fix(app): preserve normalized image URLs in the lightbox

Use the decoder URL spelling when tracking image dimensions so mixed-case hosts still initialize the viewport. Keep the source check against queued loads and wait for refreshed image fitting before asserting geometry.

packages/app/e2e/browser/agent-tab-image-stability.spec.ts

@@ -146,6 +146,36 @@ test("opens a timeline image in a zoomable lightbox", async ({
   await expectAgentReadyToInterrupt(page);
 });
 
+test("opens a remote Markdown image whose URL needs normalization", async ({
+  imageWorkspace: workspace,
+  page,
+}) => {
+  const image = await createSmallAssistantPng(workspace, {
+    alt: "Remote image with a mixed-case host",
+    fileName: "remote.png",
+    width: 240,
+    height: 160,
+  });
+  const delivery = await serveDelayedImage(path.join(workspace.repoPath, image.relativePath));
+  const url = delivery.url.replace("127.0.0.1", "LOCALHOST");
+  try {
+    delivery.release();
+    const agent = await createSettledMockAgent(workspace, "Remote image lightbox");
+    await emitSettledAssistantImage(workspace.client, agent, image, url);
+    await openAssistantImageTimeline(page, agent);
+    const rendered = page.getByRole("button", { name: image.alt }).first();
+    await expect(rendered).toHaveJSProperty("naturalWidth", image.width);
+    await rendered.click();
+    await expect(page.getByTestId("attachment-lightbox-canvas")).toBeVisible();
+    await page.getByTestId("zoomable-viewport-toolbar").hover();
+    await page.getByRole("button", { name: "Zoom in", exact: true }).click();
+    await page.getByRole("button", { name: "Close image", exact: true }).click();
+    await expect(page.getByTestId("attachment-lightbox-image")).toHaveCount(0);
+  } finally {
+    await delivery.close();
+  }
+});
+
 test("reloading a timeline reserves image height without a load-time scroll jump", async ({
   imageWorkspace: workspace,
   page,

packages/app/e2e/browser/file-editing.spec.ts

@@ -38,6 +38,15 @@ function editor(page: Page) {
   return page.getByTestId("file-source-editor").filter({ visible: true }).locator(".cm-content");
 }
 
+async function expectTallImageFrame(frame: Locator): Promise<void> {
+  await expect
+    .poll(async () => {
+      const box = await frame.boundingBox();
+      return box ? box.height - box.width : 0;
+    })
+    .toBeGreaterThan(0);
+}
+
 function hasHorizontalOverflow(element: HTMLElement): boolean {
   return element.scrollWidth > element.clientWidth;
 }
@@ -806,8 +815,7 @@ test.describe("CodeMirror workspace file editing", () => {
       await pendingLoad.release();
     }
     await expect(imageCanvas).toBeVisible();
-    const tallFrame = await transformedContent.boundingBox();
-    expect(tallFrame!.height).toBeGreaterThan(tallFrame!.width);
+    await expectTallImageFrame(transformedContent);
   });
 
   test("renders local relative images inside Markdown preview", async ({ page, withWorkspace }) => {

packages/app/src/components/zoomable-viewport/image.tsx

@@ -37,14 +37,16 @@ export function ZoomableImage({
   testID = "zoomable-image",
   wheelActivation = "always",
 }: ZoomableImageProps) {
+  const source = useMemo(() => ({ uri: normalizeImageUri(uri) }), [uri]);
   const [loadedImage, setLoadedImage] = useState<{ uri: string; size: ViewportSize } | null>(null);
-  const resolvedSize = contentSize ?? (loadedImage?.uri === uri ? loadedImage.size : null);
-  const source = useMemo(() => ({ uri }), [uri]);
+  const resolvedSize = contentSize ?? (loadedImage?.uri === source.uri ? loadedImage.size : null);
   const handleLoad = useCallback(
     ({ source: { url, width, height } }: ImageLoadEventData) => {
-      if (url === uri && width > 0 && height > 0) setLoadedImage({ uri, size: { width, height } });
+      if (url === source.uri && width > 0 && height > 0) {
+        setLoadedImage({ uri: source.uri, size: { width, height } });
+      }
     },
-    [uri],
+    [source.uri],
   );
 
   if (!resolvedSize) {
@@ -88,6 +90,15 @@ export function ZoomableImage({
   );
 }
 
+// Use the same URL spelling as the decoder while preserving opaque native URIs.
+function normalizeImageUri(uri: string): string {
+  try {
+    return new URL(uri).href;
+  } catch {
+    return uri;
+  }
+}
+
 const styles = StyleSheet.create(() => ({
   root: { flex: 1, minHeight: 0 },
   image: { width: "100%", height: "100%" },