e2e coverage gaps from review: prerender Passthrough+loading(), redirect under loading() #567

Summary

Three correctness fixes from the multi-agent review landed with unit coverage but still lack the dev + production e2e fixtures the repo mandates (CLAUDE.md: "All e2e tests MUST cover BOTH dev AND production modes"). This issue tracks adding them. The fixtures below are already written and verified to compile; they were pulled out of the stabilization PR because regenerating the test-app .gen.ts + running dual-mode Playwright is a separate, heavier step.

Gap 1 — Prerender Passthrough + loading() + ctx.passthrough() (was M16)

Consumer story. A consumer pre-renders a route, declares a loading() skeleton, and skips specific params at build with ctx.passthrough():

// urls.tsx — what a consumer writes
path("/:slug", Passthrough(ProductDef, LiveProduct), { name: "product" }, () => [
  loading(<ProductSkeleton />),            // <- the loading() boundary is the trigger
])

// ProductDef build handler
async (ctx) => {
  if (!(await isPublished(ctx.params.slug))) return ctx.passthrough(); // skip baking
  return <Product slug={ctx.params.slug} />;
}

Before the fix: because loading() defers the build handler, ctx.passthrough() arrived as a Promise-wrapped component and the synchronous sentinel check missed it — the build baked a corrupt artifact for the skipped param instead of deferring to the live handler. After the fix (detectPrerenderPassthrough awaits the thenable), the param correctly passes through. Unit test: prerender-passthrough-detect.test.ts.

Fixture to add (e2e/test-app/src/urls/prerender-loading.tsx):

import { urls, Prerender, Passthrough } from "@rangojs/router";

export const PrerenderLoadingDef = Prerender<{ slug: string }>(
  async () => [{ slug: "baked" }, { slug: "skip" }],
  async (ctx) => {
    if (ctx.params.slug === "skip") return ctx.passthrough();
    return (
      <div data-testid="prerender-loading-page">
        <h1 data-testid="prerender-loading-title">{ctx.params.slug}</h1>
        <p data-testid="prerender-loading-build">{String(ctx.build)}</p>
        <p data-testid="prerender-loading-ts">{Date.now()}</p>
      </div>
    );
  },
);
export const PrerenderLoadingTest = Passthrough(PrerenderLoadingDef, async (ctx) => (
  <div data-testid="prerender-loading-page">
    <h1 data-testid="prerender-loading-title">{ctx.params.slug}</h1>
    <p data-testid="prerender-loading-build">{String(ctx.build)}</p>
    <p data-testid="prerender-loading-live">live</p>
    <p data-testid="prerender-loading-ts">{Date.now()}</p>
  </div>
));
export const prerenderLoadingPatterns = urls(({ path, loading }) => [
  path("/:slug", PrerenderLoadingTest, { name: "detail" }, () => [
    loading(<div data-testid="prerender-loading-skeleton">Loading...</div>),
  ]),
]);

Wire into urls.tsx: include("/prerender-loading", prerenderLoadingPatterns, { name: "prerenderLoading" }).

Assertions (dev + production):

• baked → prerendered (ctx.build true at build; served from manifest).
• skip → passes through to the live handler (prerender-loading-live present; ctx.build false).
• production: /__test/prerender-manifest-entries?route=prerenderLoading.detail count includes baked but not skip (the M16 regression guard — without the fix, skip would be baked).

Gap 2 — redirect() from a loading() route (was M9)

Consumer story. A sync handler return of redirect() on a loading() route short-circuits to a real HTTP redirect (supported); an async handler return is streamed instead (documented limitation — dev warns via warnOnStreamedResponse).

// supported: synchronous return redirects
path("/sync", () => redirect("/loading-redirect/target"), { name: "sync" }, () => [
  loading(<Skeleton />),
])

Fixture to add (e2e/test-app/src/urls/loading-redirect.tsx):

import { urls, redirect } from "@rangojs/router";
export const loadingRedirectPatterns = urls(({ path, loading }) => [
  path("/sync", () => redirect("/loading-redirect/target"), { name: "sync" }, () => [
    loading(<div data-testid="lr-skeleton">Loading...</div>),
  ]),
  path("/target", () => <div data-testid="lr-target">arrived</div>, { name: "target" }),
]);

Assertions (dev + production): navigating to /loading-redirect/sync lands on /loading-redirect/target (lr-target visible). (The async-swallow limitation is intentionally not e2e'd — it produces a degraded render, not a navigable outcome; it's covered by the unit test + execution-model.md.)

Additional e2e gaps surfaced by the review (lower priority)

• Build-time intercept _currentSegmentId not pinned → ctx.use handle data dropped from the intercept prerender artifact. Needs a test-app intercept handler that pushes a handle, asserted dev + prod.
• server-action-bridge pre-dispatch failure over-invalidates the client cache + broadcasts staleness even though nothing reached the server (over-invalidation only — safe today).
• document-cache private, s-maxage writes to the shared store (spec-correct per RFC 7234 but a defense-in-depth gap); document-cache.test.ts:268 covers private alone.

Test plan

• Wire both fixtures into e2e/test-app/src/urls.tsx; regenerate .gen.ts via the test-app build/dev (runtime discovery — the static CLI can't resolve the factory include); commit router.named-routes.gen.ts.
• Add prerender-loading.test.ts and loading-redirect.test.ts with the assertions above, dev + (production) describes (use prodDescribe/the bucketing convention).
• Run both in dev and production locally; confirm green.