That link does go over an optimized tree-diffing algorithm for ASTs, but the question I'm wondering is how to extend incremental parsing into incremental diffing, as opposed to full parse into full diff.
The short answer is that it's unsolved in general and just done ad-hoc in practice. I'm working on incremental & demand-driven analysis techniques for my PhD research and currently building essentially what you describe. The state-of-the-art is probably this technique from this year's PLDI [1] -- last I heard they were using a batch parser but planning on integrating with tree-sitter at some point.
[1] https://dl.acm.org/doi/10.1145/3453483.3454052