fix(e2e): hydration infinite-loop — drop broken use-sync-external-store polyfill, adopt gell-v2 optimizeDeps + PLAYWRIGHT env

Root cause (from Playwright trace artifacts on run 26543764735):

  console: 'The result of getServerSnapshot should be cached to avoid
           an infinite loop'
  console: 'Maximum update depth exceeded'
  console: 'Warning: Error in route match: __root__/'

SSR rendered perfectly (the dehydrated HTML has <h1>Tasks</h1>, the
session user, the empty task list — the whole shell). On the client,
hydration hit React's infinite-loop guard and tore the DOM down, so
'getByText("Tasks")' resolved to undefined for every test. ALL 15
e2e tests failed for the same reason — not just the public-marketing
subset that flaked under the earlier dep bump.

The source: src/polyfills/use-sync-external-store-shim.ts (lines
19-23) returned 'selector(getSnapshot())' as a brand-new arrow
function on every render. React's useSyncExternalStore reads the
snapshot fn and detects the new closure as a snapshot change, which
schedules a re-render, which creates another new closure, infinite
loop. TanStack 1.149 happened not to trigger this path; 1.167 does.

Three changes:

1. vite.config.ts: drop the resolve.alias block that pointed every
   'use-sync-external-store/shim*' specifier at the broken polyfill.
   Vite resolves the real package (v1.6.0, already in node_modules,
   peerDeps include React 19) via optimizeDeps.
   src/polyfills/use-sync-external-store-shim.ts deleted — gell-v2
   keeps an identical file as dead code but never aliases it; we
   delete instead to keep the polyfills/ dir honest.

2. vite.config.ts: optimizeDeps restructured to match gell-v2.
   - include: 8 deps Vite would otherwise discover on first request
     (TanStack history/router-core + helpers). Pre-bundling at
     startup prevents the 'optimized → reloading' mid-flight
     invalidation that crashes hydrating pages.
   - exclude: better-auth ecosystem (server-only by design — TSS-2
     keeps them out of the client graph), jose / @noble/* /
     h3-v2 (server-only transitive deps).
   - force: true when PLAYWRIGHT=true (stale-hash references from a
     prior CI run can't break the first request).

   The previous include list shipped @better-auth/core/* + h3-v2 to
   the client optimizer pass — opposite direction from what TSS-2
   demands. Caught here, but worth flagging as a near-miss.

3. playwright.config.ts: PLAYWRIGHT=true added to webServer.env so
   the optimizeDeps.force kicks in. vite.config.ts also reads it for
   server.hmr.overlay=false (the TanStack Start streaming-warning
   overlay otherwise intercepts Playwright clicks —
   TanStack/router#3584) and
   server.watch.ignored=['**/routeTree.gen.ts'] (Router's
   watchChange handler self-feeds otherwise).

Quality gates: check-types ✓, biome ci ✓, check-tss-2 ✓ (8
createServerFn files clean), 62 unit tests pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: Enalmada

playwright.config.ts

@@ -57,7 +57,7 @@ const config: PlaywrightTestConfig = {
 	webServer: {
 		reuseExistingServer: true,
 		command:
-			"bun run docker:up && sh scripts/wait-for.sh && bun run drizzle:migrate && cross-env GOOGLE_CLIENT_ID=test-client-id GOOGLE_CLIENT_SECRET=test-client-secret BETTER_AUTH_SECRET=test-auth-secret APP_ENV=development bun run dev:vite",
+			"bun run docker:up && sh scripts/wait-for.sh && bun run drizzle:migrate && cross-env GOOGLE_CLIENT_ID=test-client-id GOOGLE_CLIENT_SECRET=test-client-secret BETTER_AUTH_SECRET=test-auth-secret APP_ENV=development PLAYWRIGHT=true bun run dev:vite",
 		url: "http://localhost:3000",
 		stdout: "pipe",
 		stderr: "pipe",

src/polyfills/use-sync-external-store-shim.ts

@@ -1,4 +1,3 @@
-import path from "node:path";
 import { lingui } from "@lingui/vite-plugin";
 // TODO: Re-enable when Serwist Vite plugin works with Nitro v3
 // import { serwist } from "@serwist/vite";
@@ -32,23 +31,25 @@ export default defineConfig({
 		// Note: Warning about "native plugins disabled" is a known beta issue - can be ignored
 		enableNativePlugin: true,
 	},
+	server: {
+		hmr: {
+			// PLAYWRIGHT env var is set in playwright.config.ts webServer.env.
+			// The HMR error overlay intercepts pointer events and blocks
+			// Playwright clicks when a transient SSR/streaming warning fires
+			// (e.g. TanStack Start's "Response body object should not be
+			// disturbed" — https://github.com/TanStack/router/issues/3584).
+			// Keep the overlay on for human dev for visibility.
+			overlay: process.env.PLAYWRIGHT !== "true",
+		},
+		watch: {
+			// Prevent infinite watch loop: TanStack Router's `watchChange`
+			// handler fires on its own output file, triggering regeneration,
+			// which fires `watchChange` again.
+			ignored: ["**/routeTree.gen.ts"],
+		},
+	},
 	resolve: {
 		tsconfigPaths: true,
-		alias: {
-			"use-sync-external-store/shim/with-selector.js": path.resolve(
-				__dirname,
-				"./src/polyfills/use-sync-external-store-shim.ts",
-			),
-			"use-sync-external-store/shim/with-selector": path.resolve(
-				__dirname,
-				"./src/polyfills/use-sync-external-store-shim.ts",
-			),
-			"use-sync-external-store/shim/index.js": path.resolve(
-				__dirname,
-				"./src/polyfills/use-sync-external-store-shim.ts",
-			),
-			"use-sync-external-store/shim": path.resolve(__dirname, "./src/polyfills/use-sync-external-store-shim.ts"),
-		},
 	},
 	plugins: [
 		tailwindcss(),
@@ -144,57 +145,50 @@ export default defineConfig({
 		noExternal: ["better-auth"],
 	},
 	optimizeDeps: {
-		exclude: ["better-auth"],
-		// Pre-bundle the deps that vite would otherwise discover lazily on the
-		// first request and then trigger a full client reload after pre-bundling
-		// (the "✨ new dependencies optimized → ✨ reloading" pair in the dev
-		// log). Without this list, the bump to @tanstack/react-start 1.167 +
-		// better-auth 1.4 racks up ~38 newly-discovered deps on the first
-		// request after `vite dev` starts, and the resulting mid-flight reload
-		// breaks every Playwright test in that 10-15s window. The names below
-		// are exactly what the dev-mode optimizer logged on a cold start —
-		// keep them in sync if the dep tree shifts (the CI failure mode is
-		// obvious: "✨ new dependencies optimized" lines you don't see in
-		// the include list).
+		// Pre-bundle deps Vite would otherwise discover at runtime. When the
+		// dev server discovers a new dep mid-session it triggers a full
+		// client reload after pre-bundling (the "✨ new dependencies
+		// optimized → ✨ reloading" pair in the dev log), which invalidates
+		// `react/jsx-runtime` hashes mid-flight and crashes any pages
+		// hydrating in that 10-15s window. Listing the discoverable deps
+		// here forces the first-request optimization to happen at startup
+		// before Playwright is allowed to send its first navigation (the
+		// readiness check on the dev server is HTTP, not just TCP).
+		//
+		// Mirrors gell-v2/vite.config.ts. If the dep tree shifts, watch for
+		// "✨ new dependencies optimized" lines that aren't on this list
+		// and add them.
 		include: [
-			"@better-auth/core/api",
-			"@better-auth/core/context",
-			"@better-auth/core/db",
-			"@better-auth/core/db/adapter",
-			"@better-auth/core/env",
-			"@better-auth/core/error",
-			"@better-auth/core/social-providers",
-			"@better-auth/core/utils",
-			"@better-auth/telemetry",
-			"@better-auth/utils",
-			"@better-auth/utils/base64",
-			"@better-auth/utils/binary",
-			"@better-auth/utils/hash",
-			"@better-auth/utils/hex",
-			"@better-auth/utils/hmac",
-			"@better-auth/utils/random",
-			"@better-fetch/fetch",
-			"@noble/ciphers/chacha.js",
-			"@noble/ciphers/utils.js",
-			"@noble/hashes/hkdf.js",
-			"@noble/hashes/scrypt.js",
-			"@noble/hashes/sha2.js",
-			"@noble/hashes/utils.js",
 			"@tanstack/history",
 			"@tanstack/router-core",
-			"@tanstack/router-core/isServer",
 			"@tanstack/router-core/ssr/client",
 			"@tanstack/router-core/ssr/server",
-			"better-call",
-			"better-sse",
 			"defu",
-			"h3-v2",
-			"jose",
-			"jose/errors",
-			"kysely",
 			"nanostores",
 			"seroval",
-			"zod",
+			"tiny-invariant",
+		],
+		exclude: [
+			// better-auth ecosystem — server-only by design (drizzle / postgres
+			// behind every export). Letting Vite pre-bundle these into the
+			// client graph is the TSS-2 leak we sweep for in CI; keep them
+			// out of the optimizer pass entirely.
+			"better-auth",
+			"@better-auth/core",
+			"@better-auth/telemetry",
+			"@better-auth/utils",
+			"@better-fetch/fetch",
+			"better-call",
+			"better-sse",
+			// better-auth transitive deps — no browser exports.
+			"@noble/ciphers",
+			"@noble/hashes",
+			"jose",
+			// Server-only framework deps leaked from SSR.
+			"h3-v2",
 		],
+		// Force re-bundling under Playwright so stale-hash references from
+		// a prior CI run can't break the first request.
+		...(process.env.PLAYWRIGHT === "true" && { force: true }),
 	},
 });