Fix postinstall patches for partial workspace installs

package.json

@@ -15,7 +15,7 @@
     "dev:server": "NODE_ENV=development tsx packages/server/scripts/dev-runner.ts",
     "dev:app": "npm run start --workspace=@paseo/app",
     "dev:website": "npm run dev --workspace=@paseo/website",
-    "postinstall": "patch-package",
+    "postinstall": "node scripts/postinstall-patches.mjs",
     "build": "npm run build --workspaces --if-present",
     "typecheck": "npm run typecheck --workspaces --if-present",
     "test": "npm run test --workspaces --if-present",

scripts/postinstall-patches.mjs

@@ -0,0 +1,14 @@
+import { existsSync } from "node:fs";
+import { spawnSync } from "node:child_process";
+
+// In CI we often install a single workspace (e.g. server/relay/website). Only apply patches
+// when the patched dependency is actually present.
+const hasDraggableFlatlist = existsSync("node_modules/react-native-draggable-flatlist");
+if (!hasDraggableFlatlist) {
+  process.exit(0);
+}
+
+const cmd = process.platform === "win32" ? "patch-package.cmd" : "patch-package";
+const result = spawnSync(cmd, { stdio: "inherit" });
+process.exit(result.status ?? 1);
+