Resize chat image previews naturally

web/src/embedded/chat/components/markdown/overrides/img.tsx

@@ -1,5 +1,12 @@
 import { Menu } from '@/utils/webview-context-menu';
-import { useCallback, useState } from 'react';
+import { cn } from '@/utils/cn';
+import {
+  useCallback,
+  useState,
+  type CSSProperties,
+  type SyntheticEvent,
+} from 'react';
+import { fitImagePreviewSize } from '../../messages/image-preview-size';
 
 /**
  * Custom image component with loading animation and error handling.
@@ -8,10 +15,17 @@ export const CueStreamdownImg = ({
   src,
   alt,
   className,
+  onLoad,
+  onError,
+  style,
   ...props
 }: React.ComponentProps<'img'>) => {
   const [imageLoaded, setImageLoaded] = useState(false);
   const [error, setError] = useState<string | null>(null);
+  const [naturalSize, setNaturalSize] = useState<{
+    width: number;
+    height: number;
+  } | null>(null);
 
   const handleContextMenu = useCallback(
     (event: React.MouseEvent<HTMLImageElement>) => {
@@ -31,6 +45,43 @@ export const CueStreamdownImg = ({
     [src]
   );
 
+  const handleLoad = useCallback(
+    (event: SyntheticEvent<HTMLImageElement>) => {
+      const image = event.currentTarget;
+      if (image.naturalWidth > 0 && image.naturalHeight > 0) {
+        setNaturalSize({
+          width: image.naturalWidth,
+          height: image.naturalHeight,
+        });
+      }
+      setImageLoaded(true);
+      onLoad?.(event);
+    },
+    [onLoad]
+  );
+
+  const handleError = useCallback(
+    (event: SyntheticEvent<HTMLImageElement>) => {
+      setError('Failed to load image');
+      onError?.(event);
+    },
+    [onError]
+  );
+
+  const previewSize = naturalSize
+    ? fitImagePreviewSize(naturalSize.width, naturalSize.height)
+    : null;
+  const imageStyle = {
+    ...style,
+    ...(previewSize && naturalSize
+      ? {
+          width: previewSize.width,
+          maxHeight: previewSize.height,
+          aspectRatio: `${naturalSize.width} / ${naturalSize.height}`,
+        }
+      : {}),
+  } satisfies CSSProperties;
+
   // Error state
   if (error) {
     return (
@@ -48,13 +99,14 @@ export const CueStreamdownImg = ({
       src={src}
       alt={alt || 'Generated image'}
       onContextMenu={handleContextMenu}
-      className={`
-        ${className || ''}
-        transition-opacity duration-500 ease-out
-        ${imageLoaded ? 'opacity-100' : 'opacity-0'}
-      `}
-      onLoad={() => setImageLoaded(true)}
-      onError={() => setError('Failed to load image')}
+      className={cn(
+        'inline-block h-auto max-w-full rounded-lg object-contain transition-opacity duration-500 ease-out',
+        className,
+        imageLoaded ? 'opacity-100' : 'opacity-0'
+      )}
+      style={imageStyle}
+      onLoad={handleLoad}
+      onError={handleError}
       {...props}
     />
   );

web/src/embedded/chat/components/messages/assistant-message.tsx

@@ -255,7 +255,7 @@ function renderContentBlock(
           mimeType={content.mimeType ?? undefined}
           sourcePath={content.fileRef?.path}
           environmentId={content.fileRef?.environmentId ?? undefined}
-          className="max-h-80 w-fit"
+          className="w-fit"
           data-artifact={key}
         />
       ) : null;

web/src/embedded/chat/components/messages/attachment-image.tsx

@@ -5,7 +5,13 @@ import {
   resolveAttachmentDisplayURL,
 } from '@/utils/agent-file-url';
 import { hasNativeJSBridge } from '@/utils/bridge-runtime';
-import { useCallback, useEffect, useRef, useState } from 'react';
+import {
+  useCallback,
+  useEffect,
+  useRef,
+  useState,
+  type CSSProperties,
+} from 'react';
 import { Spinner } from '../loading/spinner';
 import { Menu } from '@/utils/webview-context-menu';
 import { EyeSFSymbolMedium } from '@/assets/sf-symbols/medium/eye';
@@ -14,8 +20,14 @@ import {
   previewAttachmentSource,
   previewSourceRectForElement,
 } from './file-reference-actions';
+import {
+  fitImagePreviewSize,
+  imagePreviewBounds,
+  type ImagePreviewBounds,
+} from './image-preview-size';
 
 type PreviewButtonTone = 'dark' | 'light';
+type NaturalImageSize = { width: number; height: number };
 
 function detectPreviewButtonTone(image: HTMLImageElement): PreviewButtonTone {
   const naturalWidth = image.naturalWidth;
@@ -95,6 +107,8 @@ export const AttachmentImage = ({
   sourcePath,
   environmentId,
   className,
+  style,
+  previewBounds = imagePreviewBounds,
   ...props
 }: {
   className?: string;
@@ -103,13 +117,15 @@ export const AttachmentImage = ({
   mimeType?: string;
   sourcePath?: string;
   environmentId?: string;
+  previewBounds?: ImagePreviewBounds;
 } & React.HTMLAttributes<HTMLElement>) => {
   const [status, setStatus] = useState<'loading' | 'loaded' | 'error'>(
     'loading'
   );
   const [resolvedSrc, setResolvedSrc] = useState<string | null>(null);
   const [previewButtonTone, setPreviewButtonTone] =
     useState<PreviewButtonTone>('dark');
+  const [naturalSize, setNaturalSize] = useState<NaturalImageSize | null>(null);
   const figureRef = useRef<HTMLElement | null>(null);
   const imageRef = useRef<HTMLImageElement | null>(null);
 
@@ -229,6 +245,7 @@ export const AttachmentImage = ({
     setStatus('loading');
     setResolvedSrc(null);
     setPreviewButtonTone('dark');
+    setNaturalSize(null);
     resolveUrl();
 
     return () => {
@@ -247,6 +264,12 @@ export const AttachmentImage = ({
       return;
     }
 
+    if (image.naturalWidth > 0 && image.naturalHeight > 0) {
+      setNaturalSize({
+        width: image.naturalWidth,
+        height: image.naturalHeight,
+      });
+    }
     setPreviewButtonTone(detectPreviewButtonTone(image));
     if (resolvedSrc) {
       preparePreviewAsset(resolvedSrc, fileName, mimeType);
@@ -330,6 +353,24 @@ export const AttachmentImage = ({
     ]
   );
 
+  const previewSize = naturalSize
+    ? fitImagePreviewSize(naturalSize.width, naturalSize.height, previewBounds)
+    : null;
+  const imageStyle =
+    previewSize && naturalSize
+      ? ({
+          width: previewSize.width,
+          maxHeight: previewSize.height,
+          aspectRatio: `${naturalSize.width} / ${naturalSize.height}`,
+        } satisfies CSSProperties)
+      : undefined;
+  const figureStyle = {
+    minWidth: previewBounds.minWidth,
+    minHeight: previewBounds.minHeight,
+    ...style,
+    ...(previewSize ? { width: previewSize.width } : {}),
+  } satisfies CSSProperties;
+
   return (
     <figure
       ref={node => {
@@ -338,9 +379,10 @@ export const AttachmentImage = ({
       onContextMenu={handleContextMenu}
       className={cn(
         'group/image overflow-hidden rounded-lg border border-black/10 dark:border-white/20 relative',
-        'min-h-24 w-fit',
+        'inline-flex max-w-full items-center justify-center bg-black/5 dark:bg-white/5',
         className
       )}
+      style={figureStyle}
       data-source-path={sourcePath}
       {...props}
     >
@@ -403,9 +445,10 @@ export const AttachmentImage = ({
           alt="Uploaded attachment"
           className={cn(
             'attachment-image',
-            'h-full max-h-[inherit] w-auto object-contain transition-opacity duration-200',
+            'block h-auto max-w-full object-contain transition-opacity duration-200',
             status !== 'loaded' && 'opacity-0'
           )}
+          style={imageStyle}
           loading={isDataUrl ? undefined : 'lazy'}
           decoding="async"
           onLoad={handleLoad}

web/src/embedded/chat/components/messages/image-preview-size.ts

@@ -0,0 +1,68 @@
+export type ImagePreviewBounds = {
+  minWidth: number;
+  minHeight: number;
+  maxWidth: number;
+  maxHeight: number;
+};
+
+export type ImagePreviewSize = {
+  width: number;
+  height: number;
+  scale: number;
+};
+
+export const imagePreviewBounds: ImagePreviewBounds = {
+  minWidth: 160,
+  minHeight: 120,
+  maxWidth: 640,
+  maxHeight: 520,
+};
+
+export const imageThumbnailPreviewBounds: ImagePreviewBounds = {
+  minWidth: 96,
+  minHeight: 96,
+  maxWidth: 240,
+  maxHeight: 96,
+};
+
+export function fitImagePreviewSize(
+  naturalWidth: number,
+  naturalHeight: number,
+  bounds: ImagePreviewBounds = imagePreviewBounds
+): ImagePreviewSize | null {
+  if (
+    !isPositiveFiniteNumber(naturalWidth) ||
+    !isPositiveFiniteNumber(naturalHeight)
+  ) {
+    return null;
+  }
+
+  const maxScale = Math.min(
+    bounds.maxWidth / naturalWidth,
+    bounds.maxHeight / naturalHeight
+  );
+  let scale = 1;
+
+  if (maxScale < 1) {
+    scale = maxScale;
+  } else if (
+    naturalWidth < bounds.minWidth ||
+    naturalHeight < bounds.minHeight
+  ) {
+    const minScale = Math.max(
+      bounds.minWidth / naturalWidth,
+      bounds.minHeight / naturalHeight
+    );
+    scale = Math.min(minScale, maxScale);
+  }
+
+  return {
+    width: Math.max(1, Math.round(naturalWidth * scale)),
+    height: Math.max(1, Math.round(naturalHeight * scale)),
+    scale,
+  };
+}
+
+function isPositiveFiniteNumber(value: number): boolean {
+  return Number.isFinite(value) && value > 0;
+}

web/src/embedded/chat/components/messages/user-message.tsx

@@ -13,6 +13,7 @@ import { cn } from '@/utils/cn';
 import { animate } from 'motion';
 import { FileAttachmentCard } from './file-attachment';
 import { AttachmentImage } from './attachment-image';
+import { imageThumbnailPreviewBounds } from './image-preview-size';
 import { LinkifiedText } from '../linkified-text';
 import { MaskedScrollArea } from '../masked-scrollarea';
 import { collectUserMessageContent, CopyButton, copyUserMessage } from './copy';
@@ -233,6 +234,7 @@ export const UserMessage = ({
                       sourcePath={image.fileRef?.path}
                       environmentId={image.fileRef?.environmentId ?? undefined}
                       className="h-24 shrink-0"
+                      previewBounds={imageThumbnailPreviewBounds}
                     />
                   ) : null
                 )}

web/tests/embedded/image-preview-size.test.ts

@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest';
+import {
+  fitImagePreviewSize,
+  imageThumbnailPreviewBounds,
+} from '../../src/embedded/chat/components/messages/image-preview-size';
+
+describe('fitImagePreviewSize', () => {
+  it('keeps images at their natural size when they are inside the preview bounds', () => {
+    expect(fitImagePreviewSize(400, 300)).toMatchObject({
+      width: 400,
+      height: 300,
+      scale: 1,
+    });
+  });
+
+  it('scales oversized images down to fit the maximum preview bounds', () => {
+    expect(fitImagePreviewSize(1436, 1240)).toMatchObject({
+      width: 602,
+      height: 520,
+    });
+  });
+
+  it('scales tiny images up to satisfy the minimum preview bounds', () => {
+    expect(fitImagePreviewSize(80, 60)).toMatchObject({
+      width: 160,
+      height: 120,
+    });
+  });
+
+  it('preserves aspect ratio and lets max bounds win for very tall images', () => {
+    expect(fitImagePreviewSize(300, 1200)).toMatchObject({
+      width: 130,
+      height: 520,
+    });
+  });
+
+  it('supports smaller thumbnail bounds for user-uploaded images', () => {
+    expect(
+      fitImagePreviewSize(1436, 1240, imageThumbnailPreviewBounds)
+    ).toMatchObject({
+      width: 111,
+      height: 96,
+    });
+  });
+});