feat(hosts): the Hosts list searches, filters by group and status, sorts by column, and shows each host's groups (#5294)

#5294 "Hosts list: search, group and status filters; sortable columns; a Groups column".
Ansible inventory groups are Steward's grouping system (operator's ruling): a host's
groups are its linked target's, and membership overlaps, so the list filters by group
rather than sectioning by it.

- Filter bar: search on name or address, a group (or "No group"), a status (Down,
  Agent silent, Up, No monitors). The table swaps in alone and the URL keeps the filters.
- Name, Status, Latency, 30d uptime, CPU and Memory headers sort (sort_th in _macros);
  problems-first stays the default, and a host with no value goes last either way.
- A Groups column of chips, each filtering to its group; shown when any group exists.
- A swap is keyed on HX-Target, so Back to a pushed URL still gets the page.

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

steward/hosts/routes.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 import asyncio
 import uuid
 from datetime import datetime, timezone
-from quart import Blueprint, render_template, request, redirect, url_for, current_app, session
+from quart import Blueprint, make_response, render_template, request, redirect, url_for, current_app, session
 from sqlalchemy import select
 from steward.ansible import executor, sources as ansible_src
 from steward.alerts import service as alert_svc
@@ -47,25 +47,61 @@ async def list_hosts():
 
 async def _list_page(add: dict | None = None):
     """The Hosts list. `add` opens the Add host dialog: {} for an empty form,
-    or {"values": form, "error": msg} when a submit comes back."""
+    or {"values": form, "error": msg} when a submit comes back.
+
+    Search, group and Status filters and a column sort come from the query
+    string (#5294). An HTMX request from the filter bar gets the table alone."""
+    args = request.args
+    sort = args.get("sort") if args.get("sort") in host_svc.HOST_SORTS else "status"
+    default_desc = host_svc.HOST_SORTS[sort]
+    desc = {"desc": True, "asc": False}.get(args.get("dir"), default_desc)
+    f = {"q": args.get("q", "").strip(), "group": args.get("group", ""),
+         "state": args.get("state") if args.get("state") in host_svc.HOST_STATES else "",
+         "sort": sort, "dir": "desc" if desc else "asc"}
+
     async with current_app.db_sessionmaker() as db:
         result = await db.execute(select(Host).order_by(Host.name))
         hosts = result.scalars().all()
-        host_status = await host_svc.host_status(db, [h.id for h in hosts])
+        ids = [h.id for h in hosts]
+        host_status = await host_svc.host_status(db, ids)
         uptime = await host_svc.compute_uptime(db)
         agent = await host_svc.agent_overview_by_host(
             db, [h.name for h in hosts], host_svc.agent_stale_after_seconds(current_app.config))
+        groups = await host_svc.host_groups(db, ids)
+        group_names = await host_svc.group_names(db)
 
-    hosts = sorted(hosts, key=lambda h: (
-        host_svc.host_rank(host_status.get(h.id), agent.get(h.name)), h.name.lower()))
-    return await render_template(
-        "hosts/list.html",
-        hosts=hosts,
-        host_status=host_status,
-        uptime=uptime,
-        agent=agent,
-        add=add,
-    )
+    shown = host_svc.filter_hosts(hosts, q=f["q"], group=f["group"], state=f["state"],
+                                  status=host_status, agent=agent, groups=groups)
+    shown = host_svc.sort_hosts(shown, sort, desc, status=host_status, agent=agent, uptime=uptime)
+
+    def filter_url(**change) -> str:
+        """This list's URL with some filters changed; defaults are left out."""
+        want = {**f, **change}
+        if want["dir"] == ("desc" if host_svc.HOST_SORTS[want["sort"]] else "asc"):
+            want["dir"] = ""
+        if want["sort"] == "status":
+            want["sort"] = ""
+        return url_for("hosts.list_hosts", **{k: v for k, v in want.items() if v})
+
+    def sort_url(key: str) -> str:
+        """A column header's link: its own default direction, or the other
+        way when it is already the sort."""
+        if key == sort:
+            return filter_url(sort=key, dir="asc" if desc else "desc")
+        return filter_url(sort=key, dir="desc" if host_svc.HOST_SORTS[key] else "asc")
+
+    ctx = dict(hosts=shown, total=len(hosts), host_status=host_status, uptime=uptime, agent=agent,
+               groups=groups, group_names=group_names, f=f, filter_url=filter_url, sort_url=sort_url,
+               states=host_svc.HOST_STATES, no_group=host_svc.NO_GROUP, add=add)
+    # The filter bar's swap gets the table alone. A history restore (Back to a
+    # pushed URL) is an HTMX request too but wants the page, so key on the
+    # target; Vary keeps the browser from caching one as the other.
+    partial = request.headers.get("HX-Target") == "hosts-table" \
+        and not request.headers.get("HX-History-Restore-Request")
+    resp = await make_response(await render_template(
+        "hosts/_table.html" if partial else "hosts/list.html", **ctx))
+    resp.headers["Vary"] = "HX-Request"
+    return resp
 
 
 @hosts_bp.get("/<host_id>")