From e4428efb8d8878fbe015fb12c002b5e4f9e1bb8e Mon Sep 17 00:00:00 2001
From: stroblme <stroblme@posteo.de>
Date: Sun, 30 Aug 2026 17:25:14 +0200
Subject: [PATCH] Draw a node that is down as a troubled neuron
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`brain_graph` read `self.issues` alone, which is what a build found — so a
node that loaded and then lost its device was a well neuron on Home, and
that is what someone comes to this view to find.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KYM38KSb4V4v2T71eifnZv
---
 backend/fluksio/flow/controller.py     |  8 +++++---
 backend/tests/flow/test_brain_graph.py | 22 +++++++++++++++++++++-
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/backend/fluksio/flow/controller.py b/backend/fluksio/flow/controller.py
index 6f43120..5b57dfe 100644
--- a/backend/fluksio/flow/controller.py
+++ b/backend/fluksio/flow/controller.py
@@ -1497,10 +1497,12 @@ class FlowController:
         compiled pipeline, so a node that failed to load still appears — a
         broken neuron is exactly what someone comes to this view to find.
         """
-        # What validation found, by the node it names. A cycle names every node
-        # in it, so all of them are marked rather than an arbitrary one.
+        # What validation found, by the node it names, plus what is down right
+        # now — a neuron someone comes here to find is as often a node that
+        # stopped working as one that never built. A cycle names every node in
+        # it, so all of them are marked rather than an arbitrary one.
         troubled: dict[str, str] = {}
-        for issue in self.issues:
+        for issue in self.issues + self._health_issues():
             if issue.code in ADVISORY_ISSUES:
                 continue
             for member in (*issue.nodes, *filter(None, [issue.node])):
diff --git a/backend/tests/flow/test_brain_graph.py b/backend/tests/flow/test_brain_graph.py
index 3be0868..8cf982c 100644
--- a/backend/tests/flow/test_brain_graph.py
+++ b/backend/tests/flow/test_brain_graph.py
@@ -9,7 +9,7 @@ from pathlib import Path
 
 import pytest
 
-from fluksio.flow.controller import FlowController
+from fluksio.flow.controller import FlowController, LoadedNode
 from fluksio.flow.messages import DType, MessageSpec
 from fluksio.flow.nodes import MqttNode
 from fluksio.flow.pipeline import ValidationIssue
@@ -105,6 +105,26 @@ def test_a_neuron_carries_what_stops_it_running(controller: FlowController):
     }
 
 
+def test_a_node_that_is_down_is_a_troubled_neuron(controller: FlowController):
+    """A node that stopped working is what someone comes to this view to find.
+
+    `self.issues` is what a build found; being down happens afterwards, so the
+    graph has to read the health issues too or a dead node draws as a well one.
+    """
+    controller.loaded["house.scale"] = LoadedNode(
+        id="house.scale",
+        flow="house",
+        health="down",
+        health_detail="broker unreachable",
+    )
+
+    marked = {
+        node.id: node.issue for node in controller.brain_graph().nodes if node.issue
+    }
+    assert list(marked) == ["house.scale"]
+    assert "broker unreachable" in marked["house.scale"]
+
+
 def test_an_advisory_issue_leaves_the_graph_clean(controller: FlowController):
     controller.issues = [
         ValidationIssue(