Method streamCompletion

cmd/wasm/runtime_wasm.go:431–530

streamCompletion runs one streaming completion call and emits deltas.

(ctx context.Context, prov provider.Provider, messages []chat.Message, agentTools []tools.Tool)

// streamCompletion runs one streaming completion call and emits deltas.
func (rt *wasmRuntime) streamCompletion(ctx context.Context, prov provider.Provider, messages []chat.Message, agentTools []tools.Tool) (*wasmStreamResult, error) {
	stream, err := prov.CreateChatCompletionStream(ctx, messages, agentTools)
	if err != nil {
		return nil, fmt.Errorf("opening stream: %w", err)
	}
	defer stream.Close()

	var content strings.Builder
	var reasoning strings.Builder
	var toolCalls []tools.ToolCall
	var usage *chat.Usage
	var finishReason chat.FinishReason

	toolCallIndex := make(map[string]int)

	for {
		resp, err := stream.Recv()
		if errors.Is(err, io.EOF) {
			break
		}
		if err != nil {
			return nil, fmt.Errorf("reading stream: %w", err)
		}

		if resp.Usage != nil {
			usage = resp.Usage
		}

		for _, choice := range resp.Choices {
			// Tool call deltas.
			if len(choice.Delta.ToolCalls) > 0 {
				for _, delta := range choice.Delta.ToolCalls {
					idx, exists := toolCallIndex[delta.ID]
					if !exists {
						idx = len(toolCalls)
						toolCallIndex[delta.ID] = idx
						toolCalls = append(toolCalls, tools.ToolCall{
							ID:   delta.ID,
							Type: delta.Type,
						})
					}
					tc := &toolCalls[idx]
					if delta.Type != "" {
						tc.Type = delta.Type
					}
					if delta.Function.Name != "" {
						tc.Function.Name = delta.Function.Name
					}
					if delta.Function.Arguments != "" {
						tc.Function.Arguments += delta.Function.Arguments
					}

					// Emit partial tool call event.
					if tc.Function.Name != "" {
						rt.emitEvent(map[string]any{
							"type":      "tool_call_delta",
							"id":        tc.ID,
							"name":      tc.Function.Name,