fix(mobile): show video, audio and media cards as plain rows

Mobile has no media UI yet, so video, audio and media-card blocks rendered
as empty bubbles or fell out of previews.

- Thread text and reply previews describe video and audio files and the
  media card's title and status.
- The bubble lists video, audio and a finished card's outputs as tappable
  rows that open the file like other attachments.
- Opening video or audio downloads it from the artifact route to the cache
  instead of a base64 RPC, so long recordings open without the server
  holding them in memory.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MRtGG9ARfqqhma3t85Ro2u

apps/mobile/app/thread.tsx

@@ -77,6 +77,7 @@ import {
   type MobileMessagePage,
   type MobileSnapshot,
   mergeMobileSnapshot,
+  messageAttachments,
   messagingProviderLabel,
   prependMobileMessagePage,
   rpc,
@@ -2243,7 +2244,11 @@ function previewMessageText(message: MobileMessage): string {
     .join(" ")
     .trim();
   if (text) return text;
-  if (message.blocks.some((block) => block.kind === "image" || block.kind === "file")) {
+  if (
+    message.blocks.some((block) =>
+      ["image", "file", "video", "audio", "media"].includes(block.kind),
+    )
+  ) {
     return t("Attachment");
   }
   return t("Message");
@@ -2676,9 +2681,7 @@ const MessageBubble = memo(function MessageBubble({
       </View>
     );
   }
-  const attachments = message.blocks.filter(
+  const attachments = messageAttachments(message.blocks);
-    (block) => block.kind === "image" || block.kind === "file",
-  );
   const caption = message.blocks
     .flatMap((block) => {
       if (block.kind === "channel_message" && block.text) {
@@ -2686,6 +2689,7 @@ const MessageBubble = memo(function MessageBubble({
           `${messagingProviderLabel(block.provider, block.transport)} · ${block.fromLabel}: ${block.text}`,
         ];
       }
+      if (block.kind === "media") return [block.title];
       return block.kind === "text" && block.text ? [block.text] : [];
     })
     .join("\n");
@@ -2797,7 +2801,8 @@ const MessageBubble = memo(function MessageBubble({
                   fontSize: 15,
                 }}
               >
-                📎 {attachment.name ?? t("File")}
+                {attachment.kind === "video" ? "🎬" : attachment.kind === "audio" ? "🎵" : "📎"}{" "}
+                {attachment.name ?? t("File")}
               </Text>
               {attachment.size ? (
                 <Text

apps/mobile/lib/api.test.ts

@@ -16,6 +16,7 @@ import {
   MAX_MOBILE_AUTH_RESPONSE_BYTES,
   MAX_MOBILE_RPC_RESPONSE_BYTES,
   mergeMobileSnapshot,
+  messageAttachments,
   passwordResetCapabilities,
   prependMobileMessagePage,
   requestPasswordReset,
@@ -1857,6 +1858,51 @@ describe("mobile thread event reduction", () => {
     ).toBe("Slack · Alex: Hello from the group");
   });
 
+  it("falls back to plain text and file rows for video, audio and media cards", () => {
+    const blocks = [
+      {
+        kind: "video" as const,
+        artifactId: "vid-1",
+        mimeType: "video/mp4",
+        name: "clip.mp4",
+        size: 10,
+        width: 1080,
+        height: 1920,
+      },
+      {
+        kind: "audio" as const,
+        artifactId: "aud-1",
+        mimeType: "audio/mpeg",
+        name: "memo.mp3",
+        size: 5,
+      },
+      {
+        kind: "media" as const,
+        jobId: "job-1",
+        operation: "export_video" as const,
+        status: "done" as const,
+        title: "Vertical cut",
+        outputs: [
+          {
+            artifactId: "out-1",
+            kind: "video" as const,
+            mimeType: "video/mp4",
+            name: "cut.mp4",
+            size: 7,
+          },
+        ],
+      },
+    ];
+    expect(blockText(mobileMessage("media-1", blocks))).toBe(
+      "[video: clip.mp4]\n[audio: memo.mp3]\nVertical cut: done",
+    );
+    expect(messageAttachments(blocks).map((item) => [item.kind, item.artifactId])).toEqual([
+      ["video", "vid-1"],
+      ["audio", "aud-1"],
+      ["video", "out-1"],
+    ]);
+  });
+
   it("deduplicates durable messages and replaces matching transient subagent state", () => {
     const initial = snapshot([
       mobileMessage("message-1", [{ kind: "text", text: "old" }]),

apps/mobile/lib/api.ts

@@ -860,6 +860,24 @@ export function copyableMobileMessageText(message: MobileMessage): string {
     .trim();
 }
 
+export type MobileAttachment = {
+  kind: "image" | "video" | "audio" | "file";
+  artifactId: string;
+  name: string;
+  mimeType: string;
+  size?: number;
+};
+
+/** Files a message carries, including the outputs of a finished media card, as tappable rows. */
+export function messageAttachments(blocks: readonly MessageBlock[]): MobileAttachment[] {
+  return blocks.flatMap((block): MobileAttachment[] => {
+    if (block.kind === "image") return [{ ...block, kind: "image" }];
+    if (block.kind === "video" || block.kind === "audio" || block.kind === "file") return [block];
+    if (block.kind === "media") return block.outputs;
+    return [];
+  });
+}
+
 export function blockText(message: MobileMessage) {
   return message.blocks
     .map((block) => {
@@ -879,6 +897,10 @@ export function blockText(message: MobileMessage) {
       if (block.kind === "file") {
         return `[file: ${block.name ?? "attachment"}${block.size ? ` (${block.size} bytes)` : ""}]`;
       }
+      if (block.kind === "video" || block.kind === "audio") {
+        return `[${block.kind}: ${block.name ?? "attachment"}]`;
+      }
+      if (block.kind === "media") return `${block.title}: ${block.status}`;
       if (block.kind === "steps") {
         return (block.steps ?? [])
           .map((step) => `${step.label}${step.count > 1 ? ` ×${step.count}` : ""}`)

apps/mobile/lib/artifact-open.ts

@@ -1,6 +1,7 @@
+import { attachmentKindOf } from "@rakazo/contracts";
 import { File, Paths } from "expo-file-system";
 import * as Sharing from "expo-sharing";
-import { rpc } from "./api";
+import { captureApiRequestContext, rpc } from "./api";
 import { artifactCacheFileName } from "./artifact-file";
 import { t } from "./i18n";
 
@@ -11,6 +12,16 @@ async function cacheMobileArtifact(
   artifactId: string,
   mimeType: string,
 ): Promise<File> {
+  const kind = attachmentKindOf(mimeType);
+  if (kind === "video" || kind === "audio") {
+    // Media can be hundreds of megabytes: stream it to disk instead of a base64 RPC payload.
+    const { apiBase, headers } = await captureApiRequestContext();
+    return File.downloadFileAsync(
+      `${apiBase}/api/artifacts/${encodeURIComponent(artifactId)}`,
+      new File(Paths.cache, artifactCacheFileName(artifactId, mimeType)),
+      { headers, idempotent: true },
+    );
+  }
   const artifact = await rpc<{ contentBase64: string }>("artifacts/get", {
     ...target,
     artifactId,