docs(agents): add per-package AGENTS.md for eslint-config + typescript-config

packages/typescript-config/AGENTS.md

@@ -0,0 +1,77 @@
+# AGENTS.md — typescript-config
+
+Shared TypeScript base configs (`tsconfig.json` files) and Vitest base config, consumed by all packages.
+
+## What it owns
+
+- **`base.json`** — Base `tsconfig.json`: target ES2022, module ESM, `experimentalDecorators` + `emitDecoratorMetadata` for InversifyJS
+- **`nextjs.json`** — Next.js app config: extends base, adds `jsx: "preserve"`, Next.js lib types
+- **`react-library.json`** — React library config: extends base, adds `jsx: "react-jsx"`, DOM lib
+- **`vitest.base.ts`** — Vitest base config: globals, isolate modules, common ignore patterns
+
+## How packages consume them
+
+Packages extend the appropriate base:
+
+```json
+// packages/blog/tsconfig.json
+{
+  "extends": "@repo/typescript-config/base.json",
+  "compilerOptions": {
+    "rootDir": ".",
+    "outDir": "dist",
+    "lib": ["ES2022"]
+  },
+  "include": ["src/**/*"]
+}
+```
+
+Apps extend Next.js config:
+
+```json
+// apps/web-next/tsconfig.json
+{
+  "extends": "@repo/typescript-config/nextjs.json",
+  "compilerOptions": {
+    "rootDir": ".",
+    "outDir": ".next"
+  }
+}
+```
+
+Vitest configs import the base:
+
+```typescript
+// packages/blog/vitest.config.ts
+import { defineConfig } from "vitest/config";
+import path from "path";
+import { vitestBase } from "@repo/typescript-config";
+
+export default defineConfig({
+  ...vitestBase,
+  test: {
+    environment: "node",
+  },
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "./src"),
+    },
+  },
+});
+```
+
+## Test conventions
+
+- No unit tests (config validation via `pnpm typecheck` in other packages)
+- Verify at CI: `pnpm typecheck` succeeds across all packages
+- Type errors should propagate: `pnpm typecheck` fails on invalid source code
+
+## Structure
+
+```
+base.json                    # ES2022, ESM, decorators
+nextjs.json                  # Next.js-specific paths + lib
+react-library.json           # React JSX + DOM
+vitest.base.ts               # Vitest defaults (globals, isolate)
+package.json                 # Exports above files
+```