🐛(backend) improve url hallucination instruction

CHANGELOG.md

@@ -48,6 +48,7 @@ and this project adheres to
 - ✨(dev) setup Tilt for local development
 - 🐛(front) project modal now respects document-upload feature flag
 - 🐛(back) self-doc tool no longer triggers on generic or document questions
+- 🐛(backend) improve url hallucination instruction
 
 ## [0.0.15] - 2026-03-31
 

src/backend/chat/agents/conversation.py

@@ -17,11 +17,17 @@
 logger = logging.getLogger(__name__)
 
 PREVENT_URL_HALLUCINATION_INSTRUCTION = (
-    "Never invent or guess URLs. "
-    "Only include URLs explicitly found in tool outputs (e.g., web search results) "
-    "or in provided documents when available. Do not introduce new URLs."
-    "If you need to reference a web page that was not returned by a tool, "
-    "use a descriptive placeholder such as [official link] instead of a URL."
+    "URL POLICY (STRICT): Only include a URL if it appears verbatim in a tool result "
+    "or the user's current message. "
+    "Never write a URL in any other context — not in direct answers, "
+    "suggestions, examples, templates, "
+    "code blocks, or resource recommendations. "
+    "Never write a URL to well-known websites you know from training. "
+    "When no verified URL is available, refer to resources "
+    "by plain text name only (e.g., 'the ANSSI website'). "
+    "When you cannot access a linked document, do not generate "
+    "fictional templates or mock examples of "
+    "its content — ask the user to share the relevant content directly."
 )
 
 MOCKED_RESPONSE = """

src/backend/chat/tests/agents/test_build_conversation_agent.py

@@ -23,7 +23,7 @@ def assert_base_instructions(instructions, date_str=None, language_str=""):
     assert instructions[2].__name__ == "enforce_response_language"
     assert instructions[2]() == language_str
     assert instructions[3].__name__ == "prevent_url_hallucination"
-    assert "Never invent or guess URLs" in instructions[3]()
+    assert "URL POLICY" in instructions[3]()
 
 
 @pytest.fixture(autouse=True)