Svelte used to have compile-time reactivity, but switched to runtime reactivity via signals: https://svelte.dev/blog/runes

I'm curious if Coi will also suffer from the drawbacks of compile-time reactivity. Or as its own language that doesn't have to "fit" into JS, can Coi side-step the disadvantages via syntax?

Runes allowed simpler Svelte syntax while making it more clear, consistent, flexible, and composable.

Support for signals may help in terms of interop with native browser JS and other frameworks: https://github.com/tc39/proposal-signals

I suspect Svelte’s heavy lift with compile-time reactivity came largely from trying to infer "reactive intent" from standard JavaScript code. Since JS is so dynamic, the compiler had to rely on heuristics or strict assignment rules

Coi avoids this ambiguity because the compiler can definitively trace usage patterns. Since mut variables are explicitly declared, the compiler essentially just looks at where they are used in the view {} block to establish dependencies at compile time. This static analysis is precise and doesn't require the compiler to "guess" intent, effectively preserving the benefits of compile-time reactivity without the fragility found in dynamic languages