diff --git a/.github/workflows/build-host.yml b/.github/workflows/build-host.yml
index eb99f65146..7ebe755c7d 100644
--- a/.github/workflows/build-host.yml
+++ b/.github/workflows/build-host.yml
@@ -25,13 +25,11 @@ jobs:
           INPUT_ENVIRONMENT: ${{ inputs.environment }}
         run: |
           if [ "$INPUT_ENVIRONMENT" = "production" ]; then
-            echo "OWN_REALM_URL=https://app.boxel.ai/experiments/" >> $GITHUB_ENV
             echo "RESOLVED_BASE_REALM_URL=https://app.boxel.ai/base/" >> $GITHUB_ENV
             echo "MATRIX_URL=https://matrix.boxel.ai" >> $GITHUB_ENV
             echo "MATRIX_SERVER_NAME=boxel.ai" >> $GITHUB_ENV
             echo "EXPERIMENTAL_AI_ENABLED=true" >> $GITHUB_ENV
           elif [ "$INPUT_ENVIRONMENT" = "staging" ]; then
-            echo "OWN_REALM_URL=https://realms-staging.stack.cards/experiments/" >> $GITHUB_ENV
             echo "RESOLVED_BASE_REALM_URL=https://realms-staging.stack.cards/base/" >> $GITHUB_ENV
             echo "MATRIX_URL=https://matrix-staging.stack.cards" >> $GITHUB_ENV
             echo "MATRIX_SERVER_NAME=stack.cards" >> $GITHUB_ENV
diff --git a/.github/workflows/pr-boxel-host.yml b/.github/workflows/pr-boxel-host.yml
index 6929080e8b..3682ae213c 100644
--- a/.github/workflows/pr-boxel-host.yml
+++ b/.github/workflows/pr-boxel-host.yml
@@ -56,7 +56,6 @@ jobs:
       - name: Deploy boxel-host preview
         uses: ./.github/actions/deploy-ember-preview
         env:
-          OWN_REALM_URL: https://realms-staging.stack.cards/experiments/
           RESOLVED_BASE_REALM_URL: https://realms-staging.stack.cards/base/
           MATRIX_URL: https://matrix-staging.stack.cards
           MATRIX_SERVER_NAME: stack.cards
@@ -87,7 +86,6 @@ jobs:
       - name: Deploy boxel-host preview
         uses: ./.github/actions/deploy-ember-preview
         env:
-          OWN_REALM_URL: https://app.boxel.ai/experiments/
           RESOLVED_BASE_REALM_URL: https://app.boxel.ai/base/
           MATRIX_URL: https://matrix.boxel.ai
           MATRIX_SERVER_NAME: boxel.ai
diff --git a/README.md b/README.md
index 1bddceb8d6..5def205cf8 100644
--- a/README.md
+++ b/README.md
@@ -47,12 +47,10 @@ In order to run the ember-cli hosted app:
 
 1. `pnpm build` in the boxel-ui/addon workspace to build the boxel-ui addon.
 2. `pnpm build` in the boxel-motion/addon workspace to build the boxel-motion addon.
-3. `pnpm start` in the host/ workspace to serve the ember app. Note that this script includes the environment variable `OWN_REALM_URL=http://localhost:4201/experiments/` which configures the host to point to the experiments realm's cards realm by default.
+3. `pnpm start` in the host/ workspace to serve the ember app.
 4. `pnpm start:all` in the realm-server/ to serve the base and experiments realms -- this will also allow you to switch between the app and the tests without having to restart servers). This expects the Ember application to be running at `http://localhost:4200`, if you’re running it elsewhere you can specify it with `HOST_URL=http://localhost:5200 pnpm start:all`.
 
-The app is available at http://localhost:4200. It will serve the experiments realm (configurable with OWN_REALM_URL, as mentioned above). You can open the base and experiments cards workspace directly by entering http://localhost:4201/base or http://localhost:4201/experiments in the browser.
-
-If you want to use operator mode, you need to register an account on Matrix. To make it easier, you can execute `pnpm register-test-user` in `packages/matrix/`. Now you can sign in with the test user using the credentials `username: user`, `password: password`.
+The app is available at http://localhost:4200. You will be prompted to register an account. To make it easier, you can execute `pnpm register-test-user` in `packages/matrix/`. Now you can sign in with the test user using the credentials `username: user`, `password: password`.
 
 When you are done running the app you can stop the synapse server by running the following from the `packages/matrix` workspace:
 
diff --git a/packages/boxel-ui/addon/bin/conditional-build.sh b/packages/boxel-ui/addon/bin/conditional-build.sh
new file mode 100755
index 0000000000..e489b8edad
--- /dev/null
+++ b/packages/boxel-ui/addon/bin/conditional-build.sh
@@ -0,0 +1,25 @@
+#! /bin/sh
+
+CURRENT_DIR="$(pwd)"
+SCRIPTS_DIR="$(cd "$(dirname "$0")" && pwd)"
+
+SRC_DIR="${SCRIPTS_DIR}/../src"
+DIST_DIR="${SCRIPTS_DIR}/../dist"
+
+if [ ! -d "$DIST_DIR" ]; then
+  echo "boxel-ui/addon dist dir does not exist. Building in ${SRC_DIR}/.."
+  cd "${SRC_DIR}/.."
+  pnpm run build
+  exit 0
+fi
+
+mod_time_src=$(find "$SRC_DIR" -type f -exec stat -f %m {} + | sort -nr | head -n1)
+mod_time_dist=$(find "$DIST_DIR" -type f -exec stat -f %m {} + | sort -nr | head -n1)
+
+if [ "$mod_time_src" -gt "$mod_time_dist" ]; then
+  echo "boxel-ui/addon dist dir is out of date. Building in ${SRC_DIR}/.."
+  cd "${SRC_DIR}/.."
+  pnpm run build
+else
+  echo "✔️ boxel-ui/addon dist dir is up to date"
+fi
diff --git a/packages/host/package.json b/packages/host/package.json
index 117d1c1a40..16706a64ff 100644
--- a/packages/host/package.json
+++ b/packages/host/package.json
@@ -21,7 +21,8 @@
     "lint:js": "eslint . --cache",
     "lint:js:fix": "eslint . --fix",
     "lint:glint": "glint",
-    "start": "NODE_OPTIONS='--max-old-space-size=8192' FASTBOOT_DISABLED=true OWN_REALM_URL=http://localhost:4201/experiments/ ember serve",
+    "ensure-boxel-ui": "../boxel-ui/addon/bin/conditional-build.sh",
+    "start": "pnpm ensure-boxel-ui && NODE_OPTIONS='--max-old-space-size=8192' FASTBOOT_DISABLED=true ember serve",
     "start:build": "NODE_OPTIONS='--max-old-space-size=8192' FASTBOOT_DISABLED=true ember build --watch",
     "test": "concurrently \"pnpm:lint\" \"pnpm:test:*\" --names \"lint,test:\"",
     "test-with-percy": "percy exec --parallel -- pnpm test:wait-for-servers",