diff --git a/app-proto/full-interface/.gitignore b/app-proto/full-interface/.gitignore
deleted file mode 100644
index 19aa86b..0000000
--- a/app-proto/full-interface/.gitignore
+++ /dev/null
@@ -1,4 +0,0 @@
-target
-dist
-profiling
-Cargo.lock
\ No newline at end of file
diff --git a/app-proto/full-interface/main.css b/app-proto/full-interface/main.css
deleted file mode 100644
index a687aac..0000000
--- a/app-proto/full-interface/main.css
+++ /dev/null
@@ -1,120 +0,0 @@
-body {
-  margin: 0px;
-  color: #fcfcfc;
-  background-color: #222;
-}
-
-/* sidebar */
-
-#sidebar {
-  display: flex;
-  flex-direction: column;
-  float: left;
-  width: 450px;
-  height: 100vh;
-  margin: 0px;
-  padding: 0px;
-  border-width: 0px 1px 0px 0px;
-  border-style: solid;
-  border-color: #555;
-}
-
-/* add-remove */
-
-#add-remove {
-  display: flex;
-  gap: 8px;
-  margin: 8px;
-}
-
-#add-remove > button {
-  width: 32px;
-  height: 32px;
-  font-size: large;
-}
-
-/* outline */
-
-#outline {
-  flex-grow: 1;
-  margin: 0px;
-  padding: 0px;
-  overflow-y: scroll;
-}
-
-li {
-  user-select: none;
-}
-
-summary {
-  display: flex;
-}
-
-summary.selected {
-  color: #fff;
-  background-color: #444;
-}
-
-summary > div, .cst {
-  padding-top: 4px;
-  padding-bottom: 4px;
-}
-
-.elt, .cst {
-  display: flex;
-  flex-grow: 1;
-  padding-left: 8px;
-  padding-right: 8px;
-}
-
-.elt-switch {
-  width: 18px;
-  padding-left: 2px;
-  text-align: center;
-}
-
-details:has(li) .elt-switch::after {
-  content: '▸';
-}
-
-details[open]:has(li) .elt-switch::after {
-  content: '▾';
-}
-
-.elt-label {
-  flex-grow: 1;
-}
-
-.cst-label {
-  flex-grow: 1;
-}
-
-.elt-rep {
-  display: flex;
-}
-
-.elt-rep > div, .cst-rep {
-  padding: 2px 0px 0px 0px;
-  font-size: 10pt;
-  text-align: center;
-  width: 56px;
-}
-
-.cst {
-  font-style: italic;
-}
-
-/* display */
-
-canvas {
-  float: left;
-  margin-left: 20px;
-  margin-top: 20px;
-  background-color: #020202;
-  border: 1px solid #555;
-  border-radius: 16px;
-}
-
-canvas:focus {
-  border-color: #aaa;
-}
\ No newline at end of file
diff --git a/app-proto/full-interface/src/add_remove.rs b/app-proto/full-interface/src/add_remove.rs
deleted file mode 100644
index 59220ae..0000000
--- a/app-proto/full-interface/src/add_remove.rs
+++ /dev/null
@@ -1,55 +0,0 @@
-use sycamore::prelude::*;
-use web_sys::{MouseEvent, console, wasm_bindgen::JsValue};
-
-use crate::AppState;
-use crate::Constraint;
-
-#[component]
-pub fn AddRemove() -> View {
-    let state = use_context::<AppState>();
-    
-    view! {
-        div(id="add-remove") {
-            button(
-                on:click=move |event: MouseEvent| {
-                    console::log_1(&JsValue::from("constraints:"));
-                    state.assembly.constraints.with(|csts| {
-                        for (_, cst) in csts.into_iter() {
-                            console::log_4(
-                                &JsValue::from(cst.args.0),
-                                &JsValue::from(cst.args.1),
-                                &JsValue::from(":"),
-                                &JsValue::from(cst.rep)
-                            );
-                        }
-                    });
-                }
-            ) { "+" }
-            button(
-                disabled={
-                    state.selection.with(|sel| sel.len() != 2)
-                },
-                on:click=move |event: MouseEvent| {
-                    let args = state.selection.with(
-                        |sel| {
-                            let arg_vec: Vec<_> = sel.into_iter().collect();
-                            (arg_vec[0].clone(), arg_vec[1].clone())
-                        }
-                    );
-                    console::log_5(
-                        &JsValue::from("add constraint"),
-                        &JsValue::from(args.0),
-                        &JsValue::from(args.1),
-                        &JsValue::from(":"),
-                        &JsValue::from(0.0)
-                    );
-                    state.assembly.insert_constraint(Constraint {
-                        args: args,
-                        rep: 0.0
-                    });
-                    state.selection.update(|sel| sel.clear());
-                }
-            ) { "🔗" }
-        }
-    }
-}
\ No newline at end of file
diff --git a/app-proto/full-interface/src/assembly.rs b/app-proto/full-interface/src/assembly.rs
deleted file mode 100644
index 6fac59f..0000000
--- a/app-proto/full-interface/src/assembly.rs
+++ /dev/null
@@ -1,44 +0,0 @@
-use nalgebra::DVector;
-use rustc_hash::FxHashSet;
-use slab::Slab;
-use sycamore::prelude::*;
-
-#[derive(Clone, PartialEq)]
-pub struct Element {
-    pub id: String,
-    pub label: String,
-    pub color: [f32; 3],
-    pub rep: DVector<f64>,
-    pub constraints: FxHashSet<usize>
-}
-
-#[derive(Clone)]
-pub struct Constraint {
-    pub args: (usize, usize),
-    pub rep: f64
-}
-
-// a complete, view-independent description of an assembly
-#[derive(Clone)]
-pub struct Assembly {
-    pub elements: Signal<Slab<Element>>,
-    pub constraints: Signal<Slab<Constraint>>
-}
-
-impl Assembly {
-    pub fn new() -> Assembly {
-        Assembly {
-            elements: create_signal(Slab::new()),
-            constraints: create_signal(Slab::new())
-        }
-    }
-    
-    pub fn insert_constraint(&self, constraint: Constraint) {
-        let args = constraint.args;
-        let key = self.constraints.update(|csts| csts.insert(constraint));
-        self.elements.update(|elts| {
-            elts[args.0].constraints.insert(key);
-            elts[args.1].constraints.insert(key);
-        })
-    }
-}
\ No newline at end of file
diff --git a/app-proto/full-interface/src/outline.rs b/app-proto/full-interface/src/outline.rs
deleted file mode 100644
index be5a9b1..0000000
--- a/app-proto/full-interface/src/outline.rs
+++ /dev/null
@@ -1,155 +0,0 @@
-use itertools::Itertools;
-use sycamore::{prelude::*, web::tags::div};
-use web_sys::{Element, KeyboardEvent, MouseEvent, wasm_bindgen::JsCast};
-
-use crate::AppState;
-
-// this component lists the elements of the assembly, showing the constraints
-// on each element as a collapsible sub-list. its implementation is based on
-// Kate Morley's HTML + CSS tree views:
-//
-//   https://iamkate.com/code/tree-views/
-//
-#[component]
-pub fn Outline() -> View {
-    // sort the elements alphabetically by ID
-    let elements_sorted = create_memo(|| {
-        let state = use_context::<AppState>();
-        state.assembly.elements
-            .get_clone()
-            .into_iter()
-            .sorted_by_key(|(_, elt)| elt.id.clone())
-            .collect()
-    });
-    
-    view! {
-        ul(
-            id="outline",
-            on:click={
-                let state = use_context::<AppState>();
-                move |_| state.selection.update(|sel| sel.clear())
-            }
-        ) {
-            Keyed(
-                list=elements_sorted,
-                view=|(key, elt)| {
-                    let state = use_context::<AppState>();
-                    let class = create_memo({
-                        move || {
-                            if state.selection.with(|sel| sel.contains(&key)) {
-                                "selected"
-                            } else {
-                                ""
-                            }
-                        }
-                    });
-                    let label = elt.label.clone();
-                    let rep_components = elt.rep.iter().map(|u| {
-                        let u_coord = u.to_string().replace("-", "\u{2212}");
-                        View::from(div().children(u_coord))
-                    }).collect::<Vec<_>>();
-                    let constrained = elt.constraints.len() > 0;
-                    let details_node = create_node_ref();
-                    view! {
-                        /* [TO DO] switch to integer-valued parameters whenever
-                        that becomes possible again */
-                        li {
-                            details(ref=details_node) {
-                                summary(
-                                    class=class.get(),
-                                    on:keydown={
-                                        move |event: KeyboardEvent| {
-                                            match event.key().as_str() {
-                                                "Enter" => {
-                                                    if event.shift_key() {
-                                                        state.selection.update(|sel| {
-                                                            if !sel.remove(&key) {
-                                                                sel.insert(key);
-                                                            }
-                                                        });
-                                                    } else {
-                                                        state.selection.update(|sel| {
-                                                            sel.clear();
-                                                            sel.insert(key);
-                                                        });
-                                                    }
-                                                    event.prevent_default();
-                                                },
-                                                "ArrowRight" if constrained => {
-                                                    let _ = details_node
-                                                        .get()
-                                                        .unchecked_into::<Element>()
-                                                        .set_attribute("open", "");
-                                                },
-                                                "ArrowLeft" => {
-                                                    let _ = details_node
-                                                        .get()
-                                                        .unchecked_into::<Element>()
-                                                        .remove_attribute("open");
-                                                },
-                                                _ => ()
-                                            }
-                                        }
-                                    }
-                                ) {
-                                    div(
-                                        class="elt-switch",
-                                        on:click=|event: MouseEvent| event.stop_propagation()
-                                    )
-                                    div(
-                                        class="elt",
-                                        on:click={
-                                            move |event: MouseEvent| {
-                                                if event.shift_key() {
-                                                    state.selection.update(|sel| {
-                                                        if !sel.remove(&key) {
-                                                            sel.insert(key);
-                                                        }
-                                                    });
-                                                } else {
-                                                    state.selection.update(|sel| {
-                                                        sel.clear();
-                                                        sel.insert(key);
-                                                    });
-                                                }
-                                                event.stop_propagation();
-                                                event.prevent_default();
-                                            }
-                                        }
-                                    ) {
-                                        div(class="elt-label") { (label) }
-                                        div(class="elt-rep") { (rep_components) }
-                                    }
-                                }
-                                ul(class="constraints") {
-                                    Keyed(
-                                        list=elt.constraints.into_iter().collect::<Vec<_>>(),
-                                        view=move |c_key: usize| {
-                                            let c_state = use_context::<AppState>();
-                                            let assembly = &c_state.assembly;
-                                            let cst = assembly.constraints.with(|csts| csts[c_key].clone());
-                                            let other_arg = if cst.args.0 == key {
-                                                cst.args.1
-                                            } else {
-                                                cst.args.0
-                                            };
-                                            let other_arg_label = assembly.elements.with(|elts| elts[other_arg].label.clone());
-                                            view! {
-                                                li(class="cst") {
-                                                    div(class="cst-label") { (other_arg_label) }
-                                                    div(class="cst-rep") { (cst.rep) }
-                                                }
-                                            }
-                                        },
-                                        key=|c_key| c_key.clone()
-                                    )
-                                }
-                            }
-                        }
-                    }
-                },
-                key=|(key, _)| key.clone()
-            )
-        }
-    }
-}
\ No newline at end of file
diff --git a/app-proto/inversive-display/.gitignore b/app-proto/inversive-display/.gitignore
index 19aa86b..238273d 100644
--- a/app-proto/inversive-display/.gitignore
+++ b/app-proto/inversive-display/.gitignore
@@ -1,4 +1,3 @@
 target
 dist
-profiling
 Cargo.lock
\ No newline at end of file
diff --git a/app-proto/sketch-outline/.gitignore b/app-proto/sketch-outline/.gitignore
new file mode 100644
index 0000000..238273d
--- /dev/null
+++ b/app-proto/sketch-outline/.gitignore
@@ -0,0 +1,3 @@
+target
+dist
+Cargo.lock
\ No newline at end of file
diff --git a/app-proto/full-interface/Cargo.toml b/app-proto/sketch-outline/Cargo.toml
similarity index 98%
rename from app-proto/full-interface/Cargo.toml
rename to app-proto/sketch-outline/Cargo.toml
index 920469a..35d199b 100644
--- a/app-proto/full-interface/Cargo.toml
+++ b/app-proto/sketch-outline/Cargo.toml
@@ -12,7 +12,6 @@ itertools = "0.13.0"
 js-sys = "0.3.70"
 nalgebra = "0.33.0"
 rustc-hash = "2.0.0"
-slab = "0.4.9"
 sycamore = "0.9.0-beta.3"
 
 # The `console_error_panic_hook` crate provides better debugging of panics by
diff --git a/app-proto/full-interface/index.html b/app-proto/sketch-outline/index.html
similarity index 100%
rename from app-proto/full-interface/index.html
rename to app-proto/sketch-outline/index.html
diff --git a/app-proto/sketch-outline/main.css b/app-proto/sketch-outline/main.css
new file mode 100644
index 0000000..cd7bc44
--- /dev/null
+++ b/app-proto/sketch-outline/main.css
@@ -0,0 +1,79 @@
+body {
+  margin-left: 20px;
+  margin-top: 20px;
+  color: #fcfcfc;
+  background-color: #222;
+}
+
+/* outline */
+
+ul {
+  float: left;
+  width: 450px;
+  height: 750px;
+  margin: 0px;
+  padding: 8px;
+  border: 1px solid #555;
+  border-radius: 16px;
+  box-sizing: border-box;
+}
+
+li {
+  display: flex;
+  padding: 3px;
+  list-style-type: none;
+  background-color: #444;
+  border-radius: 8px;
+}
+
+li.selected {
+  color: #fff;
+  background-color: #666;
+}
+
+li:not(:last-child) {
+  margin-bottom: 8px;
+}
+
+li > .elt-label {
+  flex-grow: 1;
+  padding: 2px 0px 2px 4px;
+}
+
+li > .elt-rep {
+  display: flex;
+}
+
+li > .elt-rep > div {
+  padding: 2px;
+  margin-left: 3px;
+  text-align: center;
+  width: 60px;
+  background-color: #333;
+}
+
+li.selected > .elt-rep > div {
+  background-color: #555;
+}
+
+li > .elt-rep > div:first-child {
+  border-radius: 6px 0px 0px 6px;
+}
+
+li > .elt-rep > div:last-child {
+  border-radius: 0px 6px 6px 0px;
+}
+
+/* display */
+
+canvas {
+  float: left;
+  margin-left: 16px;
+  background-color: #020202;
+  border: 1px solid #555;
+  border-radius: 16px;
+}
+
+canvas:focus {
+  border-color: #aaa;
+}
\ No newline at end of file
diff --git a/app-proto/sketch-outline/src/assembly.rs b/app-proto/sketch-outline/src/assembly.rs
new file mode 100644
index 0000000..fa7fc3e
--- /dev/null
+++ b/app-proto/sketch-outline/src/assembly.rs
@@ -0,0 +1,18 @@
+use nalgebra::DVector;
+use rustc_hash::FxHashMap;
+use sycamore::reactive::Signal;
+
+#[derive(Clone, PartialEq)]
+pub struct Element {
+    pub id: String,
+    pub label: String,
+    pub color: [f32; 3],
+    pub rep: DVector<f64>
+}
+
+// a complete, view-independent description of an assembly
+#[derive(Clone)]
+pub struct Assembly {
+    // the order of the elements is arbitrary, and it could change at any time
+    pub elements: Signal<FxHashMap<String, Element>>
+}
\ No newline at end of file
diff --git a/app-proto/full-interface/src/display.rs b/app-proto/sketch-outline/src/display.rs
similarity index 97%
rename from app-proto/full-interface/src/display.rs
rename to app-proto/sketch-outline/src/display.rs
index 52b2ae9..2d0900d 100644
--- a/app-proto/full-interface/src/display.rs
+++ b/app-proto/sketch-outline/src/display.rs
@@ -288,17 +288,17 @@ pub fn Display() -> View {
                 
                 // get the assembly
                 let elements = state.assembly.elements.get_clone();
-                let element_iter = (&elements).into_iter();
-                let reps_world: Vec<_> = element_iter.clone().map(|(_, elt)| &assembly_to_world * &elt.rep).collect();
-                let colors: Vec<_> = element_iter.clone().map(|(key, elt)|
-                    if state.selection.with(|sel| sel.contains(&key)) {
+                let element_iter = (&elements).values();
+                let reps_world: Vec<_> = element_iter.clone().map(|elt| &assembly_to_world * &elt.rep).collect();
+                let colors: Vec<_> = element_iter.clone().map(|elt|
+                    if state.selection.with(|sel| sel.contains(&elt.id)) {
                         elt.color.map(|ch| 0.2 + 0.8*ch)
                     } else {
                         elt.color
                     }
                 ).collect();
-                let highlights: Vec<_> = element_iter.map(|(key, _)|
-                    if state.selection.with(|sel| sel.contains(&key)) {
+                let highlights: Vec<_> = element_iter.map(|elt|
+                    if state.selection.with(|sel| sel.contains(&elt.id)) {
                         1.0_f32
                     } else {
                         HIGHLIGHT
@@ -386,8 +386,8 @@ pub fn Display() -> View {
         // again
         canvas(
             ref=display,
-            width="600",
-            height="600",
+            width="750",
+            height="750",
             tabindex="0",
             on:keydown=move |event: KeyboardEvent| {
                 if event.key() == "Shift" {
diff --git a/app-proto/full-interface/src/identity.vert b/app-proto/sketch-outline/src/identity.vert
similarity index 100%
rename from app-proto/full-interface/src/identity.vert
rename to app-proto/sketch-outline/src/identity.vert
diff --git a/app-proto/full-interface/src/inversive.frag b/app-proto/sketch-outline/src/inversive.frag
similarity index 100%
rename from app-proto/full-interface/src/inversive.frag
rename to app-proto/sketch-outline/src/inversive.frag
diff --git a/app-proto/full-interface/src/main.rs b/app-proto/sketch-outline/src/main.rs
similarity index 61%
rename from app-proto/full-interface/src/main.rs
rename to app-proto/sketch-outline/src/main.rs
index 2f31ada..0d1b0c7 100644
--- a/app-proto/full-interface/src/main.rs
+++ b/app-proto/sketch-outline/src/main.rs
@@ -1,79 +1,66 @@
-mod add_remove;
 mod assembly;
 mod display;
 mod outline;
 
 use nalgebra::DVector;
-use rustc_hash::FxHashSet;
+use rustc_hash::{FxHashMap, FxHashSet};
 use sycamore::prelude::*;
 
-use add_remove::AddRemove;
-use assembly::{Assembly, Constraint, Element};
+use assembly::{Assembly, Element};
 use display::Display;
 use outline::Outline;
 
 #[derive(Clone)]
 struct AppState {
     assembly: Assembly,
-    selection: Signal<FxHashSet<usize>>
-}
-
-impl AppState {
-    fn new() -> AppState {
-        AppState {
-            assembly: Assembly::new(),
-            selection: create_signal(FxHashSet::default())
-        }
-    }
+    selection: Signal<FxHashSet<String>>
 }
 
 fn main() {
     sycamore::render(|| {
-        let state = AppState::new();
-        let key_a = state.assembly.elements.update(
+        let state = AppState {
+            assembly: Assembly {
+                elements: create_signal(FxHashMap::default())
+            },
+            selection: create_signal(FxHashSet::default())
+        };
+        state.assembly.elements.update(
             |elts| elts.insert(
+                "wing_a".to_string(),
                 Element {
                     id: String::from("wing_a"),
                     label: String::from("Wing A"),
                     color: [1.00_f32, 0.25_f32, 0.00_f32],
-                    rep: DVector::<f64>::from_column_slice(&[0.5, 0.5, 0.0, 0.5, -0.25]),
-                    constraints: FxHashSet::default()
+                    rep: DVector::<f64>::from_column_slice(&[0.5, 0.5, 0.0, 0.5, -0.25])
                 }
             )
         );
-        let key_b = state.assembly.elements.update(
+        state.assembly.elements.update(
             |elts| elts.insert(
+                "wing_b".to_string(),
                 Element {
                     id: String::from("wing_b"),
                     label: String::from("Wing B"),
                     color: [0.00_f32, 0.25_f32, 1.00_f32],
-                    rep: DVector::<f64>::from_column_slice(&[-0.5, -0.5, 0.0, 0.5, -0.25]),
-                    constraints: FxHashSet::default()
+                    rep: DVector::<f64>::from_column_slice(&[-0.5, -0.5, 0.0, 0.5, -0.25])
                 },
             )
         );
         state.assembly.elements.update(
             |elts| elts.insert(
+                "central".to_string(),
                 Element {
                     id: String::from("central"),
                     label: String::from("Central"),
                     color: [0.75_f32, 0.75_f32, 0.75_f32],
-                    rep: DVector::<f64>::from_column_slice(&[0.0, 0.0, 0.0, 0.4, -0.625]),
-                    constraints: FxHashSet::default()
+                    rep: DVector::<f64>::from_column_slice(&[0.0, 0.0, 0.0, 0.4, -0.625])
                 }
             )
         );
-        state.assembly.insert_constraint(Constraint {
-            args: (key_a, key_b),
-            rep: 0.5
-        });
         provide_context(state);
         
         view! {
-            div(id="sidebar") {
-                AddRemove {}
-                Outline {}
-            }
+            Outline {}
             Display {}
         }
     });
diff --git a/app-proto/sketch-outline/src/outline.rs b/app-proto/sketch-outline/src/outline.rs
new file mode 100644
index 0000000..13e506e
--- /dev/null
+++ b/app-proto/sketch-outline/src/outline.rs
@@ -0,0 +1,80 @@
+use itertools::Itertools;
+use sycamore::{prelude::*, web::tags::div};
+use web_sys::KeyboardEvent;
+
+use crate::AppState;
+
+#[component]
+pub fn Outline() -> View {
+    // sort the elements alphabetically by ID
+    let elements_sorted = create_memo(|| {
+        let state = use_context::<AppState>();
+        state.assembly.elements
+            .get_clone()
+            .into_iter()
+            .sorted_by_key(|(id, _)| id.clone())
+            .map(|(_, elt)| elt)
+            .collect()
+    });
+    
+    view! {
+        ul {
+            Keyed(
+                list=elements_sorted,
+                view=|elt| {
+                    let state = use_context::<AppState>();
+                    let class = create_memo({
+                        let id = elt.id.clone();
+                        move || {
+                            if state.selection.with(|sel| sel.contains(&id)) {
+                                "selected"
+                            } else {
+                                ""
+                            }
+                        }
+                    });
+                    let label = elt.label.clone();
+                    let rep_components = elt.rep.iter().map(|u| {
+                        let u_coord = u.to_string().replace("-", "\u{2212}");
+                        View::from(div().children(u_coord))
+                    }).collect::<Vec<_>>();
+                    view! {
+                        /* [TO DO] switch to integer-valued parameters whenever
+                        that becomes possible again */
+                        li(
+                            class=class.get(),
+                            tabindex="0",
+                            on:click={
+                                let id = elt.id.clone();
+                                move |_| {
+                                    state.selection.update(|sel| {
+                                        if !sel.remove(&id) {
+                                            sel.insert(id.clone());
+                                        }
+                                    });
+                                }
+                            },
+                            on:keydown={
+                                let id = elt.id.clone();
+                                move |event: KeyboardEvent| {
+                                    if event.key() == "Enter" {
+                                        state.selection.update(|sel| {
+                                            if !sel.remove(&id) {
+                                                sel.insert(id.clone());
+                                            }
+                                        });
+                                        event.prevent_default();
+                                    }
+                                }
+                            }
+                        ) {
+                            div(class="elt-label") { (label) }
+                            div(class="elt-rep") { (rep_components) }
+                        }
+                    }
+                },
+                key=|elt| elt.id.clone()
+            )
+        }
+    }
+}
\ No newline at end of file