[Design idea] File blob page: Make it easier for users to access different versions of a file through different commits
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# Context
Design feedback from @nickleonard [Slack](https://gitlab.slack.com/archives/CM7BZ903G/p1745258851224439).
# Problem
Sometimes, it is helpful for users to see how the contents of a file have changed over time, in different commits.
On the GitLab interface today, users have a few ways to view the contents of a file in different commits, but they are roundabout and not ideal:
1. View Blame for the file. This shows bits and pieces of how a file has changed in different commits, but does not allow users to easily see all the changes of 1 commit in 1 view. Users can "View blame prior to this change," but the timeline of commits is not very understandable or linear. Users can also click on a commit in the Blame view, then "View file," but this is requires many clicks and users may lose context.
{width=992 height=786}
2. In the file blob page, change branches to show the state of the file in a certain commit. The branch selector doesn't communicate well that users can search for a commit, so this may not be clear for users. Users also have to pull the commit ID from a different page, which is more of a process.
{width=994 height=828}
# Design solution
Design a way for users to browse through the commit history of a file, and see the file contents in relation to different commits. This is a common pattern used in many development tools.
_\< Design TBD, awaiting prioritization \>_
issue