atlasbot: prefer qualified longhorn node subsets

services/comms/scripts/atlasbot/bot.py

@@ -4112,6 +4112,7 @@ def _fallback_fact_answer(prompt: str, context: str) -> str:
                 return f"{hw} nodes: {len(items)}."
 
     if list_intent and include_hw:
+        wants_longhorn = "longhorn" in tokens
         if "control" in q:
             cp_by_hw = _find_value("control_plane_by_hardware")
             if cp_by_hw:
@@ -4122,11 +4123,59 @@ def _fallback_fact_answer(prompt: str, context: str) -> str:
             cp_nodes = _find_value("control_plane_nodes")
             if cp_nodes:
                 return f"Control-plane nodes: {cp_nodes}."
+        if wants_longhorn:
+            for hw in include_hw:
+                best_nodes: list[str] = []
+                best_val = ""
+                for _fact, key, val in parsed_facts:
+                    if not key or not val:
+                        continue
+                    key_tokens = set(_tokens(key))
+                    if "longhorn" not in key_tokens:
+                        continue
+                    if hw not in key_tokens:
+                        continue
+                    nodes = _extract_titan_nodes(val)
+                    if nodes and len(nodes) > len(best_nodes):
+                        best_nodes = nodes
+                        best_val = val
+                    elif not best_nodes and val:
+                        best_val = val
+                if best_nodes:
+                    return f"{hw} longhorn nodes: {', '.join(best_nodes)}."
+                if best_val:
+                    return f"{hw} longhorn nodes: {best_val}."
         for hw in include_hw:
+            if wants_longhorn:
+                continue
             hw_line = _find_value(hw)
             if hw_line:
                 return f"{hw} nodes: {hw_line}."
 
+    if list_intent and "longhorn" in tokens:
+        best_nodes: list[str] = []
+        best_key = ""
+        best_val = ""
+        for _fact, key, val in parsed_facts:
+            if not key or not val:
+                continue
+            key_tokens = set(_tokens(key))
+            if "longhorn" not in key_tokens:
+                continue
+            nodes = _extract_titan_nodes(val)
+            if nodes and len(nodes) > len(best_nodes):
+                best_nodes = nodes
+                best_key = key
+                best_val = val
+            elif not best_nodes and val:
+                best_key = key
+                best_val = val
+        if best_nodes:
+            return f"Longhorn nodes: {', '.join(best_nodes)}."
+        if best_val:
+            label = (best_key or "Longhorn nodes").replace("_", " ").strip()
+            return f"{label.capitalize()}: {best_val}."
+
     if list_intent and "control" in q:
         cp_nodes = _find_value("control_plane_nodes")
         if cp_nodes:

services/comms/scripts/tests/test_atlasbot_modes.py

@@ -162,3 +162,32 @@ class AtlasbotModeTests(TestCase):
 
         self.assertIn("worker nodes", reply.lower())
         self.assertIn("Confidence:", reply)
+
+    def test_longhorn_rpi4_subset_beats_generic_rpi4_list(self):
+        fact_lines = [
+            "rpi4: titan-12, titan-13, titan-14, titan-15, titan-17, titan-18, titan-19",
+            "rpi4 armbian longhorn: titan-13/15/17/19",
+        ]
+
+        with (
+            mock.patch.object(self.bot, "_fact_pack_lines", return_value=fact_lines),
+            mock.patch.object(self.bot, "_ollama_call", side_effect=AssertionError("LLM should not be called")),
+        ):
+            reply = self.bot.open_ended_answer(
+                "which nodes in titan are the rpi4 longhorn nodes?",
+                inventory=[],
+                snapshot=None,
+                workloads=[],
+                history_lines=[],
+                mode="smart",
+                allow_tools=True,
+            )
+
+        self.assertIn("titan-13", reply)
+        self.assertIn("titan-15", reply)
+        self.assertIn("titan-17", reply)
+        self.assertIn("titan-19", reply)
+        self.assertNotIn("titan-12", reply)
+        self.assertNotIn("titan-14", reply)
+        self.assertNotIn("titan-18", reply)
+        self.assertIn("Confidence:", reply)