What should be done after merging a user story branch to the develop branch?

After merging a user story branch into the develop branch, it's essential to run automated unit tests against the tip of the branch. This practice is crucial because it ensures that the integration of the changes from the user story did not introduce any regressions or errors in the codebase. Automated tests provide immediate feedback on the stability of the software, confirming that existing features continue to work as expected after the new code has been added.

Running these tests helps maintain the quality of the code and is in line with continuous integration practices, where regular merges and testing are performed to minimize risks associated with integration. By prioritizing testing after a merge, teams can catch and address potential issues early in the development process, which is key to delivering reliable software.

The other choices might have their relevance in different contexts, but they do not directly address the most critical action immediately following a merge that impacts software quality and stability. Notifying users about the merge, archiving previous versions, or deleting the user story branch may be part of a broader workflow or housekeeping tasks, but they do not contribute directly to validating the integrity of the code right after integration.