Implement ESLint rules based on TypeScript/JavaScript patterns analysis with test exceptions and update Copilot instructions

.github/copilot-instructions.md

@@ -46,6 +46,30 @@ npm run bootstrap           # Build native components (weak-node-api, examples)
 
 ## Key Patterns
 
+### Code Style and Conventions
+
+**Import Organization**:
+- Use Node.js built-in prefix: `import assert from "node:assert/strict"`
+- Group imports: builtin → external → internal → local
+- Prefer type-only imports: `import type { NodePath } from "@babel/core"`
+
+**Type Definitions**:
+- Prefer `type` over `interface` for simple types and unions
+- Use `as const` for readonly arrays and objects: `const PLATFORMS = ["android", "apple"] as const`
+- Common pattern: `type PlatformName = (typeof PLATFORMS)[number]`
+
+**Function Style**:
+- Prefer `export function` over `export const fn =`
+- Use async/await consistently for asynchronous operations
+- Prefer arrow functions for callbacks and inline functions (except in tests where `describe` and `it` use regular functions)
+
+**Error Handling**:
+- Prefer `assert()` from `node:assert/strict` over throwing errors directly
+- Use structured error handling with custom error types when needed
+
+**Immutable Data Patterns**:
+- Use `const` assertions for compile-time immutability
+
 ### Babel Transformation
 
 The core magic happens in `packages/host/src/node/babel-plugin/plugin.ts`:

eslint.config.js

@@ -1,13 +1,17 @@
 // @ts-check
 
-import { globalIgnores } from "eslint/config";
+// import { globalIgnores } from "eslint/config";
 import globals from "globals";
 import eslint from "@eslint/js";
 import tseslint from "typescript-eslint";
 import eslintConfigPrettier from "eslint-config-prettier/flat";
+import importPlugin from "eslint-plugin-import";
+import nodePlugin from "eslint-plugin-n";
+import unusedImports from "eslint-plugin-unused-imports";
 
 export default tseslint.config(
-  globalIgnores([
+  {
+    ignores: [
     "**/dist/**",
     "**/build/**",
     "apps/test-app/ios/**",
@@ -20,11 +24,18 @@ export default tseslint.config(
     "packages/node-tests/tests/**",
     "packages/node-tests/*.generated.js",
     "packages/node-tests/*.generated.d.ts",
-  ]),
+  ],
+  },
   eslint.configs.recommended,
   tseslint.configs.recommendedTypeChecked,
   {
+    plugins: {
+      import: importPlugin,
+      n: nodePlugin,
+      "unused-imports": unusedImports,
+    },
     rules: {
+      // Existing rule
       "@typescript-eslint/no-floating-promises": [
         "error",
         {
@@ -33,6 +44,56 @@ export default tseslint.config(
           ],
         },
       ],
+
+      // Import/Export Organization
+      "@typescript-eslint/consistent-type-imports": [
+        "error",
+        { prefer: "type-imports" },
+      ],
+      "import/order": [
+        "error",
+        {
+          groups: ["builtin", "external", "internal", "parent", "sibling"],
+          "newlines-between": "always",
+          alphabetize: { order: "asc", caseInsensitive: true },
+        },
+      ],
+      "n/prefer-node-protocol": "error",
+
+      // Type Consistency
+      "@typescript-eslint/consistent-type-definitions": ["error", "type"],
+      "@typescript-eslint/prefer-as-const": "error",
+
+      // Immutable Patterns (excluding prefer-readonly-parameter-types per feedback)
+      "@typescript-eslint/prefer-readonly": "error",
+
+      // Error Standards
+      "@typescript-eslint/prefer-promise-reject-errors": "error",
+      "@typescript-eslint/only-throw-error": "error",
+
+      // Function Style
+      "@typescript-eslint/promise-function-async": "error",
+      "@typescript-eslint/require-await": "error",
+      "prefer-arrow-callback": "error",
+
+      // Console Control
+      "no-console": ["warn", { allow: ["error", "warn"] }],
+
+      // Unused Code
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        {
+          argsIgnorePattern: "^_",
+          varsIgnorePattern: "^_",
+        },
+      ],
+      "unused-imports/no-unused-imports": "error",
+
+      // Strict Typing Enhancements
+      "@typescript-eslint/strict-boolean-expressions": "warn",
+      "@typescript-eslint/no-unnecessary-condition": "warn",
+      "@typescript-eslint/prefer-nullish-coalescing": "error",
+      "@typescript-eslint/prefer-optional-chain": "error",
     },
   },
   {
@@ -81,4 +142,11 @@ export default tseslint.config(
       },
     },
   },
+  {
+    // Exception for test files: allow regular functions in describe() and it() callbacks
+    files: ["**/*.test.ts", "**/*.spec.ts"],
+    rules: {
+      "prefer-arrow-callback": "off",
+    },
+  },
 );