feat(ui-flow): attachment download, forward, and viewer IPC routes

Wire cancel-attachment-download, forward-attachment, open-attachment-in-viewer,
and attachment-download-progress polling for Phase 665 media gallery UX.

Co-authored-by: Cursor <[email protected]>

README.md

@@ -2,6 +2,8 @@
 
 Pearcord desktop UI IPC dispatch and automated flow scenarios for Bare smokes. Mirrors `apps/pearcord` pear-pipe message handling.
 
+**Phase 665 batch 2 (v0.8.640):** IPC `cancel-attachment-download`, `forward-attachment`, `open-attachment-in-viewer`; download progress polling via `attachment-download-progress` event. Bundle: `npm run test:phase665-media-batch2`.
+
 **v0.8.638 (Phase 659):** Added DM poll IPC routes: `vote-dm-poll` (optional `voted` desired-state) -> `dm-poll-voted`, `edit-dm-poll` -> `dm-poll-edited`, `close-dm-poll` -> `dm-poll-closed`, and `delete-dm-poll` -> `dm-poll-deleted`.
 
 **v0.8.638 (Phase 659):** Added DM scheduled-message IPC routes: `create-dm-scheduled-message`, `list-dm-scheduled-messages`, `cancel-dm-scheduled-message`, and `send-now-dm-scheduled-message`.

index.js

@@ -1772,13 +1772,29 @@ async function dispatchUiMessage (platform, msg, hooks = {}) {
         /* pipe closed */
       }
     }
+    let progressTimer = null
     try {
+      progressTimer = setInterval(() => {
+        const p = platform.attachments?.getFetchProgress?.(attachmentId)
+        if (!p) return
+        try {
+          send({
+            type: 'attachment-download-progress',
+            attachmentId,
+            progress: Number(p.progress) || 0,
+            status: p.status || 'fetching'
+          })
+        } catch {
+          /* pipe closed */
+        }
+      }, 180)
       const exported = await Promise.race([
         platform.exportAttachmentForDownload(attachmentId),
         new Promise((_, reject) => {
           setTimeout(() => reject(new Error('download timed out')), downloadTimeoutMs)
         })
       ])
+      if (progressTimer) clearInterval(progressTimer)
       if (!exported?.filePath) throw new Error('attachment file empty')
       if (maxInlineBytes > 0 && exported.size > maxInlineBytes) {
         try {
@@ -1810,10 +1826,40 @@ async function dispatchUiMessage (platform, msg, hooks = {}) {
         sendDownloadError(err?.message || String(err))
       }
     } catch (err) {
+      if (progressTimer) clearInterval(progressTimer)
       sendDownloadError(err?.message || String(err))
     }
     return true
   }
+  if (t === 'cancel-attachment-download') {
+    platform.cancelAttachmentDownload?.(msg.attachmentId)
+    return true
+  }
+  if (t === 'forward-attachment') {
+    const out = await platform.forwardAttachment({
+      messageId: msg.messageId,
+      targetChannelId: msg.targetChannelId,
+      attachmentIds: msg.attachmentIds || null
+    })
+    pushState()
+    send({ type: 'show-toast', message: 'Attachment forwarded' })
+    return out
+  }
+  if (t === 'open-attachment-in-viewer') {
+    const exported = await platform.exportAttachmentForDownload(msg.attachmentId)
+    if (!exported?.filePath) throw new Error('attachment file missing')
+    const os = require('bare-os')
+    const child = require('bare-subprocess')
+    const cmd =
+      os.platform() === 'darwin'
+        ? 'open'
+        : os.platform() === 'win32'
+          ? 'explorer'
+          : 'xdg-open'
+    child.spawn(cmd, [exported.filePath], { detached: true, stdio: 'ignore' })
+    send({ type: 'show-toast', message: `Opened ${exported.filename || 'attachment'}` })
+    return true
+  }
   if (t === 'upsert-guild-emoji') {
     await platform.upsertGuildEmoji({
       name: msg.name,