diff --git a/crates/engine/src/cmd/browser.rs b/crates/engine/src/cmd/browser.rs
index d3591bdd..a7e3beb2 100644
--- a/crates/engine/src/cmd/browser.rs
+++ b/crates/engine/src/cmd/browser.rs
@@ -442,7 +442,6 @@ mod tests {
     }
 
     #[test]
-    #[ignore = "waits for unit-less parameters used as lengths to read in the design's units (solvecraft-params)"]
     fn a_bare_width_keeps_its_inches_when_the_design_goes_metric() {
         let mut s = Session::default();
         run(&mut s, "document.units", json!({"units": "in"}));
diff --git a/crates/ui-egui/src/browser.rs b/crates/ui-egui/src/browser.rs
index ca93c781..ab45a983 100644
--- a/crates/ui-egui/src/browser.rs
+++ b/crates/ui-egui/src/browser.rs
@@ -17,6 +17,17 @@ use crate::context_menu::{Item, Target};
 use crate::theme::Tokens;
 use crate::{SolveApp, icons};
 
+thread_local! {
+    /// The rows drawn this frame: (label, row, fold arrow area, open). For automation
+    /// (`ui.at {browser | chevron}`, `ui.browser`).
+    static DRAWN: std::cell::RefCell<Vec<(String, Rect, Option<Rect>, Option<bool>)>> = const { std::cell::RefCell::new(Vec::new()) };
+}
+
+/// The rows on screen: (label, row rect, fold arrow area, open).
+pub fn drawn_rows() -> Vec<(String, Rect, Option<Rect>, Option<bool>)> {
+    DRAWN.with(|d| d.borrow().clone())
+}
+
 /// Browser state kept between frames.
 #[derive(Default)]
 pub struct TreeState {
@@ -246,6 +257,8 @@ struct RowResp {
     hovered: bool,
     /// The row's response (drag and drop).
     resp: Option<egui::Response>,
+    /// The press began on the fold arrow, eye or radio (not a drag of the row).
+    on_control: bool,
 }
 
 fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
@@ -256,7 +269,10 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         ui.allocate_space(r.size());
         return RowResp { rect: Some(r), ..Default::default() };
     }
-    let (r, resp) = ui.allocate_exact_size(vec2(ui.available_width(), ROW_H), Sense::click_and_drag());
+    // A stable id per row (not the layout position), so a press and its release stay on the
+    // same row while rows above open or close.
+    let (r, _) = ui.allocate_exact_size(vec2(ui.available_width(), ROW_H), Sense::hover());
+    let resp = ui.interact(r, id, Sense::click_and_drag());
     // While something is dragged (an appearance swatch, drawn under the pointer) `hovered` is
     // off; the row under the pointer still counts, so a drop lands on it.
     let dragged_over = egui::DragAndDrop::has_any_payload(ui.ctx()) && ui.input(|i| i.pointer.hover_pos()).is_some_and(|p| r.contains(p));
@@ -269,6 +285,27 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
     let mut x = r.left() + 2.0 + row.depth as f32 * INDENT;
     let cy = r.center().y;
     let ink = if row.dim { t.text_dim } else { t.icon };
+    // The row is one widget: where a click lands decides what it does (the fold arrow with
+    // padding, the eye, the radio, or the row itself), so a click on the arrow never also
+    // selects the row or starts a drag.
+    let fold_r = Rect::from_min_max(pos2(x - 4.0, r.top()), pos2(x + 15.0, r.bottom()));
+    let eye_r = Rect::from_center_size(pos2(x + 14.0 + 8.0, cy), vec2(19.0, r.height()));
+    let radio_r = Rect::from_center_size(pos2(x + 32.0 + 6.0, cy), vec2(15.0, r.height()));
+    let at = |p: Pos2| -> u8 {
+        if row.fold.is_some() && fold_r.contains(p) {
+            1
+        } else if row.eye.is_some() && eye_r.contains(p) {
+            2
+        } else if row.radio.is_some() && radio_r.contains(p) {
+            3
+        } else {
+            0
+        }
+    };
+    DRAWN.with(|d| d.borrow_mut().push((row.label.to_string(), r, row.fold.map(|_| fold_r), row.fold)));
+    let press_on = ui.input(|i| i.pointer.press_origin()).map_or(0, at);
+    let click_on = resp.interact_pointer_pos().map_or(0, at);
+    let hover_on = resp.hover_pos().map_or(0, at);
     // Fold arrow.
     if let Some(open) = row.fold {
         let ar = Rect::from_center_size(pos2(x + 6.0, cy), vec2(12.0, 12.0));
@@ -277,9 +314,10 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         } else {
             vec![pos2(ar.left() + 4.0, ar.top() + 2.0), pos2(ar.right() - 3.0, ar.center().y), pos2(ar.left() + 4.0, ar.bottom() - 2.0)]
         };
-        ui.painter().add(egui::Shape::convex_polygon(pts, t.text_dim, Stroke::NONE));
-        out.fold = ui.interact(ar.expand(3.0), id.with("fold"), Sense::click()).clicked();
-        crate::scenario::publish_handle(&format!("fold:{}", row.label), ar.center());
+        let ink = if hover_on == 1 { t.text } else { t.text_dim };
+        ui.painter().add(egui::Shape::convex_polygon(pts, ink, Stroke::NONE));
+        out.fold = resp.clicked() && click_on == 1;
+        crate::scenario::publish_handle(&format!("fold:{}", row.label), fold_r.center());
     }
     x += 14.0;
     // Eye.
@@ -289,9 +327,7 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         if !vis {
             ui.painter().line_segment([er.left_bottom() + vec2(2.0, -2.0), er.right_top() + vec2(-2.0, 2.0)], Stroke::new(1.4, t.text_dim));
         }
-        let e = ui.interact(er.expand(2.0), id.with("eye"), Sense::click());
-        out.eye = e.clicked();
-        e.on_hover_text(if vis { "Hide" } else { "Show" });
+        out.eye = resp.clicked() && click_on == 2;
     }
     x += 18.0;
     // Activation radio (components).
@@ -301,9 +337,7 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         if active {
             ui.painter().circle_filled(rc, 2.8, t.accent);
         }
-        let rr = ui.interact(Rect::from_center_size(rc, vec2(14.0, 14.0)), id.with("radio"), Sense::click());
-        out.radio = rr.clicked();
-        rr.on_hover_text(if active { "Active component" } else { "Activate" });
+        out.radio = resp.clicked() && click_on == 3;
         x += 15.0;
     }
     if !row.icon.is_empty() {
@@ -322,9 +356,20 @@ fn draw_row(ui: &mut egui::Ui, id: egui::Id, row: &Row) -> RowResp {
         bx += 15.0;
     }
     crate::scenario::publish_handle(&format!("row:{}", row.label), r.center());
+    let tip = match hover_on {
+        1 => Some(if row.fold == Some(true) { "Collapse" } else { "Expand" }),
+        2 => Some(if row.eye == Some(true) { "Hide" } else { "Show" }),
+        3 => Some(if row.radio == Some(true) { "Active component" } else { "Activate" }),
+        _ => None,
+    };
+    let resp = match tip {
+        Some(t) => resp.on_hover_text(t),
+        None => resp,
+    };
+    out.on_control = press_on != 0;
+    out.clicked = resp.clicked() && click_on == 0;
+    out.double = resp.double_clicked() && click_on == 0;
     out.resp = Some(resp.clone());
-    out.clicked = resp.clicked();
-    out.double = resp.double_clicked();
     if resp.secondary_clicked() {
         out.secondary = resp.interact_pointer_pos().or(Some(r.left_bottom()));
     }
@@ -424,6 +469,7 @@ struct Actions {
 pub fn browser(app: &mut SolveApp, ui: &mut egui::Ui) {
     let t = Tokens::get();
     app.tree.order.clear();
+    DRAWN.with(|d| d.borrow_mut().clear());
     let mut acts = Actions::default();
     egui::Panel::left("sc_browser")
         .exact_size(250.0)
@@ -1227,7 +1273,7 @@ fn entry_row(
     }
     let Some(resp) = &r.resp else { return };
     // Drag: the selected items of this folder when this one is selected, else just this one.
-    if resp.drag_started() {
+    if resp.drag_started() && !r.on_control {
         let keys: Vec<String> = if e.selected { selected_keys(app, comp, folder) } else { vec![e.key.clone()] };
         resp.dnd_set_drag_payload(Drag { comp, folder, keys });
     }
diff --git a/crates/ui-egui/src/control.rs b/crates/ui-egui/src/control.rs
index 3031d003..4b03fe61 100644
--- a/crates/ui-egui/src/control.rs
+++ b/crates/ui-egui/src/control.rs
@@ -287,6 +287,20 @@ pub fn handle(app: &mut SolveApp, ctx: &egui::Context, req: &ControlRequest) ->
                     None => err(format!("handle {h} is not shown")),
                 };
             }
+            // A browser row by its label: the row itself, or its fold arrow.
+            for (k, chevron) in [("browser", false), ("chevron", true)] {
+                if let Some(label) = p.get(k).and_then(Value::as_str) {
+                    let rows = crate::browser::drawn_rows();
+                    let found = rows
+                        .iter()
+                        .find(|r| r.0 == label)
+                        .and_then(|r| if chevron { r.2.map(|f| f.center()) } else { Some(r.1.left_center() + egui::vec2(120.0, 0.0)) });
+                    return match found {
+                        Some(q) => ok(json!([q.x, q.y])),
+                        None => err(format!("no browser row `{label}`{} on screen", if chevron { " with a fold arrow" } else { "" })),
+                    };
+                }
+            }
             if let Some(d) = p.get("dimension").and_then(Value::as_str) {
                 return match crate::dim_view::text_at(d) {
                     Some(q) => ok(json!([q.x, q.y])),
@@ -426,6 +440,11 @@ pub fn handle(app: &mut SolveApp, ctx: &egui::Context, req: &ControlRequest) ->
                 None => ok(json!({"command": id, "key": crate::keymap::effective(app, id)})),
             }
         }
+        "ui.browser" => ok(json!({
+            "rows": crate::browser::drawn_rows().iter().map(|(label, r, _, open)| json!({"label": label, "y": r.center().y, "open": open})).collect::<Vec<_>>(),
+            "selection": app.session.selection,
+            "picked_components": app.tree.picked_components,
+        })),
         "ui.capture" => match s("action") {
             Some(a) => match crate::browser::answer_capture(app, a) {
                 Ok(()) => ok(json!({"pending_moves": app.session.pending_moves.len()})),
diff --git a/crates/ui-egui/src/scenario.rs b/crates/ui-egui/src/scenario.rs
index 87a848bf..183c1c8a 100644
--- a/crates/ui-egui/src/scenario.rs
+++ b/crates/ui-egui/src/scenario.rs
@@ -24,7 +24,8 @@
 //! - `{"camera": {"yaw": rad, "pitch": rad}}` puts the camera at an orbit; `{"view_anim": "top",
 //!   "max_deg": 10}` animates to a view and fails if any frame turns the view more than that
 //! - AT may also be `{"plane": "XY"}` (the middle of an origin plane's square), `{"axis": "Z"}`,
-//!   `{"dimension": "d1"}` or `{"handle": "arrow"}` (a manipulator handle: see [`publish_handle`])
+//!   `{"dimension": "d1"}`, `{"handle": "arrow"}` (a manipulator handle: see [`publish_handle`]),
+//!   `{"browser": "Bodies"}` (a browser row by its label) or `{"chevron": "Bodies"}` (its fold arrow)
 //! - `{"autosave": true}`: autosave into the scenario's recovery folder; `{"restart": "crash" |
 //!   "close"}`: the app dies (or closes) and a new one starts on the same folders
 //! - `{"script": "examples/…/x.json"}`: run a command script through the engine; `"$DIR"` in a
@@ -864,6 +865,27 @@ pub fn check(h: &mut Harness, e: &Value) -> Result<(), String> {
                     return Err(format!("design name: got {}, want {v}", doc["name"]));
                 }
             }
+            "browser_has" | "browser_lacks" => {
+                // Browser rows on screen, by label.
+                let r = h.call("ui.browser", json!({}));
+                let labels: Vec<String> =
+                    r["result"]["rows"].as_array().into_iter().flatten().filter_map(|x| x["label"].as_str().map(str::to_string)).collect();
+                for want in v.as_array().into_iter().flatten().filter_map(Value::as_str) {
+                    let there = labels.iter().any(|l| l == want);
+                    if there != (k.as_str() == "browser_has") {
+                        return Err(format!("browser row `{want}` {}: rows {labels:?}", if there { "still shown" } else { "missing" }));
+                    }
+                }
+            }
+            "browser_selected" => {
+                // Nothing selected and no component picked (a fold click selects nothing).
+                let r = h.call("ui.browser", json!({}));
+                let none = r["result"]["selection"].as_array().is_none_or(|a| a.is_empty())
+                    && r["result"]["picked_components"].as_array().is_none_or(|a| a.is_empty());
+                if none == v.as_bool().unwrap_or(false) {
+                    return Err(format!("browser selection: {}", r["result"]));
+                }
+            }
             "query" => {
                 // {command, params?, path: [keys or indices], value}: a command's result at path.
                 let cmd = v["command"].as_str().ok_or("query needs `command`")?;
diff --git a/crates/ui-egui/tests/scenarios/browser_chevrons.json b/crates/ui-egui/tests/scenarios/browser_chevrons.json
new file mode 100644
index 00000000..5a6b36a8
--- /dev/null
+++ b/crates/ui-egui/tests/scenarios/browser_chevrons.json
@@ -0,0 +1,505 @@
+[
+ {
+  "note": "A design with every kind of browser folder: bodies in a group, a component, a sketch, a construction plane, a canvas and named views."
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "solid.box",
+   "params": {
+    "length": 10,
+    "width": 10,
+    "height": 10
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "solid.box",
+   "params": {
+    "length": 10,
+    "width": 10,
+    "height": 10,
+    "corner": [
+     30,
+     0,
+     0
+    ]
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "solid.box",
+   "params": {
+    "length": 10,
+    "width": 10,
+    "height": 10,
+    "corner": [
+     60,
+     0,
+     0
+    ]
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "component.from_bodies",
+   "params": {
+    "bodies": [
+     "Body3"
+    ]
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "browser.group",
+   "params": {
+    "folder": "bodies",
+    "items": [
+     "Body1"
+    ]
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "construct.plane.offset",
+   "params": {
+    "base": "XY",
+    "offset": 20
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "sketch.create",
+   "params": {
+    "plane": "XZ"
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "sketch.rectangle.two_point",
+   "params": {
+    "p0": [
+     0,
+     0
+    ],
+    "p1": [
+     5,
+     5
+    ]
+   }
+  }
+ },
+ {
+  "call": "engine.execute",
+  "params": {
+   "command": "sketch.finish",
+   "params": {}
+  }
+ },
+ {
+  "make_image": "pic.png"
+ },
+ {
+  "choose_file": "pic.png"
+ },
+ {
+  "start": "canvas.insert"
+ },
+ {
+  "click": {
+   "plane": "XY"
+  }
+ },
+ {
+  "key": "Escape"
+ },
+ {
+  "call": "ui.set",
+  "params": {
+   "dark": true
+  }
+ },
+ {
+  "note": "Folders that start closed open with their arrow, and close again; the click selects nothing."
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Units: mm"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Document Settings"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Units: mm"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Document Settings"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Units: mm"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Top"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Named Views"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Top"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Named Views"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Top"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "XY"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Origin"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "XY"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Origin"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "XY"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "note": "Folders that start open close with their arrow, and open again."
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Body1"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Group1 (1)"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Body1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Group1 (1)"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Body1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Sketch1"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Sketches"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Sketch1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Sketches"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Sketch1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Plane1"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Construction"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Plane1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Construction"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Plane1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Canvas1"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Canvases"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Canvas1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Canvases"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Canvas1"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Body3"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Body3:1"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Body3"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Body3:1"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Body3"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Body2"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Bodies"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Body2"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Bodies"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Body2"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "note": "The design's own row closes the whole tree."
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Bodies"
+   ]
+  }
+ },
+ {
+  "click": {
+   "chevron": "Untitled"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Bodies"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "click": {
+   "chevron": "Untitled"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Bodies"
+   ],
+   "browser_selected": false
+  }
+ },
+ {
+  "note": "Clicking the row of a folder (not its arrow) toggles it too; clicking a component's arrow doesn't pick it."
+ },
+ {
+  "click": {
+   "browser": "Sketches"
+  }
+ },
+ {
+  "expect": {
+   "browser_lacks": [
+    "Sketch1"
+   ]
+  }
+ },
+ {
+  "click": {
+   "browser": "Sketches"
+  }
+ },
+ {
+  "expect": {
+   "browser_has": [
+    "Sketch1"
+   ]
+  }
+ },
+ {
+  "shot": "browser_folds"
+ }
+]
\ No newline at end of file