fix(fleet): align migration SSH parity docs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/mosaic/src/fleet/v1-v2-migration.spec.ts

@@ -352,6 +352,41 @@ describe('v1-to-v2 migration preview', (): void => {
     },
   );
 
+  it('matches production v1 locality for a remote agent with a bare-host SSH target', async () => {
+    const source = v1Source.replace('ssh: operator@build.example.test', 'ssh: build.example.test');
+    const rosterPath = join(
+      await mkdtemp(join(tmpdir(), 'v1-bare-host-ssh-parity-')),
+      'roster.yaml',
+    );
+    temporaryDirectories.push(dirname(rosterPath));
+    await writeFile(rosterPath, source);
+
+    await expect(loadFleetRoster(rosterPath)).resolves.toMatchObject({
+      agents: [
+        expect.any(Object),
+        expect.objectContaining({ host: 'build.example.test', ssh: 'build.example.test' }),
+      ],
+    });
+
+    const preview = await previewV1ToV2Migration({
+      source,
+      decisions: decisions(),
+      observations: observations(),
+      personaDirs: await semanticDirs(),
+    });
+
+    expect(preview.status).toBe('ready');
+    expect(preview.blockers).toEqual([]);
+    expect(preview.inventoryOnlyAgents).toEqual([
+      {
+        name: 'remote0',
+        fields: ['host', 'socket', 'ssh'],
+        disposition: 'inventory-only',
+      },
+    ]);
+    expect(preview.canonicalRoster?.agents.map(({ name }) => name)).toEqual(['coder0']);
+  });
+
   it.each([
     ['socket_name', "  socket_name: ''\n  holder_session: _holder"],
     ['socketName', "  socketName: ''\n  holder_session: _holder"],

packages/mosaic/src/fleet/v1-v2-migration.ts

@@ -778,8 +778,8 @@ function classifyAgentLocality(
   if (hasSsh) {
     if (!ssh) return 'ambiguous';
     const separator = ssh.lastIndexOf('@');
-    const sshHost = separator >= 0 ? ssh.slice(separator + 1) : undefined;
-    if (!sshHost || sshHost !== host) return 'ambiguous';
+    const sshHost = separator >= 0 ? ssh.slice(separator + 1) : ssh;
+    if (sshHost !== host) return 'ambiguous';
   }
   return host === fleetHost ? 'local' : 'remote';
 }