fix(sync): return not_started for unsynced episodes

docs/designs/cloud-sync-ui-implementation.md

@@ -52,7 +52,7 @@ endpoints recommended for the episode-centered Cloud Sync Center redesign:
 | `POST` | `/api/v1/sync/episodes/:id` | Enqueue one episode for cloud sync by numeric episode ID |
 | `GET` | `/api/v1/sync/episodes` | Existing: list raw sync log entries for history/diagnosis |
 | `GET` | `/api/v1/sync/episodes/summary` | Recommended new endpoint: list latest sync state grouped by episode |
-| `GET` | `/api/v1/sync/episodes/:id/status` | Get latest sync log for one episode |
+| `GET` | `/api/v1/sync/episodes/:id/status` | Get current sync status for one episode |
 | `GET` | `/api/v1/sync/episodes/:id/logs` | Recommended new endpoint: list raw sync log history for one episode |
 | `GET` | `/api/v1/sync/config` | Get sanitized sync worker configuration |
 
@@ -482,8 +482,11 @@ Update `synapse/src/views/admin/episodes/EpisodeDetail.vue`:
 
 Important status handling:
 
-- `GET /sync/episodes/:id/status` may return 404 before the worker creates a
-  `sync_logs` row. Treat this as `queued` after a trigger, not as failure.
+- `GET /sync/episodes/:id/status` returns `200 status=not_started` when the
+  episode exists but has no `sync_logs` row. This is a virtual status and is not
+  inserted into `sync_logs`.
+- `GET /sync/episodes/:id/status` returns `404 episode not found` only when the
+  episode does not exist or has been soft-deleted.
 - `POST /sync/episodes/:id` returns `202 Accepted`, not completion.
 - `409 already synced` should refresh episode detail.
 - `409 already queued` should switch UI to `queued` or `syncing`.

docs/designs/episode-qa-checks-mcap-integrity.zh.html

@@ -835,8 +835,9 @@ <h3>列表字段</h3>
       <h3>交互规则</h3>
       <ul>
         <li>点击 <code>重新质检</code> 后按钮进入提交中状态。</li>
-        <li>返回 <code>passed=true</code> 时刷新列表和详情，展示最新状态。</li>
-        <li>返回 <code>passed=false</code> 时展示 <code>details</code>，并刷新 <code>qa_status</code> 与 <code>quality_flag</code>。</li>
+        <li>返回 <code>passed=true</code> 时刷新列表和详情，展示最新状态，并在 episode 详情页弹出本次质检结果。</li>
+        <li>返回 <code>passed=false</code> 时在结果弹窗展示 <code>details</code>，并刷新 <code>qa_status</code> 与 <code>quality_flag</code>。</li>
+        <li>episode 详情页的质量检查卡片只常驻展示当前状态和 <code>quality_flag</code>；本次重新质检结果不再作为“最近结果”行常驻，避免与质量说明重复。</li>
         <li>返回 <code>409</code> 时提示该 episode 正在质检中，不重复提交。</li>
         <li>质检历史使用抽屉或轻量面板展示 <code>GET /api/v1/qa/episodes/:id/checks</code> 的完整记录。</li>
       </ul>
@@ -870,6 +871,7 @@ <h3>Synapse</h3>
             <li>列表展示最近一次质检结果。</li>
             <li>质检历史抽屉能展示完整 <code>qa_checks</code>。</li>
             <li>质检中心和 episode 详情页都通过 <code>重新质检</code> 调用 <code>POST /api/v1/qa/episodes/:id/run</code>。</li>
+            <li>episode 详情页重新质检完成后展示结果弹窗；关闭后页面仅保留当前质量状态和质量说明。</li>
           </ul>
         </div>
       </div>

internal/api/handlers/sync.go

@@ -632,13 +632,13 @@ func (h *SyncHandler) ListEpisodeSyncLogs(c *gin.Context) {
 // GetSyncStatus returns the sync status for a specific episode.
 //
 // @Summary      Get episode sync status
-// @Description  Returns the latest sync log entry for a specific episode
+// @Description  Returns the latest sync log entry for a specific episode, or status=not_started when the episode has no sync log
 // @Tags         sync
 // @Produce      json
 // @Param        id   path      int  true  "Episode ID"
 // @Success      200  {object}  SyncJobResponse
 // @Failure      400  {object}  map[string]string
-// @Failure      404  {object}  map[string]string
+// @Failure      404  {object}  map[string]string  "Episode not found"
 // @Router       /sync/episodes/{id}/status [get]
 func (h *SyncHandler) GetSyncStatus(c *gin.Context) {
 	idStr := c.Param("id")
@@ -648,6 +648,25 @@ func (h *SyncHandler) GetSyncStatus(c *gin.Context) {
 		return
 	}
 
+	var episode struct {
+		ID       int64          `db:"id"`
+		PublicID sql.NullString `db:"episode_id"`
+	}
+	err = h.db.Get(&episode, `
+		SELECT id, episode_id
+		FROM episodes
+		WHERE id = ? AND deleted_at IS NULL
+	`, episodeID)
+	if err == sql.ErrNoRows {
+		c.JSON(http.StatusNotFound, gin.H{"error": "episode not found"})
+		return
+	}
+	if err != nil {
+		logger.Printf("[SYNC] Failed to query episode %d for sync status: %v", episodeID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to get sync status"})
+		return
+	}
+
 	var row syncLogRow
 	err = h.db.Get(&row, `
 		SELECT
@@ -672,7 +691,13 @@ func (h *SyncHandler) GetSyncStatus(c *gin.Context) {
 		LIMIT 1
 	`, episodeID)
 	if err == sql.ErrNoRows {
-		c.JSON(http.StatusNotFound, gin.H{"error": "no sync record found for this episode"})
+		c.JSON(http.StatusOK, SyncJobResponse{
+			ID:              0,
+			EpisodeID:       episode.ID,
+			EpisodePublicID: nullableString(episode.PublicID),
+			Status:          "not_started",
+			AttemptCount:    0,
+		})
 		return
 	}
 	if err != nil {

internal/api/handlers/sync_test.go

@@ -128,6 +128,92 @@ func TestListEpisodeSyncSummariesGroupsByEpisode(t *testing.T) {
 	}
 }
 
+func TestGetSyncStatusReturnsNotStartedWhenEpisodeHasNoSyncLog(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	db := setupSyncHandlerTestDB(t)
+
+	if _, err := db.Exec(`
+		INSERT INTO episodes (id, episode_id, deleted_at)
+		VALUES (4181, 'episode-no-sync', NULL)
+	`); err != nil {
+		t.Fatalf("insert episode: %v", err)
+	}
+
+	router := gin.New()
+	handler := NewSyncHandler(db, nil)
+	handler.RegisterRoutes(router.Group("/api/v1"))
+
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/sync/episodes/4181/status", nil)
+	rec := httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", rec.Code, rec.Body.String())
+	}
+
+	var got SyncJobResponse
+	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
+		t.Fatalf("decode response: %v", err)
+	}
+	if got.ID != 0 {
+		t.Fatalf("id = %d, want 0 for virtual status", got.ID)
+	}
+	if got.EpisodeID != 4181 {
+		t.Fatalf("episode_id = %d, want 4181", got.EpisodeID)
+	}
+	if got.EpisodePublicID == nil || *got.EpisodePublicID != "episode-no-sync" {
+		t.Fatalf("episode_public_id = %v, want episode-no-sync", got.EpisodePublicID)
+	}
+	if got.Status != "not_started" {
+		t.Fatalf("status = %q, want not_started", got.Status)
+	}
+	if got.AttemptCount != 0 {
+		t.Fatalf("attempt_count = %d, want 0", got.AttemptCount)
+	}
+}
+
+func TestGetSyncStatusReturnsNotFoundWhenEpisodeDoesNotExist(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	db := setupSyncHandlerTestDB(t)
+
+	if _, err := db.Exec(`
+		INSERT INTO episodes (id, episode_id, deleted_at)
+		VALUES (42, 'episode-deleted', ?)
+	`, time.Date(2026, 5, 9, 10, 0, 0, 0, time.UTC)); err != nil {
+		t.Fatalf("insert deleted episode: %v", err)
+	}
+
+	router := gin.New()
+	handler := NewSyncHandler(db, nil)
+	handler.RegisterRoutes(router.Group("/api/v1"))
+
+	tests := []struct {
+		name string
+		path string
+	}{
+		{name: "missing", path: "/api/v1/sync/episodes/404/status"},
+		{name: "soft deleted", path: "/api/v1/sync/episodes/42/status"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tt.path, nil)
+			rec := httptest.NewRecorder()
+			router.ServeHTTP(rec, req)
+
+			if rec.Code != http.StatusNotFound {
+				t.Fatalf("status = %d, body = %s", rec.Code, rec.Body.String())
+			}
+			var got map[string]string
+			if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
+				t.Fatalf("decode response: %v", err)
+			}
+			if got["error"] != "episode not found" {
+				t.Fatalf("error = %q, want episode not found", got["error"])
+			}
+		})
+	}
+}
+
 func setupSyncHandlerTestDB(t *testing.T) *sqlx.DB {
 	t.Helper()