Method runStructuredFinalization

packages/ai/src/activities/chat/index.ts:1951–2310

* Run the final structured-output adapter call through the middleware * pipeline. Yields chunks to the caller only when * `this.finalStructuredOutput.yieldChunks` is true; otherwise consumes * silently while still piping through middleware. * * On success, populates this.structuredOut

()

   * On failure, populates this.finalizationError.
   */
  private async *runStructuredFinalization(): AsyncGenerator<StreamChunk> {
    if (!this.finalStructuredOutput) {
      throw new Error(
        'runStructuredFinalization called without finalStructuredOutput config',
      )
    }

    this.middlewareCtx.phase = 'structuredOutput'

    // Build the structured-output config view. `tools` is intentionally
    // excluded from the type because it isn't forwarded to the structured-
    // output adapter call — including it here would be misleading API.
    const baseConfig = this.buildMiddlewareConfig()
    const { tools: _omitTools, ...baseWithoutTools } = baseConfig
    let structuredConfig: StructuredOutputMiddlewareConfig = {
      ...baseWithoutTools,
      outputSchema: this.finalStructuredOutput.jsonSchema,
    }

    // 1) onStructuredOutputConfig — middleware can transform messages, options, outputSchema
    structuredConfig = await this.middlewareRunner.runOnStructuredOutputConfig(
      this.middlewareCtx,
      structuredConfig,
    )

    // 2) onConfig — phase-aware general-purpose middleware re-runs at the
    // boundary. Re-attach the engine's current tools so onConfig observers
    // see the live tool set (they still won't be forwarded to the structured
    // call — same constraint applies — but the view is consistent with the
    // ChatMiddlewareConfig shape).
    const { outputSchema: pinnedSchema, ...chatConfigSlice } = structuredConfig
    const postOnConfig = await this.middlewareRunner.runOnConfig(
      this.middlewareCtx,
      { ...chatConfigSlice, tools: baseConfig.tools },
    )

    // Apply merged config back to engine state
    this.applyMiddlewareConfig(postOnConfig)

    // Build the StructuredOutputOptions the adapter expects.
    // `this.adapter` is already `TAdapter extends AnyTextAdapter` per the
    // class generics — no cast needed.
    const structuredCallOptions = {
      chatOptions: {
        model: this.params.model,
        messages: this.messages,
        metadata: postOnConfig.metadata,
        modelOptions: postOnConfig.modelOptions,
        systemPrompts: postOnConfig.systemPrompts,
        logger: this.logger,
        threadId: this.threadId,
        runId: this.runIdOverride,
        parentRunId: this.parentRunIdOverride,
        ...(this.effectiveRequest ? { request: this.effectiveRequest } : {}),
      },
      outputSchema: pinnedSchema,
    }