diff --git a/tests/e2e/pages/modules/flex-render.ts b/tests/e2e/pages/modules/flex-render.ts
index 6014797..5415d95 100644
--- a/tests/e2e/pages/modules/flex-render.ts
+++ b/tests/e2e/pages/modules/flex-render.ts
@@ -10,6 +10,7 @@ export class FlexRender {
   readonly inlineEmbed: Locator
   readonly inlineRuntime: Locator
   readonly ssrEmbed: Locator
+  readonly ssrHydrated: Locator
   readonly embed: (mode: DeliveryMode) => Locator
 
   constructor(readonly root: Page | FrameLocator) {
@@ -19,6 +20,9 @@ export class FlexRender {
       .locator('div[data-flex-inline] + script[src*="flex-client"]')
       .describe('flex inline runtime script')
     this.ssrEmbed = root.locator('div.ceros-block__flex-ssr').describe('flex server-rendered embed')
+    this.ssrHydrated = root
+      .locator('div.ceros-block__flex-ssr[data-flex-router-ready] > [data-flex-ready="true"]')
+      .describe('flex server-rendered embed, hydrated')
     this.embed = (mode: DeliveryMode) =>
       ({ iframe: this.iframeEmbed, inline: this.inlineEmbed, ssr: this.ssrEmbed })[mode]
   }
diff --git a/tests/e2e/pages/published-post.page.ts b/tests/e2e/pages/published-post.page.ts
index 00d7971..b315e69 100644
--- a/tests/e2e/pages/published-post.page.ts
+++ b/tests/e2e/pages/published-post.page.ts
@@ -1,11 +1,13 @@
 import type { Locator, Page } from '@playwright/test'
 import { WP_ROUTES } from '@constants/wordpress-constants'
 import { FlexRender } from '@pages/modules/flex-render'
+import type { ImportMap } from '@utils/ceros-embed'
 
 /** A published post on the front end — where the render cascade shows its work. */
 export class PublishedPostPage {
   readonly flex: FlexRender
   readonly iframeEmbed: Locator
+  readonly importMaps: Locator
   readonly missingExperience: Locator
   readonly missingExperienceHeading: Locator
 
@@ -14,6 +16,7 @@ export class PublishedPostPage {
     this.iframeEmbed = page
       .locator('div[data-ceros-experience], div[data-aspectRatio] iframe.ceros-experience')
       .describe('iframe embed marker')
+    this.importMaps = page.locator('script[type="importmap"]').describe('import map')
     this.missingExperience = page
       .locator('div.ceros-missing-experience')
       .describe('missing experience block')
@@ -25,4 +28,21 @@ export class PublishedPostPage {
   async open(postId: number): Promise<void> {
     await this.page.goto(WP_ROUTES.permalink(postId))
   }
+
+  async importMap(): Promise<ImportMap> {
+    return JSON.parse(String(await this.importMaps.first().textContent())) as ImportMap
+  }
+
+  /** The module scripts and module preloads that come before the import map. */
+  async modulesBeforeImportMap(): Promise<string[]> {
+    return this.page.evaluate(() => {
+      const map = document.querySelector('script[type="importmap"]')
+      if (!map) return ['no import map']
+      return Array.from(
+        document.querySelectorAll('script[type="module"], link[rel="modulepreload"]'),
+      )
+        .filter((m) => !(map.compareDocumentPosition(m) & Node.DOCUMENT_POSITION_FOLLOWING))
+        .map((m) => m.outerHTML)
+    })
+  }
 }
diff --git a/tests/e2e/tests/flex-ssr-import-map.spec.ts b/tests/e2e/tests/flex-ssr-import-map.spec.ts
new file mode 100644
index 0000000..a35cc21
--- /dev/null
+++ b/tests/e2e/tests/flex-ssr-import-map.spec.ts
@@ -0,0 +1,41 @@
+import { expect, test } from '@fixtures/fixtures'
+import { TIMEOUTS } from '@constants/timeouts'
+import { PublishedPostPage } from '@pages/published-post.page'
+import { resolvedFlexBlock } from '@utils/block-serializer'
+import { expectImportMapCarries, readManifestImportMap } from '@utils/ceros-embed'
+import { cerosFlexExperienceUrl, cerosFlexManifestUrl, experienceSlug } from '@utils/env-utils'
+import { TAGS } from '@utils/test-tags'
+
+const manifestUrl = cerosFlexManifestUrl()
+
+/** WordPress prints one import map for the page; the SSR runtime's imports join it. */
+test.describe('Flex SSR import map', { tag: [TAGS.cerosBlock, TAGS.rendered, TAGS.flex] }, () => {
+  // A real reader is anonymous; render the published page logged out.
+  test.use({ storageState: { cookies: [], origins: [] } })
+
+  test.use({
+    postOptions: {
+      title: 'flex ssr import map',
+      blocks: [resolvedFlexBlock(experienceSlug(cerosFlexExperienceUrl()), manifestUrl, 'ssr')],
+      status: 'publish',
+    },
+  })
+
+  test("the import map leads the modules and carries the experience's imports", async ({
+    page,
+    post,
+    request,
+  }) => {
+    const pageErrors: Error[] = []
+    page.on('pageerror', (error) => pageErrors.push(error))
+    const manifestMap = await readManifestImportMap(request, manifestUrl)
+
+    const publishedPost = new PublishedPostPage(page)
+    await publishedPost.open(post.id)
+
+    // The runtime loads from the Ceros CDN, slower on a cold edge after a deploy.
+    await expect(publishedPost.flex.ssrHydrated).toHaveCount(1, { timeout: TIMEOUTS.MEDIUM })
+    await expectImportMapCarries(publishedPost, manifestMap)
+    expect(pageErrors).toEqual([])
+  })
+})
diff --git a/tests/e2e/utils/ceros-embed.ts b/tests/e2e/utils/ceros-embed.ts
index 6d4ff8d..c965edc 100644
--- a/tests/e2e/utils/ceros-embed.ts
+++ b/tests/e2e/utils/ceros-embed.ts
@@ -1,5 +1,6 @@
-import { expect, type Locator } from '@playwright/test'
+import { expect, type APIRequestContext, type Locator } from '@playwright/test'
 import type { RequestUtils } from '@wordpress/e2e-test-utils-playwright'
+import type { PublishedPostPage } from '@pages/published-post.page'
 import { readStoredBlockAttributes } from '@utils/wp-rest-client'
 
 /** The two iframe embed sizes the block stores as `selectedOption`. */
@@ -8,6 +9,9 @@ export type EmbedSize = 'full' | 'scroll'
 /** How a Flex experience is delivered, stored as `deliveryMode`. */
 export type DeliveryMode = 'iframe' | 'inline' | 'ssr'
 
+/** A page or manifest import map. */
+export type ImportMap = { imports: Record<string, string>; integrity?: Record<string, string> }
+
 /** The wrapper every stored Studio embed code keeps, even after filtering strips its iframe and script. */
 const STUDIO_EMBED_WRAPPER = /data-aspectratio=/i
 
@@ -91,3 +95,34 @@ export async function expectStoredFlexAttributes(
   )
   expect(String(stored.inlineEmbedCode ?? '')).toContain(FLEX_INLINE_MARKER)
 }
+
+/**
+ * Read the import map from a Flex manifest. Fails when it has no imports or hashes,
+ * since checks against it would then prove nothing.
+ */
+export async function readManifestImportMap(
+  request: APIRequestContext,
+  manifestUrl: string,
+): Promise<ImportMap> {
+  const response = await request.get(manifestUrl)
+  await expect(response).toBeOK()
+  const { importMap } = (await response.json()) as { importMap?: ImportMap }
+  expect(Object.keys(importMap?.imports ?? {}), 'manifest import map entries').not.toEqual([])
+  expect(importMap?.integrity, 'manifest import map integrity').toBeTruthy()
+  return importMap as ImportMap
+}
+
+/** Assert the page prints one import map, ahead of every module, carrying the manifest's imports and hashes. */
+export async function expectImportMapCarries(
+  publishedPost: PublishedPostPage,
+  manifestMap: ImportMap,
+): Promise<void> {
+  await expect(publishedPost.importMaps).toHaveCount(1)
+  expect(await publishedPost.modulesBeforeImportMap()).toEqual([])
+  const map = await publishedPost.importMap()
+  const specifiers = Object.keys(manifestMap.imports)
+  expect(Object.keys(map.imports)).toEqual(expect.arrayContaining(specifiers))
+  for (const specifier of specifiers) {
+    expect(map.integrity?.[map.imports[specifier]], specifier).toBeTruthy()
+  }
+}