diff --git a/packages/base/command.gts b/packages/base/command.gts
index e9d0f2d17c..162b0aac7e 100644
--- a/packages/base/command.gts
+++ b/packages/base/command.gts
@@ -70,6 +70,11 @@ export class CreateAIAssistantRoomResult extends CardDef {
   @field roomId = contains(StringField);
 }
 
+export class SetActiveLLMInput extends CardDef {
+  @field roomId = contains(StringField);
+  @field model = contains(StringField);
+}
+
 export class AddSkillsToRoomInput extends CardDef {
   @field roomId = contains(StringField);
   @field skills = linksToMany(SkillCard);
diff --git a/packages/experiments-realm/set-llm-example.gts b/packages/experiments-realm/set-llm-example.gts
new file mode 100644
index 0000000000..3ca2f43506
--- /dev/null
+++ b/packages/experiments-realm/set-llm-example.gts
@@ -0,0 +1,210 @@
+import { CardDef, Component } from 'https://cardstack.com/base/card-api';
+import { tracked } from '@glimmer/tracking';
+import { action } from '@ember/object';
+import { on } from '@ember/modifier';
+import SetActiveLLMCommand from '@cardstack/boxel-host/commands/set-active-llm';
+import CreateAiAssistantRoomCommand from '@cardstack/boxel-host/commands/create-ai-assistant-room';
+import OpenAiAssistantRoomCommand from '@cardstack/boxel-host/commands/open-ai-assistant-room';
+import { Button } from '@cardstack/boxel-ui/components';
+
+class IsolatedTemplate extends Component<typeof SetLlmExample> {
+  @tracked modelId = 'microsoft/phi-4';
+  @tracked currentRoomId: string | null = null;
+
+  @action
+  async createRoom() {
+    let commandContext = this.args.context?.commandContext;
+    if (!commandContext) return;
+
+    let createAIAssistantRoomCommand = new CreateAiAssistantRoomCommand(
+      commandContext,
+    );
+    let { roomId } = await createAIAssistantRoomCommand.execute({
+      name: `Chat with ${this.modelId}`,
+    });
+
+    let openAiAssistantRoomCommand = new OpenAiAssistantRoomCommand(
+      commandContext,
+    );
+    await openAiAssistantRoomCommand.execute({
+      roomId,
+    });
+
+    this.currentRoomId = roomId;
+  }
+
+  @action
+  async setLLM() {
+    if (!this.currentRoomId) return;
+
+    let commandContext = this.args.context?.commandContext;
+    if (!commandContext) return;
+
+    let setActiveLLMCommand = new SetActiveLLMCommand(commandContext);
+
+    await setActiveLLMCommand.execute({
+      model: this.modelId,
+      roomId: this.currentRoomId,
+    });
+  }
+
+  @action
+  updatemodelId(event: Event) {
+    this.modelId = (event.target as HTMLInputElement).value;
+  }
+
+  <template>
+    <div class='llm-setter'>
+      <div class='content'>
+        <div class='input-section'>
+          <label for='llm-model-name-input'>LLM Model Name</label>
+          <input
+            type='text'
+            value={{this.modelId}}
+            {{on 'input' this.updatemodelId}}
+            class='model-input'
+            id='llm-model-name-input'
+          />
+        </div>
+
+        <div class='buttons-section'>
+          <Button
+            class='create-button'
+            data-test-create-room
+            {{on 'click' this.createRoom}}
+          >
+            Create Room
+          </Button>
+
+          <Button
+            class='set-button'
+            data-test-set-llm
+            {{on 'click' this.setLLM}}
+          >
+            Set Active LLM
+          </Button>
+        </div>
+
+        {{#if this.currentRoomId}}
+          <div class='room-info'>
+            <span class='room-label'>Room ID:</span>
+            <span class='room-id'>{{this.currentRoomId}}</span>
+          </div>
+        {{/if}}
+      </div>
+    </div>
+    <style scoped>
+      .llm-setter {
+        max-width: 600px;
+        margin: 0 auto;
+        padding: 2rem;
+      }
+
+      .content {
+        background: white;
+        border-radius: 16px;
+        box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
+        padding: 1.5rem;
+      }
+
+      .input-section {
+        margin-bottom: 1.5rem;
+      }
+
+      .input-section label {
+        display: block;
+        margin-bottom: 0.5rem;
+        color: #7f8c8d;
+        font-size: 0.9rem;
+      }
+
+      .model-input {
+        width: 100%;
+        padding: 0.75rem;
+        border: 1px solid #e2e8f0;
+        border-radius: 8px;
+        font-size: 1rem;
+        transition: border-color 0.2s;
+      }
+
+      .model-input:focus {
+        outline: none;
+        border-color: #34d399;
+        box-shadow: 0 0 0 3px rgba(52, 211, 153, 0.2);
+      }
+
+      .buttons-section {
+        display: flex;
+        gap: 1rem;
+        margin-bottom: 1rem;
+      }
+
+      .create-button,
+      .set-button {
+        flex: 1;
+        padding: 0.75rem 1.5rem;
+        font-size: 1.1rem;
+        color: white;
+        border: none;
+        border-radius: 8px;
+        cursor: pointer;
+        transition:
+          transform 0.2s,
+          box-shadow 0.2s;
+      }
+
+      .create-button {
+        background: linear-gradient(135deg, #4f46e5, #3730a3);
+      }
+
+      .set-button {
+        background: linear-gradient(135deg, #34d399, #059669);
+      }
+
+      .create-button:hover,
+      .set-button:hover {
+        transform: translateY(-1px);
+      }
+
+      .create-button:hover {
+        box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
+      }
+
+      .set-button:hover {
+        box-shadow: 0 4px 12px rgba(52, 211, 153, 0.3);
+      }
+
+      .set-button[disabled] {
+        opacity: 0.5;
+        cursor: not-allowed;
+        transform: none;
+        box-shadow: none;
+      }
+
+      .room-info {
+        margin-top: 1rem;
+        padding: 1rem;
+        background: #f8fafc;
+        border-radius: 8px;
+        font-size: 0.9rem;
+      }
+
+      .room-label {
+        color: #64748b;
+        margin-right: 0.5rem;
+      }
+
+      .room-id {
+        color: #1e293b;
+        font-family: monospace;
+        font-size: 0.95rem;
+      }
+    </style>
+  </template>
+}
+
+export class SetLlmExample extends CardDef {
+  static displayName = 'SetLLMExample';
+
+  static isolated = IsolatedTemplate;
+}
diff --git a/packages/host/app/commands/index.ts b/packages/host/app/commands/index.ts
index 54006dce6f..b4ecb331f6 100644
--- a/packages/host/app/commands/index.ts
+++ b/packages/host/app/commands/index.ts
@@ -9,6 +9,7 @@ import * as ReloadCardCommandModule from './reload-card';
 import * as SaveCardCommandModule from './save-card';
 import * as SearchCardsCommandModule from './search-cards';
 import * as SendAiAssistantMessageModule from './send-ai-assistant-message';
+import * as SetActiveLlmModule from './set-active-llm';
 import * as ShowCardCommandModule from './show-card';
 import * as SwitchSubmodeCommandModule from './switch-submode';
 import * as UpdateSkillActivationCommandModule from './update-skill-activation';
@@ -51,6 +52,10 @@ export function shimHostCommands(virtualNetwork: VirtualNetwork) {
     '@cardstack/boxel-host/commands/send-ai-assistant-message',
     SendAiAssistantMessageModule,
   );
+  virtualNetwork.shimModule(
+    '@cardstack/boxel-host/commands/set-active-llm',
+    SetActiveLlmModule,
+  );
   virtualNetwork.shimModule(
     '@cardstack/boxel-host/commands/show-card',
     ShowCardCommandModule,
diff --git a/packages/host/app/commands/set-active-llm.ts b/packages/host/app/commands/set-active-llm.ts
new file mode 100644
index 0000000000..dbd1e00fbd
--- /dev/null
+++ b/packages/host/app/commands/set-active-llm.ts
@@ -0,0 +1,27 @@
+import { service } from '@ember/service';
+
+import type * as BaseCommandModule from 'https://cardstack.com/base/command';
+
+import HostBaseCommand from '../lib/host-base-command';
+
+import type MatrixService from '../services/matrix-service';
+
+export default class SetActiveLLMCommand extends HostBaseCommand<
+  typeof BaseCommandModule.SetActiveLLMInput,
+  undefined
+> {
+  @service private declare matrixService: MatrixService;
+
+  async getInputType() {
+    let commandModule = await this.loadCommandModule();
+    const { SetActiveLLMInput } = commandModule;
+    return SetActiveLLMInput;
+  }
+
+  protected async run(
+    input: BaseCommandModule.SetActiveLLMInput,
+  ): Promise<undefined> {
+    await this.matrixService.sendActiveLLMEvent(input.roomId, input.model);
+    return undefined;
+  }
+}