Method createStreamAtomically

src/node/services/streamManager.ts:1555–1666

* Atomically creates a new stream with all necessary setup

(
    workspaceId: WorkspaceId,
    streamToken: StreamToken,
    runtimeTempDir: string,
    runtime: Runtime,
    messages: ModelMessage[],
    model: LanguageModel,
    modelString: string,
    abortController: AbortController,
    system: string,
    historySequence: number,
    messageId: string,
    tools?: Record<string, Tool>,
    initialMetadata?: Partial<MuxMetadata>,
    providerOptions?: Record<string, unknown>,
    maxOutputTokens?: number,
    toolPolicy?: ToolPolicy,
    callSettingsOverrides?: ResolvedCallSettingsOverrides,
    hasQueuedMessages?: (dispatchMode?: "tool-end" | "turn-end") => boolean,
    workspaceName?: string,
    thinkingLevel?: string,
    headers?: Record<string, string | undefined>,
    anthropicCacheTtlOverride?: AnthropicCacheTtl,
    onChunk?: StreamTextOnChunk,
    onStepMessages?: (messages: ModelMessage[]) => void,
    modelFallback?: ModelFallbackOptions
  )

   * Atomically creates a new stream with all necessary setup
   */
  private createStreamAtomically(
    workspaceId: WorkspaceId,
    streamToken: StreamToken,
    runtimeTempDir: string,
    runtime: Runtime,
    messages: ModelMessage[],
    model: LanguageModel,
    modelString: string,
    abortController: AbortController,
    system: string,
    historySequence: number,
    messageId: string,
    tools?: Record<string, Tool>,
    initialMetadata?: Partial<MuxMetadata>,
    providerOptions?: Record<string, unknown>,
    maxOutputTokens?: number,
    toolPolicy?: ToolPolicy,
    callSettingsOverrides?: ResolvedCallSettingsOverrides,
    hasQueuedMessages?: (dispatchMode?: "tool-end" | "turn-end") => boolean,
    workspaceName?: string,
    thinkingLevel?: string,
    headers?: Record<string, string | undefined>,
    anthropicCacheTtlOverride?: AnthropicCacheTtl,
    onChunk?: StreamTextOnChunk,
    onStepMessages?: (messages: ModelMessage[]) => void,
    modelFallback?: ModelFallbackOptions
  ): WorkspaceStreamInfo {
    // abortController is created and linked to the caller-provided abortSignal in startStream().

    const stepTracker: StepMessageTracker = {};
    const metadataModel = this.resolveMetadataModel(modelString);
    const request = this.buildStreamRequestConfig(
      model,
      modelString,
      messages,
      system,
      tools,
      providerOptions,
      maxOutputTokens,
      callSettingsOverrides,
      toolPolicy,
      hasQueuedMessages,
      headers,
      anthropicCacheTtlOverride,
      onChunk,
      onStepMessages
    );

    // Start streaming - this can throw immediately if API key is missing
    let streamResult;
    try {
      streamResult = this.createStreamResult(request, abortController, stepTracker);
    } catch (error) {
      // Clean up abort controller if stream creation fails
      abortController.abort();
      // Re-throw the error to be caught by startStream
      throw error;
    }