ts-core

Write a src/core.ts module exporting a Model interface, a Msg discriminated union, an initialModel function, and one pure update function. The @native-sdk/core frontend checks the subset and the core compiler compiles it to native code.

Banned features include npm imports, async/Promises, regexes, generators, eval, mutation of shared data, module-level let, Map/Set, typeof/instanceof checks, string concatenation, and class inheritance. Each violation produces a named teaching diagnostic with the fix.

Yes, arrays your function creates locally can be mutated with push, pop, splice, sort, and indexed writes until they escape by being returned, stored, or aliased. Parameters, model data, and module constants are never mutable.

Effects are returned as Cmd data alongside the model from update or initialModel, and recurring timers come from an exported subscriptions function returning Sub values. The runtime interprets commands after the model commits and dispatches results back as Msgs.

Use the TypeScript core path for new apps unless the user explicitly chose Zig. A tree containing both src/core.ts and src/main.zig is a teaching error, since the build detects the core path from the file tree.