });
+    if (!value?.file || typeof value.file !== 'object' || Array.isArray(value.file)) {
+      throw new Error('Slack files.info returned no file object');
+    }
+    return value.file;
+  }
+
   postMessage({ channelId, text, threadTs, signal }) {
     return this.#request('chat.postMessage', {
       tokenKind: 'bot',
@@ -396,6 +409,14 @@ export class SlackApi {
   }
 
   async downloadFile({ url, signal, maxBytes }) {
+    return this.#downloadFile({ url, signal, maxBytes, stream: false });
+  }
+
+  async downloadFileStream({ url, signal }) {
+    return this.#downloadFile({ url, signal, stream: true });
+  }
+
+  async #downloadFile({ url, signal, maxBytes, stream }) {
     if (!this.#botToken) throw new TypeError('Slack bot token is required for file download');
     const target = secureSlackFileUrl(url);
     const fetchSlackFile = async (requestUrl, options) => {
@@ -414,13 +435,15 @@ export class SlackApi {
       }
       return response;
     };
-    return fetchImageBuffer(target, {
+    const options = {
       fetchImpl: fetchSlackFile,
       headers: { authorization: `Bearer ${this.#botToken}` },
       signal,
-      maxBytes,
       allowedHosts: SLACK_FILE_HOSTS,
-    });
+    };
+    return stream
+      ? fetchFileStream(target, options)
+      : fetchImageBuffer(target, { ...options, maxBytes });
   }
 
   async #request(method, {
@@ -432,7 +455,7 @@ export class SlackApi {
   }) {
     const token = tokenKind === 'app' ? this.#appToken : this.#botToken;
     if (!token) throw new TypeError(`Slack ${tokenKind} token is required for ${method}`);
-    const formEncoded = method === 'files.getUploadURLExternal';
+    const formEncoded = method === 'files.getUploadURLExternal' || method === 'files.info';
     let response;
     try {
       response = await this.#fetch(new URL(method, this.#baseUrl), {

src/channels/slack/slack-runtime.mjs

@@ -43,10 +43,14 @@ function stripBotMention(value, botUserId) {
     .trim();
 }
 
+function slackFileUrl(file) {
+  return typeof file?.url_private_download === 'string' && file.url_private_download
+    ? file.url_private_download : file?.url_private;
+}
+
 function slackImageSource(file, loadFile) {
   const mediaType = typeof file?.mimetype === 'string' ? file.mimetype.toLowerCase() : '';
-  const url = typeof file?.url_private_download === 'string' && file.url_private_download
-    ? file.url_private_download : file?.url_private;
+  const url = slackFileUrl(file);
   if (!IMAGE_MEDIA_TYPES.has(mediaType) || typeof url !== 'string' || !url) return null;
   return {
     name: typeof file.name === 'string' ? file.name : undefined,
@@ -56,9 +60,50 @@ function slackImageSource(file, loadFile) {
   };
 }
 
-export function normalizeSlackEvent(payload, botUserId, { loadFile = async () => {
-  throw new Error('Slack file downloader is unavailable');
-} } = {}) {
+function slackFileSource(file, loadFile, loadFileInfo) {
+  const mediaType = typeof file?.mimetype === 'string' && file.mimetype
+    ? file.mimetype.toLowerCase() : undefined;
+  const url = slackFileUrl(file);
+  if (IMAGE_MEDIA_TYPES.has(mediaType)) return null;
+  const requiresInfo = file?.file_access === 'check_file_info'
+    && typeof file?.id === 'string' && file.id;
+  if ((typeof url !== 'string' || !url) && !requiresInfo) return null;
+  return {
+    name: typeof file?.name === 'string' && file.name
+      ? file.name : typeof file?.title === 'string' && file.title
+        ? file.title : requiresInfo ? file.id : 'slack-file',
+    ...(mediaType ? { mediaType } : {}),
+    size: Number.isSafeInteger(file?.size) && file.size >= 0 ? file.size : undefined,
+    load: async ({ signal } = {}) => {
+      if (!requiresInfo) return loadFile(url, { signal });
+      const resolved = await loadFileInfo(file.id, { signal });
+      const resolvedUrl = slackFileUrl(resolved);
+      if (typeof resolvedUrl !== 'string' || !resolvedUrl) {
+        throw new Error('Slack files.info returned no downloadable URL');
+      }
+      const loaded = await loadFile(resolvedUrl, { signal });
+      const name = typeof resolved?.name === 'string' && resolved.name
+        ? resolved.name : typeof resolved?.title === 'string' && resolved.title
+          ? resolved.title : file.id;
+      const resolvedMediaType = typeof resolved?.mimetype === 'string' && resolved.mimetype
+        ? resolved.mimetype.toLowerCase() : undefined;
+      if (Buffer.isBuffer(loaded) || loaded instanceof Uint8Array) {
+        return { data: loaded, name, ...(resolvedMediaType ? { mediaType: resolvedMediaType } : {}) };
+      }
+      return {
+        ...loaded,
+        name,
+        ...(resolvedMediaType ? { mediaType: resolvedMediaType } : {}),
+      };
+    },
+  };
+}
+
+export function normalizeSlackEvent(payload, botUserId, {
+  loadFile = async () => { throw new Error('Slack file downloader is unavailable'); },
+  loadFileStream = loadFile,
+  loadFileInfo = async () => { throw new Error('Slack file metadata loader is unavailable'); },
+} = {}) {
   const event = payload?.event;
   if (!event || !payload?.event_id || !event.channel || !event.user || !event.ts) return null;
   const direct = event.type === 'message' && event.channel_type === 'im';
@@ -76,6 +121,9 @@ export function normalizeSlackEvent(payload, botUserId, { loadFile = async () =>
     images: Array.isArray(event.files)
       ? event.files.map((file) => slackImageSource(file, loadFile)).filter(Boolean)
       : [],
+    files: Array.isArray(event.files)
+      ? event.files.map((file) => slackFileSource(file, loadFileStream, loadFileInfo)).filter(Boolean)
+      : [],
     addressed: direct || mentioned,
     replyTarget: {
       channelId: String(event.channel),
@@ -436,6 +484,8 @@ export class SlackRuntime {
           && packet.payload.api_app_id !== this.#appId) return;
         const message = normalizeSlackEvent(packet.payload, this.#config.platformId.split(':')[1], {
           loadFile: (url, options) => this.#api.downloadFile({ url, ...options }),
+          loadFileStream: (url, options) => this.#api.downloadFileStream({ url, ...options }),
+          loadFileInfo: (fileId, options) => this.#api.fileInfo({ fileId, ...options }),
         });
         const bridge = this.#bridge;
         if (message && bridge) {