diff --git a/apps/web/e2e/media-pipeline.spec.ts b/apps/web/e2e/media-pipeline.spec.ts
index dc712cc..eb63fe8 100644
--- a/apps/web/e2e/media-pipeline.spec.ts
+++ b/apps/web/e2e/media-pipeline.spec.ts
@@ -54,10 +54,13 @@ test("an uploaded video streams from the artifact route and plays inline", async
   await captureScreenshot(page, testInfo, "media-video-block");
 });
 
-test("the image lightbox downloads the original from the artifact route", async ({ page }) => {
+test("an image in the main conversation opens and downloads from the artifact route", async ({
+  page,
+}) => {
   const stamp = Date.now();
   await signup(page, `media-image-${stamp}@rakazo.test`, "password12", "Media Image");
-  await completeOnboarding(page);
+  // The main conversation is a group thread, so this covers group uploads and reads.
+  await completeOnboarding(page, undefined, { mainConversation: true });
 
   await page
     .locator('input[type="file"]')
@@ -65,7 +68,7 @@ test("the image lightbox downloads the original from the artifact route", async
   await page.getByRole("combobox", { name: /Message/ }).fill("a pixel");
   await page.keyboard.press("Enter");
 
-  const thumbnail = page.getByRole("img", { name: "pixel.png" });
+  const thumbnail = page.getByTestId("transcript").getByRole("img", { name: "pixel.png" });
   await expect(thumbnail).toBeVisible({ timeout: 30_000 });
   await expect(thumbnail).toHaveAttribute("src", /^\/api\/artifacts\/[^/?]+$/);
   await thumbnail.click();
diff --git a/packages/adapters/src/artifact-files.ts b/packages/adapters/src/artifact-files.ts
index ad88094..b228bf1 100644
--- a/packages/adapters/src/artifact-files.ts
+++ b/packages/adapters/src/artifact-files.ts
@@ -47,6 +47,7 @@ export async function storeArtifactStream(
       stream: ArtifactStreamPut["stream"];
       maxBytes?: number;
       signal?: AbortSignal;
+      operationId?: string;
     },
 ) {
   validateAttachmentMimeType(input.mimeType);
@@ -54,7 +55,8 @@ export async function storeArtifactStream(
     input.maxBytes ?? Number.POSITIVE_INFINITY,
     artifactMaxBytes(input.mimeType),
   );
-  const operationId = `artifact-store:${input.runId ?? input.botId ?? input.userId}`;
+  const operationId =
+    input.operationId ?? `artifact-store:${input.runId ?? input.botId ?? input.userId}`;
   const context: AdapterContext = {
     operationId,
     traceId: operationId,
diff --git a/packages/adapters/src/thread-artifacts.ts b/packages/adapters/src/thread-artifacts.ts
index 8d82aef..f6630bd 100644
--- a/packages/adapters/src/thread-artifacts.ts
+++ b/packages/adapters/src/thread-artifacts.ts
@@ -37,7 +37,7 @@ const ATTACHMENT_BLOCK_KINDS: ReadonlySet<string> = new Set(["image", "video", "
 export function attachableFileMaxBytes(artifacts: ArtifactStore, mimeType: string): number {
   return artifacts.describe().capabilities.stream
     ? artifactMaxBytes(mimeType)
-    : Math.min(ATTACHMENT_MAX_BYTES, artifactMaxBytes(mimeType));
+    : ATTACHMENT_MAX_BYTES;
 }
 
 export function formatMiB(bytes: number): string {
@@ -82,6 +82,7 @@ export async function attachWorkspaceFileToThread(
       yield bytes;
     })(),
     maxBytes,
+    operationId: input.operationId,
   });
   return { artifactId: row.id, block: messageBlockForArtifact(row) };
 }