fix: type-check src/gui instead of excluding it

package.json

@@ -20,7 +20,7 @@
     "test": "vitest run",
     "test:e2e": "playwright test",
     "typecheck": "tsc -p tsconfig.json --noEmit",
-    "check": "npm run typecheck && npm test",
+    "check": "npm run typecheck && npm run typecheck:gui && npm test",
     "prepublishOnly": "npm run build && npm run check",
     "build:release": "bash scripts/build-release.sh",
     "build:release:darwin": "bash scripts/build-release.sh darwin",
@@ -41,7 +41,8 @@
     "gui:dev": "bun src/gui/index.ts",
     "build:gui": "bash scripts/build-gui.sh",
     "build:gui:darwin": "bash scripts/build-gui.sh darwin",
-    "notices:update": "node scripts/generate-third-party-notices.mjs"
+    "notices:update": "node scripts/generate-third-party-notices.mjs",
+    "typecheck:gui": "tsc -p tsconfig.gui.json"
   },
   "keywords": [
     "cli",
@@ -65,6 +66,7 @@
     "zod": "^4.1.13"
   },
   "devDependencies": {
+    "@types/bun": "^1.3.14",
     "@types/cors": "^2.8.17",
     "@types/express": "^5.0.3",
     "@types/node": "^26.1.0",

src/gui/index.ts

@@ -39,7 +39,9 @@ if (process.env.DVALINCODE_GUI_ROLE === 'server') {
 
   // The server prints "…http://localhost:<port>" once it's listening. Keep
   // draining stdout afterwards so the child never blocks on a full pipe.
-  let resolveUrl: (url: string) => void;
+  // Definite assignment: a Promise executor runs synchronously, so this is set
+  // before the reader below can reach it — TypeScript cannot see that.
+  let resolveUrl!: (url: string) => void;
   const urlPromise = new Promise<string>((resolve) => (resolveUrl = resolve));
   (async () => {
     const decoder = new TextDecoder();

tsconfig.gui.json

@@ -0,0 +1,21 @@
+{
+  // src/gui runs under Bun, not Node, so it cannot join the main tsconfig: it
+  // uses `Bun`, `import.meta.path`, and webview-bun's FFI types. It was simply
+  // excluded, which left it unchecked while it imports from src/core — a
+  // signature change there would only surface during a GUI release.
+  //
+  // `exclude` must be restated. It is inherited from the base config, and an
+  // inherited exclude wins over the include below, which silently turns this
+  // whole check into a no-op.
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    // Bun resolves like a bundler, not like Node. nodenext makes TypeScript
+    // reject webview-bun's own extensionless relative imports.
+    "module": "esnext",
+    "moduleResolution": "bundler",
+    "types": ["bun"],
+    "noEmit": true
+  },
+  "include": ["src/gui/**/*.ts", "src/core/**/*.ts", "src/version.ts"],
+  "exclude": ["dist", "node_modules"]
+}