feat(mobile): preview generated task artifacts (port #3837)

Ports the desktop artifact-preview feature to mobile. A cloud run's generated
output artifacts are now listed in the task session view and can be previewed
in-app.

- List `type === "output"` artifacts once the run reaches a terminal status,
  reusing the existing run-artifact manifest cache.
- Tap to preview in a full-screen modal: images render natively, Markdown reuses
  the existing MarkdownText renderer, and HTML renders in a hardened WebView
  (injected CSP + JavaScript disabled + external-navigation blocked), reusing the
  MCP sandbox CSP helper. Anything else falls back to open-externally.
- Every artifact keeps an open/share action via the system browser.

Generated-By: PostHog Code
Task-Id: d3b8922c-a9f2-45a2-a48c-6a05beaaf905

Author: Gilbert09

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

@@ -712,6 +712,7 @@ export default function TaskDetailScreen() {
         <TaskSessionView
           events={session?.events ?? []}
           taskId={taskId}
+          runId={task?.latest_run?.id}
           pendingPermissions={session?.pendingPermissions}
           isConnecting={isConnecting}
           isThinking={isThinking}

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

@@ -0,0 +1,178 @@
+import { useQuery } from "@tanstack/react-query";
+import { ArrowSquareOut, Warning, X } from "phosphor-react-native";
+import {
+  ActivityIndicator,
+  Image,
+  Modal,
+  Pressable,
+  ScrollView,
+  Text,
+  View,
+} from "react-native";
+import { useSafeAreaInsets } from "react-native-safe-area-context";
+import WebView from "react-native-webview";
+import { MarkdownText } from "@/features/chat";
+import { applyCspToHtml } from "@/features/mcp/sandbox/mcpAppCsp";
+import { openExternalUrl } from "@/lib/openExternalUrl";
+import { useThemeColors } from "@/lib/theme";
+import { useCloudAttachmentPreview } from "../hooks/useCloudAttachmentPreview";
+import type { TaskRunArtifact } from "../types";
+import { artifactPreviewKind } from "../utils/artifactPreview";
+
+interface ArtifactPreviewProps {
+  taskId: string;
+  runId: string;
+  artifact: TaskRunArtifact;
+  onClose: () => void;
+}
+
+export function ArtifactPreview({
+  taskId,
+  runId,
+  artifact,
+  onClose,
+}: ArtifactPreviewProps) {
+  const insets = useSafeAreaInsets();
+  const themeColors = useThemeColors();
+  const name = artifact.name ?? "artifact";
+  const kind = artifactPreviewKind(name);
+
+  const { data: url, isLoading: urlLoading } = useCloudAttachmentPreview(
+    taskId,
+    artifact.id ? { runId, artifactId: artifact.id } : undefined,
+  );
+
+  // Markdown and HTML render from the file's text; images and the external
+  // fallback only need the presigned URL.
+  const needsText = kind === "markdown" || kind === "html";
+  const {
+    data: text,
+    isLoading: textLoading,
+    isError: textError,
+  } = useQuery({
+    queryKey: ["artifactText", url],
+    enabled: needsText && Boolean(url),
+    staleTime: Infinity,
+    retry: false,
+    queryFn: async (): Promise<string> => {
+      const response = await fetch(url ?? "");
+      if (!response.ok) throw new Error("Artifact fetch failed");
+      return response.text();
+    },
+  });
+
+  const loading = urlLoading || (needsText && textLoading);
+
+  return (
+    <Modal
+      visible
+      animationType="slide"
+      presentationStyle="fullScreen"
+      onRequestClose={onClose}
+    >
+      <View className="flex-1 bg-background" style={{ paddingTop: insets.top }}>
+        <View className="flex-row items-center gap-3 px-4 pb-2">
+          <Text
+            className="flex-1 font-semibold text-[16px] text-gray-12"
+            numberOfLines={1}
+          >
+            {name}
+          </Text>
+          {url ? (
+            <Pressable
+              onPress={() => openExternalUrl(url)}
+              hitSlop={8}
+              className="active:opacity-60"
+              accessibilityLabel="Open externally"
+            >
+              <ArrowSquareOut size={20} color={themeColors.gray[12]} />
+            </Pressable>
+          ) : null}
+          <Pressable
+            onPress={onClose}
+            hitSlop={8}
+            className="active:opacity-60"
+            accessibilityLabel="Close preview"
+          >
+            <X size={20} color={themeColors.gray[12]} />
+          </Pressable>
+        </View>
+
+        <View className="flex-1" style={{ paddingBottom: insets.bottom }}>
+          {loading ? (
+            <View className="flex-1 items-center justify-center">
+              <ActivityIndicator color={themeColors.accent[9]} />
+            </View>
+          ) : !url || textError || kind === "unsupported" ? (
+            <Unsupported
+              url={url}
+              onShare={() => url && openExternalUrl(url)}
+            />
+          ) : kind === "image" ? (
+            <Image
+              source={{ uri: url }}
+              resizeMode="contain"
+              style={{ flex: 1, width: "100%" }}
+            />
+          ) : kind === "markdown" ? (
+            <ScrollView
+              className="flex-1"
+              contentContainerStyle={{ padding: 16 }}
+            >
+              <MarkdownText content={text ?? ""} />
+            </ScrollView>
+          ) : (
+            <WebView
+              originWhitelist={["*"]}
+              source={{ html: applyCspToHtml(text ?? "") }}
+              // Untrusted agent output: no scripts, and any attempt to navigate
+              // out (links, redirects) is handed to the system browser rather
+              // than loaded inside the sandbox. The injected CSP blocks remote
+              // resource loads on top of that.
+              javaScriptEnabled={false}
+              setSupportMultipleWindows={false}
+              onShouldStartLoadWithRequest={(req) => {
+                if (
+                  req.url.startsWith("http://") ||
+                  req.url.startsWith("https://")
+                ) {
+                  openExternalUrl(req.url);
+                  return false;
+                }
+                return true;
+              }}
+              style={{ flex: 1, backgroundColor: "#fff" }}
+            />
+          )}
+        </View>
+      </View>
+    </Modal>
+  );
+}
+
+function Unsupported({
+  url,
+  onShare,
+}: {
+  url: string | null | undefined;
+  onShare: () => void;
+}) {
+  const themeColors = useThemeColors();
+  return (
+    <View className="flex-1 items-center justify-center gap-4 px-8">
+      <Warning size={28} color={themeColors.gray[9]} />
+      <Text className="text-center text-[14px] text-gray-11">
+        This file can't be previewed here.
+      </Text>
+      {url ? (
+        <Pressable
+          onPress={onShare}
+          className="flex-row items-center gap-2 rounded-lg bg-gray-3 px-4 py-2.5 active:opacity-70"
+        >
+          <ArrowSquareOut size={16} color={themeColors.gray[12]} />
+          <Text className="text-[14px] text-gray-12">Open externally</Text>
+        </Pressable>
+      ) : null}
+    </View>
+  );
+}

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

@@ -0,0 +1,65 @@
+import { createElement } from "react";
+import { act, create } from "react-test-renderer";
+import { describe, expect, it, vi } from "vitest";
+import type { TaskRunArtifact } from "../types";
+import { TaskArtifacts } from "./TaskArtifacts";
+
+const mockUseTaskArtifacts = vi.fn();
+
+vi.mock("../hooks/useTaskArtifacts", () => ({
+  useTaskArtifacts: (...args: unknown[]) => mockUseTaskArtifacts(...args),
+}));
+
+vi.mock("./ArtifactPreview", () => ({
+  ArtifactPreview: (props: Record<string, unknown>) =>
+    createElement("ArtifactPreview", props),
+}));
+
+vi.mock("../api", () => ({ presignTaskRunArtifact: vi.fn() }));
+
+vi.mock("@/lib/openExternalUrl", () => ({ openExternalUrl: vi.fn() }));
+
+vi.mock("phosphor-react-native", () => ({
+  ArrowSquareOut: (props: Record<string, unknown>) =>
+    createElement("ArrowSquareOut", props),
+  File: (props: Record<string, unknown>) => createElement("File", props),
+}));
+
+vi.mock("@/lib/theme", () => ({
+  useThemeColors: () => ({ gray: { 9: "#777", 11: "#555" } }),
+}));
+
+function render(artifacts: TaskRunArtifact[] | undefined) {
+  mockUseTaskArtifacts.mockReturnValue({ data: artifacts });
+  let renderer: ReturnType<typeof create> | null = null;
+  act(() => {
+    renderer = create(
+      createElement(TaskArtifacts, {
+        taskId: "t1",
+        runId: "r1",
+        enabled: true,
+      }),
+    );
+  });
+  if (!renderer) throw new Error("Renderer not created");
+  return JSON.stringify((renderer as ReturnType<typeof create>).toJSON());
+}
+
+describe("TaskArtifacts", () => {
+  it("renders nothing when there are no artifacts", () => {
+    expect(render([])).toBe("null");
+    expect(render(undefined)).toBe("null");
+  });
+
+  it("lists artifact names and sizes", () => {
+    const output = render([
+      { id: "a1", name: "report.md", type: "output", size: 2_400 },
+      { id: "a2", name: "chart.png", type: "output", size: 512 },
+    ]);
+    expect(output).toContain("Files");
+    expect(output).toContain("report.md");
+    expect(output).toContain("chart.png");
+    expect(output).toContain("2 KB");
+    expect(output).toContain("512 B");
+  });
+});

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

@@ -0,0 +1,107 @@
+import { ArrowSquareOut, File as FileIcon } from "phosphor-react-native";
+import { useCallback, useState } from "react";
+import { ActivityIndicator, Alert, Pressable, Text, View } from "react-native";
+import { openExternalUrl } from "@/lib/openExternalUrl";
+import { useThemeColors } from "@/lib/theme";
+import { presignTaskRunArtifact } from "../api";
+import { useTaskArtifacts } from "../hooks/useTaskArtifacts";
+import type { TaskRunArtifact } from "../types";
+import { formatArtifactSize } from "../utils/artifactPreview";
+import { ArtifactPreview } from "./ArtifactPreview";
+
+interface TaskArtifactsProps {
+  taskId: string | undefined;
+  runId: string | undefined;
+  // Gate the manifest fetch on a terminal run, mirroring desktop.
+  enabled: boolean;
+}
+
+export function TaskArtifacts({ taskId, runId, enabled }: TaskArtifactsProps) {
+  const themeColors = useThemeColors();
+  const { data: artifacts } = useTaskArtifacts(taskId, runId, enabled);
+  const [preview, setPreview] = useState<TaskRunArtifact | null>(null);
+  const [sharingId, setSharingId] = useState<string | null>(null);
+
+  const shareArtifact = useCallback(
+    async (artifact: TaskRunArtifact): Promise<void> => {
+      if (!taskId || !runId || !artifact.storage_path) return;
+      setSharingId(artifact.id ?? artifact.storage_path);
+      try {
+        const url = await presignTaskRunArtifact(
+          taskId,
+          runId,
+          artifact.storage_path,
+        );
+        openExternalUrl(url);
+      } catch {
+        Alert.alert("Couldn't open file", "Please try again.");
+      } finally {
+        setSharingId(null);
+      }
+    },
+    [taskId, runId],
+  );
+
+  if (!taskId || !runId || !artifacts || artifacts.length === 0) return null;
+
+  return (
+    <View className="mx-4 mb-2 rounded-lg border border-gray-5 bg-gray-2 p-3">
+      <Text className="mb-2 font-semibold text-[13px] text-gray-12">Files</Text>
+      <View className="gap-1">
+        {artifacts.map((artifact) => {
+          const sharingKey = artifact.id ?? artifact.storage_path;
+          const size = formatArtifactSize(artifact.size);
+          const canPreview = Boolean(artifact.id);
+          return (
+            <View
+              key={sharingKey ?? artifact.name}
+              className="flex-row items-center gap-3 rounded-md bg-background px-2 py-1.5"
+            >
+              <Pressable
+                className="min-w-0 flex-1 flex-row items-center gap-2 active:opacity-70"
+                disabled={!canPreview}
+                onPress={() => setPreview(artifact)}
+              >
+                <FileIcon size={16} color={themeColors.gray[11]} />
+                <Text
+                  className="flex-shrink text-[13px] text-gray-12"
+                  numberOfLines={1}
+                >
+                  {artifact.name ?? "artifact"}
+                </Text>
+                {size ? (
+                  <Text className="text-[12px] text-gray-9">{size}</Text>
+                ) : null}
+              </Pressable>
+              <Pressable
+                hitSlop={8}
+                className="active:opacity-60"
+                disabled={!artifact.storage_path}
+                onPress={() => void shareArtifact(artifact)}
+                accessibilityLabel="Open externally"
+              >
+                {sharingId === sharingKey ? (
+                  <ActivityIndicator
+                    size="small"
+                    color={themeColors.gray[11]}
+                  />
+                ) : (
+                  <ArrowSquareOut size={16} color={themeColors.gray[11]} />
+                )}
+              </Pressable>
+            </View>
+          );
+        })}
+      </View>
+
+      {preview?.id ? (
+        <ArtifactPreview
+          taskId={taskId}
+          runId={runId}
+          artifact={preview}
+          onClose={() => setPreview(null)}
+        />
+      ) : null}
+    </View>
+  );
+}

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

@@ -56,6 +56,11 @@ vi.mock("./CloudMessageAttachment", () => ({
     createElement("CloudMessageAttachment", props),
 }));
 
+vi.mock("./TaskArtifacts", () => ({
+  TaskArtifacts: (props: Record<string, unknown>) =>
+    createElement("TaskArtifacts", props),
+}));
+
 function renderTaskSessionView(
   props: Parameters<typeof TaskSessionView>[0],
 ): ReturnType<typeof create> {