Fix create

packages/simulator/package.json

@@ -34,7 +34,7 @@
     "node": ">=22"
   },
   "scripts": {
-    "build": "tsc -p .",
+    "build": "tsc -p tsconfig.build.json",
     "types": "tsc -p tsconfig.json --noEmit",
     "test": "MIDNIGHT_BACKEND=dry vitest run",
     "test:live": "MIDNIGHT_BACKEND=live vitest run",

packages/simulator/src/factory/createSimulator.ts

@@ -199,13 +199,18 @@ export function createSimulator<
      * @param options - Backend selection, witnesses, private state, live world.
      * @returns The constructed simulator (subclass-aware via `this`).
      */
-    static async create<T extends Simulator>(
+    static async create(
       this: new (
         deps: BackendDeps<P, L>,
-      ) => T,
-      contractArgs: TArgs = [] as unknown as TArgs,
-      options: SimulatorOptions<P, W> = {},
-    ): Promise<T> {
+      ) => Simulator,
+      // Permissive so subclasses can override `create` with contract-specific
+      // params/returns without tripping TS's static-side `extends` check.
+      ...args: unknown[]
+    ): Promise<Simulator> {
+      const [
+        contractArgs = [] as unknown as TArgs,
+        options = {} as SimulatorOptions<P, W>,
+      ] = args as [TArgs?, SimulatorOptions<P, W>?];
       const deps = await prepareBackend(contractArgs, options);
       return new this(deps);
     }

packages/simulator/test/integration/Witness.test.ts

@@ -11,7 +11,10 @@ const BYTES_OVERRIDE = new Uint8Array(32).fill(1);
 const FIELD_OVERRIDE = 222n;
 const UINT_OVERRIDE = 333n;
 
-const overrideWitnesses = (): IWitnessWitnesses<WitnessPrivateState> => ({
+const overrideWitnesses = (): IWitnessWitnesses<
+  unknown,
+  WitnessPrivateState
+> => ({
   wit_secretBytes(ctx) {
     return [ctx.privateState, BYTES_OVERRIDE];
   },

packages/simulator/tsconfig.build.json

@@ -0,0 +1,20 @@
+{
+  // Emit-only config for the published package. Extends the nodenext base
+  // (NOT tsconfig.json, which is bundler/noEmit) so `src` is compiled and
+  // typechecked under the same ESM resolution consumers get. This is what
+  // enforces correct `.js` import extensions. `yarn build` runs this; the
+  // comprehensive typecheck lives in `tsconfig.json`.
+  "extends": "@tsconfig/node24/tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "./src",
+    "outDir": "./dist",
+    "declaration": true,
+    "skipLibCheck": true,
+    "sourceMap": true,
+    "rewriteRelativeImportExtensions": true,
+    "erasableSyntaxOnly": true,
+    "verbatimModuleSyntax": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}

packages/simulator/tsconfig.json

@@ -1,21 +1,17 @@
 {
+  // Comprehensive typecheck. Uses bundler resolution to match how the
+  // tests actually resolve under vitest. Never emits: `tsconfig.build.json` owns
+  // emit and enforces nodenext/ESM correctness on the published `src`.
   "extends": "@tsconfig/node24/tsconfig.json",
   "compilerOptions": {
-    "rootDir": "./src",
-    "outDir": "./dist",
-    "declaration": true,
+    "noEmit": true,
+    "declaration": false,
+    "module": "preserve",
+    "moduleResolution": "bundler",
     "skipLibCheck": true,
-    "sourceMap": true,
-    "rewriteRelativeImportExtensions": true,
     "erasableSyntaxOnly": true,
     "verbatimModuleSyntax": true
   },
-  "include": [
-    "src/**/*"
-  ],
-  "exclude": [
-    "node_modules",
-    "dist",
-    "tests"
-  ]
-}
+  "include": ["src/**/*", "test/**/*"],
+  "exclude": ["node_modules", "dist"]
+}