Add regression tests for SSE comment lines from OpenRouter

pkg/model/provider/openai/sse_comment_test.go

@@ -0,0 +1,195 @@
+package openai
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/docker/docker-agent/pkg/chat"
+	"github.com/docker/docker-agent/pkg/config/latest"
+	"github.com/docker/docker-agent/pkg/environment"
+)
+
+// writeSSEWithComments writes an SSE response prefixed with comment lines
+// (starting with ':'), as sent by providers like OpenRouter during initial
+// processing. Per the SSE spec, comment lines must be ignored by clients.
+// This is used to verify the fix for https://github.com/docker/docker-agent/issues/2349.
+func writeSSEWithComments(w http.ResponseWriter, sseLines []string) {
+	w.Header().Set("Content-Type", "text/event-stream")
+	flusher, _ := w.(http.Flusher)
+
+	// Comment lines like OpenRouter sends during processing
+	_, _ = fmt.Fprint(w, ": OPENROUTER PROCESSING\n")
+	_, _ = fmt.Fprint(w, ": OPENROUTER PROCESSING\n")
+
+	for _, line := range sseLines {
+		_, _ = fmt.Fprint(w, line+"\n")
+	}
+	flusher.Flush()
+}
+
+// TestCustomProvider_SSECommentLines_ChatCompletions is a regression test for
+// https://github.com/docker/docker-agent/issues/2349
+//
+// OpenRouter sends SSE comment lines (": OPENROUTER PROCESSING") before the
+// actual data events. This test verifies those comments don't cause
+// "unexpected end of JSON input" errors during streaming.
+func TestCustomProvider_SSECommentLines_ChatCompletions(t *testing.T) {
+	t.Parallel()
+
+	chunks := []map[string]any{
+		{
+			"id": "gen-123", "object": "chat.completion.chunk", "model": "test",
+			"choices": []map[string]any{{"index": 0, "delta": map[string]any{"role": "assistant", "content": ""}, "finish_reason": nil}},
+		},
+		{
+			"id": "gen-123", "object": "chat.completion.chunk", "model": "test",
+			"choices": []map[string]any{{"index": 0, "delta": map[string]any{"content": "hello"}, "finish_reason": nil}},
+		},
+		{
+			"id": "gen-123", "object": "chat.completion.chunk", "model": "test",
+			"choices": []map[string]any{{"index": 0, "delta": map[string]any{}, "finish_reason": "stop"}},
+		},
+		{
+			"id": "gen-123", "object": "chat.completion.chunk", "model": "test",
+			"choices": []map[string]any{}, "usage": map[string]any{"prompt_tokens": 10, "completion_tokens": 1, "total_tokens": 11},
+		},
+	}
+
+	var sseLines []string
+	for _, chunk := range chunks {
+		data, _ := json.Marshal(chunk)
+		sseLines = append(sseLines, "data: "+string(data), "")
+	}
+	sseLines = append(sseLines, "data: [DONE]", "")
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		writeSSEWithComments(w, sseLines)
+	}))
+	defer server.Close()
+
+	cfg := &latest.ModelConfig{
+		Provider: "openrouter",
+		Model:    "test-model",
+		BaseURL:  server.URL,
+		TokenKey: "OPENROUTER_API_KEY",
+		ProviderOpts: map[string]any{
+			"api_type": "openai_chatcompletions",
+		},
+	}
+	env := environment.NewMapEnvProvider(map[string]string{
+		"OPENROUTER_API_KEY": "test-key",
+	})
+
+	client, err := NewClient(t.Context(), cfg, env)
+	require.NoError(t, err)
+
+	stream, err := client.CreateChatCompletionStream(
+		t.Context(),
+		[]chat.Message{{Role: chat.MessageRoleUser, Content: "hello"}},
+		nil,
+	)
+	require.NoError(t, err)
+	defer stream.Close()
+
+	var content strings.Builder
+	for {
+		chunk, err := stream.Recv()
+		if err != nil {
+			break
+		}
+		for _, choice := range chunk.Choices {
+			content.WriteString(choice.Delta.Content)
+		}
+	}
+
+	assert.Equal(t, "hello", content.String())
+}
+
+// TestCustomProvider_SSECommentLines_Responses is a regression test for
+// https://github.com/docker/docker-agent/issues/2349 using the Responses API
+// path (api_type: openai_responses), which is exactly what the issue reporter
+// was using with OpenRouter.
+func TestCustomProvider_SSECommentLines_Responses(t *testing.T) {
+	t.Parallel()
+
+	events := []map[string]any{
+		{"type": "response.output_text.delta", "delta": "hello", "item_id": "item-1"},
+		{
+			"type": "response.completed",
+			"response": map[string]any{
+				"id":     "resp-123",
+				"status": "completed",
+				"output": []map[string]any{
+					{"type": "message", "id": "item-1"},
+				},
+				"usage": map[string]any{
+					"input_tokens":  10,
+					"output_tokens": 1,
+					"total_tokens":  11,
+					"input_tokens_details": map[string]any{
+						"cached_tokens": 0,
+					},
+					"output_tokens_details": map[string]any{
+						"reasoning_tokens": 0,
+					},
+				},
+			},
+		},
+	}
+
+	var sseLines []string
+	for _, event := range events {
+		data, _ := json.Marshal(event)
+		eventType := event["type"].(string)
+		sseLines = append(sseLines, "event: "+eventType, "data: "+string(data), "")
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		writeSSEWithComments(w, sseLines)
+	}))
+	defer server.Close()
+
+	cfg := &latest.ModelConfig{
+		Provider: "openrouter",
+		Model:    "test-model",
+		BaseURL:  server.URL,
+		TokenKey: "OPENROUTER_API_KEY",
+		ProviderOpts: map[string]any{
+			"api_type": "openai_responses",
+		},
+	}
+	env := environment.NewMapEnvProvider(map[string]string{
+		"OPENROUTER_API_KEY": "test-key",
+	})
+
+	client, err := NewClient(t.Context(), cfg, env)
+	require.NoError(t, err)
+
+	stream, err := client.CreateChatCompletionStream(
+		t.Context(),
+		[]chat.Message{{Role: chat.MessageRoleUser, Content: "hello"}},
+		nil,
+	)
+	require.NoError(t, err)
+	defer stream.Close()
+
+	var content strings.Builder
+	for {
+		chunk, err := stream.Recv()
+		if err != nil {
+			break
+		}
+		for _, choice := range chunk.Choices {
+			content.WriteString(choice.Delta.Content)
+		}
+	}
+
+	assert.Equal(t, "hello", content.String())
+}