Workers screen shows each agent's version and protocol, and who is behind

The hello carries the fluksio-worker version. An agent refused for an older
protocol stays listed as Needs upgrade until it attaches again. Docs gain an
Upgrading workers section.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WgBfkm4rCmtd1T4vHWjEPx

frontend/src/routes/_layout/workers.tsx

@@ -9,6 +9,7 @@ import {
   FlavorsService,
   WorkersService,
 } from "@/client"
+import { Badge } from "@/components/ui/badge"
 import { Button } from "@/components/ui/button"
 import {
   Dialog,
@@ -172,15 +173,38 @@ function Attached() {
                 </span>
               ) : null}
             </span>
-            <span className="pl-6 font-mono text-xs text-muted-foreground">
-              {worker.cpus} cpu
-              {worker.gpus ? ` · ${worker.gpus} gpu` : ""}
-              {worker.ram_mb ? ` · ${Math.round(worker.ram_mb / 1024)} GB` : ""}{" "}
-              · {worker.in_flight}/{worker.max_parallel} in flight
-            </span>
+            {worker.behind ? (
+              <span className="pl-6 text-xs text-muted-foreground">
+                Refused for an older protocol. Upgrade it with{" "}
+                <code className="font-mono">pip install -U fluksio-worker</code>
+              </span>
+            ) : (
+              <span className="pl-6 font-mono text-xs text-muted-foreground">
+                {worker.cpus} cpu
+                {worker.gpus ? ` · ${worker.gpus} gpu` : ""}
+                {worker.ram_mb
+                  ? ` · ${Math.round(worker.ram_mb / 1024)} GB`
+                  : ""}{" "}
+                · {worker.in_flight}/{worker.max_parallel} in flight
+              </span>
+            )}
           </span>
-          <span className="text-xs text-muted-foreground">
-            seen {ago(worker.last_seen ?? 0)}
+          <span className="flex items-center gap-3 text-xs text-muted-foreground">
+            {worker.behind ? (
+              <Badge
+                variant="outline"
+                className="border-transparent bg-destructive/15 text-destructive"
+              >
+                Needs upgrade
+              </Badge>
+            ) : null}
+            <span className="font-mono">
+              {worker.version ? `v${worker.version} · ` : ""}protocol{" "}
+              {worker.protocol}
+            </span>
+            <span>
+              {worker.behind ? "refused" : "seen"} {ago(worker.last_seen ?? 0)}
+            </span>
           </span>
         </div>
       ))}