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feat: Support StepFun (step-3.5-flash) via OpenRouter #778

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feat: Support StepFun (step-3.5-flash) via OpenRouter #778

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30 changes: 30 additions & 0 deletions providers/openrouter/models/stepfun/step-3.5-flash.toml
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name = "StepFun: Step 3.5 Flash"
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@cantalupo555 cantalupo555 Feb 6, 2026

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To maintain the project standard, you should rename it to:

Suggested change
name = "StepFun: Step 3.5 Flash"
name = "Step 3.5 Flash"

family = "step"
release_date = "2026-01-29"
last_updated = "2026-01-29"
attachment = true
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@cantalupo555 cantalupo555 Feb 6, 2026 •
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The OpenRouter page for this model shows input_modalities: ["text"] only — no image support. This should be:

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attachment = true
attachment = false

reasoning = true
temperature = true
knowledge = "2025-01"
tool_call = true
structured_output = true
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@cantalupo555 cantalupo555 Feb 6, 2026

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No evidence in OpenRouter — the page does not mention structured output

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structured_output = true

open_weights = true

[cost]
input = 0.50
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@mporracindie mporracindie Feb 2, 2026

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Might be wrong, the exact numbers are not yet advertised in OpenRouter

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@cantalupo555 cantalupo555 Feb 6, 2026 •
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We will probably have the official price next week:

Step 3.5 Flash is still dominating the#1 spot on OpenRouter Trending! Huge thanks to everyone！

Try OpenRouter for free this week!

https://x.com/StepFun_ai/status/2019257979930058903

That PR was probably a little too early 😅

output = 0.80

[limit]
context = 262_144
input = 262_144
output = 65_536
Comment on lines +17 to +20
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@cantalupo555 cantalupo555 Feb 6, 2026 •
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Values confirmed via the OpenRouter API (/api/v1/models): context_length: 256000 and max_completion_tokens: 256000. The input field is not part of the [limit] schema and should be removed.

Suggested change
[limit]
context = 262_144
input = 262_144
output = 65_536
[limit]
context = 256_000
output = 256_000


[modalities]
input = ["text", "image"]
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Suggested change
input = ["text", "image"]
input = ["text"]

output = ["text"]

[interleaved]
field = "reasoning_content"

[provider]
npm = "@openrouter/ai-sdk-provider"
Comment on lines +26 to +30
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@cantalupo555 cantalupo555 Feb 6, 2026 •
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The [interleaved] block should also be removed — most reasoning models on OpenRouter (Claude, DeepSeek, Grok, Trinity, etc.) don't include it. Reasoning works correctly without this parameter.

The [provider] block is unnecessary — npm = "@openrouter/ai-sdk-provider" is already defined in OpenRouter's provider.toml. No other model in this provider includes this block.

Suggested change
[interleaved]
field = "reasoning_content"
[provider]
npm = "@openrouter/ai-sdk-provider"