diff --git a/integration-tests/project_create_interactive_test.go b/integration-tests/project_create_interactive_test.go
new file mode 100644
index 000000000..2b91e859f
--- /dev/null
+++ b/integration-tests/project_create_interactive_test.go
@@ -0,0 +1,44 @@
+package tests
+
+import (
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/upsun/cli/pkg/mockapi"
+)
+
+// TestProjectCreate_AcceptDefaults sends two newlines to accept the
+// "Default branch" prompt and the cost-confirmation [Y/n] prompt.
+func TestProjectCreate_AcceptDefaults(t *testing.T) {
+	authServer := mockapi.NewAuthServer(t)
+	defer authServer.Close()
+
+	apiHandler := mockapi.NewHandler(t)
+	apiHandler.SetOrgs([]*mockapi.Org{
+		makeOrg("cli-test-id", "cli-tests", "CLI Test Org", "my-user-id", "flexible"),
+	})
+
+	apiServer := httptest.NewServer(apiHandler)
+	defer apiServer.Close()
+
+	f := newCommandFactory(t, apiServer.URL, authServer.URL)
+
+	stdOut, stdErr, err := f.RunInteractive(
+		"\n\n",
+		"project:create",
+		"--title", "Interactive Defaults Test",
+		"--region", "test-region",
+		"--org", "cli-tests",
+		"--no-set-remote",
+	)
+	require.NoError(t, err, "stdout: %s\nstderr: %s", stdOut, stdErr)
+
+	assert.Contains(t, stdErr, "Default branch")
+	assert.Contains(t, stdErr, "Are you sure you want to continue?")
+	assert.Contains(t, stdErr, "[Y/n]")
+	assert.NotEmpty(t, strings.TrimSpace(stdOut))
+}
diff --git a/integration-tests/tests.go b/integration-tests/tests.go
index 2bbd4a526..9cbb3bc67 100644
--- a/integration-tests/tests.go
+++ b/integration-tests/tests.go
@@ -92,6 +92,33 @@ func (f *cmdFactory) RunCombinedOutput(args ...string) (stdOut, stdErr string, e
 	return stdOutBuffer.String(), stdErrBuffer.String(), err
 }
 
+// RunInteractive runs a command with stdin piped from stdinInput. It keeps
+// the legacy CLI in interactive mode under a pipe by setting SHELL_INTERACTIVE
+// and stripping NO_INTERACTION.
+func (f *cmdFactory) RunInteractive(stdinInput string, args ...string) (stdOut, stdErr string, err error) {
+	cmd := f.buildCommand(args...)
+	newEnv := make([]string, 0, len(cmd.Env)+1)
+	for _, e := range cmd.Env {
+		if strings.HasPrefix(e, EnvPrefix+"NO_INTERACTION=") {
+			continue
+		}
+		newEnv = append(newEnv, e)
+	}
+	newEnv = append(newEnv, "SHELL_INTERACTIVE=1")
+	cmd.Env = newEnv
+	cmd.Stdin = strings.NewReader(stdinInput)
+	var stdOutBuffer bytes.Buffer
+	var stdErrBuffer bytes.Buffer
+	cmd.Stdout = &stdOutBuffer
+	cmd.Stderr = &stdErrBuffer
+	if testing.Verbose() {
+		cmd.Stderr = io.MultiWriter(&stdErrBuffer, os.Stderr)
+	}
+	f.t.Log("Running (interactive):", cmd)
+	err = cmd.Run()
+	return stdOutBuffer.String(), stdErrBuffer.String(), err
+}
+
 func (f *cmdFactory) buildCommand(args ...string) *exec.Cmd {
 	cmd := exec.Command(getCommandName(f.t), args...)
 	cmd.Env = testEnv()
diff --git a/legacy/src/Command/Organization/OrganizationCommandBase.php b/legacy/src/Command/Organization/OrganizationCommandBase.php
index e07317de8..275eefaf6 100644
--- a/legacy/src/Command/Organization/OrganizationCommandBase.php
+++ b/legacy/src/Command/Organization/OrganizationCommandBase.php
@@ -117,7 +117,10 @@ protected function chooseMember(Organization $organization): Member
             }
             $userId = $this->questionHelper->choose($choices, 'Enter a number to choose a user:', $default);
         } else {
-            $userId = $this->questionHelper->askInput('Enter an email address to choose a user', null, array_values($emailAddresses), function (string $email) use ($emailAddresses): string {
+            $userId = $this->questionHelper->askInput('Enter an email address to choose a user', null, array_values($emailAddresses), function (?string $email) use ($emailAddresses): string {
+                if ($email === null) {
+                    throw new InvalidArgumentException('An email address is required');
+                }
                 if (($key = array_search($email, $emailAddresses)) === false) {
                     throw new InvalidArgumentException('User not found: ' . $email);
                 }
diff --git a/legacy/src/Command/Organization/User/OrganizationUserAddCommand.php b/legacy/src/Command/Organization/User/OrganizationUserAddCommand.php
index 9098a13e9..262f0a107 100644
--- a/legacy/src/Command/Organization/User/OrganizationUserAddCommand.php
+++ b/legacy/src/Command/Organization/User/OrganizationUserAddCommand.php
@@ -81,7 +81,10 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             } else {
                 $questionText = 'Optionally, enter a list of permissions to add (separated by commas)';
             }
-            $response = $this->questionHelper->askInput($questionText, null, [], function ($value) {
+            $response = $this->questionHelper->askInput($questionText, null, [], function (?string $value): ?string {
+                if ($value === null) {
+                    return null;
+                }
                 foreach (ArrayArgument::split([$value]) as $permission) {
                     if (!\in_array($permission, self::$allPermissions)) {
                         throw new InvalidArgumentException('Unrecognized permission: ' . $permission);
@@ -89,7 +92,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
                 }
                 return $value;
             });
-            $permissions = ArrayArgument::split([$response]);
+            $permissions = $response === null ? [] : ArrayArgument::split([$response]);
             $this->stdErr->writeln('');
         }
 
diff --git a/legacy/src/Command/Team/User/TeamUserAddCommand.php b/legacy/src/Command/Team/User/TeamUserAddCommand.php
index b205879c3..1c65f54e7 100644
--- a/legacy/src/Command/Team/User/TeamUserAddCommand.php
+++ b/legacy/src/Command/Team/User/TeamUserAddCommand.php
@@ -56,9 +56,12 @@ protected function execute(InputInterface $input, OutputInterface $output): int
                     $emails[] = $info->email;
                 }
             }
-            $identifier = $this->questionHelper->askInput('Enter an email address to add a user', null, $emails, function (string $value): string {
+            $identifier = $this->questionHelper->askInput('Enter an email address to add a user', null, $emails, function (?string $value): string {
+                if ($value === null) {
+                    throw new InvalidArgumentException('An email address is required');
+                }
                 if (!filter_var($value, FILTER_VALIDATE_EMAIL)) {
-                    throw new InvalidArgumentException('Invalid email address:' . $value);
+                    throw new InvalidArgumentException('Invalid email address: ' . $value);
                 }
                 return $value;
             });
diff --git a/legacy/src/Selector/Selector.php b/legacy/src/Selector/Selector.php
index 1daa00f82..b8dbe834f 100644
--- a/legacy/src/Selector/Selector.php
+++ b/legacy/src/Selector/Selector.php
@@ -453,8 +453,8 @@ private function offerProjectChoice(array $projectInfos, SelectorConfig $config)
                 }
             }
             asort($autocomplete, SORT_NATURAL | SORT_FLAG_CASE);
-            return $this->questionHelper->askInput($config->enterProjectText, null, array_values($autocomplete), function ($value) use ($autocomplete): string {
-                [$id, ] = explode(' - ', $value);
+            return $this->questionHelper->askInput($config->enterProjectText, null, array_values($autocomplete), function (?string $value) use ($autocomplete): string {
+                [$id] = explode(' - ', $value ?? '', 2);
                 if (empty(trim($id))) {
                     throw new InvalidArgumentException('A project ID is required');
                 }
@@ -495,7 +495,10 @@ private function offerEnvironmentChoice(InputInterface $input, Project $project,
             $ids = array_keys($environments);
             sort($ids, SORT_NATURAL | SORT_FLAG_CASE);
 
-            $id = $this->questionHelper->askInput($config->enterEnvText, $defaultEnvironmentId, array_keys($environments), function (string $value) use ($environments): string {
+            $id = $this->questionHelper->askInput($config->enterEnvText, $defaultEnvironmentId, array_keys($environments), function (?string $value) use ($environments): string {
+                if ($value === null || $value === '') {
+                    throw new \RuntimeException('An environment ID is required');
+                }
                 if (!isset($environments[$value])) {
                     throw new \RuntimeException('Environment not found: ' . $value);
                 }