feat(hosts): a host's health tiles span the card and the gaps match; Add host is a dialog on the list (#5290, #5291)

#5290 "Host page: the health tiles span the card's width; even spacing above Ansible":
the four tiles take equal quarters (halves on a phone) and their sparklines stretch
across them; the Monitors + Agent row drops the Agent card's own margin, so the gap
above Ansible is 1rem like every other.

#5291 "Add host opens as a dialog over the Hosts list": a native <dialog> on /hosts/,
opened by Add host or /hosts/?add=1. A name clash re-renders the list with it open,
the error and what was typed. GET /hosts/new is gone; hosts/form.html is Edit only.

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

tests/core/test_host_page.py

@@ -16,6 +16,8 @@ async def test_ansible_comes_before_the_docker_list(app, monkeypatch):
             "hosts/detail.html", host=host, monitors=[], uptime=None, alerts=[],
             linked_target=None, linkable_targets=[], ansible_sources=[])
     docker = page.index('hx-get="/plugins/docker/host/h1"')
+    # #5290: Monitors and Agent share a row whose cards drop their own margin.
+    assert '<div class="host-pair">' in page
     assert page.index(">Ansible</h3>") < docker
     assert page.index('hx-get="/plugins/host_agent/panel/h1"') < docker
     # Monitors are added on their own form, filed under this host (#5277);
@@ -91,13 +93,40 @@ async def test_a_host_without_an_agent_can_get_a_manual_install(app):
     assert 'action="/plugins/host_agent/fleet/h1/register"' in page and ">Install manually</button>" in page
 
 
-async def test_add_host_sends_a_clash_back_with_what_was_typed(app):
-    """#5283: an inline error and the typed values, not a bare text page."""
-    async with app.test_request_context("/hosts/new"):
+async def test_add_host_is_a_dialog_on_the_hosts_list(app):
+    """#5291: the form was two fields on a page of its own."""
+    async with app.test_request_context("/hosts/"):
         session["user_role"] = "operator"
-        page = await render_template("hosts/form.html", host=None, error="A host named nas already exists.",
-                                     values={"name": "nas", "address": "10.0.0.9"})
+        closed = await render_template("hosts/list.html", hosts=[], host_status={}, uptime={}, agent={}, add=None)
+    dialog = re.search(r'<dialog id="add-host".*?</dialog>', closed, re.S).group(0)
+    assert 'action="/hosts/"' in dialog and ">Cancel</button>" in dialog
+    assert re.search(r'<input[^>]*name="address"[^>]*>', dialog).group(0).count("required") == 0
+    assert "showModal()\">Add host</button>" in closed
+    assert "getElementById('add-host').showModal();</script>" not in closed
+    assert "/hosts/new" not in closed
+
+    async with app.test_request_context("/hosts/"):
+        session["user_role"] = "viewer"
+        viewer = await render_template("hosts/list.html", hosts=[], host_status={}, uptime={}, agent={}, add={})
+    assert "<dialog" not in viewer and ">Add host<" not in viewer
+
+
+async def test_add_host_sends_a_clash_back_with_what_was_typed(app):
+    """#5283, #5291: the list again, the dialog open, an inline error and the typed values."""
+    async with app.test_request_context("/hosts/"):
+        session["user_role"] = "operator"
+        page = await render_template(
+            "hosts/list.html", hosts=[], host_status={}, uptime={}, agent={},
+            add={"values": {"name": "nas", "address": "10.0.0.9"}, "error": "A host named nas already exists."})
     assert 'role="alert">A host named nas already exists.<' in page
     assert 'value="nas"' in page and 'value="10.0.0.9"' in page
-    assert re.search(r'<input[^>]*name="address"[^>]*>', page).group(0).count("required") == 0
-    assert '<a href="/hosts/">Hosts</a>' in page and ">Add host</span>" in page
+    assert "getElementById('add-host').showModal();</script>" in page
+
+
+async def test_edit_host_keeps_its_page(app):
+    host = SimpleNamespace(id="h1", name="nas", address="10.0.0.5")
+    async with app.test_request_context("/hosts/h1/edit"):
+        session["user_role"] = "operator"
+        page = await render_template("hosts/form.html", host=host)
+    assert 'action="/hosts/h1"' in page and 'value="nas"' in page and 'value="10.0.0.5"' in page
+    assert '<a href="/hosts/h1">nas</a>' in page and ">Save</button>" in page

tests/core/test_status.py

@@ -69,3 +69,12 @@ def test_sparkline_svg_handles_edge_cases():
     assert "polyline" in sparkline_svg([1, 2, 3])
     assert "polyline" in sparkline_svg([4, 4, 4])      # flat series, no div-by-zero
     assert "polyline" in sparkline_svg([1, None, 3])   # None values filtered
+
+
+def test_a_sparkline_can_stretch_across_its_tile():
+    """#5290: the host page's tiles are wide; the line fills them, stroke kept."""
+    wide = sparkline_svg([1, 2, 3], height=24, fill_width=True)
+    assert 'width="100%"' in wide and 'preserveAspectRatio="none"' in wide
+    assert 'vector-effect="non-scaling-stroke"' in wide
+    fixed = sparkline_svg([1, 2, 3])
+    assert 'width="80"' in fixed and "preserveAspectRatio" not in fixed

tests/plugins/host_agent/test_fleet_page.py

@@ -31,8 +31,8 @@ async def test_silent_agents_come_first_and_the_table_leads_the_page(app):
                                             new_token=None, install_url=None, ansible_available=False,
                                             deploy_targets=[], deploy_groups=[], managed_key_set=False)
 
-    # Hosts are added in one place, Hosts → Add host (#5282).
-    assert "fleet/add-host" not in page and 'href="/hosts/new"' in page
+    # Hosts are added in one place, the Add host dialog on Hosts (#5282, #5291).
+    assert "fleet/add-host" not in page and 'href="/hosts/?add=1"' in page
     assert '<span class="badge badge-warn">Silent</span>' in page
     assert '<span class="badge badge-warn">Never reported</span>' in page
     assert '<span class="badge badge-ok">Reporting</span>' in page