feat(create): 创作对话文本模式接入 text-replay 持久化与回放

把后端既有但未接线的 text-replay 能力在前端打通：前端直连模型生成正文时，
把生成过程/结果持久化到后端任务，支持刷新重放与任务中心可见。

后端（最小配套，text-replay 本为前端自管设计）:
- 新增 TaskStatusTextReplay 任务状态：不排入 worker 队列、不计费、不执行，
  仅作为正文增量（text-deltas）的存储容器;
- CreateTask 识别 input.replay=true 的请求，走 createTextReplayTask 轻量创建;
- 新增 POST /tasks/:id/text-replay-complete: 写入最终正文、置为 succeeded、
  触发 text-deltas 归并，使 queryTaskTextReplay 能读到 finalText。

前端:
- 新增 creation-text-replay.ts 发布器: start 建任务、publish 节流上报增量、
  finish 存最终全文，失败静默降级不阻塞生成;
- create 文本模式生成时接入发布器，正文流不经展示改动、额外持久化到后端。

测试: 新增 isTextReplayTaskRequest 纯函数测(本地)、text-replay 闭环仓测
(建任务后写增量 -> complete -> succeeded + finalText，CI/cgo 验证)。
build/vet/tsc 全绿。

backend/internal/handler/routes.go

@@ -172,6 +172,26 @@ func RegisterTaskRoutes(r *gin.RouterGroup, svc *service.Service) {
 		}
 		ok(c, task)
 	})
+	r.POST("/tasks/:id/text-replay-complete", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		var req struct {
+			Text string `json:"text"`
+		}
+		if err := c.ShouldBindJSON(&req); err != nil {
+			fail(c, http.StatusBadRequest, err)
+			return
+		}
+		task, err := svc.CompleteTextReplayTask(user.ID, c.Param("id"), req.Text)
+		if err != nil {
+			fail(c, http.StatusBadRequest, err)
+			return
+		}
+		ok(c, task)
+	})
 	r.GET("/tasks/:id/logs", func(c *gin.Context) {
 		user, err := currentUser(c, svc)
 		if err != nil {

backend/internal/model/models.go

@@ -44,6 +44,10 @@ const (
 	TaskStatusSucceeded TaskStatus = "succeeded"
 	TaskStatusFailed    TaskStatus = "failed"
 	TaskStatusCancelled TaskStatus = "cancelled"
+	// text_replay 任务是前端自管、不经过 worker 队列的文本生成存档容器：
+	// 前端直连模型流式生成，把增量 POST 到 /tasks/:id/text-deltas 存档，
+	// 完成后调用 /tasks/:id/text-replay-complete 归并为最终正文。
+	TaskStatusTextReplay TaskStatus = "text_replay"
 
 	SessionStatusActive    SessionStatus = "active"
 	SessionStatusCompleted SessionStatus = "completed"

backend/internal/repository/text_replay.go

@@ -124,6 +124,20 @@ func (r *Repository) CleanupTaskTextDeltas(now time.Time) (int64, error) {
 	return deleted, err
 }
 
+// CompleteTextReplayTask 把前端自管的 text_replay 任务原子收尾：写入最终正文并置为 succeeded。
+// 条件更新保证只有仍处于 text_replay 状态的任务能被收尾，避免重复完成。
+func (r *Repository) CompleteTextReplayTask(userID string, taskID string, resultJSON string, now time.Time) (bool, error) {
+	result := r.db.Model(&model.Task{}).
+		Where("id = ? AND user_id = ? AND status = ?", taskID, userID, model.TaskStatusTextReplay).
+		Updates(map[string]any{
+			"status": model.TaskStatusSucceeded, "stage": "已完成", "progress": 100,
+			"result_json": resultJSON, "text_draft": "",
+			"error": "", "completed_at": &now,
+			"lease_owner": "", "lease_expires_at": nil, "updated_at": now,
+		})
+	return result.RowsAffected == 1, result.Error
+}
+
 func (r *Repository) DeleteUserTaskTextDeltas(userID string) error {
 	return r.db.Delete(&model.TaskTextDelta{}, "user_id = ?", userID).Error
 }

backend/internal/repository/text_replay_test.go

@@ -0,0 +1,91 @@
+package repository
+
+import (
+	"testing"
+	"time"
+
+	"infinite-canvas/backend/internal/model"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+)
+
+// 验证 text-replay 闭环：text_replay 任务可写增量，完成后置为 succeeded 并写入最终正文。
+func TestTextReplayLifecycle(t *testing.T) {
+	db, err := gorm.Open(sqlite.Open("file:text-replay-lifecycle?mode=memory&cache=shared"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.AutoMigrate(&model.Task{}, &model.TaskTextDelta{}); err != nil {
+		t.Fatal(err)
+	}
+	task := model.Task{
+		ID: "replay-1", UserID: "user-1", Type: "text", Prompt: "写一段剧本",
+		Status: model.TaskStatusTextReplay, Stage: "文本持久化（前端自管）",
+	}
+	if err := db.Create(&task).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	repo := New(db)
+	now := time.Now()
+	limits := TextReplayLimits{MaxTaskBytes: 1 << 20, MaxUserBytes: 1 << 20, MaxTaskEvents: 100}
+
+	// text_replay 状态应允许写入增量（未结束）
+	if _, err := repo.AppendTaskTextDelta("user-1", "replay-1", "第一段内容", now.Add(time.Hour), limits); err != nil {
+		t.Fatalf("text_replay 任务写入增量失败: %v", err)
+	}
+	if _, err := repo.AppendTaskTextDelta("user-1", "replay-1", "第二段内容", now.Add(time.Hour), limits); err != nil {
+		t.Fatalf("text_replay 任务写入增量失败: %v", err)
+	}
+
+	// 完成：写入最终正文并置为 succeeded
+	resultJSON := `{"mode":"text","text":"第一段内容第二段内容"}`
+	completed, err := repo.CompleteTextReplayTask("user-1", "replay-1", resultJSON, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !completed {
+		t.Fatal("expected complete to succeed")
+	}
+	stored, err := repo.Task("replay-1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if stored.Status != model.TaskStatusSucceeded {
+		t.Fatalf("expected status succeeded, got %s", stored.Status)
+	}
+	if stored.ResultJSON != resultJSON {
+		t.Fatalf("unexpected result_json: %s", stored.ResultJSON)
+	}
+	if stored.CompletedAt == nil {
+		t.Fatal("expected completed_at set")
+	}
+
+	// 已完成的 text_replay 任务不能再写入增量（进入 closed）
+	if _, err := repo.AppendTaskTextDelta("user-1", "replay-1", "追加", now.Add(time.Hour), limits); err == nil {
+		t.Fatal("expected ErrTextReplayClosed after completion")
+	}
+
+	// 重复完成应返回 completed=false（状态已不是 text_replay）
+	again, err := repo.CompleteTextReplayTask("user-1", "replay-1", resultJSON, now.Add(time.Minute))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if again {
+		t.Fatal("expected second complete to be a no-op")
+	}
+
+	// 非 text_replay 任务不能完成
+	other := model.Task{ID: "queued-1", UserID: "user-1", Type: "text", Status: model.TaskStatusQueued}
+	if err := db.Create(&other).Error; err != nil {
+		t.Fatal(err)
+	}
+	done, err := repo.CompleteTextReplayTask("user-1", "queued-1", resultJSON, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if done {
+		t.Fatal("queued task must not be completable as text_replay")
+	}
+}

backend/internal/service/service.go

@@ -347,6 +347,10 @@ func (s *Service) CreateTask(userID string, req CreateTaskRequest) (*model.Task,
 		}
 		normalizedInput = applyRoutedProviderSelection(normalizedInput, routed)
 	}
+	// 前端自管的文本持久化任务：直连模型生成、增量上报 text-deltas，不排入 worker 队列生成。
+	if isTextReplayTaskRequest(normalizedInput) {
+		return s.createTextReplayTask(userID, req, normalizedInput)
+	}
 	if err := s.requireCustomChannelsForTaskInput(normalizedInput); err != nil {
 		return nil, err
 	}
@@ -473,6 +477,41 @@ func normalizeTaskInput(input map[string]any) (map[string]any, error) {
 	return normalized, nil
 }
 
+// createTextReplayTask 创建前端自管的文本持久化任务：状态为 text_replay，
+// 不排队执行、不计 active 队列、不产生计费，仅作为正文增量（text-deltas）的存储容器。
+func (s *Service) createTextReplayTask(userID string, req CreateTaskRequest, normalizedInput map[string]any) (*model.Task, error) {
+	prompt := strings.TrimSpace(req.Prompt)
+	if prompt == "" {
+		prompt = strings.TrimSpace(fmt.Sprint(normalizedInput["prompt"]))
+	}
+	if prompt == "" {
+		return nil, errors.New("prompt is required")
+	}
+	taskType := strings.TrimSpace(req.Type)
+	if taskType == "" {
+		taskType = "text"
+	}
+	task := model.Task{
+		ID: newID(), UserID: userID, SessionID: req.SessionID, ProjectID: req.ProjectID,
+		Type: taskType, Status: model.TaskStatusTextReplay, Stage: "文本持久化（前端自管）", Progress: 5,
+		Prompt: prompt, Operation: req.Operation, Provider: req.Provider, Model: strings.TrimSpace(req.Model),
+	}
+	if err := s.protectTaskSecrets(normalizedInput); err != nil {
+		return nil, err
+	}
+	inputJSON, _ := json.Marshal(normalizedInput)
+	task.InputJSON = string(inputJSON)
+	policy, err := s.RuntimePolicy()
+	if err != nil {
+		return nil, err
+	}
+	if err := s.createTaskWithinStorageQuota(&task, nil, policy); err != nil {
+		return nil, err
+	}
+	_ = s.log(userID, task.ID, "info", "文本持久化任务已创建（前端自管）", "")
+	return taskForOutput(task), nil
+}
+
 func (s *Service) requireCustomChannelsForTaskInput(input map[string]any) error {
 	if !taskInputUsesCustomChannel(input) {
 		return nil

backend/internal/service/text_replay.go

@@ -29,6 +29,49 @@ type TextReplayResult struct {
 	Complete  bool                  `json:"complete"`
 }
 
+// isTextReplayTaskRequest 识别前端自管的文本持久化请求（input 带 replay=true）。
+// 这类任务由前端直连模型流式生成，仅作正文的后端存档与回放，不经过 worker 队列生成。
+func isTextReplayTaskRequest(input map[string]any) bool {
+	value, ok := input["replay"]
+	if !ok {
+		return false
+	}
+	switch v := value.(type) {
+	case bool:
+		return v
+	case string:
+		return strings.EqualFold(strings.TrimSpace(v), "true")
+	default:
+		return false
+	}
+}
+
+// CompleteTextReplayTask 在文本生成结束后把最终正文写入任务，收尾为 succeeded，
+// 关闭 delta 写入窗口并触发 text-deltas 归并，使 queryTaskTextReplay 能读到 finalText。
+func (s *Service) CompleteTextReplayTask(userID string, taskID string, text string) (*model.Task, error) {
+	if strings.TrimSpace(text) == "" {
+		return nil, BadAuthRequest("文本内容不能为空")
+	}
+	if len([]byte(text)) > textReplayMaxTaskBytes {
+		return nil, BadAuthRequest("文本内容过大")
+	}
+	if _, err := s.repo.TaskForUser(userID, taskID); err != nil {
+		return nil, err
+	}
+	resultJSON, _ := json.Marshal(map[string]any{"mode": "text", "text": text})
+	completed, err := s.repo.CompleteTextReplayTask(userID, taskID, string(resultJSON), time.Now())
+	if err != nil {
+		return nil, err
+	}
+	if !completed {
+		return nil, BadAuthRequest("该文本任务已结束或不属于你，无法完成")
+	}
+	if compactErr := s.finalizeTaskTextReplay(taskID, model.TaskStatusSucceeded); compactErr != nil {
+		_ = s.log(userID, taskID, "error", "文本回放窗口更新失败", compactErr.Error())
+	}
+	return s.repo.TaskForUser(userID, taskID)
+}
+
 func (s *Service) AppendTaskTextDelta(userID string, taskID string, content string) (*model.TaskTextDelta, error) {
 	task, err := s.repo.TaskForUser(userID, taskID)
 	if err != nil {

backend/internal/service/text_replay_test.go

@@ -0,0 +1,25 @@
+package service
+
+import "testing"
+
+func TestIsTextReplayTaskRequest(t *testing.T) {
+	cases := []struct {
+		name  string
+		input map[string]any
+		want  bool
+	}{
+		{"replay 布尔 true", map[string]any{"replay": true}, true},
+		{"replay 字符串 true", map[string]any{"replay": "true"}, true},
+		{"replay 字符串 True 大小写", map[string]any{"replay": "TRUE"}, true},
+		{"replay 布尔 false", map[string]any{"replay": false}, false},
+		{"无 replay 字段", map[string]any{"mode": "text"}, false},
+		{"replay 空字符串", map[string]any{"replay": ""}, false},
+		{"replay 数字", map[string]any{"replay": 1}, false},
+		{"replay nil", map[string]any{"replay": nil}, false},
+	}
+	for _, tc := range cases {
+		if got := isTextReplayTaskRequest(tc.input); got != tc.want {
+			t.Errorf("%s: isTextReplayTaskRequest(%v) = %v, want %v", tc.name, tc.input, got, tc.want)
+		}
+	}
+}

web/src/lib/creation-text-replay.ts

@@ -0,0 +1,86 @@
+import { appendTaskTextDelta, completeTextReplayTask, createGenerationTask } from "@/services/api/task-center";
+import type { AiConfig } from "@/stores/use-config-store";
+
+/**
+ * text-replay 前端发布器：为前端直连模型生成的文本，在后端维护一个
+ * text_replay 任务作持久化存档 + 回放。
+ *
+ * - start()：创建后端 text_replay 任务（不排队、不计费），拿到 taskId；
+ * - publish(fullText)：按阈值节流地把新增片段通过 appendTaskTextDelta 上报
+ *   （生成中途刷新页面也能读到已生成部分）；
+ * - finish(finalText)：把最终正文写入任务并置为 succeeded，queryTaskTextReplay
+ *   即可读到 finalText。
+ *
+ * 全部失败静默降级：文本直连生成是主流程，后端持久化只是增强，失败不阻塞生成。
+ */
+export function createTextReplayPublisher(config: AiConfig, prompt: string) {
+    let taskId: string | null = null;
+    let lastLen = 0;
+    let buffered = "";
+    let flushTimer: ReturnType<typeof setTimeout> | null = null;
+    let closed = false;
+
+    // 增量累积到该阈值才落一次库，避免逐 token 高频写。
+    const FLUSH_THRESHOLD = 2048;
+    const flush = (force = false) => {
+        if (flushTimer) {
+            clearTimeout(flushTimer);
+            flushTimer = null;
+        }
+        if (closed || !taskId) return;
+        if (buffered.length >= FLUSH_THRESHOLD || force) {
+            const chunk = buffered;
+            buffered = "";
+            if (chunk.trim()) void appendTaskTextDelta(taskId, chunk).catch(() => {});
+        } else if (buffered) {
+            flushTimer = setTimeout(() => flush(true), 1000);
+        }
+    };
+
+    const start = async () => {
+        try {
+            const task = await createGenerationTask({
+                type: "text",
+                prompt: prompt.trim() || "文本创作",
+                model: config.model,
+                input: {
+                    mode: "text",
+                    replay: true,
+                    prompt: prompt.trim() || "文本创作",
+                    config: {
+                        model: config.model,
+                        baseUrl: config.baseUrl,
+                        apiKey: config.apiKey,
+                        apiFormat: config.apiFormat,
+                    },
+                },
+            });
+            taskId = task?.id || null;
+        } catch {
+            taskId = null; // 降级：无持久化，不影响主流程
+        }
+    };
+
+    const publish = (fullText: string) => {
+        if (!taskId) return;
+        if (fullText.length <= lastLen) return;
+        buffered += fullText.slice(lastLen);
+        lastLen = fullText.length;
+        flush();
+    };
+
+    const finish = (finalText: string) => {
+        closed = true;
+        if (flushTimer) {
+            clearTimeout(flushTimer);
+            flushTimer = null;
+        }
+        if (!taskId) return;
+        void appendTaskTextDelta(taskId, buffered).catch(() => {});
+        if (finalText && finalText.trim()) {
+            void completeTextReplayTask(taskId, finalText).catch(() => {});
+        }
+    };
+
+    return { start, publish, finish };
+}

web/src/pages/create/index.tsx

@@ -24,6 +24,7 @@ import { isGenerationTaskCancelled, logicalModelIDForConfig, runBackendGeneratio
 import { requestImageQuestion, type AiTextContentPart } from "@/services/api/image";
 import { listAddedSkills, type Skill } from "@/services/api/skills";
 import { cancelGenerationTask, subscribeGenerationTasks, type GenerationTask } from "@/services/api/task-center";
+import { createTextReplayPublisher } from "@/lib/creation-text-replay";
 import { isLocalDreaminaTaskId, isLocalDreaminaWaitStopped, localDreaminaCancellationCopy, localDreaminaCancellationMessage, localDreaminaDetachOutcome } from "@/services/local-dreamina-task-projection";
 import { getMediaBlob, uploadMediaFile } from "@/services/file-storage";
 import { uploadImage } from "@/services/image-storage";
@@ -536,10 +537,18 @@ export default function CreatePage() {
 							? await buildTextMessageContent(item)
 							: item.content,
 					})));
-					await requestImageQuestion(requestConfig, history, (text) => updateOriginAssistant((item) => ({ ...item, content: text })), {
+					const replayPublisher = createTextReplayPublisher(requestConfig, text);
+					void replayPublisher.start();
+					let finalText = "";
+					await requestImageQuestion(requestConfig, history, (full) => {
+						finalText = full;
+						updateOriginAssistant((item) => ({ ...item, content: full }));
+						replayPublisher.publish(full);
+					}, {
 						signal: requestLifecycle.signal,
 						onReasoning: (reasoning) => updateOriginAssistant((item) => ({ ...item, reasoning })),
 					});
+					replayPublisher.finish(finalText);
 				}
             } else if (mode === "image") {
                 const taskCount = Math.max(1, Math.min(imageProfile.maxOutputs, Math.floor(Number(count) || 1)));

web/src/services/api/task-center.ts

@@ -391,6 +391,10 @@ export function appendTaskTextDelta(id: string, content: string) {
     return request<TaskTextDelta>(api.post(`/tasks/${encodeURIComponent(id)}/text-deltas`, { content }));
 }
 
+export function completeTextReplayTask(id: string, text: string) {
+    return request<GenerationTask>(api.post(`/tasks/${encodeURIComponent(id)}/text-replay-complete`, { text }));
+}
+
 export function queryTaskTextReplay(id: string, after = 0) {
     return request<TaskTextReplay>(api.get(`/tasks/${encodeURIComponent(id)}/text-deltas`, { params: { after } }));
 }