diff --git a/crates/engine/src/cmd/slide.rs b/crates/engine/src/cmd/slide.rs
index 3d8ad344..105678ca 100644
--- a/crates/engine/src/cmd/slide.rs
+++ b/crates/engine/src/cmd/slide.rs
@@ -108,7 +108,12 @@ fn new(s: &mut Session, p: &Value) -> Result<Value> {
         if let Some(b) = str_param(p, "body")
             && let Some(sh) = slide.shapes.iter_mut().find(|x| x.ph_type().is_some_and(|k| !k.is_title()))
         {
-            sh.text = Some(TextBody::from_text(b));
+            let mut body = TextBody::from_text(b);
+            // Leading tabs set the outline level, as in text.set.
+            for para in &mut body.paragraphs {
+                super::text::apply_leading_tabs(para);
+            }
+            sh.text = Some(body);
         }
         let at = usize_param(p, "at").unwrap_or(if doc.slides.is_empty() { 0 } else { sel.slide + 1 }).min(doc.slides.len());
         let id = slide.id;
@@ -584,3 +589,24 @@ fn from_outline(s: &mut Session, p: &Value) -> Result<Value> {
         Ok(json!({"slides": n}))
     })
 }
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use crate::Session;
+
+    #[test]
+    fn new_slide_body_leading_tabs_become_levels() {
+        let mut s = Session::with_new();
+        let text = "Level one\n\tLevel two\n\t\tLevel three\nLevel one again";
+        s.execute("slide.new", &json!({"layout": "titleAndContent", "title": "Indent", "body": text})).expect("new slide");
+        let st = s.doc().expect("doc");
+        let slide = st.doc.slides.get(st.selection.slide).expect("slide");
+        let body = slide.shapes.iter().find(|x| x.ph_type().is_some_and(|k| !k.is_title())).expect("body");
+        let paras = &body.text.as_ref().expect("text").paragraphs;
+        let got: Vec<(u8, String)> = paras.iter().map(|p| (p.level, p.text())).collect();
+        let want = [(0, "Level one"), (1, "Level two"), (2, "Level three"), (0, "Level one again")];
+        assert_eq!(got, want.iter().map(|(l, t)| (*l, t.to_string())).collect::<Vec<_>>());
+    }
+}
diff --git a/crates/engine/src/cmd/text.rs b/crates/engine/src/cmd/text.rs
index 1b2cb2d2..545ce54c 100644
--- a/crates/engine/src/cmd/text.rs
+++ b/crates/engine/src/cmd/text.rs
@@ -687,6 +687,20 @@ fn select_para(s: &mut Session, p: &Value) -> Result<Value> {
     ok()
 }
 
+/// Turn leading tabs of a paragraph into its outline level (capped at 8) and strip them.
+/// Returns whether any tab was found.
+pub(crate) fn apply_leading_tabs(para: &mut deckcraft_model::text::Paragraph) -> bool {
+    let tabs = para.runs.first().map(|r| r.text.chars().take_while(|c| *c == '\t').count()).unwrap_or(0);
+    if tabs == 0 {
+        return false;
+    }
+    if let Some(r) = para.runs.first_mut() {
+        r.text = r.text.trim_start_matches('\t').to_string();
+    }
+    para.level = tabs.min(8) as u8;
+    true
+}
+
 fn set(s: &mut Session, p: &Value) -> Result<Value> {
     let text = str_param(p, "text").ok_or_else(|| bad("text.set", "missing `text`"))?.to_string();
     let id = match id_param(p, "id") {
@@ -706,13 +720,9 @@ fn set(s: &mut Session, p: &Value) -> Result<Value> {
         let mut nb = TextBody::from_text(&text);
         for (i, para) in nb.paragraphs.iter_mut().enumerate() {
             // Leading tabs set the outline level.
-            let tabs = para.runs.first().map(|r| r.text.chars().take_while(|c| *c == '\t').count()).unwrap_or(0);
-            if tabs > 0
-                && let Some(r) = para.runs.first_mut()
+            if !apply_leading_tabs(para)
+                && let Some((lv, pp)) = levels.get(i)
             {
-                r.text = r.text.trim_start_matches('\t').to_string();
-                para.level = tabs.min(8) as u8;
-            } else if let Some((lv, pp)) = levels.get(i) {
                 para.level = *lv;
                 para.props = pp.clone();
             }