diff --git a/root/init.go b/root/init.go
index b33776f1..a9ff6463 100644
--- a/root/init.go
+++ b/root/init.go
@@ -33,7 +33,7 @@ fi
 
 # a non-interactive shell (tool runners sourcing rc files, scripts) has no
 # prompt to complete, and exec'ing here would seize the tty from the real iris
-if [[ -o interactive ]] && [ -t 0 ] && [ -z "$IRIS_PID" ] && [ -z "$IRIS_RESCUE" ]; then
+if [[ -o interactive ]] && [ -t 0 ] && [ -z "$IRIS_PID" ] && [ -z "$IRIS_RESCUE" ] && [ -z "$ZSH_EXECUTION_STRING" ]; then
     export IRIS_ACTIVE_SHELL="zsh"
     if [ -n "$FNM_MULTISHELL_PATH" ]; then
         path=(${path:#*fnm_multishells*})
@@ -84,7 +84,7 @@ fi
 
 # a non-interactive shell (tool runners sourcing rc files, scripts) has no
 # prompt to complete, and exec'ing here would seize the tty from the real iris
-if [[ $- == *i* ]] && [ -t 0 ] && [ -z "$IRIS_PID" ] && [ -z "$IRIS_RESCUE" ]; then
+if [[ $- == *i* ]] && [ -t 0 ] && [ -z "$IRIS_PID" ] && [ -z "$IRIS_RESCUE" ] && [ -z "$BASH_EXECUTION_STRING" ]; then
     export IRIS_ACTIVE_SHELL="bash"
     if [ -n "$FNM_MULTISHELL_PATH" ]; then
         PATH=":$PATH:"
@@ -134,7 +134,7 @@ if set -q IRIS_PID
     end
 end
 
-if status is-interactive; and not set -q IRIS_PID; and not set -q IRIS_RESCUE
+if status is-interactive; and test -t 0; and not set -q IRIS_PID; and not set -q IRIS_RESCUE
     set -gx IRIS_ACTIVE_SHELL "fish"
     if set -q FNM_MULTISHELL_PATH
         set -gx PATH (string match -v "*fnm_multishells*" $PATH)
diff --git a/root/init_test.go b/root/init_test.go
index 32f00ac0..eefea14a 100644
--- a/root/init_test.go
+++ b/root/init_test.go
@@ -83,3 +83,32 @@ func TestFishAutosuggestionsFollowGhostTextMode(t *testing.T) {
 		}
 	}
 }
+
+func TestInitAutostartSkipsExecutionString(t *testing.T) {
+	guards := map[string]string{
+		"zsh":  `[ -z "$ZSH_EXECUTION_STRING" ]`,
+		"bash": `[ -z "$BASH_EXECUTION_STRING" ]`,
+		"fish": "test -t 0",
+	}
+
+	for shell, guard := range guards {
+		t.Run(shell, func(t *testing.T) {
+			script := captureInitScript(t, shell)
+
+			head, _, found := strings.Cut(script, "exec iris")
+			if !found {
+				t.Fatalf("%s init script has no autostart", shell)
+			}
+
+			cond := strings.LastIndex(head, "\nif ")
+			if cond < 0 {
+				t.Fatalf("%s autostart is not inside an if", shell)
+			}
+
+			if !strings.Contains(head[cond:], guard) {
+				t.Fatalf("%s autostart is not guarded by %q:\n%s", shell, guard, head[cond:])
+			}
+		})
+	}
+}
+
diff --git a/tests/tui/autostart_test.go b/tests/tui/autostart_test.go
new file mode 100644
index 00000000..a638fb98
--- /dev/null
+++ b/tests/tui/autostart_test.go
@@ -0,0 +1,90 @@
+package tui
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os/exec"
+	"testing"
+	"time"
+
+	"github.com/creack/pty"
+)
+
+func TestAutostartDoesNotSwallowCommand(t *testing.T) {
+	bin := binary(t)
+
+	t.Run("bash", func(t *testing.T) {
+		if _, err := exec.LookPath("bash"); err != nil {
+			t.Skip("bash not installed")
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		initScript, err := exec.CommandContext(ctx, bin, "init", "bash").Output()
+		if err != nil {
+			t.Fatalf("iris init bash: %v", err)
+		}
+		cmd := exec.CommandContext(ctx, "bash", "--norc", "-i", "-c", string(initScript)+"\necho RAN_BASH_42")
+		ptmx, err := pty.Start(cmd)
+		if err != nil {
+			t.Fatalf("starting bash in pty: %v", err)
+		}
+		defer func() { _ = ptmx.Close() }()
+
+		var out bytes.Buffer
+		done := make(chan error, 1)
+		go func() {
+			_, errCopy := io.Copy(&out, ptmx)
+			done <- errCopy
+		}()
+
+		select {
+		case <-ctx.Done():
+			_ = cmd.Process.Kill()
+			t.Fatalf("timed out waiting for bash command, output:\n%s", out.String())
+		case <-done:
+		}
+
+		if !bytes.Contains(out.Bytes(), []byte("RAN_BASH_42")) {
+			t.Fatalf("expected output to contain RAN_BASH_42, got:\n%s", out.String())
+		}
+	})
+
+	t.Run("zsh", func(t *testing.T) {
+		if _, err := exec.LookPath("zsh"); err != nil {
+			t.Skip("zsh not installed")
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		initScript, err := exec.CommandContext(ctx, bin, "init", "zsh").Output()
+		if err != nil {
+			t.Fatalf("iris init zsh: %v", err)
+		}
+		cmd := exec.CommandContext(ctx, "zsh", "-f", "-i", "-c", string(initScript)+"\necho RAN_ZSH_42")
+		ptmx, err := pty.Start(cmd)
+		if err != nil {
+			t.Fatalf("starting zsh in pty: %v", err)
+		}
+		defer func() { _ = ptmx.Close() }()
+
+		var out bytes.Buffer
+		done := make(chan error, 1)
+		go func() {
+			_, errCopy := io.Copy(&out, ptmx)
+			done <- errCopy
+		}()
+
+		select {
+		case <-ctx.Done():
+			_ = cmd.Process.Kill()
+			t.Fatalf("timed out waiting for zsh command, output:\n%s", out.String())
+		case <-done:
+		}
+
+		if !bytes.Contains(out.Bytes(), []byte("RAN_ZSH_42")) {
+			t.Fatalf("expected output to contain RAN_ZSH_42, got:\n%s", out.String())
+		}
+	})
+}