Is Hy4 preview available on FastMetal?

Not at the moment. Hy3, from the same lab, is available on the FastMetal API today.

What is the context window of Hy4 preview?

1,048,576 tokens, shared between the prompt and the response.

How does Hy4 preview rank?

#18 on the public arena's Overall board (ELO 1,632). Ranks move as the leaderboard is updated.

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Tencent

tencent/hy4-preview

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Hy4 preview

Tencent: Hy4 preview is a mixture-of-experts model from Tencent, with 49B active parameters out of 770B total. It is designed for coding agents, complex tool-use workflows, and productivity tasks that...

8/28/2026

1,048,576 tokens

#18 Code (Overall)

Specifications

Modalities

Input

text

Output

text

Supported Parameters

include_reasoning

max_completion_tokens

max_tokens

reasoning

reasoning_effort

response_format

stop

structured_outputs

temperature

tool_choice

tools

Max Output Tokens

64,000

Reasoning Configuration

Default: Thinking on (effort: high)
Selectable effort levels: high
low
none
Turning thinking off: Possible (reasoning.enabled: false)

How to control thinking, and what it costs

Data policy

Prompt retention: Unknown — we could not confirm
Training: Unknown — not declared

"Unknown" does not mean "safe". It means we could not confirm it.

Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.

Frequently asked questions

Is Hy4 preview available on FastMetal?: Not at the moment. Hy3, from the same lab, is available on the FastMetal API today.
What is the context window of Hy4 preview?: 1,048,576 tokens, shared between the prompt and the response.
How does Hy4 preview rank?: #18 on the public arena's Overall board (ELO 1,632). Ranks move as the leaderboard is updated.

Leaderboard

Code

OverallELO: 1,632

#18

Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-08; category names mapped and ratings rounded by FastMetal.

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