feat(task): 资产覆盖度功能可按任务开关

创建任务时新增「资产覆盖度功能」开关(默认开)。关闭后：
- 不计算/展示测试覆盖度，总览卡片隐藏、覆盖度 API 返回 enabled:false
- 态势图仅展示资产不显示测试进度(B1：抹平 tested、去已测统计与图例)
- 不再自动累积 task_scope(source=auto)
- planner/mainagent 的 add_task_scope、list_untested_assets 从工具列表剔除
- graph_overview 丢弃 coverage 度量块、保留 scope 字段(防上下文污染)

company 关联(task_scope kind=company)与此开关无关，永不受影响：
insertTaskCompanies 不 gate，TaskCompanyIDs 照常读回，scope 字段照常喂给 agent。

DB：tasks 加 coverage_enabled 列(schema.sql + ALTER ADD COLUMN IF NOT EXISTS
补旧库，默认 true 保持存量任务原行为)。

Claude-Session: https://claude.ai/code/session_01Jm87Gr5fq5aso6SfLyguhx

db/tasks.go

@@ -40,6 +40,11 @@ type Task struct {
 	// planner 心跳触发间隔(秒)：距上轮 plan 结束/任务开始满该值且期间无触发 → 触发一轮。
 	// 下限=默认=300(5min)，低于一律抬到 300(在 CreateTask 归一)。见 docs/planner-trigger-impl-plan.md
 	PlanHeartbeatSeconds int `json:"plan_heartbeat_seconds"`
+	// CoverageEnabled 是「资产覆盖度功能」总开关(默认 true)。false 时：不计算/不展示测试
+	// 覆盖度、不自动累积 task_scope(source=auto)、不给 agent 开放 add_task_scope/
+	// list_untested_assets、态势里不注入 coverage 块(scope 字段仍保留)。company 关联
+	// (task_scope kind=company)与此开关无关，永不受影响。见 db/task_scope.go。
+	CoverageEnabled bool `json:"coverage_enabled"`
 }
 
 // TaskDeleteResult reports optional related-data cleanup performed in the same
@@ -137,6 +142,9 @@ type TaskCreateOptions struct {
 	LLMProfileIDs        []int64
 	TimeoutSeconds       int
 	PlanHeartbeatSeconds int
+	// CoverageEnabled 是「资产覆盖度功能」开关;nil=默认开(true)，让不关心该开关的创建
+	// 路径(编排 spawn、老 API)沿用原行为。仅 web 创建任务时可显式传 false 关闭。
+	CoverageEnabled *bool
 }
 
 // CreateTaskWithOptions creates an exploration, task, direct source relations,
@@ -178,6 +186,7 @@ VALUES ($1, 'fact', $2, 0, 'origin', 'system')`, expID, string(originPayload));
 		opts.TimeoutSeconds = 0
 	}
 	opts.PlanHeartbeatSeconds = normalizeHeartbeat(opts.PlanHeartbeatSeconds)
+	coverageEnabled := opts.CoverageEnabled == nil || *opts.CoverageEnabled
 	var active *int64
 	if len(opts.LLMProfileIDs) > 0 {
 		id := opts.LLMProfileIDs[0]
@@ -190,11 +199,12 @@ VALUES ($1, 'fact', $2, 0, 'origin', 'system')`, expID, string(originPayload));
 		SourceTaskIDs:  append([]int64(nil), opts.SourceTaskIDs...),
 		CompanyIDs:     append([]int64(nil), opts.CompanyIDs...),
 		TimeoutSeconds: opts.TimeoutSeconds, PlanHeartbeatSeconds: opts.PlanHeartbeatSeconds,
+		CoverageEnabled: coverageEnabled,
 	}
 	if err := tx.QueryRow(`
-INSERT INTO tasks(description, goal, exploration_id, llm_profile_id, active_llm_profile_id, timeout_seconds, plan_heartbeat_seconds)
-VALUES ($1,$2,$3,$4,$4,$5,$6)
-RETURNING id, status, paused, created_at`, description, goal, expID, active, opts.TimeoutSeconds, opts.PlanHeartbeatSeconds).Scan(&t.ID, &t.Status, &t.Paused, &t.CreatedAt); err != nil {
+INSERT INTO tasks(description, goal, exploration_id, llm_profile_id, active_llm_profile_id, timeout_seconds, plan_heartbeat_seconds, coverage_enabled)
+VALUES ($1,$2,$3,$4,$4,$5,$6,$7)
+RETURNING id, status, paused, created_at`, description, goal, expID, active, opts.TimeoutSeconds, opts.PlanHeartbeatSeconds, coverageEnabled).Scan(&t.ID, &t.Status, &t.Paused, &t.CreatedAt); err != nil {
 		return nil, err
 	}
 	if err := insertTaskRelations(tx, t.ID, opts.SourceTaskIDs); err != nil {
@@ -274,11 +284,11 @@ func insertTaskLLMProfiles(tx *sql.Tx, taskID int64, profileIDs []int64) error {
 	return nil
 }
 
-const taskCols = `id, description, goal, exploration_id, status, paused, queued, queued_at, COALESCE(queue_mode,''), llm_profile_id, active_llm_profile_id, COALESCE(parent_ref,''), created_at, completed_at, COALESCE(timeout_seconds,0), COALESCE(plan_heartbeat_seconds,300), first_run_at, deadline_at`
+const taskCols = `id, description, goal, exploration_id, status, paused, queued, queued_at, COALESCE(queue_mode,''), llm_profile_id, active_llm_profile_id, COALESCE(parent_ref,''), created_at, completed_at, COALESCE(timeout_seconds,0), COALESCE(plan_heartbeat_seconds,300), COALESCE(coverage_enabled,true), first_run_at, deadline_at`
 
 func scanTask(sc interface{ Scan(...any) error }) (*Task, error) {
 	var t Task
-	if err := sc.Scan(&t.ID, &t.Description, &t.Goal, &t.ExplorationID, &t.Status, &t.Paused, &t.Queued, &t.QueuedAt, &t.QueueMode, &t.LLMProfileID, &t.ActiveLLMProfileID, &t.ParentRef, &t.CreatedAt, &t.CompletedAt, &t.TimeoutSeconds, &t.PlanHeartbeatSeconds, &t.FirstRunAt, &t.DeadlineAt); err != nil {
+	if err := sc.Scan(&t.ID, &t.Description, &t.Goal, &t.ExplorationID, &t.Status, &t.Paused, &t.Queued, &t.QueuedAt, &t.QueueMode, &t.LLMProfileID, &t.ActiveLLMProfileID, &t.ParentRef, &t.CreatedAt, &t.CompletedAt, &t.TimeoutSeconds, &t.PlanHeartbeatSeconds, &t.CoverageEnabled, &t.FirstRunAt, &t.DeadlineAt); err != nil {
 		return nil, err
 	}
 	return &t, nil