diff --git a/scripts/init.rhai b/scripts/init.rhai
index c5715c2..3541df9 100644
--- a/scripts/init.rhai
+++ b/scripts/init.rhai
@@ -1,5 +1,23 @@
 // TODO split into user_init.rhai and system_init.rhai
 
+fn make_candidate_keymap() {
+    let keymap = new_keymap();
+    keymap.bind_key("esc", "Exit menu", || s::escape());
+    keymap.bind_key("up", "Up", || s::menu_selection_up(), false);
+    keymap.bind_key("down", "Down", || s::menu_selection_down(), false);
+    keymap.bind_key("bksp", "Backspace", || s::menu_selection_backspace(), false);
+    keymap
+}
+
+fn make_node_selection_keymap(language_name) {
+    let keymap = make_candidate_keymap();
+    for construct in s::language_constructs(s::get_language(language_name)) {
+        keymap.add_regular_candidate(s::construct_name(construct), construct);
+    }
+    keymap.bind_key_for_regular_candidates("enter", "Select", |construct| construct);
+    keymap
+}
+
 fn open_file_menu(dir) {
     let contents = s::list_files_and_dirs(dir);
     let keymap = new_keymap();
@@ -59,6 +77,12 @@ tree_keymap.bind_key("r", "Redo", || s::redo());
 tree_keymap.bind_key("m", "Save bookmark", || s::save_bookmark('a'));
 tree_keymap.bind_key("'", "Go to bookmark", || s::goto_bookmark('a'));
 
+tree_keymap.bind_key("i", "Insert", || {
+    s::open_menu("node_selection");
+    let construct = s::block();
+    s::insert_node(construct);
+});
+
 // ~~~ Text Keymap ~~~
 
 let text_keymap = new_keymap();
@@ -70,16 +94,19 @@ text_keymap.bind_key("del", "Delete", || s::text_ed_delete());
 
 // ~~~ File Selection Keymap ~~~
 
-let file_selection_keymap = new_keymap();
+let file_selection_keymap = make_candidate_keymap();
 file_selection_keymap.bind_key_for_regular_candidates("enter", "Open file", |path| s::open_doc(path));
-file_selection_keymap.bind_key("esc", "Exit menu", || s::escape());
-file_selection_keymap.bind_key("up", "Up", || s::menu_selection_up(), false);
-file_selection_keymap.bind_key("down", "Down", || s::menu_selection_down(), false);
-file_selection_keymap.bind_key("bksp", "Backspace", || s::menu_selection_backspace(), false);
+
+// ~~~ Default Layer ~~~
 
 let layer = new_layer("default");
-layer.add_menu_keymap("file_selection", file_selection_keymap);
+
 layer.add_mode_keymap("Tree", tree_keymap);
 layer.add_mode_keymap("Text", text_keymap);
+
+layer.add_menu_keymap("file_selection", file_selection_keymap);
+// TODO: use local layers
+layer.add_menu_keymap("node_selection", make_node_selection_keymap("json"));
+
 s::register_layer(layer);
 s::add_global_layer("default");
diff --git a/src/engine/engine.rs b/src/engine/engine.rs
index 6422159..57729e3 100644
--- a/src/engine/engine.rs
+++ b/src/engine/engine.rs
@@ -4,7 +4,7 @@ use super::command::Command;
 use super::doc::Doc;
 use super::doc_set::{DocDisplayLabel, DocName, DocSet};
 use super::Settings;
-use crate::language::{LanguageSpec, NotationSetSpec, Storage};
+use crate::language::{Language, LanguageSpec, NotationSetSpec, Storage};
 use crate::parsing::{Parse, ParseError};
 use crate::pretty_doc::DocRef;
 use crate::tree::Node;
@@ -92,6 +92,10 @@ impl Engine {
         Ok(notation_name)
     }
 
+    pub fn get_language(&self, name: &str) -> Result<Language, SynlessError> {
+        Ok(self.storage.language(name)?)
+    }
+
     pub fn set_display_notation(
         &mut self,
         language_name: &str,
@@ -253,12 +257,12 @@ impl Engine {
      * Editing *
      ***********/
 
-    pub fn execute(&mut self, cmd: Command) -> Result<(), SynlessError> {
+    pub fn execute(&mut self, cmd: impl Into<Command>) -> Result<(), SynlessError> {
         let doc = self
             .doc_set
             .visible_doc_mut()
             .ok_or(DocError::NoVisibleDoc)?;
-        doc.execute(&mut self.storage, cmd, &mut self.clipboard)?;
+        doc.execute(&mut self.storage, cmd.into(), &mut self.clipboard)?;
         Ok(())
     }
 
diff --git a/src/language/interface.rs b/src/language/interface.rs
index 646df4f..bfba5e9 100644
--- a/src/language/interface.rs
+++ b/src/language/interface.rs
@@ -134,6 +134,14 @@ impl Language {
         })
     }
 
+    pub fn constructs(self, s: &Storage) -> impl Iterator<Item = Construct> {
+        let constructs = &grammar(s, self.language).constructs;
+        (&constructs).into_iter().map(move |id| Construct {
+            language: self.language,
+            construct: id,
+        })
+    }
+
     pub fn root_construct(self, s: &Storage) -> Construct {
         Construct {
             language: self.language,
@@ -324,3 +332,15 @@ impl FixedSorts {
         }
     }
 }
+
+impl rhai::CustomType for Construct {
+    fn build(mut builder: rhai::TypeBuilder<Self>) {
+        builder.with_name("Construct");
+    }
+}
+
+impl rhai::CustomType for Language {
+    fn build(mut builder: rhai::TypeBuilder<Self>) {
+        builder.with_name("Language");
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 7b97570..f5f485a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -17,7 +17,8 @@ pub use engine::{DocName, Engine, Settings};
 pub use frontends::Terminal;
 pub use keymap::{KeyProg, Keymap, Layer};
 pub use language::{
-    AritySpec, ConstructSpec, GrammarSpec, LanguageSpec, NotationSetSpec, SortSpec, Storage,
+    AritySpec, Construct, ConstructSpec, GrammarSpec, Language, LanguageSpec, NotationSetSpec,
+    SortSpec, Storage,
 };
 pub use pretty_doc::DocRef;
 pub use runtime::Runtime;
diff --git a/src/main.rs b/src/main.rs
index 3ffd78f..a6a2f10 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -22,6 +22,8 @@ fn make_engine() -> rhai::Engine {
     engine.build_type::<synless::Layer>();
     engine.build_type::<synless::KeyProg>();
     engine.build_type::<synless::SynlessError>();
+    engine.build_type::<synless::Construct>();
+    engine.build_type::<synless::Language>();
 
     println!("Signatures:");
     engine
@@ -42,6 +44,7 @@ fn make_runtime() -> Rc<RefCell<Runtime<Terminal>>> {
 }
 
 fn run() -> Result<(), Box<rhai::EvalAltResult>> {
+    // TODO: Log which rhai script failed to compile (instead of simple ?s)
     let mut engine = make_engine();
 
     // Load internals_module.rhai
diff --git a/src/runtime.rs b/src/runtime.rs
index 0d52645..81b4e50 100644
--- a/src/runtime.rs
+++ b/src/runtime.rs
@@ -1,9 +1,10 @@
 use crate::engine::{
-    BookmarkCommand, Command, DocDisplayLabel, DocName, Engine, Settings, TextEdCommand,
-    TextNavCommand, TreeEdCommand, TreeNavCommand,
+    BookmarkCommand, DocDisplayLabel, DocName, Engine, Settings, TextEdCommand, TextNavCommand,
+    TreeEdCommand, TreeNavCommand,
 };
 use crate::frontends::{Event, Frontend, Key};
 use crate::keymap::{KeyLookupResult, KeyProg, Keymap, Layer, LayerManager, MenuSelectionCmd};
+use crate::language::{Construct, Language};
 use crate::style::Style;
 use crate::tree::{Mode, Node};
 use crate::util::{error, log, SynlessBug, SynlessError};
@@ -278,14 +279,25 @@ impl<F: Frontend<Style = Style> + 'static> Runtime<F> {
         self.engine.load_language_ron(Path::new(path), &ron_string)
     }
 
+    pub fn get_language(&mut self, language_name: &str) -> Result<Language, SynlessError> {
+        self.engine.get_language(language_name)
+    }
+
+    pub fn language_constructs(&mut self, language: Language) -> Vec<rhai::Dynamic> {
+        language
+            .constructs(&self.engine.raw_storage())
+            .map(rhai::Dynamic::from)
+            .collect()
+    }
+
+    pub fn construct_name(&self, construct: Construct) -> String {
+        construct.name(self.engine.raw_storage()).to_owned()
+    }
+
     /***********
      * Editing *
      ***********/
 
-    pub fn execute(&mut self, cmd: Command) -> Result<(), SynlessError> {
-        self.engine.execute(cmd)
-    }
-
     pub fn undo(&mut self) -> Result<(), SynlessError> {
         self.engine.undo()
     }
@@ -294,6 +306,11 @@ impl<F: Frontend<Style = Style> + 'static> Runtime<F> {
         self.engine.redo()
     }
 
+    pub fn insert_node(&mut self, construct: Construct) -> Result<(), SynlessError> {
+        let node = Node::new(self.engine.raw_storage_mut(), construct);
+        self.engine.execute(TreeEdCommand::Insert(node))
+    }
+
     /***********
      * Private *
      ***********/
@@ -325,7 +342,7 @@ impl<F: Frontend<Style = Style> + 'static> Runtime<F> {
                 Ok(None)
             }
             Some(KeyLookupResult::InsertChar(ch)) => {
-                self.execute(TextEdCommand::Insert(ch).into())?;
+                self.engine.execute(TextEdCommand::Insert(ch))?;
                 self.display()?;
                 Ok(None)
             }
@@ -435,7 +452,7 @@ macro_rules! register {
     ($module:expr, $runtime:ident, $command:ident :: $variant:ident as $name:ident) => {
         let rt = $runtime.clone();
         let closure = move || {
-            rt.borrow_mut().execute($command::$variant.into())
+            rt.borrow_mut().engine.execute($command::$variant)
                 .map_err(|err| Box::<rhai::EvalAltResult>::from(err))
         };
         rhai::FuncRegistration::new(stringify!($name))
@@ -445,7 +462,7 @@ macro_rules! register {
     ($module:expr, $runtime:ident, $command:ident :: $variant:ident ($( $param:ident : $type:ty ),*) as $name:ident) => {
         let rt = $runtime.clone();
         let closure = move | $( $param : $type ),* | {
-            rt.borrow_mut().execute($command::$variant( $( $param ),* ).into())
+            rt.borrow_mut().engine.execute($command::$variant( $( $param ),* ))
                 .map_err(|err| Box::<rhai::EvalAltResult>::from(err))
         };
         rhai::FuncRegistration::new(stringify!($name))
@@ -486,8 +503,11 @@ impl<F: Frontend<Style = Style> + 'static> Runtime<F> {
 
         // Languages
         register!(module, rt.load_language(path: &str)?);
+        register!(module, rt.get_language(language_name: &str)?);
+        register!(module, rt.language_constructs(language: Language));
+        register!(module, rt.construct_name(construct: Construct));
 
-        // Editing
+        // Editing: Tree Nav
         register!(module, rt, TreeNavCommand::Prev as tree_nav_prev);
         register!(module, rt, TreeNavCommand::First as tree_nav_first);
         register!(module, rt, TreeNavCommand::Next as tree_nav_next);
@@ -506,22 +526,28 @@ impl<F: Frontend<Style = Style> + 'static> Runtime<F> {
         register!(module, rt, TreeNavCommand::Parent as tree_nav_parent);
         register!(module, rt, TreeNavCommand::EnterText as tree_nav_enter_text);
 
+        // Editing: Tree Ed
         register!(module, rt, TreeEdCommand::Backspace as tree_ed_backspace);
         register!(module, rt, TreeEdCommand::Delete as tree_ed_delete);
+        register!(module, rt.insert_node(construct: Construct)?);
 
+        // Editing: Text Nav
         register!(module, rt, TextNavCommand::Left as text_nav_left);
         register!(module, rt, TextNavCommand::Right as text_nav_right);
         register!(module, rt, TextNavCommand::Beginning as text_nav_beginning);
         register!(module, rt, TextNavCommand::End as text_nav_end);
         register!(module, rt, TextNavCommand::ExitText as text_nav_exit);
 
+        // Editing: Text Ed
         register!(module, rt, TextEdCommand::Backspace as text_ed_backspace);
         register!(module, rt, TextEdCommand::Delete as text_ed_delete);
         register!(module, rt, TextEdCommand::Insert(ch: char) as text_ed_insert);
 
+        // Editing: Bookmark
         register!(module, rt, BookmarkCommand::Save(ch: char) as save_bookmark);
         register!(module, rt, BookmarkCommand::Goto(ch: char) as goto_bookmark);
 
+        // Editing: Meta
         register!(module, rt.undo()?);
         register!(module, rt.redo()?);