first commit

core/providers/vllm/transcription.go

@@ -0,0 +1,42 @@
+package vllm
+
+import (
+	"github.com/bytedance/sonic"
+	schemas "github.com/maximhq/bifrost/core/schemas"
+)
+
+// parseVLLMTranscriptionStreamChunk parses vLLM's transcription stream JSON and returns
+// a BifrostTranscriptionStreamResponse. It returns (nil, false) if the payload is not
+// valid vLLM format or has no content to emit.
+func parseVLLMTranscriptionStreamChunk(jsonData []byte) (*schemas.BifrostTranscriptionStreamResponse, bool) {
+	var chunk vLLMTranscriptionStreamChunk
+	response := &schemas.BifrostTranscriptionStreamResponse{}
+	if err := sonic.Unmarshal(jsonData, &chunk); err != nil {
+		return nil, false
+	}
+	// Done chunk: has usage (e.g. final event)
+	if chunk.Usage != nil {
+		return &schemas.BifrostTranscriptionStreamResponse{
+			Type:  schemas.TranscriptionStreamResponseTypeDone,
+			Usage: chunk.Usage,
+		}, true
+	}
+	// Delta chunk: has choices[].delta.content
+	if len(chunk.Choices) == 0 || chunk.Choices[0].Delta.Content == nil {
+		return nil, false
+	}
+	if len(chunk.Choices) > 0 {
+		reason := chunk.Choices[0].FinishReason
+		if reason == nil && chunk.Choices[0].StopReason != nil {
+			reason = chunk.Choices[0].StopReason
+		}
+		if reason != nil && *reason == "stop" {
+			response.Text = *chunk.Choices[0].Delta.Content
+			response.Type = schemas.TranscriptionStreamResponseTypeDone
+		} else {
+			response.Type = schemas.TranscriptionStreamResponseTypeDelta
+		}
+		response.Delta = chunk.Choices[0].Delta.Content
+	}
+	return response, true
+}