fix: Use OCS API to fetch absolute NC URL

Assisted-by: ClaudeCode:claude-opus-4-8
Signed-off-by: Marcel Klehr <mklehr@gmx.net>

Author: marcelklehr

ex_app/lib/agent.py

@@ -44,6 +44,30 @@
 	print(f"Reading file '{key_file_path}'.")
 	key = file.read()
 
+# The user-facing absolute base URL is stable for the app's lifetime; resolve it once.
+_absolute_base_url: str | None = None
+
+
+async def get_absolute_base_url(nc: AsyncNextcloudApp) -> str:
+	"""
+	Return the user-facing absolute base URL of the Nextcloud instance.
+
+	``nc.app_cfg.endpoint`` may be an internal address (reverse-proxy / docker host), so
+	ask app_api for the public URL. The result is cached module-wide to avoid an HTTP
+	request on every conversation turn; falls back to the endpoint if the lookup fails.
+	"""
+	global _absolute_base_url
+	if _absolute_base_url is None:
+		try:
+			_absolute_base_url = (await nc.ocs(
+				'GET', '/ocs/v2.php/apps/app_api/api/v1/info/nextcloud_url/absolute', json={'url': '/'}
+			))['absolute_url'].rstrip('/')
+		except Exception as e:
+			print(f"Could not resolve absolute Nextcloud URL, falling back to endpoint: {e}")
+			return nc.app_cfg.endpoint
+	return _absolute_base_url
+
+
 def load_conversation_old(conversation_token: str):
 	"""
 	Load a checkpointer with the conversation state from the conversation token
@@ -157,7 +181,8 @@ async def call_model(
 		if tool_enabled("web_fetch"):
 			system_prompt_text += "Use the web_fetch tool to fetch web content. You can fetch the complete page content of a duckduckgo search result using web_fetch as well.\n"
 		if tool_enabled("parse_nextcloud_url"):
-			system_prompt_text += f"This Nextcloud instance is reachable at {nc.app_cfg.endpoint}. URLs starting with this root belong to this Nextcloud instance; use the parse_nextcloud_url tool to turn such a link the user pasted into concrete ids before calling the relevant app tools.\n"
+			base_url = await get_absolute_base_url(nc)
+			system_prompt_text += f"This Nextcloud instance is reachable at {base_url}. URLs starting with this root belong to this Nextcloud instance; use the parse_nextcloud_url tool to turn such a link the user pasted into concrete ids before calling the relevant app tools.\n"
 
 		if task['input'].get('memories'):
 			system_prompt_text += "You can remember things from other conversations with the user. If relevant, take into account the following memories:\n\n" + "\n".join(task['input']['memories']) + "\n\n"