test(e2e): cover Gemini native image modelOptions on the wire

aimock's handleGemini has no image-response branch and its journal stores
a lossy OpenAI-shaped translation that drops safetySettings and
generationConfig, so neither fixtures nor /journal can see this path.
Mount the endpoint directly instead -- the same escape hatch
geminiTTSMount() already uses for the identical {model}:generateContent
inlineData shape -- and reject the request if the fields are absent, so a
dropped option fails the spec instead of passing silently.

Verified revert-proof: with packages/ai-gemini/src reverted to the parent
commit, the spec fails with "Missing top-level safetySettings".

Author: L4Ph

testing/e2e/global-setup.ts

@@ -55,6 +55,13 @@ export default async function globalSetup() {
     '/v1beta/models/gemini-3.1-flash-tts-preview:generateContent',
     geminiTTSMount(),
   )
+  // Gemini native image generation hits the same generateContent endpoint
+  // shape, one model id over — see geminiNativeImageMount for why it needs
+  // a hand-mocked response and a raw-body wire-shape check of its own.
+  mock.mount(
+    '/v1beta/models/gemini-2.5-flash-image:generateContent',
+    geminiNativeImageMount(),
+  )
   // Gemini Veo video generation. aimock 1.29 mocks Gemini's `:predict`
   // (Imagen) endpoint but not the long-running `:predictLongRunning` +
   // operations-polling pair Veo uses, so mount both here. Non-Veo paths
@@ -265,6 +272,183 @@ function geminiTTSMount(): Mountable {
   }
 }
 
+/**
+ * Gemini native image generation hits the standard Gemini generateContent
+ * endpoint too (POST /v1beta/models/{model}:generateContent) — the same
+ * shape geminiTTSMount above targets, just with `image/png` inlineData
+ * instead of PCM audio. aimock's native handleGemini recognizes only
+ * text / tool-call / text-with-tool-call / audio fixture response shapes:
+ * isImageResponse (helpers.js) is defined but never imported into
+ * gemini.js, so there is no image-response branch at all. A fixture shaped
+ * `{image}`/`{images}` matched against this endpoint falls through every
+ * isXResponse() check and hits the final fallback — a 500 "Fixture response
+ * did not match any known type." Native image generation needs a
+ * hand-mocked response for the same reason TTS does.
+ *
+ * There's a second, PR-specific reason this needs its own mount rather than
+ * a fixture even if one could match: aimock's request-journaling for this
+ * endpoint goes through geminiToCompletionRequest, which reshapes the raw
+ * Gemini request into an OpenAI-chat-shaped completionReq carrying only
+ * {model, messages, stream, temperature, max_tokens, top_p, top_k, tools} —
+ * it silently drops safetySettings, generationConfig.thinkingConfig, and
+ * generationConfig.imageConfig before anything is journaled. So GET /journal
+ * cannot show whether those fields reached the wire, even in principle.
+ * This mount reads the raw, untranslated body instead (see
+ * readJsonRequestBody, used the same way by the BytePlus mounts below) and
+ * validates it directly — the BytePlus mounts' house pattern of turning a
+ * dropped field into a failing spec rather than a silently green one.
+ *
+ * Mounted at the exact model+endpoint path (not the shared '/v1beta/models'
+ * prefix geminiVeoMount/geminiBatchEmbedMount use below) so it can never
+ * intercept an unrelated Gemini chat/text generateContent call for a
+ * different model.
+ *
+ * `/api/gemini-native-image-wire` (see that route) drives this with
+ * `modelOptions: { safetySettings, thinkingConfig }`. Reverting the
+ * ai-gemini fix that stops dropping modelOptions on the native image path
+ * removes both from the outgoing `nativeConfig`, so the request this mount
+ * receives is missing them, this mount answers 400, and the route surfaces
+ * that as `ok: false` — the companion spec's revert-detection mechanism.
+ */
+function geminiNativeImageMount(): Mountable {
+  // 1x1 transparent PNG — just enough for transformGeminiResponse's
+  // inlineData branch to produce a GeneratedImage. Mirrors FAKE_PCM_BYTES /
+  // FAKE_MP3_BYTES above: content fidelity isn't under test here.
+  const PNG_1X1_BASE64 =
+    'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNk+A8AAQUBAScY42YAAAAASUVORK5CYII='
+
+  // Field names that only belong on Imagen's GenerateImagesConfig, never on
+  // generateContent's GenerateContentConfig. The adapter's `nativeConfig`
+  // picks fields by name specifically so modelOptions carrying both shapes
+  // (or a future regression back to a wholesale `...modelOptions` spread)
+  // can't let one through — mirrors the field list documented on
+  // GeminiImageProviderOptions in image-provider-options.ts, minus `seed`
+  // (legitimately shared by both configs and always forwarded) and `labels`
+  // (also a real GenerateContentConfig field name, but the Gemini Developer
+  // API rejects it outright rather than letting it reach the wire, so it
+  // can't appear in a body this mount ever sees).
+  const IMAGEN_ONLY_FIELDS = [
+    'personGeneration',
+    'safetyFilterLevel',
+    'addWatermark',
+    'language',
+    'negativePrompt',
+    'outputMimeType',
+    'outputCompressionQuality',
+    'guidanceScale',
+    'enhancePrompt',
+    'includeSafetyAttributes',
+    'includeRaiReason',
+    'outputGcsUri',
+    // Imagen's own top-level `aspectRatio` (GenerateImagesConfig) is distinct
+    // from the native path's nested generationConfig.imageConfig.aspectRatio
+    // — its presence at either level here would mean the two configs got
+    // crossed.
+    'aspectRatio',
+  ]
+
+  return {
+    async handleRequest(
+      req: http.IncomingMessage,
+      res: http.ServerResponse,
+      // Exact-path mount — pathname is "/" for the one path this is
+      // registered on.
+      pathname: string,
+    ): Promise<boolean> {
+      if (pathname !== '/' || req.method !== 'POST') return false
+
+      const body = await readJsonRequestBody(req)
+      if (!body) {
+        return rejectGeminiImageRequest(res, 'Malformed JSON body.')
+      }
+      const generationConfig = asRecord(body.generationConfig)
+
+      const leaked = IMAGEN_ONLY_FIELDS.find(
+        (name) =>
+          name in body || (generationConfig && name in generationConfig),
+      )
+      if (leaked) {
+        return rejectGeminiImageRequest(
+          res,
+          `Imagen-only field "${leaked}" reached generateContent — GenerateImagesConfig and GenerateContentConfig got crossed.`,
+        )
+      }
+
+      if (
+        !Array.isArray(body.safetySettings) ||
+        body.safetySettings.length === 0
+      ) {
+        return rejectGeminiImageRequest(
+          res,
+          'Missing top-level safetySettings (modelOptions.safetySettings did not reach the wire).',
+        )
+      }
+      if (
+        !generationConfig ||
+        typeof generationConfig.thinkingConfig !== 'object' ||
+        generationConfig.thinkingConfig === null
+      ) {
+        return rejectGeminiImageRequest(
+          res,
+          'Missing generationConfig.thinkingConfig (modelOptions.thinkingConfig did not reach the wire).',
+        )
+      }
+
+      res.statusCode = 200
+      res.setHeader('Content-Type', 'application/json')
+      res.end(
+        JSON.stringify({
+          candidates: [
+            {
+              content: {
+                role: 'model',
+                parts: [
+                  {
+                    inlineData: {
+                      mimeType: 'image/png',
+                      data: PNG_1X1_BASE64,
+                    },
+                  },
+                ],
+              },
+              finishReason: 'STOP',
+              index: 0,
+            },
+          ],
+          usageMetadata: {
+            promptTokenCount: 8,
+            candidatesTokenCount: 1290,
+            totalTokenCount: 1298,
+          },
+        }),
+      )
+      return true
+    },
+  }
+}
+
+/**
+ * Rejects with Gemini's real MLDev error envelope shape
+ * (`{ error: { code, message, status } }`) — the same fallback shape
+ * @google/genai's own `throwErrorIfNotOK` builds for a non-JSON error body,
+ * so the thrown ApiError's `message` carries the actual validation failure
+ * (JSON.stringify'd) for debugging, the same way rejectArkRequest /
+ * rejectVoiceRequest do for BytePlus below.
+ */
+function rejectGeminiImageRequest(
+  res: http.ServerResponse,
+  message: string,
+): true {
+  res.statusCode = 400
+  res.setHeader('Content-Type', 'application/json')
+  res.end(
+    JSON.stringify({
+      error: { code: 400, message, status: 'INVALID_ARGUMENT' },
+    }),
+  )
+  return true
+}
+
 function grokSTTMount(): Mountable {
   return {
     async handleRequest(

testing/e2e/src/routeTree.gen.ts

@@ -59,6 +59,7 @@ import { Route as ApiInterruptsTestRouteImport } from './routes/api.interrupts-t
 import { Route as ApiImageRouteImport } from './routes/api.image'
 import { Route as ApiGenerationPersistenceServerRouteImport } from './routes/api.generation-persistence-server'
 import { Route as ApiGenerationPersistenceResumeRouteImport } from './routes/api.generation-persistence-resume'
+import { Route as ApiGeminiNativeImageWireRouteImport } from './routes/api.gemini-native-image-wire'
 import { Route as ApiForeignInterruptRouteImport } from './routes/api.foreign-interrupt'
 import { Route as ApiEmbeddingRouteImport } from './routes/api.embedding'
 import { Route as ApiDurableTakeoverRouteImport } from './routes/api.durable-takeover'
@@ -336,6 +337,12 @@ const ApiGenerationPersistenceResumeRoute =
     path: '/api/generation-persistence-resume',
     getParentRoute: () => rootRouteImport,
   } as any)
+const ApiGeminiNativeImageWireRoute =
+  ApiGeminiNativeImageWireRouteImport.update({
+    id: '/api/gemini-native-image-wire',
+    path: '/api/gemini-native-image-wire',
+    getParentRoute: () => rootRouteImport,
+  } as any)
 const ApiForeignInterruptRoute = ApiForeignInterruptRouteImport.update({
   id: '/api/foreign-interrupt',
   path: '/api/foreign-interrupt',
@@ -453,6 +460,7 @@ export interface FileRoutesByFullPath {
   '/api/durable-takeover': typeof ApiDurableTakeoverRoute
   '/api/embedding': typeof ApiEmbeddingRoute
   '/api/foreign-interrupt': typeof ApiForeignInterruptRoute
+  '/api/gemini-native-image-wire': typeof ApiGeminiNativeImageWireRoute
   '/api/generation-persistence-resume': typeof ApiGenerationPersistenceResumeRoute
   '/api/generation-persistence-server': typeof ApiGenerationPersistenceServerRoute
   '/api/image': typeof ApiImageRouteWithChildren
@@ -522,6 +530,7 @@ export interface FileRoutesByTo {
   '/api/durable-takeover': typeof ApiDurableTakeoverRoute
   '/api/embedding': typeof ApiEmbeddingRoute
   '/api/foreign-interrupt': typeof ApiForeignInterruptRoute
+  '/api/gemini-native-image-wire': typeof ApiGeminiNativeImageWireRoute
   '/api/generation-persistence-resume': typeof ApiGenerationPersistenceResumeRoute
   '/api/generation-persistence-server': typeof ApiGenerationPersistenceServerRoute
   '/api/image': typeof ApiImageRouteWithChildren
@@ -592,6 +601,7 @@ export interface FileRoutesById {
   '/api/durable-takeover': typeof ApiDurableTakeoverRoute
   '/api/embedding': typeof ApiEmbeddingRoute
   '/api/foreign-interrupt': typeof ApiForeignInterruptRoute
+  '/api/gemini-native-image-wire': typeof ApiGeminiNativeImageWireRoute
   '/api/generation-persistence-resume': typeof ApiGenerationPersistenceResumeRoute
   '/api/generation-persistence-server': typeof ApiGenerationPersistenceServerRoute
   '/api/image': typeof ApiImageRouteWithChildren
@@ -663,6 +673,7 @@ export interface FileRouteTypes {
     | '/api/durable-takeover'
     | '/api/embedding'
     | '/api/foreign-interrupt'
+    | '/api/gemini-native-image-wire'
     | '/api/generation-persistence-resume'
     | '/api/generation-persistence-server'
     | '/api/image'
@@ -732,6 +743,7 @@ export interface FileRouteTypes {
     | '/api/durable-takeover'
     | '/api/embedding'
     | '/api/foreign-interrupt'
+    | '/api/gemini-native-image-wire'
     | '/api/generation-persistence-resume'
     | '/api/generation-persistence-server'
     | '/api/image'
@@ -801,6 +813,7 @@ export interface FileRouteTypes {
     | '/api/durable-takeover'
     | '/api/embedding'
     | '/api/foreign-interrupt'
+    | '/api/gemini-native-image-wire'
     | '/api/generation-persistence-resume'
     | '/api/generation-persistence-server'
     | '/api/image'
@@ -871,6 +884,7 @@ export interface RootRouteChildren {
   ApiDurableTakeoverRoute: typeof ApiDurableTakeoverRoute
   ApiEmbeddingRoute: typeof ApiEmbeddingRoute
   ApiForeignInterruptRoute: typeof ApiForeignInterruptRoute
+  ApiGeminiNativeImageWireRoute: typeof ApiGeminiNativeImageWireRoute
   ApiGenerationPersistenceResumeRoute: typeof ApiGenerationPersistenceResumeRoute
   ApiGenerationPersistenceServerRoute: typeof ApiGenerationPersistenceServerRoute
   ApiImageRoute: typeof ApiImageRouteWithChildren
@@ -1258,6 +1272,13 @@ declare module '@tanstack/react-router' {
       preLoaderRoute: typeof ApiGenerationPersistenceResumeRouteImport
       parentRoute: typeof rootRouteImport
     }
+    '/api/gemini-native-image-wire': {
+      id: '/api/gemini-native-image-wire'
+      path: '/api/gemini-native-image-wire'
+      fullPath: '/api/gemini-native-image-wire'
+      preLoaderRoute: typeof ApiGeminiNativeImageWireRouteImport
+      parentRoute: typeof rootRouteImport
+    }
     '/api/foreign-interrupt': {
       id: '/api/foreign-interrupt'
       path: '/api/foreign-interrupt'
@@ -1468,6 +1489,7 @@ const rootRouteChildren: RootRouteChildren = {
   ApiDurableTakeoverRoute: ApiDurableTakeoverRoute,
   ApiEmbeddingRoute: ApiEmbeddingRoute,
   ApiForeignInterruptRoute: ApiForeignInterruptRoute,
+  ApiGeminiNativeImageWireRoute: ApiGeminiNativeImageWireRoute,
   ApiGenerationPersistenceResumeRoute: ApiGenerationPersistenceResumeRoute,
   ApiGenerationPersistenceServerRoute: ApiGenerationPersistenceServerRoute,
   ApiImageRoute: ApiImageRouteWithChildren,

testing/e2e/src/routes/api.gemini-native-image-wire.ts

@@ -0,0 +1,71 @@
+import { createFileRoute } from '@tanstack/react-router'
+import { generateImage } from '@tanstack/ai'
+import { createImageAdapter } from '@/lib/media-providers'
+
+/**
+ * Wire-format verification for Gemini-native `modelOptions` on the image
+ * generation path (fix/gemini-native-image-model-options).
+ *
+ * Before that fix, `GeminiImageAdapter`'s `generateWithGeminiApi` only ever
+ * forwarded `modelOptions.seed` into the `generateContent` request —
+ * `safetySettings`, `thinkingConfig`, `imageConfig`, and `systemInstruction`
+ * were silently dropped even though the adapter's provider-options type
+ * (`GeminiNativeImageProviderOptions`) already declared them. This route
+ * drives `generateImage()` against `gemini-2.5-flash-image` with
+ * `modelOptions: { safetySettings, thinkingConfig }` set, hitting
+ * `geminiNativeImageMount` in global-setup.ts — a hand-mocked
+ * `POST /v1beta/models/gemini-2.5-flash-image:generateContent` endpoint that
+ * reads the raw, untranslated request body (aimock's own journal cannot see
+ * these fields for this endpoint — see that mount's comment) and rejects
+ * with 400 unless `safetySettings` is present at the request root and
+ * `generationConfig.thinkingConfig` is present nested, and rejects unless no
+ * Imagen-only field (`personGeneration`, `negativePrompt`, a root-level
+ * `aspectRatio`, …) is present anywhere in the body.
+ *
+ * A regression that stops forwarding `modelOptions` on this path — reverting
+ * to only `seed`, or reverting to a wholesale `...modelOptions` spread that
+ * lets an Imagen field cross over — makes the mount reject the request, the
+ * adapter's `client.models.generateContent()` call throws, and this route
+ * returns `ok: false`. The companion spec asserts `ok: true`.
+ */
+export const Route = createFileRoute('/api/gemini-native-image-wire')({
+  server: {
+    handlers: {
+      POST: async () => {
+        const adapter = createImageAdapter('gemini')
+
+        try {
+          const result = await generateImage({
+            adapter,
+            prompt: 'a guitar in a music store',
+            stream: false,
+            modelOptions: {
+              safetySettings: [
+                {
+                  category: 'HARM_CATEGORY_DANGEROUS_CONTENT',
+                  threshold: 'BLOCK_ONLY_HIGH',
+                },
+              ],
+              thinkingConfig: { thinkingBudget: 128 },
+            },
+          })
+          return new Response(
+            JSON.stringify({ ok: true, images: result.images.length }),
+            {
+              status: 200,
+              headers: { 'Content-Type': 'application/json' },
+            },
+          )
+        } catch (error) {
+          return new Response(
+            JSON.stringify({
+              ok: false,
+              error: error instanceof Error ? error.message : String(error),
+            }),
+            { status: 200, headers: { 'Content-Type': 'application/json' } },
+          )
+        }
+      },
+    },
+  },
+})