feat: enforce durable queue resource limits and backpressure

internal/storage/mysql/worker_execution.go

@@ -81,8 +81,13 @@ func queueLimit(ctx context.Context, tx *sql.Tx, ns, queue core.ID, max uint32)
 	var used uint32
 	var configured uint32
 	err = tx.QueryRowContext(ctx, `SELECT id,used_permits,max_permits FROM pulse_concurrency_limits WHERE namespace_id=? AND scope_key='queue' AND key_digest=? FOR UPDATE`, ns, digest).Scan(&id, &used, &configured)
-	if err == nil && configured != max {
-		err = errors.New("queue limit configuration requires coordinated update")
+	// 降额时保留已有许可；队列上限控制新的领取，存储上限至少容纳在途数。
+	target := max
+	if used > target {
+		target = used
+	}
+	if err == nil && configured != target {
+		_, err = tx.ExecContext(ctx, `UPDATE pulse_concurrency_limits SET max_permits=?,revision=revision+1,updated_at=UTC_TIMESTAMP(6) WHERE namespace_id=? AND id=?`, target, ns, id)
 	}
 	return id, used, err
 }
@@ -123,6 +128,14 @@ func (s *ExecutionStore) Claim(ctx context.Context, token auth.Token, b worker.B
 		if used >= max {
 			return nil
 		}
+		now, err := dbNow(ctx, tx)
+		if err != nil {
+			return err
+		}
+		canClaim, err := queueCanClaim(ctx, tx, token.NamespaceID, state.queue, now)
+		if err != nil || !canClaim {
+			return err
+		}
 		args := []any{token.NamespaceID, state.queue}
 		matches := make([]string, 0, len(state.capabilities))
 		for _, c := range state.capabilities {
@@ -465,6 +478,9 @@ func (s *ExecutionStore) executionCommand(ctx context.Context, token auth.Token,
 			if task.view.StartDeadlineAt != nil && !task.view.StartDeadlineAt.After(now) {
 				return worker.LeaseLost
 			}
+			if err := consumeQueueStart(ctx, tx, token.NamespaceID, task.view.QueueID, now); err != nil {
+				return err
+			}
 			authorized = &now
 		} else if a.State != pulse.AttemptRunning || authorized == nil {
 			return fault.Conflict