`RunStream` causes duplicate output (twice)

[carmel]

As mentioned in the subject, I'm not sure if this is a bug.

package main

import (
	"context"
	"log"
	"os"

	"github.com/go-kratos/blades"
	"github.com/go-kratos/blades/contrib/openai"
)

func main() {
	model := openai.NewModel(os.Getenv("OPENAI_MODEL"), openai.Config{
		APIKey: os.Getenv("OPENAI_API_KEY"),
	})
	agent, err := blades.NewAgent(
		"Stream Agent",
		blades.WithModel(model),
		blades.WithInstruction("You are a helpful assistant that provides detailed answers."),
	)
	if err != nil {
		log.Fatal(err)
	}
	input := blades.UserMessage("What is the capital of France?")
	runner := blades.NewRunner(agent)
	stream := runner.RunStream(context.Background(), input)
	for m, err := range stream {
		if err != nil {
			log.Fatal(err)
		}
		log.Println(m.Status, m.Text())
	}
}

example/streaming

[majiayu000]

Hi, I've been looking into this and traced the root cause.

Proposed approach: Trace the streaming path: RunStream (runner.go) → agent.Run (agent.go) → handle() streaming branch → model.NewStreaming(). The handle() method yields each chunk from the model's streaming iterator. Likely root cause is either: (1) the OpenAI contrib provider's NewStreaming implementation yielding duplicate events (e.g., not deduplicating SSE events), or (2) the agent iteration loop in handle() somehow re-entering the streaming path. Need to read contrib/openai model implementation to confirm. Fix likely requires a single-file change with a corresponding test case.

I'll open a draft PR shortly. Happy to adjust based on your preference.