"Congratulations Melissa!! From All of Us," says the banner in State Department Room 4238, where one of the Reagan administration's most disputed ambassadorial appointments made her not-so-temporary office.

Melissa F. Wells, who was confirmed by the Senate last week as ambassador to Mozambique, is confident she broke at least two Foreign Service records -- length of time for confirmation and number of questions fielded -- and perhaps a third, the number of Senate votes against her.

Wells, 54, was nominated by the White House Oct. 7 and confirmed 11 months and two days later. The vote was 64 to 24.

"I unfortunately also hold the record in terms of questions. It was 246. It keeps appearing as 247, but I say that's just accumulated interest," she joked.

"I'm not sure I would recommend it for all ambassadorial nominees, but it was one heck of a training ground in terms of just routing out the information," she added.

Wells became the target of a group of conservative Republicans led by Sen. Jesse Helms (R-N.C.), and later joined by Minority Leader Robert J. Dole (R-Kan.), who strongly disagreed with the State Department's policy toward Mozambique, which was backed by the White House.

This led to a strange political confrontation in which the Republican White House was battling the conservative wing of the Republican Party and Democrats took the lead in supporting President Reagan's nominee.

"Helms feels the focus of attention on the country and State Department policy were certainly worth it," said an aide. "As time goes on, we feel senators will feel this is a real problem."

Mozambique is a self-described Marxist state seeking to improve its ties to the West, and may abandon its socialist course. It is in the midst of a struggle with an anti-Marxist guerrilla movement, the Mozambique National Resistance (Renamo), which Helms believes the United States should be backing instead of the central government.

Some other senators apparently shared Helms' doubts about U.S. policy because Wells, whose integrity he never questioned, drew negative votes from 23 others (20 Republicans and three Democrats), a tally of nays that Wells says "unfortunately" may also have set a record.

"It's a high number," she noted. "I take the negative votes very seriously and I shall be working to take their concerns into account to see if we can get a better consensus for {U.S.} policy."

Those "concerns" include the refusal of the Reagan administration and the Mozambican government to recognize Renamo as a legitimate movement; charges of human rights abuses by Mozambican authorities, and Mozambique's anti-American voting record at the United Nations.

The confirmation ordeal, which included a private 90-minute meeting with Helms in early June in a bid to break the deadlock, has obviously left some scars on Wells, together with a host of memories. Some were sweet, she said, others bitter.

"Sure, I got scuffed up a bit," she remarked. "But I did not feel there were any personal attacks or questions of my qualifications."

But doubts about her future there were.

"You begin to wonder. Is this going to be the rest of my life, this ambasssador-designate position? I mean, will I reach mandatory retirement like this? I wouldn't be frank with you if I didn't say I had a few downers along the road. But I never, never wanted to give up and throw in the towel," she said.

"It was a track worth running and the fighting was worth it."

The Renamo information office here, echoing Helms' charge, made much of her alleged bias against the antigovernment rebels, charging she had referred to them once as "bandits," an allegation she heatedly denies.

"If I may say, I have never used the word 'bandit' to describe the insurgency in Mozambique," Wells said.

She said her only reference to "bandits" was in discussions with Helms aides about her past experiences in Uganda, where she served as resident representative of the U.N. development program from 1979 to 1981 and ran into "genuine bandits."

I've been shot at, and what else does one call this," she said referring to Uganda.

Helms also tried to nail Wells on an analogy she made at one point between Renamo's status in Mozambique and that of the Red Brigades in northern Italy a few years ago, when the Italian extremists were using terrorist tactics but still did not control any "territory."

Renamo claims it controls 80 percent of the Mozambican countryside, a claim the State Department challenges and Helms accepts as an argument for U.S. backing of the movement.

Wells said that one of the "truly beautiful memories" she takes away from the confirmation process was the support of the entire department, from Secretary of State George P. Shultz on down.

One of her less beautiful memories was the problem of finding a place to live while awaiting confirmation. Wells said she moved four times from apartment to apartment here -- a nomadism that provoked her to comment, "I am the original bag lady. Big paper bags. I have them all set around every place we lived. You can't do it with suitcases because they take up too much space."

Wells will be sworn in at 4 p.m. Friday and has already booked her flight to Maputo 3 1/2 hours later. She should be on the job Monday morning -- finally.