diff --git a/crates/engine/src/cmd/annotate.rs b/crates/engine/src/cmd/annotate.rs
index b00414e2..92e8a009 100644
--- a/crates/engine/src/cmd/annotate.rs
+++ b/crates/engine/src/cmd/annotate.rs
@@ -8,7 +8,7 @@ use cadcraft_geom::{Segment, Vec2, Vec3};
 use serde_json::{Value, json};
 
 use super::helpers::v3;
-use super::machines::SelectRun;
+use super::machines::{SelOutcome, SelectPhase, SelectRun};
 use super::*;
 use crate::{Accept, EngineError, Input, Interactive, LeaderOrder, MLeaderOptions, Prompt, Result, Session, Step};
 
@@ -106,7 +106,8 @@ pub fn specs() -> Vec<CommandSpec> {
             .interactive(|_| Ok(Box::new(tedit::TEditM::default()))),
         CommandSpec::new("dimspace", "Dimension Space", run_dimspace)
             .menu(&["Dimension", "Dimension Space"])
-            .params("{base: hex, handles: [hex], spacing?: number (default DIMDLI)}"),
+            .params("{base: hex, handles: [hex], spacing?: number (default DIMDLI)}")
+            .interactive(|_| Ok(Box::new(DimSpaceM::default()))),
     ]
     .into_iter()
     .chain(dimedit::specs())
@@ -719,6 +720,90 @@ fn run_dimspace(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(json!({ "spaced": others.len() }))
 }
 
+/// DIMSPACE at the command line: select the base dimension, select the dimensions to space, then
+/// the spacing (Enter or Auto takes the DIMDLI-based default).
+#[derive(Default)]
+struct DimSpaceM {
+    base: Option<Handle>,
+    sel: SelectPhase,
+    spacing_phase: bool,
+}
+
+impl DimSpaceM {
+    fn apply(&self, s: &mut Session, base: Handle, spacing: Option<f64>) -> Result<Step> {
+        let mut p = serde_json::Map::new();
+        p.insert("base".into(), json!(base.hex()));
+        p.insert("handles".into(), json!(self.sel.picked.iter().map(|h| h.hex()).collect::<Vec<_>>()));
+        if let Some(v) = spacing {
+            p.insert("spacing".into(), json!(v));
+        }
+        let r = run_dimspace(s, &Value::Object(p))?;
+        s.set_selection(Vec::new());
+        s.echo(format!("{} dimension(s) spaced.", r.get("spaced").and_then(Value::as_u64).unwrap_or(0)));
+        Ok(Step::Done)
+    }
+}
+
+impl Interactive for DimSpaceM {
+    fn name(&self) -> &'static str {
+        "DIMSPACE"
+    }
+    fn begin(&mut self, _s: &mut Session) -> Result<Step> {
+        self.sel = SelectPhase::single();
+        Ok(Step::Continue)
+    }
+    fn prompt(&self, _s: &Session) -> Prompt {
+        if self.spacing_phase {
+            return Prompt::new("Enter value", Accept::NUMBER).kw(&["Auto"]).default("Auto");
+        }
+        if self.base.is_none() {
+            return Prompt::new("Select base dimension", Accept::SELECT);
+        }
+        Prompt::new("Select dimensions to space", Accept::SELECT)
+    }
+    fn input(&mut self, s: &mut Session, i: Input) -> Result<Step> {
+        if self.spacing_phase {
+            let Some(base) = self.base else { return Ok(Step::Cancel) };
+            return match i {
+                Input::Enter => self.apply(s, base, None),
+                Input::Keyword(k) | Input::Text(k) if k.trim().eq_ignore_ascii_case("a") || k.trim().eq_ignore_ascii_case("auto") => {
+                    self.apply(s, base, None)
+                }
+                Input::Text(t) => match super::machines::number(&t).filter(|v| v.is_finite() && *v >= 0.0) {
+                    Some(v) => self.apply(s, base, Some(v)),
+                    None => {
+                        s.echo("Requires a non-negative number or Auto.");
+                        Ok(Step::Continue)
+                    }
+                },
+                _ => Ok(Step::Continue),
+            };
+        }
+        match self.sel.feed(s, &i)? {
+            SelOutcome::More => Ok(Step::Continue),
+            SelOutcome::Empty => Ok(Step::Done),
+            SelOutcome::Done(hs) => {
+                if self.base.is_none() {
+                    match hs.first().copied().filter(|h| !dims_of(s, &[*h]).is_empty()) {
+                        Some(b) => {
+                            self.base = Some(b);
+                            self.sel = SelectPhase::default();
+                        }
+                        None => {
+                            s.echo("Select a dimension.");
+                            self.sel = SelectPhase::single();
+                        }
+                    }
+                } else {
+                    self.sel.picked = hs;
+                    self.spacing_phase = true;
+                }
+                Ok(Step::Continue)
+            }
+        }
+    }
+}
+
 /// DIMOVERRIDE at the command line: variable, value (repeat), Enter, then select dimensions.
 struct OverrideM {
     vars: serde_json::Map<String, Value>,
diff --git a/crates/engine/src/cmd/annotate_tests.rs b/crates/engine/src/cmd/annotate_tests.rs
index 42481198..299f9159 100644
--- a/crates/engine/src/cmd/annotate_tests.rs
+++ b/crates/engine/src/cmd/annotate_tests.rs
@@ -2,7 +2,7 @@ use cadcraft_doc::{AssocSnap, DimKind, Dimension, EntityKind, Handle};
 use cadcraft_geom::Vec2;
 use serde_json::{Value, json};
 
-use crate::Session;
+use crate::{Input, Session};
 
 fn h(v: &Value) -> Handle {
     Handle::parse_hex(v["handle"].as_str().unwrap()).unwrap()
@@ -299,6 +299,25 @@ fn dimtedit_and_dimspace() {
     assert!((dim(&s, b).defpt.y - 1.5).abs() < 1e-9, "{:?}", dim(&s, b).defpt);
 }
 
+#[test]
+fn dimspace_prompts_for_its_inputs() {
+    let mut s = Session::new();
+    let a = h(&s.execute("dimlinear", &json!({ "p1": [0, 0], "p2": [10, 0], "at": [0, 5] })).unwrap());
+    let b = h(&s.execute("dimlinear", &json!({ "p1": [0, 0], "p2": [20, 0], "at": [0, 9] })).unwrap());
+    // The menu / typed start used to fail with "`base` dimension is required".
+    s.start("dimspace").unwrap();
+    assert!(s.prompt_text().contains("Select base dimension"), "{}", s.prompt_text());
+    s.input(Input::Pick(vec![a])).unwrap();
+    assert!(s.prompt_text().contains("Select dimensions to space"), "{}", s.prompt_text());
+    s.input(Input::Pick(vec![b])).unwrap();
+    s.input(Input::Enter).unwrap();
+    assert!(s.prompt_text().contains("Enter value"), "{}", s.prompt_text());
+    s.input(Input::Text("2".into())).unwrap();
+    assert!(s.running.is_none());
+    assert!((dim(&s, a).defpt.y - 5.0).abs() < 1e-9, "{:?}", dim(&s, a).defpt);
+    assert!((dim(&s, b).defpt.y - 7.0).abs() < 1e-9, "{:?}", dim(&s, b).defpt);
+}
+
 #[test]
 fn text_style_commands() {
     let mut s = Session::new();