From 357d9e4c21386cdc6ec9fe95d035eea9c63973c8 Mon Sep 17 00:00:00 2001
From: Taras Mankovski <tarasm@gmail.com>
Date: Mon, 28 Sep 2026 10:12:19 -0400
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Stop=20doubling=20the=20prefix?=
 =?UTF-8?q?=20on=20a=20proxied=20site's=20sitemap?=
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Deploys have failed since effection started publishing under its real home.
thefrontside/effection#1248 moved its production `--base` to
`https://frontside.com/effection`, so every `<loc>` in the sitemap it serves
now carries the mount point rather than a site-relative path.

`parseSitemapUrls` added `/effection` to all of them regardless, asking
staticalize for 519 urls under `/effection/effection` that are nowhere. The
crawl reported 519 errors and exited non-zero, which is the whole deploy.

A path already under the mount is left alone. One that is not still gets it,
so Interactors and Graphgen — which advertise their own origin — are
unchanged, and so is an Effection preview, whose base is its own alias url.

Deciding on the path rather than the origin covers all three, and a sibling
such as `/effectionx` is not mistaken for the mount.
---
 routes/proxy-route.ts | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/routes/proxy-route.ts b/routes/proxy-route.ts
index 7132ac9f..60877694 100644
--- a/routes/proxy-route.ts
+++ b/routes/proxy-route.ts
@@ -199,11 +199,32 @@ function parseSitemapUrls(
       let path = options.root
         ? url.pathname.replace(`/${options.root}`, "/")
         : url.pathname;
-      let pathname = posixNormalize(`/${options.prefix}${path}`);
-      paths.push({ pathname });
+      paths.push({ pathname: prefixed(path, options.prefix) });
     } catch {
       // skip malformed URLs
     }
   }
   return paths;
 }
+
+/**
+ * Mount a path from a proxied site's sitemap under its prefix here.
+ *
+ * A site staticalized with `--base` naming the url it lives at *on this site*
+ * already carries the prefix in every `<loc>` — Effection publishes
+ * `https://frontside.com/effection/docs`, not `/docs`. Adding the prefix to
+ * that would ask for `/effection/effection/docs`, which is nowhere.
+ *
+ * A site that still advertises its own origin, as Interactors and Graphgen do,
+ * needs the prefix. So does an Effection preview, whose base is its own alias
+ * url. Deciding on the path rather than the origin covers all three.
+ */
+export function prefixed(path: string, prefix: string): string {
+  let mount = `/${prefix}`;
+
+  if (path === mount || path.startsWith(`${mount}/`)) {
+    return posixNormalize(path);
+  }
+
+  return posixNormalize(`${mount}${path}`);
+}