diff --git a/public/index.html b/public/index.html
index aea7556b..d7a15698 100644
--- a/public/index.html
+++ b/public/index.html
@@ -13,7 +13,10 @@
   <meta property="og:image" content="https://raw.githubusercontent.com/Kpa-clawbot/corescope/master/public/og-image.png">
   <meta property="og:image:width" content="1200">
   <meta property="og:image:height" content="630">
-  <meta property="og:url" content="https://analyzer.00id.net">
+  <!-- No og:url: it is the canonical destination OG consumers navigate to, so a
+       hardcoded value sends every self-hosted instance's shared links to that one
+       host (#1890). Omitted, consumers use the URL they crawled — correct for
+       every deployment, no configuration needed. -->
   <meta property="og:type" content="website">
   <meta name="theme-color" content="#0a0a0a">
 
diff --git a/test-all.sh b/test-all.sh
index c2e8e56c..86371b37 100755
--- a/test-all.sh
+++ b/test-all.sh
@@ -36,6 +36,7 @@ node test-issue-1648-m2-emoji-scan.js
 node test-issue-1648-m3-emoji-scan.js
 node test-issue-1648-m6-final-sweep.js
 node test-issue-1648-m6-lint-self.js
+node test-issue-1890-og-url.js
 node test-traces.js
 node test-live-multibyte-filter.js
 
diff --git a/test-issue-1890-og-url.js b/test-issue-1890-og-url.js
new file mode 100644
index 00000000..8db009a2
--- /dev/null
+++ b/test-issue-1890-og-url.js
@@ -0,0 +1,61 @@
+#!/usr/bin/env node
+/* Issue #1890 — index.html must not hardcode one instance's URL in its
+ * Open Graph tags.
+ *
+ * `<meta property="og:url" content="https://analyzer.00id.net">` shipped to
+ * every self-hosted CoreScope. Facebook, Messenger and other OG consumers treat
+ * og:url as the canonical destination, so clicking a shared preview from ANY
+ * instance navigated to that one host instead of the instance the link came
+ * from. With no og:url present, consumers fall back to the URL they crawled,
+ * which is correct for every deployment without any configuration.
+ *
+ * og:image is deliberately NOT covered: it points at the project's own asset on
+ * raw.githubusercontent.com, which is a shared project resource, not a
+ * redirect target.
+ */
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const assert = require('assert');
+
+const INDEX = path.resolve(__dirname, 'public', 'index.html');
+const html = fs.readFileSync(INDEX, 'utf8');
+
+let passed = 0, failed = 0;
+function test(name, fn) {
+  try {
+    fn();
+    passed++;
+    console.log(`  ✅ ${name}`);
+  } catch (e) {
+    failed++;
+    console.log(`  ❌ ${name}: ${e.message}`);
+  }
+}
+
+console.log('\n=== #1890: index.html carries no instance-specific canonical URL ===');
+
+test('no og:url meta tag pinning a single instance', () => {
+  const m = html.match(/<meta[^>]*property=["']og:url["'][^>]*>/i);
+  assert.ok(!m, `og:url must not be hardcoded; found: ${m && m[0]}`);
+});
+
+test('no rel="canonical" pinning a single instance', () => {
+  const m = html.match(/<link[^>]*rel=["']canonical["'][^>]*>/i);
+  assert.ok(!m, `canonical link must not be hardcoded; found: ${m && m[0]}`);
+});
+
+test('the analyzer.00id.net host appears nowhere in index.html', () => {
+  assert.ok(!/00id\.net/i.test(html), 'index.html still references 00id.net');
+});
+
+test('og:title and og:description are still present', () => {
+  // The fix removes one tag, not the embed. Guard against over-deletion.
+  assert.ok(/property=["']og:title["']/i.test(html), 'og:title missing');
+  assert.ok(/property=["']og:description["']/i.test(html), 'og:description missing');
+  assert.ok(/property=["']og:image["']/i.test(html), 'og:image missing');
+});
+
+console.log(`\n  #1890 og:url: ${passed} passed, ${failed} failed\n`);
+process.exit(failed ? 1 : 0);