From 530308033b0f604b05c421e260c1eeef8cf1c3fe Mon Sep 17 00:00:00 2001
From: Alexander Bocken <alexander@bocken.org>
Date: Sun, 24 May 2026 15:41:39 +0200
Subject: [PATCH] fix(build): disable prerender crawl so build stops OOMing

`/hikes` is `prerender = true` and carries the global nav, so the
prerender crawler followed those links and tried to statically render
the whole dynamic, DB-/ML-backed app. SvelteKit prerenders inside a
heap-capped worker_threads worker, so this exhausted its heap
(ERR_WORKER_OUT_OF_MEMORY) and failed the build.

- svelte.config.js: prerender.crawl = false. The intended static set is
  fully described by `prerender = true` (/hikes) + the /errors/[status]
  EntryGenerator, so crawling is unneeded. Add a defensive
  handleHttpError that ignores /hikes/*/images/* 404s (those binaries
  live in hikes-assets/, served by nginx/dev-middleware, not /static).
- hooks.server.ts: skip init when `building` so builds don't connect to
  Mongo, start the payment scheduler, or warm the romcal cache.
- hikes/[slug]: set `prerender = false`, enforcing the intent its
  comment already stated.

Version 1.86.1 -> 1.86.2.
---
 package.json                     |  2 +-
 src/hooks.server.ts              | 10 ++++++++++
 src/routes/hikes/[slug]/+page.ts |  6 +++++-
 svelte.config.js                 | 19 +++++++++++++++++++
 4 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/package.json b/package.json
index fbdc00ca..eca6ee40 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "homepage",
-	"version": "1.86.1",
+	"version": "1.86.2",
 	"private": true,
 	"type": "module",
 	"scripts": {
diff --git a/src/hooks.server.ts b/src/hooks.server.ts
index ea3b05c3..27867d82 100644
--- a/src/hooks.server.ts
+++ b/src/hooks.server.ts
@@ -1,6 +1,7 @@
 import type { Handle, HandleServerError, ServerInit } from "@sveltejs/kit"
 import { redirect } from "@sveltejs/kit"
 import { sequence } from "@sveltejs/kit/hooks"
+import { building } from "$app/environment"
 import * as auth from "./auth"
 import { initializeScheduler } from "./lib/server/scheduler"
 import { dbConnect } from "./utils/db"
@@ -122,6 +123,15 @@ async function timing({ event, resolve }: Parameters<Handle>[0]) {
 }
 
 export const init: ServerInit = async () => {
+  // SvelteKit runs prerendering/analysis inside a worker_threads worker (see
+  // @sveltejs/kit utils/fork.js) whose JS heap is capped well below the main
+  // thread's. `init` fires there too, so warming the romcal cache during a
+  // build exhausts that worker's heap → ERR_WORKER_OUT_OF_MEMORY and a failed
+  // build. None of it is needed at build time: no prerendered route touches the
+  // DB, and connecting to Mongo / starting the payment scheduler from a build
+  // is undesirable regardless. Skip startup work while building.
+  if (building) return;
+
   console.log('🚀 Server starting - initializing database connection...');
   try {
     await dbConnect();
diff --git a/src/routes/hikes/[slug]/+page.ts b/src/routes/hikes/[slug]/+page.ts
index 3653fc2b..9d0ef368 100644
--- a/src/routes/hikes/[slug]/+page.ts
+++ b/src/routes/hikes/[slug]/+page.ts
@@ -4,7 +4,11 @@ import type { PageLoad } from './$types';
 
 // Not prerendered: the page needs the live session so private images can be
 // gated behind login. Performance hit is small — the page is mostly hashed
-// static assets (track JSON, image variants).
+// static assets (track JSON, image variants). Without this flag the prerender
+// crawler still followed the overview's hike links and rendered every detail
+// page at build time, which exhausted the prerender worker's heap
+// (ERR_WORKER_OUT_OF_MEMORY); `false` keeps the crawler from prerendering them.
+export const prerender = false;
 
 // Glob the .svx modules so Vite can pre-bundle them and we can resolve
 // the matching one synchronously at load time.
diff --git a/svelte.config.js b/svelte.config.js
index 3a895ad3..4cd10587 100644
--- a/svelte.config.js
+++ b/svelte.config.js
@@ -21,6 +21,25 @@ const config = {
 		adapter: adapter({
 			precompress: true  // Enable brotli and gzip compression
 		}),
+		prerender: {
+			// The only intentionally-static pages are /hikes (prerender=true) and
+			// the /errors/[status] set (via that route's EntryGenerator). With the
+			// crawler on, it follows the global nav out of /hikes and tries to
+			// prerender the whole dynamic, DB-/ML-backed app — which runs the
+			// forked prerender worker out of heap (ERR_WORKER_OUT_OF_MEMORY) and
+			// fails the build. Disable crawling: the prerendered set is then driven
+			// entirely by `prerender = true` + EntryGenerator.
+			crawl: false,
+			handleHttpError: ({ path, message }) => {
+				// Defensive: hike image binaries live in `hikes-assets/`, outside
+				// `/static` (nginx serves them in prod, a Vite middleware in dev —
+				// see vite.config.ts), so the crawler can't fetch them. Harmless
+				// while crawl is off, but keeps a 404 from failing the build if
+				// crawling is ever re-enabled.
+				if (/^\/hikes\/[^/]+\/images\//.test(path)) return;
+				throw new Error(message);
+			}
+		},
 		alias: {
 			$models: 'src/models',
 			$utils: 'src/utils',