Context-switching is hard. Having the discipline to prioritise effectively is hard, using git branches effectively is hard, and building tools to magically make it easier is...hard.
Git-plan doesn't solve this problem outright, but I hope it moves in the right direction.
I do think that once you have draft commit messages in your workspace, it is possible to build new tools that consume them to help you context switch. For example, a tool could automatically stage hunks for you, based on the draft commit message you wrote.
There are some great thoughts and criticisms here and I'll be taking them all onboard for the next couple of versions of the tool. If anyone wants to contribute, PRs are welcome and I can help out as needed.