refactor: remove dead parseStreamResponse function

parseStreamResponse in openai_compat provider was never called —
all streaming is handled by processStreamResponse. Removing dead
code that contained the originally flagged redundant Unmarshal.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/providers/openai_compat/provider.go

@@ -542,93 +542,3 @@ type streamToolCallAcc struct {
 	Arguments strings.Builder
 }
 
-// parseStreamResponse reads an SSE (text/event-stream) response and
-// accumulates it into a single LLMResponse.
-func parseStreamResponse(r io.Reader) (*LLMResponse, error) {
-	scanner := bufio.NewScanner(r)
-	// Allow up to 1 MB per SSE line to handle large argument deltas.
-	scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)
-
-	var content strings.Builder
-	var toolCalls []streamToolCallAcc
-	var finishReason string
-	var usage *UsageInfo
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		if !strings.HasPrefix(line, "data: ") {
-			continue
-		}
-		data := strings.TrimPrefix(line, "data: ")
-		if data == "[DONE]" {
-			break
-		}
-
-		var chunk streamChunk
-		if err := json.Unmarshal([]byte(data), &chunk); err != nil {
-			continue // skip malformed chunks
-		}
-
-		if len(chunk.Choices) == 0 {
-			if chunk.Usage != nil {
-				usage = chunk.Usage
-			}
-			continue
-		}
-
-		choice := chunk.Choices[0]
-		if choice.Delta.Content != "" {
-			content.WriteString(choice.Delta.Content)
-		}
-		if choice.FinishReason != "" {
-			finishReason = choice.FinishReason
-		}
-
-		// Accumulate streaming tool calls by index.
-		for _, tc := range choice.Delta.ToolCalls {
-			for len(toolCalls) <= tc.Index {
-				toolCalls = append(toolCalls, streamToolCallAcc{})
-			}
-			if tc.ID != "" {
-				toolCalls[tc.Index].ID = tc.ID
-			}
-			if tc.Function != nil {
-				if tc.Function.Name != "" {
-					toolCalls[tc.Index].Name = tc.Function.Name
-				}
-				toolCalls[tc.Index].Arguments.WriteString(tc.Function.Arguments)
-			}
-		}
-
-		if chunk.Usage != nil {
-			usage = chunk.Usage
-		}
-	}
-	if err := scanner.Err(); err != nil {
-		return nil, fmt.Errorf("reading stream: %w", err)
-	}
-
-	result := &LLMResponse{
-		Content:      content.String(),
-		FinishReason: finishReason,
-		Usage:        usage,
-	}
-
-	for _, tc := range toolCalls {
-		arguments := make(map[string]any)
-		argStr := tc.Arguments.String()
-		if argStr != "" {
-			if err := json.Unmarshal([]byte(argStr), &arguments); err != nil {
-				log.Printf("openai_compat: failed to decode streamed tool call arguments for %q: %v", tc.Name, err)
-				arguments["raw"] = argStr
-			}
-		}
-		result.ToolCalls = append(result.ToolCalls, ToolCall{
-			ID:        tc.ID,
-			Name:      tc.Name,
-			Arguments: arguments,
-		})
-	}
-
-	return result, nil
-}