I’ve been through the same solo-dev slump while working on a long-term project. What helped me wasn’t motivation tricks, but having a structured vault to organize my thinking — feature ideas, scope changes, “half-baked” experiments, and even commit prep all in markdown.

I shared my setup + markdown templates in this post:
📄 How I Stay Productive (and Sane) as a Solo Developer

Might be useful if you’re looking for lightweight practices that still give you a sense of control and progress, even without a team around.