diff --git a/README.md b/README.md
index e818102..3a72b0d 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,7 @@ Available commands:
 - `android-builder setup`
 - `android-builder doctor`
 - `android-builder new MyApp`
+- `android-builder wrapper`
 - `android-builder new MyApp --template empty`
 - `android-builder build`
 - `android-builder export`
@@ -74,3 +75,10 @@ The project generator and the generated projects themselves do not need a system
 - The project is designed around Termux.
 - `android-builder setup` installs the SDK command-line tools and platform packages into `~/android-sdk`.
 - `android-builder export` copies the built APK into `~/storage/documents` after storage permission is granted.
+
+## Troubleshooting
+
+- If `android-builder export` says storage is not configured, run `termux-setup-storage`, grant the permission prompt, then rerun `android-builder export`.
+- If `android-builder build` says `./gradlew` is missing, regenerate the project with `android-builder new <ProjectName>`.
+- If you have an existing Android project and want to add wrapper files, run `android-builder wrapper` from the project root.
+- If Android SDK packages are missing, rerun `android-builder setup`.
diff --git a/bin/android-builder b/bin/android-builder
index 7d9fc93..5bc94a7 100755
--- a/bin/android-builder
+++ b/bin/android-builder
@@ -6,7 +6,7 @@ COMMAND="${1:-help}"
 TARGET="$COMMAND"
 
 case "$COMMAND" in
-  setup|doctor|new|build|export|help|-h|--help)
+  setup|doctor|new|wrapper|build|export|help|-h|--help)
     case "$COMMAND" in
       -h|--help) TARGET="help" ;;
     esac
diff --git a/lib/commands/build.sh b/lib/commands/build.sh
index 2717c33..49f9a55 100755
--- a/lib/commands/build.sh
+++ b/lib/commands/build.sh
@@ -22,5 +22,8 @@ if [ -f ./gradlew ]; then
 else
   echo "Error: ./gradlew is missing."
   echo "This project needs the vendored Gradle wrapper generated by android-builder new."
+  echo
+  echo "If this is an existing project, regenerate it with:"
+  echo "  android-builder new <ProjectName>"
   exit 1
 fi
diff --git a/lib/commands/export.sh b/lib/commands/export.sh
index a87d8cd..61b27e9 100755
--- a/lib/commands/export.sh
+++ b/lib/commands/export.sh
@@ -12,6 +12,9 @@ if [ ! -f "$APK" ]; then
   echo
   echo "Run:"
   echo "  android-builder build"
+  echo
+  echo "If build fails because ./gradlew is missing, regenerate the project with:"
+  echo "  android-builder new <ProjectName>"
   exit 1
 fi
 
diff --git a/lib/commands/help.sh b/lib/commands/help.sh
index 9d249fb..51f2372 100755
--- a/lib/commands/help.sh
+++ b/lib/commands/help.sh
@@ -7,6 +7,7 @@ echo "Usage:"
 echo "  android-builder setup"
 echo "  android-builder doctor"
 echo "  android-builder new MyApp"
+echo "  android-builder wrapper"
 echo "  android-builder new MyApp --template empty"
 echo "  android-builder build"
 echo "  android-builder export"
diff --git a/lib/commands/wrapper.sh b/lib/commands/wrapper.sh
new file mode 100644
index 0000000..14da098
--- /dev/null
+++ b/lib/commands/wrapper.sh
@@ -0,0 +1,17 @@
+#!/data/data/com.termux/files/usr/bin/bash
+set -e
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+source "$ROOT_DIR/lib/common.sh"
+
+if [ -f settings.gradle ] || [ -f build.gradle ] || [ -f app/build.gradle ]; then
+  install_gradle_wrapper_assets "."
+  echo "Gradle wrapper installed."
+  echo
+  echo "Next:"
+  echo "  ./gradlew assembleDebug"
+else
+  echo "Error: run this command from the root of an Android project."
+  echo "Expected files like settings.gradle, build.gradle, or app/build.gradle."
+  exit 1
+fi
diff --git a/lib/common.sh b/lib/common.sh
index e6a0059..607a676 100644
--- a/lib/common.sh
+++ b/lib/common.sh
@@ -51,6 +51,25 @@ get_apk_path() {
   esac
 }
 
+install_gradle_wrapper_assets() {
+  TARGET_DIR="$1"
+
+  mkdir -p "$TARGET_DIR/gradle/wrapper"
+  cp "$TEMPLATE_DIR/gradle-wrapper.jar" "$TARGET_DIR/gradle/wrapper/gradle-wrapper.jar"
+  cp "$TEMPLATE_DIR/gradlew" "$TARGET_DIR/gradlew"
+  chmod +x "$TARGET_DIR/gradlew"
+
+  cat > "$TARGET_DIR/gradle/wrapper/gradle-wrapper.properties" <<EOF2
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-$GRADLE_VERSION-bin.zip
+distributionSha256Sum=$GRADLE_DISTRIBUTION_SHA256
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+EOF2
+  set_gradle_wrapper_sha256 "$TARGET_DIR/gradle/wrapper/gradle-wrapper.properties"
+}
+
 create_base_project() {
   NAME="$1"
   MESSAGE="$2"
@@ -170,20 +189,7 @@ public class MainActivity extends Activity {
 }
 EOF2
 
-  mkdir -p "$NAME/gradle/wrapper"
-  cp "$TEMPLATE_DIR/gradle-wrapper.jar" "$NAME/gradle/wrapper/gradle-wrapper.jar"
-  cp "$TEMPLATE_DIR/gradlew" "$NAME/gradlew"
-  chmod +x "$NAME/gradlew"
-
-  cat > "$NAME/gradle/wrapper/gradle-wrapper.properties" <<EOF2
-distributionBase=GRADLE_USER_HOME
-distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-$GRADLE_VERSION-bin.zip
-distributionSha256Sum=$GRADLE_DISTRIBUTION_SHA256
-zipStoreBase=GRADLE_USER_HOME
-zipStorePath=wrapper/dists
-EOF2
-  set_gradle_wrapper_sha256 "$NAME/gradle/wrapper/gradle-wrapper.properties"
+  install_gradle_wrapper_assets "$NAME"
 
   echo "Created project: $NAME"
   echo