That vow, which cooled the crisis fever of late summer, bought time for elected officials to begin creating the superstructure needed to make the euro more credible, including a permanent fund for rescuing stricken member countries and a unified system for overseeing banks.

“In 2012, the euro area leaders finally got the diagnosis right,” said Jacob Funk Kirkegaard, a research fellow at the Peterson Institute for International Economics in Washington. “It wasn’t about Greek debt or Irish banks. It was about some very fundamental design flaws that needed to be fixed. That’s what markets were looking for.”

Even though European political leaders seem to argue endlessly, they have made enough progress to keep speculators at bay. Investors surveyed by UBS recently ranked the chances of a breakup of the euro zone well behind the potential danger from a combination of spending cuts and tax increases scheduled to take effect in the United States next month or a hard landing by the Chinese economy.

“There is more of a perception that nobody is better off if this thing breaks up,” said Richard Barwell, senior European economist at Royal Bank of Scotland.

The question in 2013 will be whether a fragile calm in Europe holds long enough for economic growth to resume, for banks to rebuild their balance sheets and for leaders to make progress creating a more durable currency union.

Here are some of the main things to watch:

ECONOMIC PERFORMANCE The euro crisis, arguably, will be over the day that all of the stricken countries are generating economic growth. Ireland, one of the first countries to get into debt trouble back in 2008, might already have turned the corner. Its gross domestic product grew 0.2 percent in the third quarter from the period a year earlier.

Spain, Italy and Portugal are still deep in recession, and Greece is in a de facto depression. But there are some signs of progress in one crucial measure: trade balances. All of the distressed countries have increased exports this year and reduced trade deficits. That is a sign their products have become more competitive on world markets.