diff --git a/apps/indeedhub/manifest.yml b/apps/indeedhub/manifest.yml
index 31605ef9..b4f059cd 100644
--- a/apps/indeedhub/manifest.yml
+++ b/apps/indeedhub/manifest.yml
@@ -73,6 +73,8 @@ app:
       - exec: ["sh", "-c", "if ! grep -qE '<script[^>]*nostr-provider' /usr/share/nginx/html/index.html && ! grep -qE '(sub_filter|<script).*nostr-provider' /etc/nginx/conf.d/default.conf; then sed -i 's#</head>#<script src=\"/nostr-provider.js\"></script></head>#' /usr/share/nginx/html/index.html; fi"]
       - exec: ["sed", "-i", "s#tab-signer-v2#tab-signer-v4#g; s#tab-signer-v3#tab-signer-v4#g", "/etc/nginx/conf.d/default.conf", "/usr/share/nginx/html/index.html"]
       - exec: ["sed", "-i", "s#src=\"/nostr-provider.js\"#src=\"/nostr-provider.js?v=tab-signer-v4\"#g", "/etc/nginx/conf.d/default.conf", "/usr/share/nginx/html/index.html"]
+      # Compose the outer app-proxy prefix for NIP-98 signed URL verification.
+      - exec: ["sed", "-i", "s|proxy_set_header X-Forwarded-Prefix /api;|proxy_set_header X-Forwarded-Prefix $http_x_forwarded_prefix/api;|", "/etc/nginx/conf.d/default.conf"]
       - exec: ["nginx", "-s", "reload"]
 
   # TCP liveness on the nginx port, NOT an http GET of /. nginx binds 7777 at
diff --git a/scripts/tests/test_indeehub_prefix_hook.py b/scripts/tests/test_indeehub_prefix_hook.py
new file mode 100644
index 00000000..501bda94
--- /dev/null
+++ b/scripts/tests/test_indeehub_prefix_hook.py
@@ -0,0 +1,43 @@
+"""Offline behavior checks for the native post-install proxy prefix hook."""
+import pathlib
+import subprocess
+import tempfile
+import unittest
+import yaml
+
+ROOT = pathlib.Path(__file__).resolve().parents[2]
+
+
+def prefix_hook():
+    hooks = yaml.safe_load((ROOT / "apps/indeedhub/manifest.yml").read_text())["app"]["hooks"]["post_install"]
+    matches = [index for index, hook in enumerate(hooks) if "X-Forwarded-Prefix" in " ".join(hook.get("exec", []))]
+    assert len(matches) == 1
+    index = matches[0]
+    assert hooks[index + 1] == {"exec": ["nginx", "-s", "reload"]}
+    return hooks[index]["exec"]
+
+
+class IndeeHubPrefixHook(unittest.TestCase):
+    def test_composes_prefix_before_reload_and_is_idempotent(self):
+        original = "server {\n    proxy_set_header Host $http_host;\n    proxy_set_header X-Forwarded-Prefix /api;\n}\n"
+        expected = original.replace("X-Forwarded-Prefix /api;", "X-Forwarded-Prefix $http_x_forwarded_prefix/api;")
+        with tempfile.TemporaryDirectory() as directory:
+            config = pathlib.Path(directory) / "default.conf"
+            config.write_text(original)
+            args = prefix_hook()
+            self.assertEqual(args[-1], "/etc/nginx/conf.d/default.conf")
+            for _ in range(2):
+                subprocess.run([*args[:-1], str(config)], check=True)
+                self.assertEqual(config.read_text(), expected)
+
+    def test_existing_composed_prefix_is_preserved(self):
+        original = "proxy_set_header X-Forwarded-Prefix $http_x_forwarded_prefix/api;\n"
+        with tempfile.TemporaryDirectory() as directory:
+            config = pathlib.Path(directory) / "default.conf"
+            config.write_text(original)
+            subprocess.run([*prefix_hook()[:-1], str(config)], check=True)
+            self.assertEqual(config.read_text(), original)
+
+
+if __name__ == "__main__":
+    unittest.main()