The U.S. diplomat who stilled the shooting between bitter enemies in the Middle East, Phillip C. Habib, is flying home this weekend as the Reagan administration ponders its next steps in that dangerous and strategic region.

Habib, who was in Paris yesterday savoring the cease-fire he announced Friday between Israel and the Palestine Liberation Organization, will meet President Reagan and Secretary of State Alexnder M. Haig Jr. tomorrow to discuss his future involvement in the Mideast mediation, according to official sources. Tomorrow's talks are described as first steps in a broader policy-making process toward the Middle East that is likely to last for several months.

The 61-year-old Habib, who retired from the Foreign Service in 1978 after a series of heart attacks, is reported to be ready to return to private life after the intensive shuttling and maneuvering of the last three months. Whether Reagan and Haig are prepared for him to do that is not clear.

Reagan called the gruff and tenacious Habib out of retirement in early May to undertake the "long shot" task, as it seemed then, of averting an outbreak of war between Israel and Syria over the placement of Syrian antiaircraft missiles in northern Lebanon.

By early July Habib appeared to be close to success in his initial mission, which encompassed complicated negotiations involving Israel, Syria, Lebanon, Saudi Arabia and several Lebanese Christian and Moslem groups. On July 10, however, Israel launched bombing raids against the PLO, starting a new and separate crisis, including heavy Palestinian shelling of Israeli towns and an Israeil bombing raid against central Beirut that killed 300 civilians by government count.

According to State Department officials, the militant and often unpredictable PLO, though only marginally involved, took a cooperative attitude toward the earlier phase of the Habib mission, exercising restraint in the face of occasional Israeli strikes while Habib sought to solve the missile crisis.

Unless a cease-fire in the new fighting could be obtained, Habib reportedly concluded, his usefulness in preventing a wider war on any of the Mideast fronts would be at an end.

The cease-fire, officially termed a "cessation of hostilities" in Jerusalem and Washington, provides a pause that permits all the major players to consider the next act. Through Habib, Washington played a central role in these multiple and largely unexpected Lebanon-related crises of past Middle East parties will look for signs of new direction.

It is clear that the cease-fire, in itself, will not solve anything and indeed is not likely to last in the absence of substantial new initiatives. This fact, and the unhappy history of the last three months, argues for a stroner pological role within the Middle East than was in prospect early this year.

The sketchy Middle yeast policies Haig took to the area in April centered on two ideas: the strong desire to create an anti-Soviet "strategic consensus" from the ranks of the diverse Mideast partners of the United States, and a less-developed resolve to continue the Arab-Israeli peace process inherited from the Carter administration.

In coming weeks, a series of visits to Washington as well as the continuing tension in the region will confront the Reagan administration with the need to make important choices.

President Anwar Sadat of Egypt will be here in only 10 days, asking for further definition of Reaganhs Middle East policies. The preparations for the Aug. 5-7 Sadat visit may require Reagan and his senior White House team to focus greater attention than they have so far on U.S. objectives and plans in the region.

Israeli Prime Minister Menachem Begin is due in Washington Sept. 9-10, just about the time that Congress returns from its late summer recess and official Washington returns to full-scale activity again. Begin, whose relations with the administration have been shaken in the recent Lebanese crises, will be looking for cues to the future.

And shortly after Congress meets in the fall, as currently projected, the White House will send up it delayed request to sell the controversial airborne surveillance planes, AWACS, to Saudi Arabia. A special task force headed by Richard V. Allen, the presidential national security advisor, has been assigned the job of shepherding the embattled aircraft sale through Congress.

The expected congressional struggle over the AWACS, with Israel on one side and Saudi Arabia on the other, is likely to have a major impact on Reagan administration attitudes, and hence on its broader policies.

Later in the fall, it the AWACS sale is approved, Saudi Arabia's Crown Prince Fahd is expected here. And King Hussein of Jordan is on the advance schedules for the first days of November.

One group that is not expected is the PLO, which the Reagan administration, like those immediately before it, does not officially recognize.

But as events of the past weeks demonstrated anew, the United States must recognize "the reality," in the words of State Department spokesman Dean Fischer, and that reality is that the Palestinians play a central role. How the Reagan administration will deal with this is among the most crucial questions.