diff --git a/README.md b/README.md
index 2d9b86ca5db..7b2a05134aa 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,7 @@ npx sim-setup add sandbox
 npx sim-setup add jobs
 npx sim-setup add cache
 npx sim-setup add knowledge
+npx sim-setup add chat
 npx sim-setup add llm
 npx sim-setup add integration slack
 ```
diff --git a/bun.lock b/bun.lock
index 80ba0853f61..b79e55829ff 100644
--- a/bun.lock
+++ b/bun.lock
@@ -628,7 +628,7 @@
     },
     "packages/sim-setup": {
       "name": "sim-setup",
-      "version": "1.0.1",
+      "version": "1.0.2",
       "bin": {
         "sim-setup": "dist/index.js",
       },
diff --git a/packages/deployment-config/src/env-capabilities.ts b/packages/deployment-config/src/env-capabilities.ts
index 9a4d473f8f9..2556b1a8fec 100644
--- a/packages/deployment-config/src/env-capabilities.ts
+++ b/packages/deployment-config/src/env-capabilities.ts
@@ -1339,9 +1339,12 @@ export const DEPLOYMENT_CONFIGURATION_KEYS: readonly string[] = [
   ...new Set([
     ...CORE_CONFIGURATION_KEYS,
     ...ENV_CAPABILITIES.flatMap(capabilityKeys),
+    'COPILOT_API_KEY',
     'EMAIL_VERIFICATION_ENABLED',
+    'NEXT_PUBLIC_CHAT_DISABLED',
     'NEXT_PUBLIC_E2B_ENABLED',
     'NEXT_PUBLIC_SANDBOXES_ENABLED',
+    'SIM_AGENT_API_URL',
     ...Object.values(LLM_KEY_POOLS).flatMap((pool) => [
       ...pool.keys,
       ...('fallbackKey' in pool ? [pool.fallbackKey] : []),
diff --git a/packages/sim-setup/README.md b/packages/sim-setup/README.md
index 58200c50182..3b40c8c5fe4 100644
--- a/packages/sim-setup/README.md
+++ b/packages/sim-setup/README.md
@@ -9,3 +9,9 @@ npx sim-setup
 Outside a Sim source checkout, the command creates a Docker Compose installation using published
 images. Inside a Sim source checkout, use `bun run sim-setup` to expose the complete development
 and deployment wizard.
+
+To connect or replace the Chat API key without rerunning the full wizard:
+
+```bash
+npx sim-setup add chat
+```
diff --git a/packages/sim-setup/package.json b/packages/sim-setup/package.json
index c6e5523474f..fac2cc98ed1 100644
--- a/packages/sim-setup/package.json
+++ b/packages/sim-setup/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sim-setup",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "Set up and manage a self-hosted Sim installation",
   "type": "module",
   "bin": {
diff --git a/packages/sim-setup/src/capability-config.ts b/packages/sim-setup/src/capability-config.ts
index 8bcbe13cbb0..4848d90607c 100644
--- a/packages/sim-setup/src/capability-config.ts
+++ b/packages/sim-setup/src/capability-config.ts
@@ -847,13 +847,14 @@ if (missingCapabilitySetups.length > 0) {
 }
 
 export type CapabilitySetupId = (typeof CAPABILITY_SETUPS)[number]['definition']['id']
-export type SetupFeatureId = CapabilitySetupId | 'llm' | 'integration'
+export type SetupFeatureId = CapabilitySetupId | 'chat' | 'llm' | 'integration'
 
 export const SETUP_FEATURES: readonly { id: SetupFeatureId; label: string }[] = [
   ...CAPABILITY_SETUPS.map((setup) => ({
     id: setup.definition.id,
     label: setup.label,
   })),
+  { id: 'chat', label: 'Chat' },
   { id: 'llm', label: 'LLM API keys' },
   { id: 'integration', label: 'OAuth integration' },
 ]
diff --git a/packages/sim-setup/src/capability-status.ts b/packages/sim-setup/src/capability-status.ts
index d86772f6b62..5f98e0476f2 100644
--- a/packages/sim-setup/src/capability-status.ts
+++ b/packages/sim-setup/src/capability-status.ts
@@ -27,7 +27,7 @@ import {
 } from '@sim/deployment-config/env-capabilities'
 import { SETUP_FEATURES, type SetupFeatureId } from './capability-config'
 
-export type SetupStatusFeatureId = Exclude<SetupFeatureId, 'integration'>
+export type SetupStatusFeatureId = Exclude<SetupFeatureId, 'chat' | 'integration'>
 export type CapabilityStatusState = 'default' | 'configured' | 'missing' | 'partial' | 'invalid'
 
 export interface CapabilityStatusIssue {
diff --git a/packages/sim-setup/src/configuration-sources.test.ts b/packages/sim-setup/src/configuration-sources.test.ts
index 5c2e4ce3421..bdd079aa45f 100644
--- a/packages/sim-setup/src/configuration-sources.test.ts
+++ b/packages/sim-setup/src/configuration-sources.test.ts
@@ -86,6 +86,29 @@ describe('discoverConfigurationSources', () => {
     expect(sources[0].values?.get('RESEND_API_KEY')).toBe('current')
   })
 
+  it('retains Chat configuration from a prepared Compose .env file', () => {
+    const root = temporaryDirectory()
+    writeFileSync(
+      path.join(root, '.env'),
+      [
+        'COPILOT_API_KEY=existing-chat-key',
+        'NEXT_PUBLIC_CHAT_DISABLED=false',
+        'SIM_AGENT_API_URL=https://copilot.example.com',
+      ].join('\n')
+    )
+    writeFileSync(
+      path.join(root, 'docker-compose.prod.yml'),
+      'services:\n  simstudio:\n    image: ghcr.io/simstudioai/simstudio:latest\n    env_file: .env\n'
+    )
+
+    const sources = discoverConfigurationSources({ root, runner: () => commandResult(1) })
+
+    expect(sources).toHaveLength(1)
+    expect(sources[0].values?.get('COPILOT_API_KEY')).toBe('existing-chat-key')
+    expect(sources[0].values?.get('NEXT_PUBLIC_CHAT_DISABLED')).toBe('false')
+    expect(sources[0].values?.get('SIM_AGENT_API_URL')).toBe('https://copilot.example.com')
+  })
+
   it('uses the effective environment of a stopped Compose app container', () => {
     const parent = temporaryDirectory()
     const root = path.join(parent, 'checkout')
diff --git a/packages/sim-setup/src/feature-setup-chat.test.ts b/packages/sim-setup/src/feature-setup-chat.test.ts
new file mode 100644
index 00000000000..7eeb63f2c89
--- /dev/null
+++ b/packages/sim-setup/src/feature-setup-chat.test.ts
@@ -0,0 +1,85 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const {
+  mockDiscoverConfigurationSources,
+  mockReconcileEnvValues,
+  mockPromptCopilotKey,
+  mockMothershipOverride,
+  mockChatFlagValues,
+  mockOutro,
+} = vi.hoisted(() => ({
+  mockDiscoverConfigurationSources: vi.fn(),
+  mockReconcileEnvValues: vi.fn(),
+  mockPromptCopilotKey: vi.fn(),
+  mockMothershipOverride: vi.fn(),
+  mockChatFlagValues: vi.fn(),
+  mockOutro: vi.fn(),
+}))
+
+vi.mock('./configuration-sources', () => ({
+  discoverConfigurationSources: mockDiscoverConfigurationSources,
+}))
+
+vi.mock('./env-files', () => ({
+  reconcileEnvValues: mockReconcileEnvValues,
+}))
+
+vi.mock('./prompter', () => ({
+  outro: mockOutro,
+}))
+
+vi.mock('./steps', () => ({
+  chatFlagValues: mockChatFlagValues,
+  mothershipOverride: mockMothershipOverride,
+  promptCopilotKey: mockPromptCopilotKey,
+}))
+
+vi.mock('./theme', () => ({
+  theme: { accent: (value: string) => value },
+}))
+
+import { runFeatureSetup } from './feature-setup'
+
+describe('Chat feature setup', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    mockDiscoverConfigurationSources.mockReturnValue([
+      {
+        kind: 'compose',
+        label: 'Docker Compose',
+        location: '.env',
+        values: new Map([['COPILOT_API_KEY', 'existing-key']]),
+        managedByCurrentCheckout: true,
+      },
+    ])
+    mockMothershipOverride.mockReturnValue({
+      SIM_AGENT_API_URL: 'https://copilot.example.com',
+    })
+    mockChatFlagValues.mockReturnValue({ NEXT_PUBLIC_CHAT_DISABLED: 'false' })
+  })
+
+  it('writes only the Chat configuration to the detected install', async () => {
+    mockPromptCopilotKey.mockResolvedValue('new-key')
+
+    await runFeatureSetup('chat', [])
+
+    expect(mockPromptCopilotKey).toHaveBeenCalledWith('existing-key')
+    expect(mockReconcileEnvValues).toHaveBeenCalledWith('root', [], {
+      COPILOT_API_KEY: 'new-key',
+      NEXT_PUBLIC_CHAT_DISABLED: 'false',
+      SIM_AGENT_API_URL: 'https://copilot.example.com',
+    })
+    expect(mockOutro).toHaveBeenCalledWith(
+      'Chat written to .env. Recreate the app container for it to take effect.'
+    )
+  })
+
+  it('fails without changing configuration when no key is received', async () => {
+    mockPromptCopilotKey.mockResolvedValue(null)
+
+    await expect(runFeatureSetup('chat', [])).rejects.toThrow(
+      'Chat setup did not receive an API key. No configuration was changed.'
+    )
+    expect(mockReconcileEnvValues).not.toHaveBeenCalled()
+  })
+})
diff --git a/packages/sim-setup/src/feature-setup.ts b/packages/sim-setup/src/feature-setup.ts
index 3ef0c57eb86..5fbe3e2d8fd 100644
--- a/packages/sim-setup/src/feature-setup.ts
+++ b/packages/sim-setup/src/feature-setup.ts
@@ -13,6 +13,7 @@ import { promptCapabilitySetup } from './capability-setup'
 import { type ConfigurationSource, discoverConfigurationSources } from './configuration-sources'
 import { type EnvTarget, reconcileEnvValues } from './env-files'
 import * as p from './prompter'
+import { chatFlagValues, mothershipOverride, promptCopilotKey } from './steps'
 import { theme } from './theme'
 
 function isSetupFeatureId(value: string): value is SetupFeatureId {
@@ -113,6 +114,19 @@ async function setupLlm(vars: Map<string, string>): Promise<LlmSetupResult> {
   return reconcileLlmSetup(provider, values)
 }
 
+async function setupChat(vars: Map<string, string>): Promise<Record<string, string>> {
+  const overrides = mothershipOverride()
+  const copilotKey = await promptCopilotKey(vars.get('COPILOT_API_KEY'))
+  if (!copilotKey) {
+    throw new Error('Chat setup did not receive an API key. No configuration was changed.')
+  }
+  return {
+    ...overrides,
+    COPILOT_API_KEY: copilotKey,
+    ...chatFlagValues(copilotKey),
+  }
+}
+
 export function setupFeatureUsage(): string {
   return SETUP_FEATURES.map((feature) =>
     feature.id === 'integration' ? 'integration <slug>' : feature.id
@@ -182,6 +196,9 @@ export async function runFeatureSetup(feature: string, args: readonly string[]):
     })
     values = result.values
     remove = result.remove
+  } else if (feature === 'chat') {
+    values = await setupChat(vars)
+    remove = []
   } else if (feature === 'integration') {
     values = await setupIntegration(args[0], vars)
     remove = []
diff --git a/packages/sim-setup/src/index.ts b/packages/sim-setup/src/index.ts
index 1bc546ede4d..31f63354b14 100644
--- a/packages/sim-setup/src/index.ts
+++ b/packages/sim-setup/src/index.ts
@@ -7,7 +7,7 @@ import { theme } from './theme'
 import { SETUP_VERSION } from './version'
 
 const SETUP_FEATURES =
-  'email | storage | sandbox | jobs | cache | knowledge | knowledge-embeddings | llm | integration <slug>'
+  'email | storage | sandbox | jobs | cache | knowledge | knowledge-embeddings | chat | llm | integration <slug>'
 
 const USAGE = `Usage:
   sim-setup [--quick] [--dir <path>] [--mode compose|dev|k8s]
diff --git a/packages/sim-setup/src/setup-status.ts b/packages/sim-setup/src/setup-status.ts
index ee59e863f1f..cdc2b6b35bc 100644
--- a/packages/sim-setup/src/setup-status.ts
+++ b/packages/sim-setup/src/setup-status.ts
@@ -38,7 +38,7 @@ export interface SetupStatusReport {
 const SECRET_KEYS = new Set(['BETTER_AUTH_SECRET', 'ENCRYPTION_KEY', 'INTERNAL_API_SECRET'])
 const URL_KEYS = new Set(['DATABASE_URL', 'BETTER_AUTH_URL', 'NEXT_PUBLIC_APP_URL'])
 const FEATURE_ORDER: readonly SetupStatusFeatureId[] = SETUP_FEATURES.flatMap((feature) =>
-  feature.id === 'integration' ? [] : [feature.id]
+  feature.id === 'chat' || feature.id === 'integration' ? [] : [feature.id]
 )
 
 function readString(values: EnvCapabilityValues, key: string): string | undefined {