feat(examples): OpenRouter video in ts-react-media + fix generateVideo typed-duration constraint

ts-react-media now demos openRouterVideo alongside fal:
- add @tanstack/ai-openrouter dep
- Seedance 2.0 (text-to-video) and Veo 3.1 (image-to-video) model entries
- switch cases showcasing adapter.snapDuration() to coerce raw UI seconds to
  the model's nearest supported duration (Seedance 7→7, Veo 3.1 7→6)
- videoAdapterForModel() resolver routes the poll/status path to the right
  adapter (the helpers were hardcoded to falVideo)

Building the example surfaced a pre-existing bug in the #624 typed-duration
contract: generateVideo()'s `TAdapter extends VideoAdapter<string, any, any,
any>` bound let the sixth (duration) generic fall back to its
`Record<string, number>` default. Because VideoAdapter.createVideoJob is a
contravariant function-valued property, no adapter whose `duration` is a
per-model literal union (Veo `4|6|8`, Seedance `4..15`) satisfied the bound —
so even the documented `generateVideo({ adapter: geminiVideo('veo-3.1-...') })`
failed to type-check. Widen the bound to leave size/duration unpinned at all 10
activity sites; per-model types are still recovered via inference
(VideoSizeForAdapter / VideoDurationForAdapter). Adds a compile-only regression
test and an @tanstack/ai changeset.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: tombeckenham

.changeset/video-adapter-duration-constraint.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/ai': patch
+---
+
+Fix `generateVideo()` (and the other `generateVideo` activity entry points) rejecting video adapters that declare per-model typed durations. The activity's `TAdapter extends VideoAdapter<string, any, any, any>` bound let the sixth `TModelDurationByName` generic fall back to its `Record<string, number>` default; because `createVideoJob` is a contravariant function-valued property, a concrete adapter whose `duration` is narrowed to a literal union (e.g. Veo's `4 | 6 | 8`, OpenRouter Seedance's `4..15`) failed the bound, so the documented `generateVideo({ adapter: geminiVideo('veo-3.1-generate-preview'), ... })` pattern did not type-check. The constraint now leaves the size and duration generics unpinned (`VideoAdapter<string, any, any, any, any, any>`); the real per-model types are still recovered by inference (`VideoSizeForAdapter` / `VideoDurationForAdapter`).

examples/ts-react-media/package.json

@@ -16,6 +16,7 @@
     "@tanstack/ai-fal": "workspace:*",
     "@tanstack/ai-gemini": "workspace:*",
     "@tanstack/ai-grok": "workspace:*",
+    "@tanstack/ai-openrouter": "workspace:*",
     "@tanstack/ai-react": "workspace:*",
     "@tanstack/react-router": "^1.158.4",
     "@tanstack/react-start": "^1.159.0",

examples/ts-react-media/src/lib/models.ts

@@ -195,6 +195,20 @@ export const VIDEO_MODELS = [
     mode: 'text-to-video' as const,
     provider: 'byteplus' as const,
   },
+  {
+    id: 'bytedance/seedance-2.0',
+    name: 'Seedance 2.0 (Text-to-Video, OpenRouter)',
+    description:
+      "OpenRouter's async video API; duration typed 4–15s with snapDuration()",
+    mode: 'text-to-video' as const,
+  },
+  {
+    id: 'google/veo-3.1',
+    name: 'Veo 3.1 (Image-to-Video, OpenRouter)',
+    description:
+      'OpenRouter async video; duration snaps to the nearest of 4/6/8s',
+    mode: 'image-to-video' as const,
+  },
 ] as const
 
 export type ImageModel = (typeof IMAGE_MODELS)[number]

examples/ts-react-media/src/lib/server-functions.ts

@@ -2,6 +2,7 @@ import { createServerFn } from '@tanstack/react-start'
 import { falImage, falVideo } from '@tanstack/ai-fal'
 import { geminiImage, geminiVideo } from '@tanstack/ai-gemini'
 import { grokImage, grokVideo } from '@tanstack/ai-grok'
+import { openRouterVideo } from '@tanstack/ai-openrouter'
 import {
   BYTEPLUS_VIDEO_MODELS,
   byteplusImage,
@@ -461,6 +462,34 @@ function videoStreamForModel(data: VideoRequest): AsyncIterable<StreamChunk> {
           : {}),
       })
     }
+    // OpenRouter's dedicated async video API (`POST /api/v1/videos`). Unlike
+    // fal (which takes duration in `modelOptions`), OpenRouter types the
+    // top-level `duration` per model from its published metadata, and the
+    // adapter exposes `snapDuration()` to coerce a raw UI seconds value to
+    // the model's nearest supported duration.
+    case 'bytedance/seedance-2.0': {
+      const adapter = openRouterVideo('bytedance/seedance-2.0')
+      return generateVideo({
+        stream: true,
+        pollingInterval: VIDEO_POLL_INTERVAL_MS,
+        adapter,
+        prompt: asTextPrompt(data.prompt),
+        size: '1280x720',
+        duration: adapter.snapDuration(7),
+        modelOptions: { aspectRatio: '16:9' },
+      })
+    }
+    case 'google/veo-3.1': {
+      const adapter = openRouterVideo('google/veo-3.1')
+      return generateVideo({
+        stream: true,
+        pollingInterval: VIDEO_POLL_INTERVAL_MS,
+        adapter,
+        prompt: asImageToVideoPrompt(data.prompt),
+        size: '1280x720',
+        duration: adapter.snapDuration(7),
+      })
+    }
     default:
       throw new Error(`Unknown video model: ${data.model}`)
   }

packages/ai-openrouter/tests/video-per-model-type-safety.test.ts

@@ -0,0 +1,45 @@
+/**
+ * Per-model type-safety for OpenRouter video durations.
+ *
+ * Asserts the typed-duration contract flows through `generateVideo()`: a
+ * concrete per-model adapter satisfies the activity's `TAdapter extends
+ * VideoAdapter<...>` bound, `duration` is narrowed to the model's union, and
+ * out-of-range literals are rejected.
+ *
+ * Regression guard: `createVideoJob` is a contravariant function-valued
+ * property, so if the activity constraints pin the duration generic to its
+ * default (`Record<string, number>`) instead of `any`, no per-model adapter
+ * can be passed to `generateVideo` at all. The checks below are compile-only —
+ * the inner closures are typechecked but never invoked (no network).
+ */
+import { describe, it } from 'vitest'
+import { generateVideo } from '@tanstack/ai'
+import { openRouterVideo } from '../src'
+
+describe('OpenRouter video duration type-safety', () => {
+  it('generateVideo accepts a concrete adapter + snapDuration()', () => {
+    const check = () => {
+      const adapter = openRouterVideo('bytedance/seedance-2.0') // 4..15
+      return generateVideo({
+        adapter,
+        prompt: 'A timelapse of clouds',
+        size: '1280x720',
+        duration: adapter.snapDuration(7),
+      })
+    }
+    void check
+  })
+
+  it('narrows duration to the model union (rejects out-of-range)', () => {
+    const check = () => {
+      const adapter = openRouterVideo('google/veo-3.1') // 4 | 6 | 8
+      return generateVideo({
+        adapter,
+        prompt: 'A close-up of a luthier carving a guitar neck',
+        // @ts-expect-error 7 is not a valid veo-3.1 duration (4 | 6 | 8)
+        duration: 7,
+      })
+    }
+    void check
+  })
+})