feat(ai-gemini): add Google Veo video adapter on the typed-duration contract (#634)

Builds the Veo adapter directly on the per-model typed-duration VideoAdapter
contract from #534:

- Uncomment + finalize the five Veo model entries in model-meta.ts and add
  a GEMINI_VIDEO_MODELS union.
- Add video/video-provider-options.ts with GeminiVideoModelDurationByName,
  GeminiVideoModelSizeByName, and a docs-curated GEMINI_VIDEO_DURATIONS map
  (the ai-schemas Gemini spec types :predictLongRunning parameters as
  unknown, so it carries no per-model duration data).
- Implement GeminiVideoAdapter over @google/genai generateVideos /
  getVideosOperation with availableDurations/snapDuration overrides, RAI
  filter surfacing, and geminiVideo/createGeminiVideo factories.
- Wire gemini into the video-gen E2E feature matrix with a Veo
  predictLongRunning + operations mount in global-setup.
- Update video-generation docs and the media-generation skill.
- Fix pre-existing no-unnecessary-type-assertion lint errors in the base
  branch's snap.ts / fal video.ts so the stacked PR gate is green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: tombeckenham

.changeset/gemini-veo-video-adapter.md

@@ -0,0 +1,29 @@
+---
+'@tanstack/ai-gemini': minor
+---
+
+Add a Google Veo video adapter (`geminiVideo` / `createGeminiVideo`), built
+on the per-model typed-duration contract (#534).
+
+Supported models: `veo-3.1-generate-preview`, `veo-3.1-fast-generate-preview`,
+`veo-3.0-generate-001`, `veo-3.0-fast-generate-001`, `veo-2.0-generate-001`.
+
+The adapter drives Google's long-running `:predictLongRunning` operation:
+`createVideoJob` starts the operation, `getVideoStatus` polls it (mapping
+`done`/`error`/Responsible-AI filtering), and `getVideoUrl` extracts the
+generated video URI.
+
+Durations are typed per model at compile time and introspectable at runtime:
+
+- `geminiVideo('veo-3.0-generate-001')` → `duration?: 4 | 6 | 8`
+- `geminiVideo('veo-2.0-generate-001')` → `duration?: 5 | 6 | 8`
+- `adapter.availableDurations()` → `{ kind: 'discrete', values: [4, 6, 8] }`
+- `adapter.snapDuration(7)` → `6`
+
+`size` takes Veo aspect ratios (`'16:9' | '9:16'`); everything else from the
+SDK's `GenerateVideosConfig` (e.g. `resolution`, `generateAudio`,
+`negativePrompt`) is available through `modelOptions`.
+
+Note: Veo result URLs are served by the Gemini Files API and require the
+Google API key to download (`x-goog-api-key` header or `key` query
+parameter).

docs/media/video-generation.md

@@ -2,11 +2,13 @@
 title: Video Generation
 id: video-generation
 order: 6
-description: "Generate video from text prompts with OpenAI Sora using TanStack AI's experimental generateVideo() jobs/polling API."
+description: "Generate video from text prompts with OpenAI Sora or Google Veo using TanStack AI's experimental generateVideo() jobs/polling API."
 keywords:
   - tanstack ai
   - video generation
   - sora
+  - veo
+  - gemini
   - generateVideo
   - jobs api
   - experimental
@@ -36,6 +38,7 @@ TanStack AI provides experimental support for video generation through dedicated
 
 Currently supported:
 - **OpenAI**: Sora-2 and Sora-2-Pro models (when available)
+- **Google Gemini**: Veo 3.1, Veo 3, and Veo 2 models (via the long-running operations API)
 
 ## Basic Usage
 
@@ -412,6 +415,63 @@ const { jobId } = await generateVideo({
 })
 ```
 
+### Google Veo (Gemini) Model Options
+
+Veo runs on Google's long-running operations API. The adapter starts the
+operation, and `getVideoJobStatus` polls it until the video is ready:
+
+```typescript
+import { generateVideo, getVideoJobStatus } from '@tanstack/ai'
+import { geminiVideo } from '@tanstack/ai-gemini'
+
+const adapter = geminiVideo('veo-3.1-generate-preview')
+
+const { jobId } = await generateVideo({
+  adapter,
+  prompt: 'A close-up of a luthier carving a guitar neck',
+  size: '16:9', // aspect ratio: '16:9' or '9:16'
+  duration: 8, // typed per model — see below
+  modelOptions: {
+    resolution: '1080p', // '720p' (default), '1080p', '4k' (Veo 3.1 only)
+    negativePrompt: 'cartoon, low quality',
+    generateAudio: true, // Veo 3+ generates synchronized audio
+  },
+})
+```
+
+#### Typed durations
+
+Each Veo model accepts a fixed set of durations, enforced at compile time on
+the `duration` option:
+
+| Model | `duration` values (seconds) |
+|-------|------------------------------|
+| `veo-3.1-generate-preview` | `4`, `6`, `8` |
+| `veo-3.1-fast-generate-preview` | `4`, `6`, `8` |
+| `veo-3.0-generate-001` | `4`, `6`, `8` |
+| `veo-3.0-fast-generate-001` | `4`, `6`, `8` |
+| `veo-2.0-generate-001` | `5`, `6`, `8` |
+
+If you have raw seconds (for example from a UI slider), coerce them with
+`snapDuration`, or inspect the full set with `availableDurations`:
+
+```typescript
+const adapter = geminiVideo('veo-3.0-generate-001')
+
+adapter.availableDurations() // { kind: 'discrete', values: [4, 6, 8] }
+adapter.snapDuration(7) // 6 — closest valid duration
+
+await generateVideo({
+  adapter,
+  prompt: 'A timelapse of a city skyline at dusk',
+  duration: adapter.snapDuration(7),
+})
+```
+
+> **Note:** The video URL returned for Veo jobs is served by the Gemini
+> Files API and requires your API key to download (send it as an
+> `x-goog-api-key` header or `key` query parameter).
+
 ## Response Types
 
 ### VideoJobResult (from create)
@@ -497,9 +557,11 @@ Check the [OpenAI documentation](https://platform.openai.com/docs) for current l
 
 ## Environment Variables
 
-The video adapter uses the same environment variable as other OpenAI adapters:
+The video adapters use the same environment variables as the other adapters
+for their provider:
 
-- `OPENAI_API_KEY`: Your OpenAI API key
+- `OPENAI_API_KEY`: Your OpenAI API key (Sora)
+- `GOOGLE_API_KEY` or `GEMINI_API_KEY`: Your Google API key (Veo)
 
 ## Explicit API Keys
 

packages/typescript/ai-fal/src/adapters/video.ts

@@ -139,9 +139,7 @@ export class FalVideoAdapter<TModel extends FalModel> extends BaseVideoAdapter<
   override snapDuration(
     seconds: number,
   ): FalModelVideoDuration<TModel> | undefined {
-    return snapToDurationOption(seconds, this.availableDurations()) as
-      | FalModelVideoDuration<TModel>
-      | undefined
+    return snapToDurationOption(seconds, this.availableDurations())
   }
 
   async getVideoStatus(jobId: string): Promise<VideoStatusResult> {