TK-12268: add creds-in-URL fetch guard (fleet pattern) to gated page

90c4c26423056ebc804f38209e6635d7ed7577a7 · 2026-09-25 13:55:59 -0700 · Steve Abrams

Relative fetch() on a Basic-Auth page threw on user:pass@host bookmarks.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D7LB6rCwpA7ubJTqYzqXEX

Files touched

M public/index.html

Diff

commit 90c4c26423056ebc804f38209e6635d7ed7577a7
Author: Steve Abrams <steve@designerwallcoverings.com>
Date:   Fri Sep 25 13:55:59 2026 -0700

    TK-12268: add creds-in-URL fetch guard (fleet pattern) to gated page
    
    Relative fetch() on a Basic-Auth page threw on user:pass@host bookmarks.
    
    Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
    Claude-Session: https://claude.ai/code/session_01D7LB6rCwpA7ubJTqYzqXEX
---
 public/index.html | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/public/index.html b/public/index.html
index 62c4583..2a151f5 100644
--- a/public/index.html
+++ b/public/index.html
@@ -2,6 +2,30 @@
 <html lang="en" data-theme="dark">
 <head>
 <meta charset="utf-8">
+<script>
+// Credential-safe fetch guard (fleet drop-in) — if this page is opened with
+// credentials in the URL (a saved bookmark / Chrome-remembered basic-auth:
+// https://user:pass@host/…), the browser poisons document.baseURI, so any
+// relative or root-relative fetch('/api/…') throws "Request cannot be constructed
+// from a URL that includes credentials" and callers silently fall to an empty
+// state. Resolve every non-absolute request URL against the credential-free
+// location instead of baseURI. Placed first so it wraps window.fetch before any
+// app script runs. Ref: creds-in-url-fetch-guard-fleet-pattern.
+(function () {
+  var _fetch = window.fetch.bind(window);
+  var cleanBase = function () { return location.origin + location.pathname; };
+  window.fetch = function (input, init) {
+    try {
+      if (typeof input === 'string' && !/^[a-z]+:\/\//i.test(input) && input.indexOf('//') !== 0) {
+        input = new URL(input, cleanBase()).href;
+      } else if (input instanceof Request && !/^[a-z]+:\/\//i.test(input.url)) {
+        input = new Request(new URL(input.url, cleanBase()).href, input);
+      }
+    } catch (_) { /* fall through to native */ }
+    return _fetch(input, init);
+  };
+})();
+</script>
 <meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover">
 <title>Credential Actions — agentabrams</title>
 <style>

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