remove streaming from experimental in agent

[tkattkat]

why

streaming no longer needs to be behind experimental

what changed

removed experimental error when stream is used

test plan

---

Summary by cubic

Allow streaming in agents without the experimental gate. Removed the streaming check in validateExperimentalFeatures so enabling stream (via agentConfig.stream or inferred) no longer triggers an experimental error.

^{Written for commit f654ac4. Summary will update on new commits. Review in cubic}

[changeset-bot]

⚠️ No Changeset found

Latest commit: f654ac4

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[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant Client
    participant Agent as Stagehand Agent (v3)
    participant Validator as validateExperimentalFeatures
    participant LLM as LLM Provider

    Note over Client,LLM: Agent Request Flow with Streaming

    Client->>Agent: Call act/extract with { stream: true }
    
    Agent->>Validator: validateExperimentalFeatures(agentConfig)
    Note over Validator: CHANGED: Streaming is no longer added<br/>to the experimental features list.
    Validator-->>Agent: Continue (No experimental error thrown)

    Agent->>LLM: Request completion with streaming enabled
    
    loop Stream Response
        LLM-->>Agent: Partial data chunk
        Agent-->>Client: Stream event / callback
    end

    LLM-->>Agent: Stream complete
    Agent-->>Client: Final result / Metadata

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[greptile-apps]

Greptile Overview

Greptile Summary

Removed the experimental flag requirement for streaming in non-CUA mode by deleting the validation check that enforced it.

• Streaming is still correctly blocked for CUA mode (lines 47-49)
• The change allows stream: true to be used without experimental: true in non-CUA mode
• Critical: The test in agent-experimental-validation.spec.ts (lines 132-144) expects streaming to throw ExperimentalNotConfiguredError when experimental: false, but this PR removes that check - the test will now fail
• Documentation in packages/docs/v3/basics/agent.mdx (line 535) still mentions experimental: true is required for streaming
• JSDoc comment on line 27 still lists streaming as an experimental feature for non-CUA mode

Confidence Score: 2/5

• This PR will break existing tests and has outdated documentation
• The code change itself is clean and simple, but it introduces a breaking test failure and leaves documentation inconsistent with the new behavior
• Test file agent-experimental-validation.spec.ts and documentation agent.mdx need updates to align with this change

Important Files Changed

Filename	Overview
packages/core/lib/v3/agent/utils/validateExperimentalFeatures.ts	Removed experimental flag requirement for streaming in non-CUA mode, but breaking test needs update

Sequence Diagram

sequenceDiagram
    participant User
    participant Agent
    participant Validator as validateExperimentalFeatures
    participant ErrorHandler
    
    User->>Agent: agent({ stream: true })
    Agent->>Validator: validateExperimentalFeatures(options)
    
    alt CUA mode enabled
        Validator->>Validator: Check if agentConfig.stream is true
        Validator->>ErrorHandler: throw StagehandInvalidArgumentError
        ErrorHandler-->>User: "streaming is not supported with CUA"
    else Non-CUA mode (BEFORE this PR)
        Validator->>Validator: Check if stream is enabled
        alt experimental: false
            Validator->>ErrorHandler: throw ExperimentalNotConfiguredError
            ErrorHandler-->>User: "Agent streaming"
        else experimental: true
            Validator-->>Agent: Validation passed
            Agent-->>User: Agent with streaming
        end
    else Non-CUA mode (AFTER this PR)
        Note over Validator: Streaming check removed
        Validator-->>Agent: Validation passed (no experimental check)
        Agent-->>User: Agent with streaming
    end

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[greptile-apps]

_{1 file reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Additional Comments (2)

packages/core/lib/v3/agent/utils/validateExperimentalFeatures.ts
test on line 132-144 in agent-experimental-validation.spec.ts expects streaming to throw ExperimentalNotConfiguredError when experimental: false, but this change removes that check

test("throws ExperimentalNotConfiguredError for streaming mode", async () => {
  try {
    const agent = v3.agent({
      stream: true,
      model: "anthropic/claude-sonnet-4-20250514",
    });
    await agent.execute("test instruction");
    throw new Error("Expected error to be thrown");
  } catch (error) {
    expect(error).toBeInstanceOf(ExperimentalNotConfiguredError);
    expect((error as Error).message).toContain("streaming");
  }
});

Prompt To Fix With AI

This is a comment left during a code review.
Path: packages/core/lib/v3/agent/utils/validateExperimentalFeatures.ts
Line: 87:103

Comment:
test on line 132-144 in `agent-experimental-validation.spec.ts` expects streaming to throw `ExperimentalNotConfiguredError` when `experimental: false`, but this change removes that check

```typescript
test("throws ExperimentalNotConfiguredError for streaming mode", async () => {
  try {
    const agent = v3.agent({
      stream: true,
      model: "anthropic/claude-sonnet-4-20250514",
    });
    await agent.execute("test instruction");
    throw new Error("Expected error to be thrown");
  } catch (error) {
    expect(error).toBeInstanceOf(ExperimentalNotConfiguredError);
    expect((error as Error).message).toContain("streaming");
  }
});
```

How can I resolve this? If you propose a fix, please make it concise.

---

packages/core/lib/v3/agent/utils/validateExperimentalFeatures.ts
update the JSDoc comment to remove the mention of streaming as an experimental feature for non-CUA mode (line 27)

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review.
Path: packages/core/lib/v3/agent/utils/validateExperimentalFeatures.ts
Line: 20:31

Comment:
update the JSDoc comment to remove the mention of streaming as an experimental feature for non-CUA mode (line 27)

<sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub>

How can I resolve this? If you propose a fix, please make it concise.