Serve a branded homepage fallback when the here.now shell is unavailable

[HMAKT99]

Summary

The homepage is served by fetching the here.now shell, injecting the catalog, and returning it (loop-routes.js). When that origin fetch throws or the shell returns a 5xx, the Worker passed the upstream failure straight through:

const originResponse = await dependencies.fetch(originRequest);
if (!originResponse.ok) return originResponse;

So during a shell/here.now hiccup, visitors hit an unbranded, catalog-less dead end — even though the Worker already holds every loop record in its own database and renders detail pages from it.

Change

When the shell is unavailable on the homepage, render a minimal branded fallback from the catalog the Worker already has, instead of leaking the upstream error:

• Keeps the site chrome (header/nav/footer) and theme.
• Lists every published loop with working links, so nothing becomes unreachable during an outage.
• Points agents at catalog.json and llms.txt (still live).
• Preserves the real failure status — the upstream 5xx, or 502 when the shell is unreachable — so the outage stays honest, and marks the page noindex so the degraded view isn't indexed.

Behavior is unchanged on the happy path and for non-5xx responses (4xx still passes through as before). Detail pages already render from the DB, so they're unaffected.

Files

• worker/src/render-loops.js — new renderHomepageFallback(loops).
• worker/src/loop-routes.js — serve it on a thrown fetch (502) or upstream 5xx (status preserved).
• worker/test/loop-routes.test.js — two tests (5xx → branded 503 fallback, not the upstream body; unreachable → 502).

Verification

• npm --prefix loop-library/worker run check → 49/49 pass.
• node loop-library/scripts/check.mjs → "Loop Library database-only checks passed."
• git diff --check → clean.

Happy to adjust or close if you'd rather the homepage stay strictly shell-driven on failure — this is meant as a resilience nicety, leaning on the fact that the Worker is now the source of truth for loops.