From 12e4ae584752c7b78f15555318a81fa843734a1c Mon Sep 17 00:00:00 2001
From: Mridankan Mandal <xerontitan90@gmail.com>
Date: Wed, 15 Jul 2026 08:30:48 +0000
Subject: [PATCH] fix(openapi): avoid cached request URL

The cached OpenAPI HTML page embedded the first request's absolute JSON URL. Derive the JSON path from the current browser pathname so the cached page stays request-independent across hosts and mount paths.

Signed-off-by: Mridankan Mandal <xerontitan90@gmail.com>
---
 CHANGELOG.md                    |  1 +
 lib/rage/openapi/index.html.erb |  2 +-
 lib/rage/openapi/openapi.rb     |  6 ++----
 spec/openapi/openapi_spec.rb    | 36 +++++++++++++++++++++++++++++++++
 4 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3021af3e..ae22b5ae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 ### Fixed
 
+- [OpenAPI] Avoid caching a request-specific spec URL in the HTML docs page.
 - [OpenAPI] Fix schema registry key collisions for Blueprinter classes referenced under different views.
 
 ## [1.26.0] - 2026-07-07
diff --git a/lib/rage/openapi/index.html.erb b/lib/rage/openapi/index.html.erb
index 13b8c4b6..aeb31b87 100644
--- a/lib/rage/openapi/index.html.erb
+++ b/lib/rage/openapi/index.html.erb
@@ -13,7 +13,7 @@
     <script>
       window.onload = () => {
         window.ui = SwaggerUIBundle({
-          url: '<%= spec_url %>',
+          url: window.location.pathname.replace(/\/?$/, "/json"),
           dom_id: '#swagger-ui',
         });
       };
diff --git a/lib/rage/openapi/openapi.rb b/lib/rage/openapi/openapi.rb
index b9abc145..a7c89b99 100644
--- a/lib/rage/openapi/openapi.rb
+++ b/lib/rage/openapi/openapi.rb
@@ -42,11 +42,9 @@ module Rage::OpenAPI
   #     run Rage.openapi.application(namespace: "Api::V2")
   #   end
   def self.application(namespace: nil)
-    html_app = ->(env) do
+    html_app = ->(_) do
       __data_cache[[:page, namespace]] ||= begin
-        scheme, host, path = env["rack.url_scheme"], env["HTTP_HOST"], env["SCRIPT_NAME"]
-        spec_url = "#{scheme}://#{host}#{path}/json"
-        page = ERB.new(File.read("#{__dir__}/index.html.erb")).result(binding)
+        page = ERB.new(File.read("#{__dir__}/index.html.erb")).result
 
         [200, { "content-type" => "text/html; charset=UTF-8" }, [page]]
       end
diff --git a/spec/openapi/openapi_spec.rb b/spec/openapi/openapi_spec.rb
index af331453..e71187fa 100644
--- a/spec/openapi/openapi_spec.rb
+++ b/spec/openapi/openapi_spec.rb
@@ -3,6 +3,42 @@
 require "prism"
 
 RSpec.describe Rage::OpenAPI do
+  describe ".application" do
+    subject(:app) { described_class.application }
+
+    let(:first_env) do
+      {
+        "PATH_INFO" => "/",
+        "SCRIPT_NAME" => "/docs-a",
+        "HTTP_HOST" => "first.test:3000",
+        "rack.url_scheme" => "http"
+      }
+    end
+
+    let(:second_env) do
+      {
+        "PATH_INFO" => "/",
+        "SCRIPT_NAME" => "/docs-b",
+        "HTTP_HOST" => "second.test:4000",
+        "rack.url_scheme" => "https"
+      }
+    end
+
+    before do
+      allow(Rage.config).to receive(:middleware).and_return([])
+    end
+
+    it "renders a request-independent html page" do
+      _, _, first_body = app.call(first_env)
+      _, _, second_body = app.call(second_env)
+
+      expect(first_body.join).to eq(second_body.join)
+      expect(first_body.join).to include('url: window.location.pathname.replace(/\/?$/, "/json"),')
+      expect(first_body.join).not_to include("first.test:3000")
+      expect(first_body.join).not_to include("/docs-a/json")
+    end
+  end
+
   describe ".__try_parse_collection" do
     subject { described_class.__try_parse_collection(input) }