feat(mobile): show S3-backed image attachment thumbnails (port #3707)

apps/mobile/src/app/task/[id].tsx

@@ -704,6 +704,7 @@ export default function TaskDetailScreen() {
             small visual buffer at the bottom. */}
         <TaskSessionView
           events={session?.events ?? []}
+          taskId={taskId}
           pendingPermissions={session?.pendingPermissions}
           isConnecting={isConnecting}
           isThinking={isThinking}

apps/mobile/src/features/chat/components/HumanMessage.tsx

@@ -2,7 +2,7 @@ import * as Clipboard from "expo-clipboard";
 import * as Haptics from "expo-haptics";
 import { LinearGradient } from "expo-linear-gradient";
 import { CaretDown, CaretUp, File as FileIcon } from "phosphor-react-native";
-import { useCallback, useState } from "react";
+import { type ReactNode, useCallback, useState } from "react";
 import {
   Alert,
   type LayoutChangeEvent,
@@ -12,20 +12,38 @@ import {
 } from "react-native";
 import { formatRelativeTime } from "@/lib/format";
 import { toRgba, useThemeColors } from "@/lib/theme";
-import { MarkdownImage } from "./MarkdownImage";
 import { MarkdownText } from "./MarkdownText";
 
 export interface HumanMessageAttachment {
   kind: "image" | "document";
   uri: string;
   fileName: string;
   mimeType?: string;
+  // Bytes stored as a cloud run artifact rather than on this device. When set,
+  // the preview must be resolved through a presigned URL — the raw `uri` points
+  // at the sandbox filesystem and is not fetchable here.
+  cloudArtifact?: { runId: string; artifactId: string };
 }
 
 interface HumanMessageProps {
   content: string;
   timestamp?: number;
   attachments?: HumanMessageAttachment[];
+  // Lets a host (e.g. tasks) resolve cloud-backed image previews. Without one,
+  // attachments render as plain file chips.
+  renderAttachment?: (attachment: HumanMessageAttachment) => ReactNode;
+}
+
+export function MessageFileChip({ fileName }: { fileName: string }) {
+  const themeColors = useThemeColors();
+  return (
+    <View className="flex-row items-center gap-2 self-start rounded-md border border-gray-6 bg-gray-3 px-2 py-1.5">
+      <FileIcon size={14} color={themeColors.gray[11]} />
+      <Text className="font-mono text-[12px] text-gray-12" numberOfLines={1}>
+        {fileName}
+      </Text>
+    </View>
+  );
 }
 
 const COLLAPSED_MAX_HEIGHT = 160;
@@ -34,6 +52,7 @@ export function HumanMessage({
   content,
   timestamp,
   attachments,
+  renderAttachment,
 }: HumanMessageProps) {
   const themeColors = useThemeColors();
   const [isExpanded, setIsExpanded] = useState(false);
@@ -109,28 +128,15 @@ export function HumanMessage({
           )}
           {hasAttachments && (
             <View className={hasContent ? "mt-2 gap-2" : "gap-2"}>
-              {attachments?.map((att) =>
-                att.kind === "image" ? (
-                  <MarkdownImage
-                    key={`${att.uri}-${att.fileName}`}
-                    url={att.uri}
-                    alt={att.fileName}
-                  />
-                ) : (
-                  <View
-                    key={`${att.uri}-${att.fileName}`}
-                    className="flex-row items-center gap-2 self-start rounded-md border border-gray-6 bg-gray-3 px-2 py-1.5"
-                  >
-                    <FileIcon size={14} color={themeColors.gray[11]} />
-                    <Text
-                      className="font-mono text-[12px] text-gray-12"
-                      numberOfLines={1}
-                    >
-                      {att.fileName}
-                    </Text>
-                  </View>
-                ),
-              )}
+              {attachments?.map((att) => (
+                <View key={`${att.uri}-${att.fileName}`}>
+                  {renderAttachment ? (
+                    renderAttachment(att)
+                  ) : (
+                    <MessageFileChip fileName={att.fileName} />
+                  )}
+                </View>
+              ))}
             </View>
           )}
         </View>

apps/mobile/src/features/chat/index.ts

@@ -5,7 +5,12 @@
 
 // Components
 export { AgentMessage } from "./components/AgentMessage";
-export { HumanMessage } from "./components/HumanMessage";
+export {
+  HumanMessage,
+  type HumanMessageAttachment,
+  MessageFileChip,
+} from "./components/HumanMessage";
+export { MarkdownImage } from "./components/MarkdownImage";
 export { MarkdownText } from "./components/MarkdownText";
 export type {
   ToolKind,

apps/mobile/src/features/tasks/api.test.ts

@@ -24,7 +24,12 @@ vi.mock("@/lib/api", () => ({
     }),
 }));
 
-import { cancelRun, HttpError, runTaskInCloud } from "./api";
+import {
+  cancelRun,
+  HttpError,
+  presignTaskRunArtifact,
+  runTaskInCloud,
+} from "./api";
 
 function bodyOf(call: unknown): Record<string, unknown> {
   const [, init] = call as [string, RequestInit];
@@ -155,3 +160,39 @@ describe("cancelRun", () => {
     );
   });
 });
+
+describe("presignTaskRunArtifact", () => {
+  beforeEach(() => {
+    mockFetch.mockReset();
+  });
+
+  it("posts the storage path and returns the presigned URL", async () => {
+    mockFetch.mockResolvedValue(
+      new Response(
+        JSON.stringify({ url: "https://s3.example.com/x.png?sig=abc" }),
+        { status: 200 },
+      ),
+    );
+
+    await expect(
+      presignTaskRunArtifact("task-1", "run-1", "tasks/run-1/artifacts/x.png"),
+    ).resolves.toBe("https://s3.example.com/x.png?sig=abc");
+
+    const [url, init] = mockFetch.mock.calls[0] as [string, RequestInit];
+    expect(url).toBe(
+      "https://app.posthog.test/api/projects/42/tasks/task-1/runs/run-1/artifacts/presign/",
+    );
+    expect(init.method).toBe("POST");
+    expect(bodyOf(mockFetch.mock.calls[0])).toEqual({
+      storage_path: "tasks/run-1/artifacts/x.png",
+    });
+  });
+
+  it("throws an HttpError on a non-OK response", async () => {
+    mockFetch.mockResolvedValue(new Response("nope", { status: 500 }));
+
+    await expect(
+      presignTaskRunArtifact("task-1", "run-1", "tasks/run-1/artifacts/x.png"),
+    ).rejects.toBeInstanceOf(HttpError);
+  });
+});

apps/mobile/src/features/tasks/api.ts

@@ -564,6 +564,38 @@ export async function getTaskRun(
   return await response.json();
 }
 
+/**
+ * Exchanges an artifact's storage path for a short-lived presigned S3 URL used
+ * to render image attachment previews.
+ */
+export async function presignTaskRunArtifact(
+  taskId: string,
+  runId: string,
+  storagePath: string,
+): Promise<string> {
+  const baseUrl = getBaseUrl();
+  const projectId = getProjectId();
+
+  const response = await authedFetch(
+    `${baseUrl}/api/projects/${projectId}/tasks/${taskId}/runs/${runId}/artifacts/presign/`,
+    {
+      method: "POST",
+      body: JSON.stringify({ storage_path: storagePath }),
+    },
+  );
+
+  if (!response.ok) {
+    throw new HttpError(
+      response.status,
+      response.statusText,
+      "Failed to generate artifact preview URL",
+    );
+  }
+
+  const data = (await response.json()) as { url: string };
+  return data.url;
+}
+
 export async function cancelRun(
   taskId: string,
   runId: string,

apps/mobile/src/features/tasks/components/CloudMessageAttachment.tsx

@@ -0,0 +1,32 @@
+import {
+  type HumanMessageAttachment,
+  MarkdownImage,
+  MessageFileChip,
+} from "@/features/chat";
+import { useCloudAttachmentPreview } from "../hooks/useCloudAttachmentPreview";
+
+export function CloudMessageAttachment({
+  attachment,
+  taskId,
+}: {
+  attachment: HumanMessageAttachment;
+  taskId?: string;
+}) {
+  const { data: previewUrl } = useCloudAttachmentPreview(
+    taskId,
+    attachment.cloudArtifact,
+  );
+
+  if (attachment.kind !== "image") {
+    return <MessageFileChip fileName={attachment.fileName} />;
+  }
+
+  // Cloud images resolve to a presigned URL; local (in-flight) images render
+  // straight from their device uri. Fall back to a chip when neither is ready.
+  const imageUrl = attachment.cloudArtifact ? previewUrl : attachment.uri;
+  if (!imageUrl) {
+    return <MessageFileChip fileName={attachment.fileName} />;
+  }
+
+  return <MarkdownImage url={imageUrl} alt={attachment.fileName} />;
+}

apps/mobile/src/features/tasks/components/TaskSessionView.test.tsx

@@ -51,6 +51,11 @@ vi.mock("./PlanApprovalCard", () => ({
     createElement("PlanApprovalCard", props),
 }));
 
+vi.mock("./CloudMessageAttachment", () => ({
+  CloudMessageAttachment: (props: Record<string, unknown>) =>
+    createElement("CloudMessageAttachment", props),
+}));
+
 function renderTaskSessionView(
   props: Parameters<typeof TaskSessionView>[0],
 ): ReturnType<typeof create> {

apps/mobile/src/features/tasks/components/TaskSessionView.tsx

@@ -29,6 +29,7 @@ import type {
   SessionNotification,
   SessionNotificationAttachment,
 } from "../types";
+import { CloudMessageAttachment } from "./CloudMessageAttachment";
 import { PlanApprovalCard } from "./PlanApprovalCard";
 import { PlanStatusBar } from "./PlanStatusBar";
 import { QuestionCard } from "./QuestionCard";
@@ -52,6 +53,7 @@ interface OptimisticUserMessage {
 
 interface TaskSessionViewProps {
   events: SessionEvent[];
+  taskId?: string;
   pendingPermissions?: Record<string, CloudPendingPermissionRequest>;
   isConnecting?: boolean;
   isThinking?: boolean;
@@ -797,6 +799,7 @@ function ConnectingIndicator() {
 
 export function TaskSessionView({
   events,
+  taskId,
   pendingPermissions,
   isConnecting,
   isThinking,
@@ -929,6 +932,13 @@ export function TaskSessionView({
     [],
   );
 
+  const renderAttachment = useCallback(
+    (attachment: SessionNotificationAttachment) => (
+      <CloudMessageAttachment attachment={attachment} taskId={taskId} />
+    ),
+    [taskId],
+  );
+
   const renderMessage = useCallback(
     ({ item }: { item: ParsedMessage }) => {
       switch (item.type) {
@@ -938,6 +948,7 @@ export function TaskSessionView({
               content={item.content}
               timestamp={item.ts}
               attachments={item.attachments}
+              renderAttachment={renderAttachment}
             />
           );
         case "agent":
@@ -994,7 +1005,12 @@ export function TaskSessionView({
           return null;
       }
     },
-    [onOpenTask, onSendPermissionResponse, pendingPermissions],
+    [
+      onOpenTask,
+      onSendPermissionResponse,
+      pendingPermissions,
+      renderAttachment,
+    ],
   );
 
   return (

apps/mobile/src/features/tasks/hooks/useCloudAttachmentPreview.ts

@@ -0,0 +1,47 @@
+import { useQuery, useQueryClient } from "@tanstack/react-query";
+import { getProjectId } from "@/lib/api";
+import { getTaskRun, presignTaskRunArtifact } from "../api";
+import type { CloudArtifactRef } from "../types";
+
+// Presigned URLs outlive this comfortably (backend issues ~1h), so we refetch
+// well before expiry rather than on every render.
+const PREVIEW_STALE_MS = 50 * 60 * 1000;
+
+/**
+ * Resolves a cloud attachment to a presigned S3 preview URL. The run's artifact
+ * manifest is fetched once per run through the shared query cache, so a message
+ * with several images does not fire a manifest request per image. Returns
+ * `null` when the artifact is missing so callers can fall back to a file chip.
+ */
+export function useCloudAttachmentPreview(
+  taskId: string | undefined,
+  cloudArtifact: CloudArtifactRef | undefined,
+) {
+  const queryClient = useQueryClient();
+  const projectId = getProjectId();
+
+  return useQuery({
+    queryKey: [
+      "cloudArtifactPreview",
+      projectId,
+      taskId,
+      cloudArtifact?.runId,
+      cloudArtifact?.artifactId,
+    ],
+    enabled: Boolean(taskId && cloudArtifact),
+    staleTime: PREVIEW_STALE_MS,
+    retry: false,
+    queryFn: async () => {
+      if (!taskId || !cloudArtifact) return null;
+      const { runId, artifactId } = cloudArtifact;
+      const artifacts = await queryClient.fetchQuery({
+        queryKey: ["taskRunArtifacts", projectId, taskId, runId],
+        queryFn: async () => (await getTaskRun(taskId, runId)).artifacts ?? [],
+        staleTime: PREVIEW_STALE_MS,
+      });
+      const match = artifacts.find((artifact) => artifact.id === artifactId);
+      if (!match?.storage_path) return null;
+      return presignTaskRunArtifact(taskId, runId, match.storage_path);
+    },
+  });
+}