fix(runtimes): always show machine header in picker; pre-fill rename with shared name only

Testing + review follow-ups on #5087:

1. The create-agent picker hid the machine group header when there was only
   one machine (e.g. after a search narrowed to one), collapsing to a flat
   list. Always render the machine header so grouping stays consistent.

2. (Elon) RenameMachineDialog pre-filled from the first non-empty custom_name
   on the machine, but the machine title only uses a name when ALL runtimes
   share one (sharedCustomName). A lone per-runtime name would thus pre-fill as
   if it were the machine name — the same runtime-vs-machine confusion this PR
   set out to remove. Export sharedCustomName and use it for the pre-fill;
   otherwise pre-fill empty. Added direct unit tests.

Co-authored-by: multica-agent <github@multica.ai>

packages/views/agents/components/runtime-picker.tsx

@@ -72,7 +72,6 @@ export function RuntimePicker({
   }, [filteredRuntimes, search, currentUserId]);
 
   const showSearch = runtimes.length > SEARCH_THRESHOLD;
-  const showGroupHeaders = machines.length > 1;
 
   const selectedRuntime =
     runtimes.find((d) => d.id === selectedRuntimeId) ?? null;
@@ -210,17 +209,19 @@ export function RuntimePicker({
             ) : (
               machines.map((machine) => (
                 <div key={machine.id}>
-                  {showGroupHeaders && (
-                    <div className="flex items-center justify-between gap-2 px-2 pb-0.5 pt-2 text-[11px] font-medium text-muted-foreground">
-                      <span className="truncate">{machine.title}</span>
-                      <span className="shrink-0 tabular-nums">
-                        {t(($) => $.create_dialog.runtime_group_online, {
-                          online: machine.onlineCount,
-                          total: machine.runtimes.length,
-                        })}
-                      </span>
-                    </div>
-                  )}
+                  {/* Always show the machine header — even when a search or a
+                      single-machine workspace narrows it to one group — so the
+                      grouping stays consistent instead of collapsing to a flat
+                      list. */}
+                  <div className="flex items-center justify-between gap-2 px-2 pb-0.5 pt-2 text-[11px] font-medium text-muted-foreground">
+                    <span className="truncate">{machine.title}</span>
+                    <span className="shrink-0 tabular-nums">
+                      {t(($) => $.create_dialog.runtime_group_online, {
+                        online: machine.onlineCount,
+                        total: machine.runtimes.length,
+                      })}
+                    </span>
+                  </div>
                   {machine.runtimes.map((device) => {
                     const ownerMember = getOwnerMember(device.owner_id);
                     const disabled = !isRuntimeUsableForUser(

packages/views/runtimes/components/runtime-machines.test.ts

@@ -4,6 +4,7 @@ import {
   buildRuntimeMachines,
   filterRuntimeMachines,
   runtimeMachineCounts,
+  sharedCustomName,
   splitRuntimeName,
 } from "./runtime-machines";
 
@@ -349,3 +350,33 @@ describe("splitRuntimeName", () => {
     });
   });
 });
+
+describe("sharedCustomName", () => {
+  it("returns the name when every runtime shares one non-empty custom_name", () => {
+    expect(
+      sharedCustomName([
+        makeRuntime({ id: "a", custom_name: "Bohan's MacBook" }),
+        makeRuntime({ id: "b", custom_name: "Bohan's MacBook" }),
+      ]),
+    ).toBe("Bohan's MacBook");
+  });
+
+  it("returns null when only some runtimes are named (a lone per-runtime name is not the machine name)", () => {
+    expect(
+      sharedCustomName([
+        makeRuntime({ id: "a", custom_name: "just this one" }),
+        makeRuntime({ id: "b", custom_name: null }),
+      ]),
+    ).toBeNull();
+  });
+
+  it("returns null when the names disagree, or the set is empty", () => {
+    expect(
+      sharedCustomName([
+        makeRuntime({ id: "a", custom_name: "Air" }),
+        makeRuntime({ id: "b", custom_name: "Pro" }),
+      ]),
+    ).toBeNull();
+    expect(sharedCustomName([])).toBeNull();
+  });
+});

packages/views/runtimes/components/runtime-machines.ts

@@ -274,7 +274,7 @@ function runtimeDeviceName(runtime: AgentRuntime): string | null {
 // daemon, so a name shared by all of them is the machine's label. A one-off
 // per-runtime rename (not shared) is deliberately ignored here so it can't
 // masquerade as the whole machine's name.
-function sharedCustomName(runtimes: AgentRuntime[]): string | null {
+export function sharedCustomName(runtimes: AgentRuntime[]): string | null {
   if (runtimes.length === 0) return null;
   const names = runtimes.map((r) => r.custom_name?.trim() ?? "");
   const first = names[0];

packages/views/runtimes/components/runtimes-page.tsx

@@ -44,6 +44,7 @@ import {
   buildRuntimeMachines,
   filterRuntimeMachines,
   runtimeMachineCounts,
+  sharedCustomName,
   type RuntimeMachine,
   type RuntimeMachineFilter,
 } from "./runtime-machines";
@@ -254,8 +255,10 @@ export function RuntimesPage({
       ? m.runtimes[0]
       : m.runtimes.find((r) => r.owner_id === currentUserId);
     if (!editable) return null;
-    const currentName =
-      m.runtimes.find((r) => r.custom_name?.trim())?.custom_name?.trim() ?? "";
+    // Pre-fill only a real machine name — the same rule the machine title uses
+    // (every runtime shares one non-empty custom_name). A lone per-runtime
+    // custom name must NOT masquerade as the machine's current name.
+    const currentName = sharedCustomName(m.runtimes) ?? "";
     return { runtimeId: editable.id, currentName };
   }, [selectedMachine, canManageProfiles, currentUserId]);