Update CerebrasClient to use ai-sdk instead of OpenAI

[clayostroff]

why

Cerebras integration was out of date for models and not buildable. AI-SDK ships a first‑party Cerebras provider that's now used.

what changed

• Replace lib/llm/CerebrasClient.ts with an AI‑SDK‑based implementation.
• Update lib/llm/LLMProvider.ts to instantiate the Cerebras AI‑SDK client for Cerebras models.
• Keep old and add new Cerebras models added in types/model.ts.

test plan

I tested using the form_filling_sensible file and the 2048 tests to test all the Cerebras models.

notes

Message & tool mapping mirrors the existing AISdkClient example for consistent behavior. No changes to other providers.

[changeset-bot]

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Latest commit: f8c3a74

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[greptile-apps]

Greptile Overview

Summary

Migrated Cerebras integration from OpenAI client to AI SDK's official Cerebras provider, adding support for 7 new Cerebras models.

Major changes:

• Replaced custom OpenAI-based implementation in lib/llm/CerebrasClient.ts with AI SDK wrapper using createCerebras provider
• Simplified from ~310 lines to ~70 lines by delegating to AISdkClient
• Added new models: gpt-oss-120b, llama-4-maverick-17b-128e-instruct, llama-4-scout-17b-16e-instruct, qwen-3-235b-a22b-instruct-2507, qwen-3-235b-a22b-thinking-2507, qwen-3-32b, qwen-3-coder-480b
• Exported CerebrasClient in public API (lib/index.ts)

Issues found:

• Critical bug: Logger implementation references non-existent this.logger property, will cause runtime error
• Config file (stagehand.config.ts) mistakenly changed to test Cerebras model instead of production default

Confidence Score: 1/5

• This PR has critical bugs that will cause runtime errors and should not be merged without fixes
• Score reflects a critical logic error in CerebrasClient.ts:41-50 where the logger implementation references a non-existent this.logger property. This will cause a runtime error when the logger is invoked. Additionally, the config file changes should be reverted. Missing changeset also violates repository requirements.
• Pay close attention to lib/llm/CerebrasClient.ts (logger bug) and revert stagehand.config.ts to production defaults

Important Files Changed

File Analysis

Filename	Score	Overview
lib/llm/CerebrasClient.ts	2/5	Refactored to use AI SDK client with Cerebras provider instead of OpenAI client, but contains a critical bug in logger implementation
lib/llm/LLMProvider.ts	4/5	Added type casts for Cerebras provider and added model mappings for 7 new Cerebras models
stagehand.config.ts	5/5	Updated default config to use Cerebras model for testing purposes

Sequence Diagram

sequenceDiagram
    participant User
    participant LLMProvider
    participant CerebrasClient
    participant AISdkClient
    participant CerebrasProvider
    participant CerebrasAPI

    User->>LLMProvider: getClient("cerebras-qwen-3-32b")
    LLMProvider->>LLMProvider: Check modelToProviderMap
    LLMProvider->>CerebrasClient: new CerebrasClient(options)
    CerebrasClient->>CerebrasClient: Extract model name (remove "cerebras-" prefix)
    CerebrasClient->>CerebrasProvider: createCerebras({apiKey})
    CerebrasProvider-->>CerebrasClient: provider instance
    CerebrasClient->>CerebrasProvider: provider(modelName)
    CerebrasProvider-->>CerebrasClient: LanguageModel
    CerebrasClient->>AISdkClient: new AISdkClient({model, logger, cache})
    AISdkClient-->>CerebrasClient: client instance
    CerebrasClient-->>LLMProvider: CerebrasClient instance
    LLMProvider-->>User: LLMClient

    User->>CerebrasClient: createChatCompletion(options)
    CerebrasClient->>AISdkClient: createChatCompletion(options)
    AISdkClient->>AISdkClient: Format messages to CoreMessage[]
    AISdkClient->>CerebrasAPI: generateObject/generateText
    CerebrasAPI-->>AISdkClient: response
    AISdkClient->>AISdkClient: Transform to LLMResponse format
    AISdkClient-->>CerebrasClient: LLMResponse
    CerebrasClient-->>User: LLMResponse

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Additional Comments (2)

1. lib/llm/CerebrasClient.ts, line 41-50 (link)

   logic: The logger passed to AISdkClient constructor is immediately invoked inline, but this.logger doesn't exist yet (not defined in the class). This code transforms log messages but the original logger isn't stored anywhere to call.

2. stagehand.config.ts, line 10-12 (link)

   logic: Config file should be reverted to use default production settings, not test configuration from this PR

_{5 files reviewed, 2 comments}

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[JerryWu1234]

test