THE PRESIDENT won the debate over the War Powers Act, but he is resisting, excessively, the debate over war powers. The case against invoking the War Powers Act was strong: it would have been the first use of legislation on whose applicability and constitutionality there is scant agreement. But with American forces actually engaged in military operations in the Persian Gulf, it had become increasingly difficult for Congress to escape its responsibility for sharing in a combat commitment. The Senate Democrats' solution was to write a one-time-only prescription for executive-congressional consultation designed for the Gulf. This produced the proposal to require the president to make a formal report on his Gulf escort mission in 30 days and to require Congress to approve continuance of the mission within four months for it to go on. As befits a proposal launched months after the mission began, these terms of presidential notice and congressional review are easier than those in the War Powers Act.

President Reagan has dug in his heels, and he has some reason. The Johnny-come-lately aspect of the congressional performance has to be upsetting. A president engaged in conduct of a delicate policy cannot be indifferent to the readings of American intent and constancy that friends and adversaries are likely to take from this late congressional arrival upon the scene.

The very uncertainty of the Gulf prospect, however, ought to be taken as reason to welcome Congress as a partner. The president should consider that Congress is not asserting its prerogatives in order to compel him to change course. The Gulf is not Central America -- territory of bitter contention. Congress is already in broad agreement with the president. In the Gulf, events have clarified the risks of deeper engagement, and a congressional majority feels at once obliged, ready and determined to assume a role in dealing with them. Nervous as Mr. Reagan may be to take on a copilot in midflight, he should be comforted by the consideration that having Congress aboard could reinforce the signals of constancy he wants to send in the Gulf, and cushion the political damages of a crash.

In short, the president and the presidency are safe from the particular rigidities and precedents of the War Powers Act. In its stead arises an occasion for useful bipartisanship. The president gets to avail himself of congressional advice and support in a context where a broad policy consensus already exists and where the president has been establishing himself in most Americans' eyes as a responsible steward of policy. It may be a nervous parliamentary moment for Mr. Reagan, but he should not turn it into a political crisis by fighting an unnecessary battle with Congress