diff --git a/cmd/install.go b/cmd/install.go
index 6ce2e89..353d2fe 100644
--- a/cmd/install.go
+++ b/cmd/install.go
@@ -34,6 +34,11 @@ func promptInitConfig() error {
 		return err
 	}
 
+	if !isPromptTTY() {
+		fmt.Fprintln(os.Stderr, output.WarnStderr("bight: no config file found and stdin is not a TTY; skipping interactive setup. Create .bight.yml manually or re-run from a terminal."))
+		return nil
+	}
+
 	if !confirm("bight: no config file found. Create .bight.yml?", true) {
 		return nil
 	}
diff --git a/cmd/install_test.go b/cmd/install_test.go
new file mode 100644
index 0000000..25e93b2
--- /dev/null
+++ b/cmd/install_test.go
@@ -0,0 +1,48 @@
+package cmd
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestPromptInitConfig_NonTTYBailsOut(t *testing.T) {
+	// Isolate from any real ~/.bight.yml and from the worktree's .bight.yml
+	// so config.Load() returns os.ErrNotExist.
+	t.Setenv("HOME", t.TempDir())
+	t.Chdir(t.TempDir())
+
+	withStubPrompt(t, false, "")
+
+	if err := promptInitConfig(); err != nil {
+		t.Fatalf("promptInitConfig: %v", err)
+	}
+
+	if _, err := os.Stat(".bight.yml"); !os.IsNotExist(err) {
+		t.Errorf("expected no .bight.yml to be written under non-TTY, stat err=%v", err)
+	}
+}
+
+func TestPromptInitConfig_TTYCreatesConfig(t *testing.T) {
+	t.Setenv("HOME", t.TempDir())
+	t.Chdir(t.TempDir())
+
+	// Accept "Create .bight.yml?" (Y), accept default project, default env
+	// file, decline seed, decline add vars.
+	withStubPrompt(t, true, strings.Join([]string{
+		"y", // Create .bight.yml?
+		"",  // Project name (default)
+		"",  // Env file path (default)
+		"n", // Seed from another path?
+		"n", // Add env vars?
+		"",
+	}, "\n"))
+
+	if err := promptInitConfig(); err != nil {
+		t.Fatalf("promptInitConfig: %v", err)
+	}
+
+	if _, err := os.Stat(".bight.yml"); err != nil {
+		t.Errorf("expected .bight.yml to be written under TTY: %v", err)
+	}
+}