diff --git a/Cargo.lock b/Cargo.lock
index 0ba0ef4..97bf463 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -938,6 +938,7 @@ version = "0.13.0"
 dependencies = [
  "crossterm",
  "tengri",
+ "tengri_core",
  "tengri_dsl",
  "tengri_input",
  "tengri_output",
@@ -945,6 +946,10 @@ dependencies = [
  "tengri_tui",
 ]
 
+[[package]]
+name = "tengri_core"
+version = "0.13.0"
+
 [[package]]
 name = "tengri_dsl"
 version = "0.13.0"
@@ -952,6 +957,7 @@ dependencies = [
  "itertools 0.14.0",
  "konst",
  "proptest",
+ "tengri_core",
  "tengri_tui",
  "thiserror",
 ]
@@ -960,6 +966,7 @@ dependencies = [
 name = "tengri_input"
 version = "0.13.0"
 dependencies = [
+ "tengri_core",
  "tengri_dsl",
  "tengri_tui",
 ]
@@ -971,6 +978,7 @@ dependencies = [
  "proptest",
  "proptest-derive",
  "tengri",
+ "tengri_core",
  "tengri_dsl",
  "tengri_tui",
 ]
@@ -983,6 +991,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn",
+ "tengri_core",
 ]
 
 [[package]]
@@ -998,6 +1007,7 @@ dependencies = [
  "rand",
  "ratatui",
  "tengri",
+ "tengri_core",
  "tengri_dsl",
  "tengri_input",
  "tengri_output",
diff --git a/Cargo.toml b/Cargo.toml
index 4a6d408..a7bb2eb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,11 +1,15 @@
-[workspace.package]
-version = "0.13.0"
-edition = "2024"
+[profile.release]
+lto = true
+
+[profile.coverage]
+inherits = "test"
+lto = false
 
 [workspace]
 resolver = "2"
 members = [
   "./tengri",
+  "./core",
   "./input",
   "./output",
   "./tui",
@@ -13,9 +17,25 @@ members = [
   "./proc",
 ]
 
-[profile.release]
-lto = true
+[workspace.package]
+version = "0.13.0"
+edition = "2024"
 
-[profile.coverage]
-inherits = "test"
-lto = false
+[workspace.dependencies]
+atomic_float    = { version = "1" }
+better-panic    = { version = "0.3.0" }
+crossterm       = { version = "0.28.1" }
+heck            = { version = "0.5" }
+itertools       = { version = "0.14.0" }
+konst           = { version = "0.3.16", features = [ "rust_1_83" ] }
+palette         = { version = "0.7.6", features = [ "random" ] }
+proc-macro2     = { version = "1", features = ["span-locations"] }
+proptest        = { version = "^1" }
+proptest-derive = { version = "^0.5.1" }
+quanta          = { version = "0.12.3" }
+quote           = { version = "1" }
+rand            = { version = "0.8.5" }
+ratatui         = { version = "0.29.0", features = [ "unstable-widget-ref", "underline-color" ] }
+syn             = { version = "2", features = ["full", "extra-traits"] }
+thiserror       = { version = "2.0" }
+unicode-width   = { version = "0.2" }
diff --git a/core/Cargo.toml b/core/Cargo.toml
new file mode 100644
index 0000000..b4e9baa
--- /dev/null
+++ b/core/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name        = "tengri_core"
+description = "UI metaframework, core definitions."
+version     = { workspace = true }
+edition     = { workspace = true }
+
diff --git a/core/src/lib.rs b/core/src/lib.rs
new file mode 100644
index 0000000..22288d1
--- /dev/null
+++ b/core/src/lib.rs
@@ -0,0 +1,7 @@
+use std::error::Error;
+
+/// Standard result type.
+pub type Usually<T> = Result<T, Box<dyn Error>>;
+
+/// Standard optional result type.
+pub type Perhaps<T> = Result<Option<T>, Box<dyn Error>>;
diff --git a/dsl/Cargo.toml b/dsl/Cargo.toml
index 3609ada..ab0bc37 100644
--- a/dsl/Cargo.toml
+++ b/dsl/Cargo.toml
@@ -5,12 +5,10 @@ version     = { workspace = true }
 edition     = { workspace = true }
 
 [dependencies]
-konst     = { version = "0.3.16", features = [ "rust_1_83" ] }
-itertools = "0.14.0"
-thiserror = "2.0"
-
-[features]
-default = []
+tengri_core = { path = "../core" }
+konst       = { workspace = true }
+itertools   = { workspace = true }
+thiserror   = { workspace = true }
 
 [dev-dependencies]
 tengri_tui = { path = "../tui" }
diff --git a/dsl/src/dsl.rs b/dsl/src/dsl_parse.rs
similarity index 81%
rename from dsl/src/dsl.rs
rename to dsl/src/dsl_parse.rs
index f4eedaf..3923cd4 100644
--- a/dsl/src/dsl.rs
+++ b/dsl/src/dsl_parse.rs
@@ -1,5 +1,4 @@
 use crate::*;
-use thiserror::Error;
 
 pub type ParseResult<T> = Result<T, ParseError>;
 
@@ -16,41 +15,6 @@ pub type ParseResult<T> = Result<T, ParseError>;
     Code(u8),
 }
 
-pub trait TryFromDsl<'state, T>: Sized {
-    fn try_from_expr <'source: 'state> (
-        _state: &'state T, _iter: &mut TokenIter<'source>
-    ) -> Option<Self> {
-        None
-    }
-    fn try_from_atom <'source: 'state> (
-        state: &'state T, value: Value<'source>
-    ) -> Option<Self> {
-        if let Exp(0, mut iter) = value {
-            return Self::try_from_expr(state, &mut iter)
-        }
-        None
-    }
-}
-
-/// Map EDN tokens to parameters of a given type for a given context
-pub trait Context<'state, U>: Sized {
-    fn get <'source> (&'state self, _iter: &mut TokenIter<'source>) -> Option<U> {
-        None
-    }
-}
-
-impl<'state, T: Context<'state, U>, U> Context<'state, U> for &T {
-    fn get <'source> (&'state self, iter: &mut TokenIter<'source>) -> Option<U> {
-        (*self).get(iter)
-    }
-}
-
-impl<'state, T: Context<'state, U>, U> Context<'state, U> for Option<T> {
-    fn get <'source> (&'state self, iter: &mut TokenIter<'source>) -> Option<U> {
-        self.as_ref().map(|s|s.get(iter)).flatten()
-    }
-}
-
 /// Implement the const iterator pattern.
 #[macro_export] macro_rules! const_iter {
     ($(<$l:lifetime>)?|$self:ident: $Struct:ty| => $Item:ty => $expr:expr) => {
@@ -138,6 +102,7 @@ impl<'a> SourceIter<'a> {
         }
     }
 }
+
 /// Static iteration helper.
 #[macro_export] macro_rules! iterate {
     ($expr:expr => $arg: pat => $body:expr) => {
@@ -240,7 +205,9 @@ pub const fn to_digit (c: char) -> Result<usize, ParseError> {
 }
 
 impl<'source> Token<'source> {
-    pub const fn new (source: &'source str, start: usize, length: usize, value: Value<'source>) -> Self {
+    pub const fn new (
+        source: &'source str, start: usize, length: usize, value: Value<'source>
+    ) -> Self {
         Self { source, start, length, value }
     }
     pub const fn end (&self) -> usize {
@@ -248,7 +215,6 @@ impl<'source> Token<'source> {
     }
     pub const fn slice (&'source self) -> &'source str {
         self.slice_source(self.source)
-        //str_range(self.source, self.start, self.end())
     }
     pub const fn slice_source <'range> (&'source self, source: &'range str) -> &'range str {
         str_range(source, self.start, self.end())
@@ -256,6 +222,9 @@ impl<'source> Token<'source> {
     pub const fn slice_source_exp <'range> (&'source self, source: &'range str) -> &'range str {
         str_range(source, self.start.saturating_add(1), self.end())
     }
+    pub const fn with_value (self, value: Value<'source>) -> Self {
+        Self { value, ..self }
+    }
     pub const fn value (&self) -> Value {
         self.value
     }
@@ -272,49 +241,43 @@ impl<'source> Token<'source> {
         }
     }
     pub const fn grow_key (self) -> Self {
-        let mut token = self.grow();
-        token.value = Key(token.slice_source(self.source));
-        token
+        let token = self.grow();
+        token.with_value(Key(token.slice_source(self.source)))
     }
     pub const fn grow_sym (self) -> Self {
-        let mut token = self.grow();
-        token.value = Sym(token.slice_source(self.source));
-        token
+        let token = self.grow();
+        token.with_value(Sym(token.slice_source(self.source)))
     }
     pub const fn grow_str (self) -> Self {
-        let mut token = self.grow();
-        token.value = Str(token.slice_source(self.source));
-        token
+        let token = self.grow();
+        token.with_value(Str(token.slice_source(self.source)))
     }
     pub const fn grow_exp (self) -> Self {
-        let mut token = self.grow();
+        let token = self.grow();
         if let Exp(depth, _) = token.value {
-            token.value = Exp(depth, TokenIter::new(token.slice_source_exp(self.source)));
+            token.with_value(Exp(depth, TokenIter::new(token.slice_source_exp(self.source))))
         } else {
             unreachable!()
         }
-        token
     }
     pub const fn grow_in (self) -> Self {
-        let mut token = self.grow_exp();
+        let token = self.grow_exp();
         if let Value::Exp(depth, source) = token.value {
-            token.value = Value::Exp(depth.saturating_add(1), source)
+            token.with_value(Value::Exp(depth.saturating_add(1), source))
         } else {
             unreachable!()
         }
-        token
     }
     pub const fn grow_out (self) -> Self {
-        let mut token = self.grow_exp();
+        let token = self.grow_exp();
         if let Value::Exp(depth, source) = token.value {
             if depth > 0 {
-                token.value = Value::Exp(depth - 1, source)
+                token.with_value(Value::Exp(depth - 1, source))
             } else {
                 return self.error(Unexpected(')'))
             }
         } else {
             unreachable!()
         }
-        token
     }
 }
diff --git a/dsl/src/dsl_provide.rs b/dsl/src/dsl_provide.rs
new file mode 100644
index 0000000..209b37c
--- /dev/null
+++ b/dsl/src/dsl_provide.rs
@@ -0,0 +1,44 @@
+use crate::*;
+
+/// Map EDN tokens to parameters of a given type for a given context
+pub trait Dsl<U>: Sized {
+    fn take <'state, 'source> (_: &'state Self, _: &mut TokenIter<'source>) -> Perhaps<U> {
+        Ok(None)
+    }
+}
+
+/// Map EDN tokens to parameters of a given type for a given context
+pub trait Context<'state, U>: Sized {
+    fn get <'source> (&'state self, _iter: &mut TokenIter<'source>) -> Option<U> {
+        None
+    }
+}
+
+impl<'state, T: Context<'state, U>, U> Context<'state, U> for &T {
+    fn get <'source> (&'state self, iter: &mut TokenIter<'source>) -> Option<U> {
+        (*self).get(iter)
+    }
+}
+
+impl<'state, T: Context<'state, U>, U> Context<'state, U> for Option<T> {
+    fn get <'source> (&'state self, iter: &mut TokenIter<'source>) -> Option<U> {
+        self.as_ref().map(|s|s.get(iter)).flatten()
+    }
+}
+
+pub trait TryFromDsl<'state, T>: Sized {
+    fn try_from_expr <'source: 'state> (
+        _state: &'state T, _iter: &mut TokenIter<'source>
+    ) -> Option<Self> {
+        None
+    }
+    fn try_from_atom <'source: 'state> (
+        state: &'state T, value: Value<'source>
+    ) -> Option<Self> {
+        if let Exp(0, mut iter) = value {
+            return Self::try_from_expr(state, &mut iter)
+        }
+        None
+    }
+}
+
diff --git a/dsl/src/lib.rs b/dsl/src/lib.rs
index c685572..c72ff23 100644
--- a/dsl/src/lib.rs
+++ b/dsl/src/lib.rs
@@ -1,3 +1,7 @@
+#![feature(adt_const_params)]
+#![feature(type_alias_impl_trait)]
+#![feature(impl_trait_in_fn_trait_return)]
+
 //! [Token]s are parsed substrings with an associated [Value].
 //!
 //! * [ ] FIXME: Value may be [Err] which may shadow [Result::Err]
@@ -31,17 +35,18 @@
 //! assert_eq!(view.0.0, src);
 //! assert_eq!(view.peek(), view.0.peek())
 //! ```
-#![feature(adt_const_params)]
-#![feature(type_alias_impl_trait)]
-#![feature(impl_trait_in_fn_trait_return)]
 
-pub(crate) use self::Value::*;
-pub(crate) use self::ParseError::*;
+pub(crate) use ::tengri_core::*;
+
+pub(crate) use std::fmt::Debug;
 pub(crate) use konst::iter::{ConstIntoIter, IsIteratorKind};
 pub(crate) use konst::string::{split_at, str_range, char_indices};
-pub(crate) use std::fmt::Debug;
+pub(crate) use thiserror::Error;
+pub(crate) use self::Value::*;
+pub(crate) use self::ParseError::*;
 
-mod dsl; pub use self::dsl::*;
+mod dsl_parse;   pub use self::dsl_parse::*;
+mod dsl_provide; pub use self::dsl_provide::*;
 
 #[cfg(test)] mod test_token_iter {
     use crate::*;
diff --git a/input/Cargo.toml b/input/Cargo.toml
index 3b7772f..d3bf1ec 100644
--- a/input/Cargo.toml
+++ b/input/Cargo.toml
@@ -4,12 +4,13 @@ description = "UI metaframework, input layer."
 version     = { workspace = true }
 edition     = { workspace = true }
 
-[dependencies]
-tengri_dsl = { optional = true, path = "../dsl" }
-
 [features]
 dsl = [ "tengri_dsl" ]
 
+[dependencies]
+tengri_core = { path = "../core" }
+tengri_dsl  = { optional = true, path = "../dsl" }
+
 [dev-dependencies]
 tengri_tui = { path = "../tui" }
 tengri_dsl = { path = "../dsl" }
diff --git a/input/src/lib.rs b/input/src/lib.rs
index c4c230d..21035fe 100644
--- a/input/src/lib.rs
+++ b/input/src/lib.rs
@@ -1,18 +1,16 @@
 #![feature(associated_type_defaults)]
-pub(crate) use std::error::Error;
-pub(crate) type Perhaps<T> = Result<Option<T>, Box<dyn Error>>;
-#[cfg(test)] pub(crate) type Usually<T> = Result<T, Box<dyn Error>>;
 
-#[cfg(feature = "dsl")] pub(crate) use ::tengri_dsl::*;
-#[cfg(feature = "dsl")] mod input_dsl;
-#[cfg(feature = "dsl")] pub use self::input_dsl::*;
+pub(crate) use tengri_core::*;
 
 mod input_macros;
 mod input_command; pub use self::input_command::*;
 mod input_handle;  pub use self::input_handle::*;
 
-#[cfg(test)]
-#[test] fn test_stub_input () -> Usually<()> {
+#[cfg(feature = "dsl")] pub(crate) use ::tengri_dsl::*;
+#[cfg(feature = "dsl")] mod input_dsl;
+#[cfg(feature = "dsl")] pub use self::input_dsl::*;
+
+#[cfg(test)] #[test] fn test_stub_input () -> Usually<()> {
     use crate::*;
     struct TestInput(bool);
     enum TestEvent { Test1 }
@@ -33,8 +31,7 @@ mod input_handle;  pub use self::input_handle::*;
     Ok(())
 }
 
-#[cfg(all(test, feature = "dsl"))]
-#[test] fn test_dsl_keymap () -> Usually<()> {
+#[cfg(all(test, feature = "dsl"))] #[test] fn test_dsl_keymap () -> Usually<()> {
     let keymap = SourceIter::new("");
     Ok(())
 }
diff --git a/output/Cargo.toml b/output/Cargo.toml
index 2505df5..5172710 100644
--- a/output/Cargo.toml
+++ b/output/Cargo.toml
@@ -4,15 +4,16 @@ description = "UI metaframework, output layer."
 version     = { workspace = true }
 edition     = { workspace = true }
 
-[dependencies]
-tengri_dsl = { optional = true, path = "../dsl" }
-
 [features]
 dsl = [ "tengri_dsl" ]
 
+[dependencies]
+tengri_core = { path = "../core" }
+tengri_dsl  = { optional = true, path = "../dsl" }
+
 [dev-dependencies]
 tengri          = { path = "../tengri", features = [ "dsl", "tui" ] }
 tengri_tui      = { path = "../tui" }
 tengri_dsl      = { path = "../dsl" }
-proptest        = "^1"
-proptest-derive = "^0.5.1"
+proptest        = { workspace = true }
+proptest-derive = { workspace = true }
diff --git a/output/src/lib.rs b/output/src/lib.rs
index 45bf90a..2b12b04 100644
--- a/output/src/lib.rs
+++ b/output/src/lib.rs
@@ -7,18 +7,13 @@ mod space;   pub use self::space::*;
 mod ops;     pub use self::ops::*;
 mod output;  pub use self::output::*;
 
+pub(crate) use tengri_core::*;
 pub(crate) use std::marker::PhantomData;
-pub(crate) use std::error::Error;
 
 #[cfg(feature = "dsl")] pub(crate) use ::tengri_dsl::*;
 #[cfg(feature = "dsl")] mod view;
 #[cfg(feature = "dsl")] pub use self::view::*;
 
-/// Standard result type.
-pub type Usually<T> = Result<T, Box<dyn Error>>;
-/// Standard optional result type.
-pub type Perhaps<T> = Result<Option<T>, Box<dyn Error>>;
-
 #[cfg(test)] use proptest_derive::Arbitrary;
 
 #[cfg(test)] #[test] fn test_stub_output () -> Usually<()> {
diff --git a/proc/Cargo.toml b/proc/Cargo.toml
index 6001947..d7c3a9a 100644
--- a/proc/Cargo.toml
+++ b/proc/Cargo.toml
@@ -8,7 +8,8 @@ edition     = { workspace = true }
 proc-macro = true
 
 [dependencies]
-syn         = { version = "2", features = ["full", "extra-traits"] }
-quote       = { version = "1" }
-proc-macro2 = { version = "1", features = ["span-locations"] }
-heck        = { version = "0.5" }
+tengri_core = { path = "../core" }
+syn         = { workspace = true }
+quote       = { workspace = true }
+proc-macro2 = { workspace = true }
+heck        = { workspace = true }
diff --git a/proc/src/proc_command.rs b/proc/src/proc_command.rs
index cc5b134..502041f 100644
--- a/proc/src/proc_command.rs
+++ b/proc/src/proc_command.rs
@@ -10,10 +10,7 @@ pub(crate) struct CommandMeta(Ident);
 pub(crate) struct CommandImpl(ItemImpl, BTreeMap<Arc<str>, CommandArm>);
 
 #[derive(Debug, Clone)]
-struct CommandArm(Ident, Vec<FnArg>, ReturnType);
-
-#[derive(Debug, Clone)]
-struct CommandVariant(Ident, Vec<FnArg>);
+struct CommandArm(Ident, Vec<FnArg>, #[allow(unused)] ReturnType);
 
 impl Parse for CommandMeta {
     fn parse (input: ParseStream) -> Result<Self> {
@@ -203,25 +200,3 @@ impl CommandArm {
         write_quote(quote! { Self::#variant => Self::#ident(state, #(#give_args)* #give_rest), })
     }
 }
-
-impl ToTokens for CommandVariant {
-    fn to_tokens (&self, out: &mut TokenStream2) {
-        let Self(ident, args) = self;
-        out.append(LitStr::new(&format!("{}", ident), Span::call_site())
-            .token());
-        out.append(Group::new(Delimiter::Parenthesis, {
-            let mut out = TokenStream2::new();
-            for arg in args.iter() {
-                if let FnArg::Typed(PatType { ty, .. }) = arg {
-                    out.append(LitStr::new(
-                        &format!("{}", quote! { #ty }),
-                        Span::call_site()
-                    ).token());
-                    out.append(Punct::new(',', Alone));
-                }
-            }
-            out
-        }));
-        out.append(Punct::new(',', Alone));
-    }
-}
diff --git a/tengri/Cargo.toml b/tengri/Cargo.toml
index 23e87f8..cd87dfc 100644
--- a/tengri/Cargo.toml
+++ b/tengri/Cargo.toml
@@ -4,7 +4,15 @@ edition     = "2024"
 description = "UI metaframework."
 version     = { workspace = true }
 
+[features]
+default = [ "input", "output", "tui" ]
+input   = [ "tengri_input" ]
+output  = [ "tengri_output" ]
+tui     = [ "tengri_tui" ]
+dsl     = [ "tengri_dsl", "tengri_input/dsl", "tengri_output/dsl", "tengri_tui/dsl" ]
+
 [dependencies]
+tengri_core   = { path = "../core" }
 tengri_dsl    = { optional = true, path = "../dsl"    }
 tengri_input  = { optional = true, path = "../input"  }
 tengri_output = { optional = true, path = "../output" }
@@ -13,11 +21,4 @@ tengri_tui    = { optional = true, path = "../tui"    }
 [dev-dependencies]
 tengri_proc = { path = "../proc" }
 tengri      = { path = ".", features = [ "dsl" ] }
-crossterm   = "0.28.1"
-
-[features]
-default = [ "input", "output", "tui" ]
-input   = [ "tengri_input" ]
-output  = [ "tengri_output" ]
-tui     = [ "tengri_tui" ]
-dsl     = [ "tengri_dsl", "tengri_input/dsl", "tengri_output/dsl", "tengri_tui/dsl" ]
+crossterm   = { workspace = true }
diff --git a/tengri/src/lib.rs b/tengri/src/lib.rs
index 53850cd..5fd2870 100644
--- a/tengri/src/lib.rs
+++ b/tengri/src/lib.rs
@@ -1,3 +1,4 @@
+pub use ::tengri_core::*;
 #[cfg(feature="output")] pub use ::tengri_output as output;
 #[cfg(feature="input")]  pub use ::tengri_input  as input;
 #[cfg(feature="dsl")]    pub use ::tengri_dsl    as dsl;
diff --git a/tui/Cargo.toml b/tui/Cargo.toml
index a9eb4d9..5fe3f34 100644
--- a/tui/Cargo.toml
+++ b/tui/Cargo.toml
@@ -4,25 +4,26 @@ description = "UI metaframework, Ratatui backend."
 version     = { workspace = true }
 edition     = { workspace = true }
 
-[dependencies]
-palette       = { version = "0.7.6", features = [ "random" ] }
-rand          = "0.8.5"
-crossterm     = "0.28.1"
-ratatui       = { version = "0.29.0", features = [ "unstable-widget-ref", "underline-color" ] }
-better-panic  = "0.3.0"
-konst         = { version = "0.3.16", features = [ "rust_1_83" ] }
-atomic_float  = "1"
-quanta        = "0.12.3"
-unicode-width = "0.2"
+[features]
+dsl = [ "tengri_dsl", "tengri_input/dsl", "tengri_output/dsl" ]
 
+[dependencies]
+tengri_core   = { path = "../core" }
 tengri_input  = { path = "../input"  }
 tengri_output = { path = "../output" }
 tengri_dsl    = { optional = true, path = "../dsl" }
 
+palette       = { workspace = true }
+rand          = { workspace = true }
+crossterm     = { workspace = true }
+ratatui       = { workspace = true }
+better-panic  = { workspace = true }
+konst         = { workspace = true }
+atomic_float  = { workspace = true }
+quanta        = { workspace = true }
+unicode-width = { workspace = true }
+
 [dev-dependencies]
 tengri      = { path = "../tengri", features = [ "dsl" ] }
 tengri_dsl  = { path = "../dsl"  }
 tengri_proc = { path = "../proc" }
-
-[features]
-dsl = [ "tengri_dsl", "tengri_input/dsl", "tengri_output/dsl" ]
diff --git a/tui/src/lib.rs b/tui/src/lib.rs
index 8e98c58..01eb7d9 100644
--- a/tui/src/lib.rs
+++ b/tui/src/lib.rs
@@ -3,6 +3,8 @@
 mod tui_engine;  pub use self::tui_engine::*;
 mod tui_content; pub use self::tui_content::*;
 
+pub(crate) use ::tengri_core::*;
+
 pub use ::tengri_input as input;
 pub(crate) use ::tengri_input::*;