BENEATH the snow-capped peaks of the Tian Shan mountains, what began as a Slavic commonwealth expanded on Saturday to embrace almost all of the former Soviet Union.The survivors of the collapse of the Soviet state managed to agree on who would constitute the new Commonwealth of Independent States - 11 of the 12 former Soviet republics, with the three already independent Baltic nations and Georgia opting out for now. But they failed to concur on how to coordinate their defense and economic policies, leaving open the question of whether this loose commonwealth can handle the complex and divisive issues before it. The leaders of the commonwealth who assembled in Alma Ata, the capital of Kazakhstan, invited Soviet President Mikhail Gorbachev "to resign with dignity," as Russian President Boris Yeltsin put it. They offered Mr. Gorbachev a pension and other post-presidential benefits, gently urging him to depart the Kremlin stronghold he has held for more than six years. Gorbachev is said to be preparing a final televised address to the nation, but the timing of his resignation remains a mystery, even to his close aides. "Nobody knows," longtime adviser Georgi Shaknazarov told the Monitor yesterday. "He will declare it himself. He says it's his own business when to do it." The commonwealth leaders adopted five documents at their meeting, all of them negotiated in advance by teams of officials. Some thorny issues were dispatched: * Russia won its demand to inherit the Soviet seat at the United Nations and its seat on the UN Security Council. * Single control over nuclear weapons was confirmed. * A coordinating structure was created. * The existing borders were recognized. However, the leaders failed to agree on the text of a new collective security treaty precisely defining their joint military system, including what forces will be under joint command and how the new unified defense structure will operate. Nor did they settle how the commonwealth will practically manage common economic policies such as currency. The leaders will meet again in Minsk on Dec. 30 to settle these questions. Until then a "transitional period" is established during which the military will continue to operate under the command of present Soviet Defense Minister Air Marshal Yevgeny Shaposhnikov. A commonwealth council of heads of state will be the coordinating body until they can agree on a more defined structure. Kazakhstan government spokesman Seitcazy Matayev explained that "There were many objections" to the military treaty, "including those from the Ukraine." He said the Ukraine had also objected to the appointment of Marshal Shaposhnikov as the permanent commander in chief. "The main thing that satisfies me is that strategic [nuclear] weapons remain under single control," Shaposhnikov said. "Thus both the Soviet and world public will be calmed down." He said that he will be working on a revised plan for conventional forces and will submit it shortly to the Soviet General Staff. A special agreement on nuclear arms was issued by the four states in which long-range nuclear weapons are based: Russia, Byelorussia, the Ukraine, and Kazakhstan. With the apprehensions of the West clearly in mind, the document states the weapons will be under unified command with decisions on their use made by the Russian president in agreement with the other three. Byelorussia and the Ukraine agree to join the Nuclear Non-Proliferation Treaty as nonnuclear weapons states. The three non-Russian states a lso agree to allow transfer of tactical nuclear warheads to Russia for dismantling under "joint supervision." Some aspects, however, will trouble Western powers. The actual procedures for joint control remain to be determined in a separate document. And Kazakhstan has clearly decided to retain its weapons so long as Russia does, although Russian officials repeat their view that Russia will emerge as the sole nuclear weapons power out of the former Union. Such ambiguity also surrounds economic cooperation. Mr. Yeltsin, according to a Tass news agency dispatch, told reporters upon his return to Moscow that the ruble will remain the common currency and that coordinating institutions will be created at the Dec. 30 meeting which will set the pace of reforms. But the Russian reforms are already set to begin with liberalization of all state-controlled price liberalization on Jan. 2. Uzbekistan President Islam Karimov told the news conference after the signing t hat prices should be freed only after the poorer regions had been adequately safeguarded. The leaders also deferred for final approval a draft agreement on institutions for the commonwealth, including regular meetings of leaders and creation of ministerial level committees to coordinate policies on foreign affairs, defense, economics and finances, transport and communications, social security and law enforcement. Nor have they settled two controversial problems: the division of Soviet property, including its embassies abroad, and how to pay for joint projects such as the military. The clearest document provides for Russia to inherit the Soviet UN seat and its permanent membership (and veto rights) in the Security Council. The Ukraine and Byelorussia are already members of the UN, and the other states are expected to follow. Aside from the three Slavic republics, the 11 members of the commonwealth include Azerbaijan, Armenia, Kazakhstan, Kirghizia, Moldavia, Tadzhikstan, and Uzbekistan. Georgia sent observers to the meeting.