Porting from JavaScript to TypeScript

.fallowrc.json

@@ -0,0 +1,11 @@
+{
+  "entry": [
+    "source/cloudflare/worker.mjs",
+    "source/engine/main-browser.ts",
+    "source/game/**/main.ts"
+  ],
+  "ignorePatterns": [
+    ".fallow/**",
+    "dist/**"
+  ]
+}

.github/copilot-instructions.md

@@ -63,6 +63,10 @@ eventBus.subscribe("registry.frozen", () => {
 - **No `any`, `unknown`, or `*`**. Use specific types (e.g. `ArrayBuffer`).
 - **No `@returns {void}`**.
 
+### Helper Functions
+- **Prefer function declarations** for helper functions when lexical `this`, expression semantics, or very local inline usage are not needed.
+- **Use `const foo = (...) => ...`** only when arrow-function behavior is actually relevant.
+
 ## Specific Patterns to Observe
 
 - **Module System**: ES Modules exclusively (`type: "module"` in package.json).

.github/instructions/build-and-deploy.instructions.md

@@ -14,8 +14,12 @@
 
 ### Three different kinds of builds
 
-We need to make sure the correct build is used at all times.
+All code is always compiled through esbuild (via Vite) before execution. This ensures full TypeScript feature support (decorators, const enum, etc.) across every environment.
 
-1. Dedicated development server: The code is executed in node.js directly, no build step required.
-2. Dedicated production server: The code is built using `npm run build:production` and the output files in `dist/` are executed in node.js. This is required to strip out all console.assert statements and other development-only code for optimal performance.
-3. Client code: The code is built using `npm run build:production` and the output files in `dist/` are executed in the browser.
+1. Dedicated development server: Build with `npm run dedicated:dev` (Vite watch mode), run with `npm run dedicated:start`. The build step compiles TypeScript to JavaScript in `dist/dedicated/` with source maps enabled.
+2. Dedicated production server: Build with `npm run dedicated:build:production` and run with `npm run dedicated:start`. Strips console.assert and other development-only code for optimal performance.
+3. Client code: Build with `npm run build:production` and serve the output in `dist/browser/` to the browser.
+
+### Testing
+
+Tests use `tsx` (esbuild-based) as the Node.js loader, ensuring the same TypeScript compilation behavior as the Vite builds. Run with `npm test`.

.github/instructions/code-style-guide.instructions.md

@@ -53,17 +53,18 @@ Use `eventBus` for **business logic events and lifecycle hooks**.
 
 ## File Organization
 
-### No index.mjs Files
+### No index.ts Files
 
 - **Avoid barrel exports**. Use direct imports instead.
-- Example: Import `BrushModelRenderer` from `./renderer/BrushModelRenderer.mjs`, not `./renderer`.
+- Example: Import `BrushModelRenderer` from `./renderer/BrushModelRenderer.ts`, not `./renderer`.
 
 ## General Style Guidelines
 
 - **Use `const` and `let`** instead of `var`.
 - **Use camelCase** for variables and functions, PascalCase for classes.
 - **Use descriptive names** for variables and functions.
 - **Keep functions small** and focused on a single task or a single responsibility.
+- **Prefer function declarations** for helper functions when arrow-function semantics are not needed.
 - **Use early returns** to reduce nesting and improve readability.
 - **Avoid deep nesting**; refactor into helper functions if necessary.
 - **Never mutate function parameters**; create new variables instead.
@@ -153,13 +154,15 @@ class GL {
 
 ### `null` initializations
 
-- **Explicitly initialize variables to `null`** when they will later hold an object reference and provide JSDoc type annotations either as cast or an inline comment.
-  - Example: `let model = /** @type {BaseModel} */ (null);`
+- **Explicitly initialize variables to `null`** when they will later hold an object reference.
+  - In `.ts` files: `let model: BaseModel | null = null;`
+  - In `.mjs` files: `let model = /** @type {BaseModel} */ (null);`
 
 ### Empty Arrays
 
-- **Initialize empty arrays with `[]`** instead of `new Array()` and provide JSDoc type annotations.
-  - Example: `let vertices = /** @type {number[]} */ ([]);`
+- **Initialize empty arrays with `[]`** instead of `new Array()`.
+  - In `.ts` files: `const vertices: number[] = [];`
+  - In `.mjs` files: `let vertices = /** @type {number[]} */ ([]);`
 
 ## Class and Interface Design
 
@@ -172,6 +175,7 @@ class GL {
 
 - **Use `_` prefix** for protected methods. Add `@protected` JSDoc tag.
 - **Use `#` prefix** for private methods.
+- In `.ts` files, prefer native `protected` / `private` keywords. See `typescript-port.instructions.md`.
 
 ### Respect boundaries of abstraction
 
@@ -184,7 +188,7 @@ class GL {
   - `model` (or `clmodel`) instead of `m`.
   - `entity` instead of `ent` or `e`.
 - **Constants:** UPPER_CASE.
-- **Files:** PascalCase for classes (`BrushModelRenderer.mjs`), camelCase for utils (`modelUtils.mjs`). Always `.mjs`.
+- **Files:** PascalCase for classes (`BrushModelRenderer.ts`), camelCase for utils (`modelUtils.ts`). Always `.ts` for TypeScript source files.
 
 ## Comments