These threads kind of rule. Lots of different answers!
For my part: I've put some of my tooling energy into code comprehension tools. You can get remarkably far quickly by just replacing the Github PR viewer! I started with a (native SwiftUI) read-only front end for tree-sitter and SCIP (the code-indexing standard). Then: as I reviewed PRs, I tried to catch myself doing annoying repetitive things and just building out additional features, like "show me all the knowable call chains for this function", or "show me every implementation of this trait".
You can get a fair ways just by thinking of things to hide in a PR viewer, just to clear space for the things you need to comprehend.
For my part: I've put some of my tooling energy into code comprehension tools. You can get remarkably far quickly by just replacing the Github PR viewer! I started with a (native SwiftUI) read-only front end for tree-sitter and SCIP (the code-indexing standard). Then: as I reviewed PRs, I tried to catch myself doing annoying repetitive things and just building out additional features, like "show me all the knowable call chains for this function", or "show me every implementation of this trait".
You can get a fair ways just by thinking of things to hide in a PR viewer, just to clear space for the things you need to comprehend.