feat(dashboard): Hosts widget worst first, load against cores, one home per fact (#5251)

The Hosts — Overview widget opens with a verdict ("VDNT-Util01: CPU high."
or "All 3 hosts healthy."), then one row per host under one header: CPU,
memory, disk / and load. Rows sort by host_glance: a down monitor, a
reading past critical, a quiet agent, a warning, then the healthy. Load
reads "16.8 / 8 cores", graded per core as Settings → Thresholds intends
(cores counted from the per-core CPU sub-resources, as on the host page).
A quiet agent's last figures are shown uncoloured, with when it last reported.

Ping and 24h uptime are gone from this widget: they belong to Monitors. So
are the unlabelled CPU sparkline and the 30-day uptime query it no longer
needs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/core/test_dashboard_defaults.py

@@ -84,13 +84,59 @@ async def test_a_quiet_overview_says_so(app):
     assert ">host<" in page and 'href="/alerts/"' not in page   # the share view has no links
 
 
-async def test_the_hosts_widget_shows_load(app):
-    host = SimpleNamespace(id="h1", name="web-1")
-    agent = {"web-1": {"cpu_pct": 12.0, "mem_used_pct": 40.0, "load_1m": 0.734, "fresh": True}}
+def _host(hid, name):
+    return SimpleNamespace(id=hid, name=name)
+
+
+def test_hosts_sort_worst_first():
+    """#5251: a down monitor, then a reading past critical, then a quiet agent,
+    then a warning, then the healthy, by name; a host with nothing last."""
+    from steward.core.settings import to_thresholds_cfg
+    from steward.hosts.service import host_glance
+    th = to_thresholds_cfg({})
+    hosts = [_host("a", "alpha"), _host("b", "busy"), _host("d", "dead"), _host("q", "quiet"),
+             _host("w", "warm"), _host("n", "nothing")]
+    status = {"d": {"state": "down"}, "a": {"state": "up"}}
+    agent = {"alpha": {"cpu_pct": 10.0, "fresh": True}, "busy": {"cpu_pct": 99.0, "fresh": True},
+             "quiet": {"cpu_pct": 99.0, "fresh": False},
+             "warm": {"cpu_pct": 10.0, "load_per_core": 85, "fresh": True}}
+    rows = host_glance(hosts, status, agent, th)
+    assert [(r["host"].name, r["state"]) for r in rows] == [
+        ("dead", "down"), ("busy", "crit"), ("quiet", "stale"), ("warm", "warn"),
+        ("alpha", "up"), ("nothing", "unknown")]
+    assert rows[1]["worst"][0] == "CPU" and rows[3]["worst"][0] == "Load"
+    assert rows[2]["worst"] is None          # a quiet agent's old figures aren't graded
+
+
+async def test_the_hosts_widget_gives_a_verdict_and_load_against_cores(app):
+    from datetime import datetime, timezone
+    rows = [
+        {"host": _host("h2", "VDNT-Util01"), "state": "crit", "worst": ("CPU", 99.0, "crit"),
+         "agent": {"cpu_pct": 99.0, "mem_used_pct": 28.0, "disk_root": 52.0, "load_1m": 16.77,
+                   "cores": 8, "load_per_core": 210, "fresh": True}},
+        {"host": _host("h1", "VDNT-Docker02"), "state": "up", "worst": None,
+         "agent": {"cpu_pct": 1.0, "mem_used_pct": 4.0, "disk_root": 44.0, "load_1m": 0.92,
+                   "cores": 4, "load_per_core": 23, "fresh": True}},
+        {"host": _host("h3", "nas"), "state": "stale", "worst": None,
+         "agent": {"cpu_pct": 5.0, "fresh": False, "last_at": datetime(2026, 10, 7, tzinfo=timezone.utc)}},
+    ]
     async with app.test_request_context("/hosts/overview/widget"):
-        page = await render_template("hosts/overview_widget.html", hosts=[host], host_status={},
-                                     uptime={}, agent=agent, cpu_sparks={})
-    assert ">load</span> 0.73" in page
+        session["user_id"] = "u1"
+        page = await render_template("hosts/overview_widget.html", rows=rows)
+    assert "2 of 3 hosts need a look." in page
+    assert page.index("VDNT-Util01") < page.index("VDNT-Docker02")
+    assert "16.8 / 8 cores" in page and "0.9 / 4 cores" in page
+    assert "agent last reported" in page
+    assert page.count("<th>") == 5 and ">ping<" not in page and "24h" not in page
+    assert not hex_colours(page), hex_colours(page)
+
+
+async def test_one_busy_host_is_named_in_the_verdict(app):
+    rows = [{"host": _host("h2", "web-1"), "state": "crit", "worst": ("CPU", 99.0, "crit"),
+             "agent": {"cpu_pct": 99.0, "fresh": True}}]
+    async with app.test_request_context("/hosts/overview/widget"):
+        page = await render_template("hosts/overview_widget.html", rows=rows)
+    assert "web-1:" in page and "CPU high." in page and "tone-crit" in page
 
 
 async def test_a_widget_polls_at_its_own_pace(app):