fix(gateway): send ByteDance video ratio field

[steebchen]

Problem

Users reported that Seedance video jobs requesting a 9:16 (portrait) output were coming back as 16:9 (landscape) — the aspect ratio parameter was being ignored (e.g. task xpaVAmcv5CHAqtZFCLIC).

Root cause

ByteDance's Ark video generation API (/contents/generations/tasks, used by Seedance 2.0 / 2.0 Fast / 1.5 Pro) reads the aspect ratio from a top-level ratio field. We were sending it as aspect_ratio, which Ark silently ignores, defaulting the output to 16:9. So portrait sizes (720x1280, 1080x1920) never took effect.

Confirmed against the BytePlus ModelArk Seedance 2.0 API reference and multiple integration guides: the field is ratio, alongside the already-correct top-level resolution and duration fields.

Fix

• Rename the upstream request field aspect_ratio -> ratio in createBytedanceVideoJob.
• Keep the gateway's own response metadata aspect_ratio sourced from the same computed value (getBytedanceVideoAspectRatio), so no client-facing shape changes.

Tests

• Added a test asserting a portrait size (1080x1920) forwards ratio: "9:16" and resolution: "1080p" to the ByteDance mock.
• Extended the existing Seedance 2.0 test to assert ratio: "16:9" for landscape.
• Mock ByteDance endpoint now captures ratio/resolution.

Notes / out of scope

This PR only fixes the aspect-ratio bug that was explicitly requested. The other issues raised in the thread (15s duration support for Seedance 2.0 Fast, and the intermittent 401 on video downloads) are separate and not addressed here.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Corrected Bytedance Seedance job requests so the correct ratio metadata is sent and saved.
  • Portrait-size generations now yield the expected vertical ratio, resolution, and duration.
  • Frame-input flows now preserve ratio metadata in results.
• New Supported Options
  • Expanded Seedance-supported video durations to 4–15 seconds.
  • Seedance 2.0 Fast size support is now restricted to two portrait/landscape variants.
• Documentation
  • Updated the Video Generation model catalog, size/duration tables, and pricing details.
• Tests
  • Strengthened test coverage for Seedance ratio, resolution, and duration expectations.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 069e0b07-fab3-4c35-8e8f-0acb2f6e0d53

📥 Commits

Reviewing files that changed from the base of the PR and between 7e18065 and be0c467.

📒 Files selected for processing (4)

• apps/docs/content/features/video-generation.mdx
• apps/gateway/src/videos/videos.spec.ts
• apps/playground/src/lib/video-gen.ts
• packages/models/src/models/bytedance.ts

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Walkthrough

The ByteDance video job flow now sends ratio instead of aspect_ratio, stores ratio and resolution in the mock job state, and adds tests for portrait and frame-input cases. Seedance duration support was expanded to 4–15 seconds across playground types, model capability data, and docs.

Changes

ByteDance Ratio/Resolution Handling

Layer / File(s)	Summary
Upstream request and response ratio field apps/gateway/src/videos/videos.ts	createBytedanceVideoJob computes videoRatio, sends it as ratio in the upstream request, and uses the same value for response metadata.
Mock server ratio/resolution persistence apps/gateway/src/test-utils/mock-openai-server.ts	MockVideoJobState gains ratio, and mocked task creation stores ratio and resolution from the request body.
Tests validating ratio and resolution apps/gateway/src/videos/videos.spec.ts	The frame-input test asserts ratio is 16:9, and a new portrait-size test checks ratio 9:16, resolution 1080p, and duration 15.

Seedance Duration Support Expansion

Layer / File(s)	Summary
Duration contract and model registry apps/playground/src/lib/video-gen.ts, packages/models/src/models/bytedance.ts	VideoDuration and VIDEO_DURATIONS now cover 4 through 15, and Seedance 2.0 / 2.0 Fast capability data lists the same supported duration range.
Video generation docs update apps/docs/content/features/video-generation.mdx	The video-generation docs update Seedance model listings, split the duration table rows, and remove the old Seedance 2.0 Fast 1080p pricing row.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• theopenco/llmgateway#2270: Shares the same ByteDance job-construction path and upstream payload handling in apps/gateway/src/videos/videos.ts.
• theopenco/llmgateway#2538: Also modifies createBytedanceVideoJob and the ByteDance upstream content payload structure.
• theopenco/llmgateway#2768: Touches apps/playground/src/lib/video-gen.ts and the same duration set used by VideoDuration and VIDEO_DURATIONS.

Suggested reviewers: smakosh

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: sending ByteDance video ratio via the upstream request field.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/seedance-aspect-ratio

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[Copilot]

Pull request overview

Fixes ByteDance/Ark video generation aspect ratio handling by sending the upstream field ratio (instead of the ignored aspect_ratio) while keeping the gateway’s client-facing aspect_ratio metadata unchanged.

Changes:

• Update createBytedanceVideoJob to compute the aspect ratio once and send it upstream as ratio.
• Preserve response metadata shape by continuing to expose aspect_ratio derived from the same computed value.
• Extend mocks/tests to capture and assert forwarded ratio (and resolution) for both landscape and portrait Seedance requests.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
apps/gateway/src/videos/videos.ts	Sends ByteDance upstream ratio and keeps gateway aspect_ratio metadata stable.
apps/gateway/src/videos/videos.spec.ts	Adds assertions/tests verifying portrait/landscape sizes forward correct ratio/resolution to the ByteDance mock.
apps/gateway/src/test-utils/mock-openai-server.ts	Captures ratio (and resolution) in the ByteDance tasks mock for test assertions.

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