fix(hydrate): keep options.layers alive for the app's lifetime

[jonlaing]

Summary

Effect.provide(element, scopedLayer) uses scopedWith(scope => ...) internally (effect/internal/layer.js:516), which creates a fresh scope tied to the effect's lifetime. Because element functions return synchronously after building the DOM, every scoped resource — Navigation's popstate listener, SubscriptionRef PubSub subscribers, cache entries — was torn down before the user could interact. Browser back/forward, reactive updates, and anything relying on Effect.addFinalizer silently no-op'd.

Fix in packages/dom/src/Render/hydrate/index.ts: build the merged layers as a Context in hydrate's outer program scope (kept alive by Effect.never), then provide the context.

Investigation timeline

• Symptom: browser back/forward didn't re-render (or fetch loader data) in SSG dev mode; forward via <Link> worked.
• First fix attempt (PR fix(router): run popstate updates on app Runtime via runFork #76) — switched popstate handler from Effect.runSync to Runtime.runFork. Correct fix for that async-set problem, but symptom persisted.
• Second suspicion — Layer.mergeAll(navLayer, dataProviderLayer) inside makeClientLayer. Reproduced in isolation → mergeAll delivered signal updates fine, exonerated.
• Third stop — @effex/vite-plugin's stripStaticConfig transform. The workspace packages/vite-plugin/dist/index.js was stale (source fix from b1241f4 wasn't re-committed), producing Route.render(() => (fn)(undefined)). Portfolio's npm-installed @effex/vite-plugin@1.1.2 had the correct dist. Rebuilding the workspace dist unblocked further diagnosis.
• Final layer — instrumented Navigation.make to log build & finalize. [FINALIZER] fired immediately after registration, before the user could click anything. Root cause: hydrate's inner Effect.provide was scoping the layer to the short-lived element.

Also fixed (found during investigation)

• create-effex SSG template: called hydrate(App(), root) with no layers even though App uses Outlet/Link. Now passes Platform.makeClientLayer(router) via options.layers.
• create-effex SPA template: passed { layers: ... } as a third arg to mount, which doesn't accept options — the arg was silently dropped and the returned Effect was never run. Now uses runApp(mount(...), { layer: ... }).
• apps/docs/src/client.ts: was using the buggy Effect.provide(App(), navLayer) bake-in. Switched to options.layers.

Regression test

packages/dom/src/Render/hydrate/hydrate.test.ts adds a test that builds a scoped layer with a finalizer, hands its element to hydrate with options.layers, and asserts the finalizer has NOT fired 10ms after the initial render. Confirmed to fail against the pre-fix code and pass after.

Test plan

• pnpm --filter @effex/dom test — 17/17 hydrate tests pass, regression test present
• Reverted the fix locally → regression test fails as expected
• Full packages/dom + packages/router suite: 465 passed, 2 skipped, 0 failed
• apps/docs boots and renders (kept Navigation.makeLayer via options.layers)

🤖 Generated with Claude Code

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