feat(mobile): preview HEIC images and share session attachments

apps/mobile/src/app/(app)/agent-chat/new.tsx

@@ -415,6 +415,7 @@ function NewSessionScreenBody() {
     ? remoteSpawn.isSpawningRemote ||
       isSubmitting ||
       attachments.hasFailedAttachments ||
+      attachments.isUploading ||
       modelView.isSelectionUnavailable ||
       instanceCatalog.isLoading
     : resolveNewSessionStartDisabled({

apps/mobile/src/components/agents/attachment-picker.test.ts

@@ -5,7 +5,7 @@ import * as SecureStore from 'expo-secure-store';
 import * as Sentry from '@sentry/react-native';
 import { describe, expect, it, vi } from 'vitest';
 
-import { pickAgentAttachments } from './attachment-picker';
+import { normalizeImageAsset, pickAgentAttachments } from './attachment-picker';
 
 const reactNativeMock = vi.hoisted(() => ({
   alert: vi.fn(),
@@ -70,6 +70,54 @@ async function pickWithSheetSelection(
   return resultPromise;
 }
 
+describe('normalizeImageAsset', () => {
+  it('keeps the picker fileName when present', () => {
+    expect(
+      normalizeImageAsset({
+        uri: 'file:///tmp/IMG_0001.HEIC',
+        fileName: 'IMG_0001.HEIC',
+        mimeType: 'application/octet-stream',
+      }).name
+    ).toBe('IMG_0001.HEIC');
+  });
+
+  it('treats a whitespace-only fileName as missing and synthesizes from the URI', () => {
+    expect(
+      normalizeImageAsset({
+        uri: 'file:///tmp/IMG_0001.HEIC',
+        fileName: '   ',
+        mimeType: 'application/octet-stream',
+      }).name
+    ).toBe('image.heic');
+  });
+
+  it('synthesizes image.heic from the URI extension when fileName is missing', () => {
+    expect(
+      normalizeImageAsset({
+        uri: 'file:///tmp/IMG_0001.HEIC',
+        mimeType: 'application/octet-stream',
+      }).name
+    ).toBe('image.heic');
+  });
+
+  it('synthesizes image.jpeg from the MIME subtype for an extension-less URI', () => {
+    expect(
+      normalizeImageAsset({
+        uri: 'file:///tmp/Camera/uuid',
+        mimeType: 'image/jpeg',
+      }).name
+    ).toBe('image.jpeg');
+  });
+
+  it('falls back to image.png when no signal carries the extension', () => {
+    expect(
+      normalizeImageAsset({
+        uri: 'file:///tmp/Camera/uuid',
+      }).name
+    ).toBe('image.png');
+  });
+});
+
 describe('agent attachment picker', () => {
   it('opens a native action sheet that keeps all sources and the cancel action', () => {
     const showActionSheet = vi.fn() as unknown as ShowActionSheet & {

apps/mobile/src/components/agents/attachment-picker.ts

@@ -5,6 +5,7 @@ import { type ActionSheetProps } from '@expo/react-native-action-sheet';
 import { Alert, Linking } from 'react-native';
 import * as Sentry from '@sentry/react-native';
 
+import { AGENT_ATTACHMENT_EXTENSION_REGEX } from '@/lib/agent-attachments/constants';
 import { mimeForExtension, normalizeAttachmentExtension } from '@/lib/agent-attachments/validate';
 import { IMAGE_PICKER_OPTIONS, launchImagePicker } from '@/lib/agent-attachments/image-picker';
 import { writePickerLaunchContext } from '@/lib/agent-attachments/picker-launch-context';
@@ -23,14 +24,30 @@ export function normalizeImageAsset(asset: {
   mimeType?: string | null;
   fileSize?: number | null;
 }): AgentAttachmentCandidate {
-  // Image picker cannot return a filename with an arbitrary extension;
-  // synthesize one from the picker's MIME so `normalizeAttachmentExtension`
-  // can resolve a known key. The actual byte size is re-measured by the
-  // upload hook via `getInfoAsync`; `size` here is informational.
-  const fallbackName = `image.${(asset.mimeType ?? 'image/png').split('/')[1] ?? 'png'}`;
-  const name = asset.fileName ?? fallbackName;
+  // Keep the picker's filename when it is non-empty after trimming.
+  const fileName = asset.fileName?.trim();
+  if (fileName) {
+    return {
+      name: fileName,
+      uri: asset.uri,
+      mimeType: asset.mimeType ?? undefined,
+      size: asset.fileSize ?? undefined,
+    };
+  }
+
+  // The image picker can omit the filename — camera HEIC assets report
+  // `application/octet-stream` with no name. Synthesize `image.<ext>` from
+  // the URI extension, then the MIME subtype, then fall back to `image.png`.
+  // The upload hook re-measures size via `getInfoAsync`; `size` here is
+  // informational.
+  const uriExtension = asset.uri.split('.').pop()?.toLowerCase();
+  const mimeSubtype = asset.mimeType?.split('/')[1]?.toLowerCase();
+  const extension =
+    (uriExtension && AGENT_ATTACHMENT_EXTENSION_REGEX.test(uriExtension) ? uriExtension : null) ??
+    (mimeSubtype && AGENT_ATTACHMENT_EXTENSION_REGEX.test(mimeSubtype) ? mimeSubtype : null) ??
+    'png';
   return {
-    name,
+    name: `image.${extension}`,
     uri: asset.uri,
     mimeType: asset.mimeType ?? undefined,
     size: asset.fileSize ?? undefined,

apps/mobile/src/components/agents/attachment-preview-strip.mounted.test.tsx

@@ -581,3 +581,66 @@ describe('AttachmentPreviewStrip — tappable unsent chips', () => {
     renderer.unmount();
   });
 });
+
+describe('AttachmentPreviewStrip — thumbnail decode fallback', () => {
+  it('shows the AlertCircle fallback while the upload spinner still renders', async () => {
+    const renderer = await mount([
+      makeAttachment({
+        kind: 'image',
+        filename: 'photo.png',
+        status: 'uploading',
+        progress: null,
+      }),
+    ]);
+
+    const images = nodesByType(renderer.root, 'Image');
+    expect(images).toHaveLength(1);
+    expect(nodesByType(renderer.root, 'ActivityIndicator')).toHaveLength(1);
+
+    const image = images[0];
+    if (!image) {
+      throw new Error('thumbnail Image missing');
+    }
+    await act(async () => {
+      await Promise.resolve();
+      (image.props.onError as () => void)();
+    });
+
+    expect(nodesByType(renderer.root, 'Image')).toHaveLength(0);
+    expect(nodesByType(renderer.root, 'AlertCircle')).toHaveLength(1);
+    // The upload overlay is driven by status alone and stays unchanged.
+    expect(nodesByType(renderer.root, 'ActivityIndicator')).toHaveLength(1);
+
+    renderer.unmount();
+  });
+
+  it('shows the AlertCircle fallback with no spinner for an uploaded image', async () => {
+    const renderer = await mount([
+      makeAttachment({
+        kind: 'image',
+        filename: 'photo.png',
+        status: 'uploaded',
+        progress: 1,
+      }),
+    ]);
+
+    const images = nodesByType(renderer.root, 'Image');
+    expect(images).toHaveLength(1);
+    expect(nodesByType(renderer.root, 'ActivityIndicator')).toHaveLength(0);
+
+    const image = images[0];
+    if (!image) {
+      throw new Error('thumbnail Image missing');
+    }
+    await act(async () => {
+      await Promise.resolve();
+      (image.props.onError as () => void)();
+    });
+
+    expect(nodesByType(renderer.root, 'Image')).toHaveLength(0);
+    expect(nodesByType(renderer.root, 'AlertCircle')).toHaveLength(1);
+    expect(nodesByType(renderer.root, 'ActivityIndicator')).toHaveLength(0);
+
+    renderer.unmount();
+  });
+});

apps/mobile/src/components/agents/attachment-preview-strip.tsx

@@ -1,3 +1,4 @@
+/* eslint-disable max-lines -- cohesive chip: thumbnail, status overlays, retry/remove controls, viewer, and text preview share one strip component */
 import { useState } from 'react';
 import { ActivityIndicator, Modal, Pressable, ScrollView, View } from 'react-native';
 import { File } from 'expo-file-system';
@@ -59,6 +60,7 @@ function AttachmentChip({
   const colors = useThemeColors();
   const { showActionSheetWithOptions } = useActionSheet();
   const [viewerVisible, setViewerVisible] = useState(false);
+  const [imageFailed, setImageFailed] = useState(false);
   const [textPreview, setTextPreview] = useState<{
     mode: 'markdown' | 'text';
     text: string;
@@ -131,6 +133,25 @@ function AttachmentChip({
   const accessibilityState =
     isUploading && attachment.progress === null ? { busy: true } : undefined;
 
+  const imageThumbnail = imageFailed ? (
+    <View className="h-full w-full items-center justify-center">
+      <AlertCircle size={20} color={colors.mutedForeground} />
+    </View>
+  ) : (
+    <Image
+      source={{ uri: attachment.localUri }}
+      className="h-full w-full"
+      contentFit="cover"
+      transition={0}
+      allowDownscaling
+      recyclingKey={attachment.id}
+      cachePolicy="memory"
+      onError={() => {
+        setImageFailed(true);
+      }}
+    />
+  );
+
   const bodyContent = (
     // Visual descendants are excluded from the accessibility tree so
     // the body stays the single announced element: the nested Texts,
@@ -142,15 +163,7 @@ function AttachmentChip({
       importantForAccessibility="no-hide-descendants"
     >
       {isImage ? (
-        <Image
-          source={{ uri: attachment.localUri }}
-          className="h-full w-full"
-          contentFit="cover"
-          transition={0}
-          allowDownscaling
-          recyclingKey={attachment.id}
-          cachePolicy="memory"
-        />
+        imageThumbnail
       ) : (
         <View
           className={cn(