docs(deploy): 文本事件流 - 补充 SSE 反向代理与断线恢复指南 (#143)

Fixes #143

backend/internal/handler/text_events_test.go

@@ -0,0 +1,53 @@
+package handler
+
+import (
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"infinite-canvas/backend/internal/model"
+	"infinite-canvas/backend/internal/service"
+
+	"github.com/gin-gonic/gin"
+)
+
+func TestTaskTextEventCursorPrefersQueryAndSupportsLastEventID(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	request := httptest.NewRequest("GET", "/api/tasks/task-1/text-events?after=7", nil)
+	request.Header.Set("Last-Event-ID", "3")
+	context, _ := gin.CreateTestContext(httptest.NewRecorder())
+	context.Request = request
+	after, err := taskTextEventCursor(context)
+	if err != nil || after != 7 {
+		t.Fatalf("cursor = %d, err = %v", after, err)
+	}
+
+	request = httptest.NewRequest("GET", "/api/tasks/task-1/text-events", nil)
+	request.Header.Set("Last-Event-ID", "3")
+	context, _ = gin.CreateTestContext(httptest.NewRecorder())
+	context.Request = request
+	after, err = taskTextEventCursor(context)
+	if err != nil || after != 3 {
+		t.Fatalf("Last-Event-ID cursor = %d, err = %v", after, err)
+	}
+}
+
+func TestStreamTaskTextEventsWritesSequenceAndTerminalEvent(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	response := httptest.NewRecorder()
+	context, _ := gin.CreateTestContext(response)
+	context.Request = httptest.NewRequest("GET", "/api/tasks/task-1/text-events", nil)
+	replay := &service.TextReplayResult{
+		Deltas:    []model.TaskTextDelta{{Sequence: 8, Content: "增量"}},
+		Complete:  true,
+		FinalText: "增量",
+	}
+	streamTaskTextEvents(context, nil, "user-1", "task-1", 7, replay)
+	if response.Header().Get("Content-Type") != "text/event-stream; charset=utf-8" {
+		t.Fatalf("content type = %q", response.Header().Get("Content-Type"))
+	}
+	body := response.Body.String()
+	if !strings.Contains(body, "id: 8\nevent: delta") || !strings.Contains(body, "event: terminal") {
+		t.Fatalf("unexpected SSE body: %q", body)
+	}
+}