We’re following SemVer. At this point bumps of the minor (second) version number are considered feature releases and always include new features or significant changes to existing features. API compatibility will almost never be broken.
The development cycle for the next feature release starts immediately after the previous one has been shipped. Bugfix/point releases (if any) address only serious bugs and never contain new features. Here are a few examples:
0.5.0 - Feature release
0.5.1 - Bug-fix release
0.5.2 - Bug-fix release
0.6.0 - Feature release
Historically this wasn’t always the case. Versions 0.2, 0.3 and 0.4 introduced major backward-incompatible changes. Back then point releases (e.g. 0.4.2) could mean either bug-fixes or new backwards-compatible functionality. That changed with nREPL 0.5 for the sake of making it obvious which releases add new functionality and which simply patch bugs. That brings up one step closer to the SemVer ideal.
1. As much as one can be following it when the major version is 0.
2. Unless explicitly stated via deprecation warnings for a few releases beforehand.