diff --git a/Cargo.lock b/Cargo.lock
index 75fb0b5..685868f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1139,6 +1139,7 @@ dependencies = [
  "ordered-float",
  "pastey",
  "substack",
+ "task-local",
  "tokio",
  "tokio-util",
  "trait-set",
diff --git a/async-fn-stream/src/lib.rs b/async-fn-stream/src/lib.rs
index 1b5ff22..808c70e 100644
--- a/async-fn-stream/src/lib.rs
+++ b/async-fn-stream/src/lib.rs
@@ -23,7 +23,7 @@ pub fn stream<'a, T: 'a>(
 	let (send, recv) = mpsc::channel::<T>(1);
 	let fut = async { f(StreamCtx(send, PhantomData)).await };
 	// use options to ensure that the stream is driven to exhaustion
-	select_with_strategy(fut.into_stream().map(|()| None), recv.map(|t| Some(t)), left_strat)
+	select_with_strategy(fut.into_stream().map(|()| None), recv.map(Some), left_strat)
 		.filter_map(async |opt| opt)
 }
 
diff --git a/notes/commands.md b/notes/commands.md
index 404da3f..3470e34 100644
--- a/notes/commands.md
+++ b/notes/commands.md
@@ -18,4 +18,4 @@ The orchid embedder and extension API mean something different by command than a
 
 ## Continuation
 
-Since commands are expected to be composed into arbitrarily deep TC structures,to avoid a memory leak, commands should not remain passively present in the system; they must be able to express certain outcomes as plain data and return. The most obvious of such outcomes is the single continuation wherein a subexpression evaluating to another command from the same set will eventually run, but other ones may potentially exist. Are there any that cannot be emulated by continuing with a call to an environment constant which expresses the outcome in terms of its parameters?
+Since commands are expected to be composed into arbitrarily deep TC structures,to avoid a memory leak, commands should not remain passively present in the system; they must be able to express certain outcomes as plain data and return. The most obvious of such outcomes is the single continuation wherein a subexpression evaluating to another command from the same set will eventually run, and it can emulate more complex patterns by continuing with a call to an environment constant which expresses the more complex outcome in terms of its parameters
diff --git a/orchid-api/src/atom.rs b/orchid-api/src/atom.rs
index 5c33c1b..260ba2f 100644
--- a/orchid-api/src/atom.rs
+++ b/orchid-api/src/atom.rs
@@ -5,9 +5,7 @@ use itertools::Itertools;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 
-use crate::{
-	ExprTicket, Expression, ExtHostReq, FormattingUnit, HostExtReq, OrcResult, SysId, TStrv,
-};
+use crate::{ExprTicket, Expression, ExtHostReq, FormattingUnit, HostExtReq, SysId, TStrv};
 
 #[derive(Clone, Coding)]
 pub struct AtomData(pub Vec<u8>);
@@ -97,8 +95,8 @@ impl Request for DeserAtom {
 /// A request blindly routed to the system that provides an atom.
 #[derive(Clone, Debug, Coding, Hierarchy)]
 #[extends(AtomReq, HostExtReq)]
-pub struct Fwded(pub Atom, pub TStrv, pub Vec<u8>);
-impl Request for Fwded {
+pub struct FinalFwded(pub Atom, pub TStrv, pub Vec<u8>);
+impl Request for FinalFwded {
 	type Response = Option<Vec<u8>>;
 }
 
@@ -109,32 +107,6 @@ impl Request for Fwd {
 	type Response = Option<Vec<u8>>;
 }
 
-/// What to do after a command has finished executing
-#[derive(Clone, Debug, Coding)]
-pub enum NextStep {
-	/// Add more work. Parallel work is fairly executed in parallel, so different
-	/// command chains can block on each other. When the command queue is empty,
-	/// the interpreter may exit without waiting for timers.
-	Continue {
-		/// Run these commands immediately. Since timers don't keep the interpreter
-		/// alive, this should usually be non-empty, but this is not required.
-		immediate: Vec<Expression>,
-		/// Schedule these commands after the specified number of milliseconds, if
-		/// the interpreter had not exited by then.
-		delayed: Vec<(NonZeroU64, Expression)>,
-	},
-	/// Discard the rest of the queue and exit. It is possible to fail the program
-	/// without raising an error because the convention on most OSes is to
-	/// separate error reporting from a failure exit.
-	Exit { success: bool },
-}
-#[derive(Clone, Debug, Coding, Hierarchy)]
-#[extends(AtomReq, HostExtReq)]
-pub struct Command(pub Atom);
-impl Request for Command {
-	type Response = OrcResult<NextStep>;
-}
-
 /// Notification that an atom is being dropped because its associated expression
 /// isn't referenced anywhere. This should have no effect if the atom's `drop`
 /// flag is false.
@@ -166,8 +138,8 @@ impl Request for ExtAtomPrint {
 pub enum AtomReq {
 	CallRef(CallRef),
 	FinalCall(FinalCall),
-	Fwded(Fwded),
-	Command(Command),
+	FwdedRef(FinalFwded),
+	FinalFwded(FinalFwded),
 	AtomPrint(AtomPrint),
 	SerializeAtom(SerializeAtom),
 }
@@ -177,9 +149,9 @@ impl AtomReq {
 	pub fn get_atom(&self) -> &Atom {
 		match self {
 			Self::CallRef(CallRef(a, ..))
-			| Self::Command(Command(a))
 			| Self::FinalCall(FinalCall(a, ..))
-			| Self::Fwded(Fwded(a, ..))
+			| Self::FwdedRef(FinalFwded(a, ..))
+			| Self::FinalFwded(FinalFwded(a, ..))
 			| Self::AtomPrint(AtomPrint(a))
 			| Self::SerializeAtom(SerializeAtom(a)) => a,
 		}
diff --git a/orchid-extension/src/atom.rs b/orchid-extension/src/atom.rs
index 2fb5100..250f183 100644
--- a/orchid-extension/src/atom.rs
+++ b/orchid-extension/src/atom.rs
@@ -1,18 +1,17 @@
 use std::any::{Any, TypeId, type_name};
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt::{self, Debug};
 use std::future::Future;
 use std::io;
 use std::marker::PhantomData;
-use std::num::{NonZero, NonZeroU32, NonZeroU64};
+use std::num::NonZeroU32;
 use std::ops::Deref;
 use std::pin::Pin;
 use std::rc::Rc;
-use std::time::Duration;
 
 use dyn_clone::{DynClone, clone_box};
 use futures::future::LocalBoxFuture;
-use futures::stream::LocalBoxStream;
 use futures::{AsyncWrite, FutureExt, StreamExt, stream};
 use orchid_api_derive::Coding;
 use orchid_api_traits::{Coding, Decode, InHierarchy, Request, UnderRoot, enc_vec};
@@ -20,15 +19,14 @@ use orchid_base::{
 	FmtCtx, FmtUnit, Format, IStr, OrcErrv, Pos, Receipt, ReqHandle, ReqReader, ReqReaderExt, Sym,
 	fmt, is, mk_errv, mk_errv_floating, take_first,
 };
+use task_local::task_local;
 use trait_set::trait_set;
 
-use crate::api;
-use crate::atom_owned::{OwnedAtom, get_obj_store};
-use crate::conv::ToExpr;
-use crate::entrypoint::request;
-use crate::expr::{Expr, ExprData, ExprHandle, ExprKind};
-use crate::gen_expr::{GExpr, IntoGExprStream};
-use crate::system::{DynSystemCardExt, cted, sys_id};
+use crate::gen_expr::GExpr;
+use crate::{
+	DynSystemCardExt, Expr, ExprData, ExprHandle, ExprKind, OwnedAtom, ToExpr, api, dyn_cted,
+	get_obj_store, request, sys_id,
+};
 
 /// Every atom managed via this system starts with an ID into the type table
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Coding)]
@@ -114,7 +112,7 @@ impl ForeignAtom {
 		let mut data = &self.atom.data.0[..];
 		let value = AtomTypeId::decode_slice(&mut data);
 		if cfg!(debug_assertions) {
-			let cted = cted();
+			let cted = dyn_cted();
 			let own_inst = cted.inst();
 			let owner_id = self.atom.owner;
 			let typ = type_name::<A>();
@@ -189,6 +187,10 @@ pub trait AtomMethod: Coding + InHierarchy {
 	const NAME: &str;
 }
 
+task_local! {
+	pub(crate) static ATOM_WITHOUT_HANDLE_FINAL_IMPL: Rc<RefCell<Option<Box<dyn Any>>>>;
+}
+
 /// A handler for an [AtomMethod] on an [Atomic]. The [AtomMethod] must also be
 /// registered in [Atomic::reg_methods]
 pub trait Supports<M: AtomMethod>: Atomic {
@@ -197,25 +199,53 @@ pub trait Supports<M: AtomMethod>: Atomic {
 		hand: Box<dyn ReqHandle<'a> + '_>,
 		req: M,
 	) -> impl Future<Output = io::Result<Receipt<'a>>>;
+	fn handle_final<'a>(
+		self,
+		hand: Box<dyn ReqHandle<'a> + '_>,
+		req: M,
+	) -> impl Future<Output = io::Result<Receipt<'a>>> {
+		async move {
+			let rcpt = self.handle(hand, req).await;
+			let _ = ATOM_WITHOUT_HANDLE_FINAL_IMPL.try_with(|cell| cell.replace(Some(Box::new(self))));
+			rcpt
+		}
+	}
+	// TODO: default-implement the above somehow while calling OwnedAtom::free if
+	// necessary
 }
 
 trait HandleAtomMethod<A> {
 	fn handle<'a, 'b: 'a>(
 		&'a self,
 		atom: &'a A,
-		req: Box<dyn ReqReader<'b> + 'a>,
+		reader: Box<dyn ReqReader<'b> + 'a>,
+	) -> LocalBoxFuture<'a, ()>;
+	fn handle_final<'a, 'b: 'a>(
+		&'a self,
+		atom: A,
+		reader: Box<dyn ReqReader<'b> + 'a>,
 	) -> LocalBoxFuture<'a, ()>;
 }
 struct AtomMethodHandler<M, A>(PhantomData<M>, PhantomData<A>);
 impl<M: AtomMethod, A: Supports<M>> HandleAtomMethod<A> for AtomMethodHandler<M, A> {
 	fn handle<'a, 'b: 'a>(
 		&'a self,
-		a: &'a A,
+		atom: &'a A,
 		mut reader: Box<dyn ReqReader<'b> + 'a>,
 	) -> LocalBoxFuture<'a, ()> {
 		Box::pin(async {
 			let req = reader.read_req::<M>().await.unwrap();
-			let _ = Supports::<M>::handle(a, reader.finish().await, req).await.unwrap();
+			let _ = Supports::<M>::handle(atom, reader.finish().await, req).await.unwrap();
+		})
+	}
+	fn handle_final<'a, 'b: 'a>(
+		&'a self,
+		atom: A,
+		mut reader: Box<dyn ReqReader<'b> + 'a>,
+	) -> LocalBoxFuture<'a, ()> {
+		Box::pin(async {
+			let req = reader.read_req::<M>().await.unwrap();
+			let _ = Supports::<M>::handle_final(atom, reader.finish().await, req).await.unwrap();
 		})
 	}
 }
@@ -252,6 +282,20 @@ pub(crate) struct MethodSet<A: Atomic> {
 	handlers: HashMap<Sym, Rc<dyn HandleAtomMethod<A>>>,
 }
 impl<A: Atomic> MethodSet<A> {
+	pub(crate) async fn final_dispatch<'a>(
+		&self,
+		atom: A,
+		key: Sym,
+		req: Box<dyn ReqReader<'a> + 'a>,
+	) -> bool {
+		match self.handlers.get(&key) {
+			None => false,
+			Some(handler) => {
+				handler.handle_final(atom, req).await;
+				true
+			},
+		}
+	}
 	pub(crate) async fn dispatch<'a>(
 		&self,
 		atom: &'_ A,
@@ -334,75 +378,6 @@ impl<A: AtomicFeatures> Format for TAtom<A> {
 
 pub(crate) struct AtomCtx<'a>(pub &'a [u8], pub Option<api::AtomId>);
 
-pub enum Next {
-	ExitSuccess,
-	Continue(Continuation),
-}
-
-#[derive(Default)]
-pub struct Continuation {
-	immediate: Vec<LocalBoxStream<'static, GExpr>>,
-	delayed: Vec<(NonZeroU64, LocalBoxStream<'static, GExpr>)>,
-}
-impl Continuation {
-	pub fn immediate<T: IntoGExprStream + 'static>(mut self, expr: T) -> Self {
-		self.immediate.push(Box::pin(expr.into_gexpr_stream()));
-		self
-	}
-	pub fn schedule<T: IntoGExprStream + 'static>(mut self, delay: Duration, expr: T) -> Self {
-		let delay = delay.as_millis().try_into().unwrap();
-		let Some(nzdelay) = NonZero::new(delay) else { return self.immediate(expr) };
-		self.delayed.push((nzdelay, Box::pin(expr.into_gexpr_stream())));
-		self
-	}
-}
-
-impl From<Continuation> for Next {
-	fn from(value: Continuation) -> Self { Self::Continue(value) }
-}
-
-impl From<Continuation> for CmdResult {
-	fn from(value: Continuation) -> Self { Ok(Next::Continue(value)) }
-}
-
-pub enum CmdError {
-	Orc(OrcErrv),
-	FatalError,
-}
-
-#[derive(Clone, Copy, Debug, Default, Hash, PartialEq, Eq, PartialOrd, Ord)]
-pub struct FatalError;
-impl From<FatalError> for CmdError {
-	fn from(FatalError: FatalError) -> Self { Self::FatalError }
-}
-impl From<OrcErrv> for CmdError {
-	fn from(value: OrcErrv) -> Self { Self::Orc(value) }
-}
-
-pub(crate) async fn encode_command_result(
-	result: Result<Next, CmdError>,
-) -> api::OrcResult<api::NextStep> {
-	match result {
-		Ok(Next::ExitSuccess) => Ok(api::NextStep::Exit { success: true }),
-		Err(CmdError::FatalError) => Ok(api::NextStep::Exit { success: false }),
-		Err(CmdError::Orc(errv)) => Err(errv.to_api()),
-		Ok(Next::Continue(Continuation { immediate, delayed })) => Ok(api::NextStep::Continue {
-			immediate: (stream::iter(immediate).flatten())
-				.then(async |x| x.serialize().await)
-				.collect()
-				.await,
-			delayed: stream::iter(delayed.into_iter().map(|(delay, expr)| {
-				expr.then(move |expr| async move { (delay, expr.serialize().await) })
-			}))
-			.flatten()
-			.collect()
-			.await,
-		}),
-	}
-}
-
-pub type CmdResult = Result<Next, CmdError>;
-
 /// A vtable-like type that collects operations defined by an [Atomic] without
 /// associating with an instance of that type. This must be registered in
 /// [crate::SystemCard]
@@ -420,7 +395,12 @@ pub trait AtomOps: 'static {
 		key: Sym,
 		req: Box<dyn ReqReader<'a> + 'a>,
 	) -> LocalBoxFuture<'a, bool>;
-	fn command<'a>(&'a self, ctx: AtomCtx<'a>) -> LocalBoxFuture<'a, CmdResult>;
+	fn handle_req_ref<'a>(
+		&'a self,
+		ctx: AtomCtx<'a>,
+		key: Sym,
+		req: Box<dyn ReqReader<'a> + 'a>,
+	) -> LocalBoxFuture<'a, bool>;
 	fn serialize<'a, 'b: 'a>(
 		&'a self,
 		ctx: AtomCtx<'a>,
@@ -504,6 +484,6 @@ pub async fn err_exit_failure() -> OrcErrv {
 pub(crate) fn resolve_atom_type(atom: &api::Atom) -> (Box<dyn AtomOps>, AtomTypeId, &[u8]) {
 	let mut data = &atom.data.0[..];
 	let atid = AtomTypeId::decode_slice(&mut data);
-	let atom_record = cted().inst().card().ops_by_atid(atid).expect("Unrecognized atom type ID");
+	let atom_record = dyn_cted().inst().card().ops_by_atid(atid).expect("Unrecognized atom type ID");
 	(atom_record, atid, data)
 }
diff --git a/orchid-extension/src/atom_owned.rs b/orchid-extension/src/atom_owned.rs
index a23b39e..b8bbe57 100644
--- a/orchid-extension/src/atom_owned.rs
+++ b/orchid-extension/src/atom_owned.rs
@@ -20,15 +20,12 @@ use orchid_api_traits::{Decode, Encode, enc_vec};
 use orchid_base::{FmtCtx, FmtCtxImpl, FmtUnit, Format, Sym, log, take_first};
 use task_local::task_local;
 
-use crate::atom::{
-	AtomCtx, AtomFactory, AtomOps, Atomic, AtomicFeaturesImpl, AtomicVariant, MethodSet,
-	MethodSetBuilder, err_not_callable, err_not_command,
-};
-use crate::conv::ToExpr;
-use crate::expr::Expr;
 use crate::gen_expr::{GExpr, bot};
-use crate::system::{DynSystemCardExt, cted};
-use crate::{CmdError, CmdResult, api};
+use crate::{
+	ATOM_WITHOUT_HANDLE_FINAL_IMPL, AtomCtx, AtomFactory, AtomOps, Atomic, AtomicFeaturesImpl,
+	AtomicVariant, DynSystemCardExt, Expr, MethodSet, MethodSetBuilder, ToExpr, api, dyn_cted,
+	err_not_callable,
+};
 
 /// Value of [Atomic::Variant] for a type that implements [OwnedAtom]
 pub struct OwnedVariant;
@@ -42,7 +39,7 @@ impl<A: OwnedAtom + Atomic<Variant = OwnedVariant>> AtomicFeaturesImpl<OwnedVari
 				*id += 1;
 				api::AtomId(NonZero::new(*id + 1).unwrap())
 			};
-			let (typ_id, _) = cted().inst().card().ops::<A>();
+			let (typ_id, _) = dyn_cted().inst().card().ops::<A>();
 			let mut data = enc_vec(&typ_id);
 			self.encode(Pin::<&mut Vec<u8>>::new(&mut data)).await;
 			obj_store.objects.read().await.insert(atom_id, Box::new(self));
@@ -121,6 +118,25 @@ impl<A: OwnedAtom> AtomOps for OwnedAtomOps<A> {
 		AtomCtx(_, id): AtomCtx<'a>,
 		key: Sym,
 		req: Box<dyn orchid_base::ReqReader<'a> + 'a>,
+	) -> LocalBoxFuture<'a, bool> {
+		Box::pin(async move {
+			let a = take_atom(id.unwrap()).await;
+			let ms = self.ms.get_or_init(self.msbuild.pack()).await;
+			let cell = Rc::new(RefCell::new(None));
+			let matched = ATOM_WITHOUT_HANDLE_FINAL_IMPL
+				.scope(cell.clone(), ms.final_dispatch(*a.as_any().downcast().unwrap(), key, req))
+				.await;
+			if let Some(val) = cell.take() {
+				val.downcast::<A>().unwrap().free().await
+			}
+			matched
+		})
+	}
+	fn handle_req_ref<'a>(
+		&'a self,
+		AtomCtx(_, id): AtomCtx<'a>,
+		key: Sym,
+		req: Box<dyn orchid_base::ReqReader<'a> + 'a>,
 	) -> LocalBoxFuture<'a, bool> {
 		Box::pin(async move {
 			let a = AtomReadGuard::new(id.unwrap()).await;
@@ -128,9 +144,6 @@ impl<A: OwnedAtom> AtomOps for OwnedAtomOps<A> {
 			ms.dispatch(a.as_any_ref().downcast_ref().unwrap(), key, req).await
 		})
 	}
-	fn command<'a>(&'a self, AtomCtx(_, id): AtomCtx<'a>) -> LocalBoxFuture<'a, CmdResult> {
-		Box::pin(async move { take_atom(id.unwrap()).await.dyn_command().await })
-	}
 	fn drop(&self, AtomCtx(_, id): AtomCtx) -> LocalBoxFuture<'_, ()> {
 		Box::pin(async move { take_atom(id.unwrap()).await.dyn_free().await })
 	}
@@ -252,10 +265,6 @@ pub trait OwnedAtom: Atomic<Variant = OwnedVariant> + Any + Clone + 'static {
 			gcl
 		}
 	}
-	/// Called when this is the final value of the program
-	fn command(self) -> impl Future<Output = CmdResult> {
-		async move { Err(CmdError::Orc(err_not_command(&self.dyn_print().await).await)) }
-	}
 	/// Drop and perform any cleanup. Unlike Rust's [Drop::drop], this is
 	/// guaranteed to be called
 	fn free(self) -> impl Future<Output = ()> { async {} }
@@ -294,10 +303,10 @@ fn assert_serializable<T: OwnedAtom>() {
 
 pub(crate) trait DynOwnedAtom: DynClone + 'static {
 	fn as_any_ref(&self) -> &dyn Any;
+	fn as_any(self: Box<Self>) -> Box<dyn Any>;
 	fn encode<'a>(&'a self, buffer: Pin<&'a mut dyn AsyncWrite>) -> LocalBoxFuture<'a, ()>;
 	fn dyn_call_ref(&self, arg: Expr) -> LocalBoxFuture<'_, GExpr>;
 	fn dyn_call(self: Box<Self>, arg: Expr) -> LocalBoxFuture<'static, GExpr>;
-	fn dyn_command(self: Box<Self>) -> LocalBoxFuture<'static, CmdResult>;
 	fn dyn_free(self: Box<Self>) -> LocalBoxFuture<'static, ()>;
 	fn dyn_print(&self) -> LocalBoxFuture<'_, FmtUnit>;
 	fn dyn_serialize<'a>(
@@ -307,6 +316,7 @@ pub(crate) trait DynOwnedAtom: DynClone + 'static {
 }
 impl<T: OwnedAtom> DynOwnedAtom for T {
 	fn as_any_ref(&self) -> &dyn Any { self }
+	fn as_any(self: Box<Self>) -> Box<dyn Any> { self }
 	fn encode<'a>(&'a self, buffer: Pin<&'a mut dyn AsyncWrite>) -> LocalBoxFuture<'a, ()> {
 		async { self.val().await.as_ref().encode(buffer).await.unwrap() }.boxed_local()
 	}
@@ -316,7 +326,6 @@ impl<T: OwnedAtom> DynOwnedAtom for T {
 	fn dyn_call(self: Box<Self>, arg: Expr) -> LocalBoxFuture<'static, GExpr> {
 		async { self.call(arg).await.to_gen().await }.boxed_local()
 	}
-	fn dyn_command(self: Box<Self>) -> LocalBoxFuture<'static, CmdResult> { Box::pin(self.command()) }
 	fn dyn_free(self: Box<Self>) -> LocalBoxFuture<'static, ()> { self.free().boxed_local() }
 	fn dyn_print(&self) -> LocalBoxFuture<'_, FmtUnit> {
 		async move { self.print_atom(&FmtCtxImpl::default()).await }.boxed_local()
diff --git a/orchid-extension/src/atom_thin.rs b/orchid-extension/src/atom_thin.rs
index a48c69d..ec2857c 100644
--- a/orchid-extension/src/atom_thin.rs
+++ b/orchid-extension/src/atom_thin.rs
@@ -3,19 +3,16 @@ use std::future::Future;
 use std::pin::Pin;
 
 use async_once_cell::OnceCell;
+use futures::AsyncWrite;
 use futures::future::LocalBoxFuture;
-use futures::{AsyncWrite, FutureExt};
 use orchid_api_traits::{Coding, enc_vec};
 use orchid_base::{FmtUnit, Sym, log};
 
-use crate::atom::{
-	AtomCtx, AtomFactory, AtomOps, Atomic, AtomicFeaturesImpl, AtomicVariant, MethodSet,
-	MethodSetBuilder, err_not_callable, err_not_command,
-};
-use crate::expr::Expr;
 use crate::gen_expr::{GExpr, bot};
-use crate::system::{DynSystemCardExt, cted};
-use crate::{CmdResult, api};
+use crate::{
+	AtomCtx, AtomFactory, AtomOps, Atomic, AtomicFeaturesImpl, AtomicVariant, DynSystemCardExt, Expr,
+	MethodSet, MethodSetBuilder, api, dyn_cted, err_not_callable,
+};
 
 /// Value of [Atomic::Variant] for a type that implements [ThinAtom]
 pub struct ThinVariant;
@@ -23,7 +20,7 @@ impl AtomicVariant for ThinVariant {}
 impl<A: ThinAtom + Atomic<Variant = ThinVariant>> AtomicFeaturesImpl<ThinVariant> for A {
 	fn _factory(self) -> AtomFactory {
 		AtomFactory::new(async move || {
-			let (id, _) = cted().inst().card().ops::<A>();
+			let (id, _) = dyn_cted().inst().card().ops::<A>();
 			let mut buf = enc_vec(&id);
 			self.encode_vec(&mut buf);
 			api::LocalAtom { drop: None, data: api::AtomData(buf) }
@@ -63,8 +60,13 @@ impl<T: ThinAtom> AtomOps for ThinAtomOps<T> {
 			ms.dispatch(&T::decode_slice(&mut &buf[..]), key, req).await
 		})
 	}
-	fn command<'a>(&'a self, AtomCtx(buf, _): AtomCtx<'a>) -> LocalBoxFuture<'a, CmdResult> {
-		async move { T::decode_slice(&mut &buf[..]).command().await }.boxed_local()
+	fn handle_req_ref<'a>(
+		&'a self,
+		ctx: AtomCtx<'a>,
+		key: Sym,
+		req: Box<dyn orchid_base::ReqReader<'a> + 'a>,
+	) -> LocalBoxFuture<'a, bool> {
+		self.handle_req(ctx, key, req)
 	}
 	fn serialize<'a, 'b: 'a>(
 		&'a self,
@@ -99,10 +101,6 @@ pub trait ThinAtom: Atomic<Data = Self> + Atomic<Variant = ThinVariant> + Coding
 		async move { bot(err_not_callable(&self.print().await).await) }
 	}
 	#[allow(unused_variables)]
-	fn command(&self) -> impl Future<Output = CmdResult> {
-		async move { Err(err_not_command(&self.print().await).await.into()) }
-	}
-	#[allow(unused_variables)]
 	fn print(&self) -> impl Future<Output = FmtUnit> {
 		async { format!("ThinAtom({})", type_name::<Self>()).into() }
 	}
diff --git a/orchid-extension/src/binary.rs b/orchid-extension/src/binary.rs
index ac70346..35c894a 100644
--- a/orchid-extension/src/binary.rs
+++ b/orchid-extension/src/binary.rs
@@ -4,9 +4,7 @@ use std::time::Duration;
 use futures::future::LocalBoxFuture;
 use orchid_base::future_to_vt;
 
-use crate::api;
-use crate::entrypoint::ExtensionBuilder;
-use crate::ext_port::ExtPort;
+use crate::{ExtPort, ExtensionBuilder, api};
 
 pub type ExtCx = api::binary::ExtensionContext;
 
diff --git a/orchid-extension/src/cmd_atom.rs b/orchid-extension/src/cmd_atom.rs
new file mode 100644
index 0000000..d34fa68
--- /dev/null
+++ b/orchid-extension/src/cmd_atom.rs
@@ -0,0 +1,60 @@
+use std::borrow::Cow;
+
+use dyn_clone::DynClone;
+use futures::future::LocalBoxFuture;
+use never::Never;
+use orchid_base::{Receipt, ReqHandle, ReqHandleExt};
+use trait_set::trait_set;
+
+use crate::gen_expr::{GExpr, new_atom};
+use crate::std_reqs::RunCommand;
+use crate::{Atomic, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports, ToExpr};
+
+trait_set! {
+	pub trait ClonableAsyncFnOnceDyn = FnOnce() -> LocalBoxFuture<'static, Option<GExpr>> + DynClone;
+}
+
+pub struct CmdAtom(Box<dyn ClonableAsyncFnOnceDyn>);
+impl Clone for CmdAtom {
+	fn clone(&self) -> Self { Self(dyn_clone::clone_box(&*self.0)) }
+}
+impl Atomic for CmdAtom {
+	type Data = ();
+	type Variant = OwnedVariant;
+	fn reg_methods() -> MethodSetBuilder<Self> { MethodSetBuilder::new().handle::<RunCommand>() }
+}
+impl Supports<RunCommand> for CmdAtom {
+	async fn handle<'a>(
+		&self,
+		hand: Box<dyn ReqHandle<'a> + '_>,
+		req: RunCommand,
+	) -> std::io::Result<Receipt<'a>> {
+		Self(dyn_clone::clone_box(&*self.0)).handle_final(hand, req).await
+	}
+	async fn handle_final<'a>(
+		self,
+		hand: Box<dyn ReqHandle<'a> + '_>,
+		req: RunCommand,
+	) -> std::io::Result<Receipt<'a>> {
+		let reply = (self.0)().await;
+		match reply {
+			None => hand.reply(&req, &None).await,
+			Some(next) => hand.reply(&req, &Some(next.serialize().await)).await,
+		}
+	}
+}
+impl OwnedAtom for CmdAtom {
+	type Refs = Never;
+	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
+}
+
+pub fn cmd<R: ToExpr>(f: impl AsyncFnOnce() -> Option<R> + Clone + 'static) -> GExpr {
+	new_atom(CmdAtom(Box::new(|| {
+		Box::pin(async {
+			match f().await {
+				None => None,
+				Some(r) => Some(r.to_gen().await),
+			}
+		})
+	})))
+}
diff --git a/orchid-extension/src/conv.rs b/orchid-extension/src/conv.rs
index f687bef..d11727b 100644
--- a/orchid-extension/src/conv.rs
+++ b/orchid-extension/src/conv.rs
@@ -2,19 +2,20 @@ use std::future::Future;
 use std::pin::Pin;
 
 use dyn_clone::DynClone;
+use futures::future::FusedFuture;
 use never::Never;
 use orchid_base::{Format, OrcErrv, OrcRes, Pos, fmt, is, mk_errv};
 use trait_set::trait_set;
 
-use crate::atom::{AtomicFeatures, ForeignAtom, TAtom};
-use crate::expr::{Expr, ExprKind};
 use crate::gen_expr::{GExpr, bot};
+use crate::{AtomicFeatures, Expr, ExprKind, ForeignAtom, TAtom};
 
-/// Attempt to cast a generic Orchid expression reference to a concrete value.
-/// Note that this cannot evaluate the expression, and if it is not already
-/// evaluated, it will simply fail. Use [crate::ExecHandle::exec] inside
-/// [crate::exec] to wait for an expression to be evaluated
+/// Values that may be converted from certain specific Orchid expressions
 pub trait TryFromExpr: Sized {
+	/// Attempt to cast a generic Orchid expression reference to a concrete value.
+	/// Note that this cannot evaluate the expression, and if it is not already
+	/// evaluated, it will simply fail. Use [crate::ExecHandle::exec] inside
+	/// [crate::exec] to wait for an expression to be evaluated
 	fn try_from_expr(expr: Expr) -> impl Future<Output = OrcRes<Self>>;
 }
 
@@ -58,6 +59,9 @@ impl<A: AtomicFeatures> TryFromExpr for TAtom<A> {
 
 /// Values that are convertible to an Orchid expression. This could mean that
 /// the value owns an [Expr] or it may involve more complex operations
+///
+/// [ToExpr] is also implemented for [orchid_base::Sym] where it converts to a
+/// reference to the constant by that name
 pub trait ToExpr {
 	/// Inline the value in an expression returned from a function or included in
 	/// the const tree returned by [crate::System::env]
@@ -69,6 +73,8 @@ pub trait ToExpr {
 	}
 }
 
+/// A wrapper for a future that implements [ToExpr]
+#[derive(Clone, Copy, Debug, Default, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub struct ToExprFuture<F>(pub F);
 
 impl<F: Future<Output: ToExpr>> ToExpr for ToExprFuture<F> {
@@ -78,6 +84,9 @@ impl<F: Future<Output: ToExpr>> ToExpr for ToExprFuture<F> {
 		self.0.await.to_expr().await
 	}
 }
+impl<F: FusedFuture> FusedFuture for ToExprFuture<F> {
+	fn is_terminated(&self) -> bool { self.0.is_terminated() }
+}
 impl<F: Future> Future for ToExprFuture<F> {
 	type Output = F::Output;
 	fn poll(self: Pin<&mut Self>, cx: &mut std::task::Context<'_>) -> std::task::Poll<Self::Output> {
diff --git a/orchid-extension/src/coroutine_exec.rs b/orchid-extension/src/coroutine_exec.rs
index f0deb5c..10d9033 100644
--- a/orchid-extension/src/coroutine_exec.rs
+++ b/orchid-extension/src/coroutine_exec.rs
@@ -9,11 +9,8 @@ use futures::{FutureExt, SinkExt, StreamExt};
 use never::Never;
 use orchid_base::OrcRes;
 
-use crate::atom::Atomic;
-use crate::atom_owned::{OwnedAtom, OwnedVariant};
-use crate::conv::{ToExpr, TryFromExpr};
-use crate::expr::Expr;
 use crate::gen_expr::{GExpr, arg, call, lam, new_atom, seq};
+use crate::{Atomic, Expr, OwnedAtom, OwnedVariant, ToExpr, TryFromExpr};
 
 enum Command {
 	Execute(GExpr, Sender<Expr>),
@@ -30,7 +27,7 @@ impl BuilderCoroutine {
 	pub async fn run(self) -> GExpr {
 		let cmd = self.0.receiver.lock().await.next().await;
 		match cmd {
-			None => panic!("Before the stream ends, we should have gotten a Halt"),
+			None => panic!("Exec handle dropped and coroutine blocked instead of returning"),
 			Some(Command::Halt(expr)) => expr,
 			Some(Command::Execute(expr, reply)) =>
 				call(lam::<0>(seq(arg(0), call(new_atom(Replier { reply, builder: self }), arg(0)))), expr)
@@ -40,7 +37,7 @@ impl BuilderCoroutine {
 }
 
 #[derive(Clone)]
-pub struct Replier {
+pub(crate) struct Replier {
 	reply: Sender<Expr>,
 	builder: BuilderCoroutine,
 }
@@ -52,12 +49,14 @@ impl OwnedAtom for Replier {
 	type Refs = Never;
 	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
 	async fn call(mut self, arg: Expr) -> impl ToExpr {
-		self.reply.send(arg).await.expect("What the heck");
+		self.reply.send(arg).await.expect("Resolution request dropped after sending");
 		std::mem::drop(self.reply);
 		self.builder.run().await
 	}
 }
 
+/// A long-lived async context that can yield to the executor. The expression
+/// representing an in-progress exec block is not serializable.
 pub async fn exec<R: ToExpr>(f: impl for<'a> AsyncFnOnce(ExecHandle<'a>) -> R + 'static) -> GExpr {
 	let (cmd_snd, cmd_recv) = channel(0);
 	let halt =
@@ -70,8 +69,11 @@ pub async fn exec<R: ToExpr>(f: impl for<'a> AsyncFnOnce(ExecHandle<'a>) -> R +
 
 static WEIRD_DROP_ERR: &str = "Coroutine dropped while we are being polled somehow";
 
+/// The handle an [exec] callback uses to yield to the executor
 pub struct ExecHandle<'a>(Sender<Command>, PhantomData<&'a ()>);
 impl ExecHandle<'_> {
+	/// Yield to the executor by resolving to an expression that normalizes the
+	/// value and then calls the continuation of the body with the result.
 	pub async fn exec<T: TryFromExpr>(&mut self, val: impl ToExpr) -> OrcRes<T> {
 		let (reply_snd, mut reply_recv) = channel(1);
 		self.0.send(Command::Execute(val.to_gen().await, reply_snd)).await.expect(WEIRD_DROP_ERR);
diff --git a/orchid-extension/src/entrypoint.rs b/orchid-extension/src/entrypoint.rs
index 9847abb..1e6e2f7 100644
--- a/orchid-extension/src/entrypoint.rs
+++ b/orchid-extension/src/entrypoint.rs
@@ -22,21 +22,16 @@ use orchid_base::{
 use substack::Substack;
 use task_local::task_local;
 
-use crate::atom::{AtomCtx, AtomTypeId, resolve_atom_type};
-use crate::atom_owned::{take_atom, with_obj_store};
-use crate::expr::{BorrowedExprStore, Expr, ExprHandle};
-use crate::ext_port::ExtPort;
-use crate::func_atom::with_funs_ctx;
 use crate::interner::new_interner;
-use crate::lexer::{LexContext, ekey_cascade, ekey_not_applicable};
 use crate::logger::LoggerImpl;
-use crate::parser::{PTokTree, ParsCtx, get_const, linev_into_api, with_parsed_const_ctx};
-use crate::reflection::with_refl_roots;
-use crate::system::{DynSystemCardExt, SysCtx, cted, with_sys};
-use crate::system_ctor::{CtedObj, DynSystemCtor, SystemCtor};
 use crate::tree::{TreeIntoApiCtxImpl, get_lazy, with_lazy_member_store};
 use crate::trivial_req::TrivialReqCycle;
-use crate::{api, encode_command_result};
+use crate::{
+	AtomCtx, AtomTypeId, BorrowedExprStore, CtedObj, DynSystemCardExt, DynSystemCtor, Expr,
+	ExprHandle, ExtPort, LexContext, PTokTree, ParsCtx, SysCtx, SystemCtor, api, dyn_cted,
+	ekey_cascade, ekey_not_applicable, get_const, linev_into_api, resolve_atom_type, take_atom,
+	with_funs_ctx, with_obj_store, with_parsed_const_ctx, with_refl_roots, with_sys,
+};
 
 task_local::task_local! {
 	static CLIENT: Rc<dyn Client>;
@@ -44,21 +39,28 @@ task_local::task_local! {
 }
 
 fn get_client() -> Rc<dyn Client> { CLIENT.get() }
+
+/// Do not expect any more requests or notifications, exit once all pending
+/// requests settle
 pub async fn exit() {
 	let cx = CTX.get().borrow_mut().take();
 	cx.unwrap().exit().await.unwrap()
 }
 
-/// Sent the client used for global [request] and [notify] functions within the
+/// Set the client used for global [request] and [notify] functions within the
 /// runtime of this future
 pub async fn with_comm<F: Future>(c: Rc<dyn Client>, ctx: CommCtx, fut: F) -> F::Output {
 	CLIENT.scope(c, CTX.scope(Rc::new(RefCell::new(Some(ctx))), fut)).await
 }
 
 task_local! {
-	pub static MUTE_REPLY: ();
+	static MUTE_REPLY: ();
 }
 
+/// Silence replies within this block even if the `msg` log channel is active to
+/// prevent excessive log noise.
+pub async fn mute_reply<F: Future>(f: F) -> F::Output { MUTE_REPLY.scope((), f).await }
+
 /// Send a request through the global client's [ClientExt::request]
 pub async fn request<T: Request + UnderRoot<Root = api::ExtHostReq>>(t: T) -> T::Response {
 	let response = get_client().request(t).await.unwrap();
@@ -73,7 +75,7 @@ pub async fn notify<T: UnderRoot<Root = api::ExtHostNotif>>(t: T) {
 	get_client().notify(t).await.unwrap()
 }
 
-pub struct SystemRecord {
+struct SystemRecord {
 	cted: CtedObj,
 }
 
@@ -88,6 +90,7 @@ async fn with_sys_record<F: Future>(id: api::SysId, fut: F) -> F::Output {
 	with_sys(SysCtx(id, cted), fut).await
 }
 
+/// Context that can be attached to a [Future] using [task_local]
 pub trait ContextModifier: 'static {
 	fn apply<'a>(self: Box<Self>, fut: LocalBoxFuture<'a, ()>) -> LocalBoxFuture<'a, ()>;
 }
@@ -108,12 +111,22 @@ task_local! {
 		Rc<dyn Fn(Duration, LocalBoxFuture<'static, Box<dyn Any>>) -> Box<dyn DynTaskHandle> + 'static>
 }
 
+/// Handle for a task that is not associated with a particular pending request
+/// or past notification
 pub struct TaskHandle<T>(Box<dyn DynTaskHandle>, PhantomData<T>);
 impl<T: 'static> TaskHandle<T> {
+	/// Immediately stop working on the task. Unlike in Tokio's abort, this is a
+	/// guarantee
 	pub fn abort(self) { self.0.abort(); }
+	/// Stop working on the task and return the nested future. The distinction
+	/// between this and waiting until the task is complete without reparenting it
+	/// is significant for the purpose of [task_local] context
 	pub async fn join(self) -> T { *self.0.join().await.downcast().unwrap() }
 }
 
+/// Spawn a future that is not associated with a pending request or a past
+/// notification. Pending tasks are cancelled and dropped when the extension
+/// exits
 pub fn spawn<F: Future<Output: 'static> + 'static>(delay: Duration, f: F) -> TaskHandle<F::Output> {
 	SPAWN.with(|spawn| {
 		TaskHandle(spawn(delay, Box::pin(async { Box::new(f.await) as Box<dyn Any> })), PhantomData)
@@ -125,24 +138,37 @@ impl DynTaskHandle for Handle<Box<dyn Any>> {
 	fn join(self: Box<Self>) -> LocalBoxFuture<'static, Box<dyn Any>> { Box::pin(Self::join(*self)) }
 }
 
+/// A new Orchid extension as specified in loaders. An extension is a unit of
+/// distribution and its name serves for debugging purposes primarily. In
+/// contrast, [SystemCtor] is a unit of features of which [ExtensionBuilder] may
+/// contain multiple
 pub struct ExtensionBuilder {
 	pub name: &'static str,
 	pub systems: Vec<Box<dyn DynSystemCtor>>,
 	pub context: Vec<Box<dyn ContextModifier>>,
 }
 impl ExtensionBuilder {
+	/// Create a new extension
 	pub fn new(name: &'static str) -> Self { Self { name, systems: Vec::new(), context: Vec::new() } }
+	/// Add a system to the extension
 	pub fn system(mut self, ctor: impl SystemCtor) -> Self {
 		self.systems.push(Box::new(ctor) as Box<_>);
 		self
 	}
+	/// Add some [task_local] state to the extension. Bear in mind that distinct
+	/// [crate::System] instances should not visibly affect each other
 	pub fn add_context(&mut self, fun: impl ContextModifier) {
 		self.context.push(Box::new(fun) as Box<_>);
 	}
+	/// Builder form of [Self::add_context]
 	pub fn context(mut self, fun: impl ContextModifier) -> Self {
 		self.add_context(fun);
 		self
 	}
+	/// Start the extension on a message channel, blocking the task until the peer
+	/// on the other side drops the extension. Extension authors would typically
+	/// pass the prepared builder into some function that is responsible for
+	/// managing the [ExtPort]
 	pub async fn run(mut self, mut ctx: ExtPort) {
 		self.add_context(with_funs_ctx);
 		self.add_context(with_parsed_const_ctx);
@@ -246,7 +272,7 @@ impl ExtensionBuilder {
 							with_sys_record(sys_id, async {
 								let mut reply = Vec::new();
 								let req = TrivialReqCycle { req: &payload, rep: &mut reply };
-								let _ = cted().inst().dyn_request(Box::new(req)).await;
+								let _ = dyn_cted().inst().dyn_request(Box::new(req)).await;
 								handle.reply(fwd_tok, &reply).await
 							})
 							.await
@@ -260,7 +286,7 @@ impl ExtensionBuilder {
 								let trigger_char = tail.chars().next().unwrap();
 								let ekey_na = ekey_not_applicable().await;
 								let ekey_cascade = ekey_cascade().await;
-								let lexers = cted().inst().dyn_lexers();
+								let lexers = dyn_cted().inst().dyn_lexers();
 								for lx in lexers.iter().filter(|l| char_filter_match(l.char_filter(), trigger_char))
 								{
 									let ctx = LexContext::new(&expr_store, &text, id, pos, src.clone());
@@ -292,7 +318,7 @@ impl ExtensionBuilder {
 							let req = Witness::of(&pline);
 							let api::ParseLine { module, src, exported, comments, sys, line, idx } = pline;
 							with_sys_record(sys, async {
-								let parsers = cted().inst().dyn_parsers();
+								let parsers = dyn_cted().inst().dyn_parsers();
 								let src = Sym::from_api(src).await;
 								let comments =
 									join_all(comments.iter().map(|c| Comment::from_api(c, src.clone()))).await;
@@ -339,14 +365,22 @@ impl ExtensionBuilder {
 									},
 									api::AtomReq::AtomPrint(print @ api::AtomPrint(_)) =>
 										handle.reply(print, &nfo.print(actx).await.to_api()).await,
-									api::AtomReq::Fwded(fwded) => {
-										let api::Fwded(_, key, payload) = &fwded;
+									api::AtomReq::FinalFwded(fwded) => {
+										let api::FinalFwded(_, key, payload) = &fwded;
 										let mut reply = Vec::new();
 										let key = Sym::from_api(*key).await;
 										let req = TrivialReqCycle { req: payload, rep: &mut reply };
 										let some = nfo.handle_req(actx, key, Box::new(req)).await;
 										handle.reply(fwded, &some.then_some(reply)).await
 									},
+									api::AtomReq::FwdedRef(fwded) => {
+										let api::FinalFwded(_, key, payload) = &fwded;
+										let mut reply = Vec::new();
+										let key = Sym::from_api(*key).await;
+										let req = TrivialReqCycle { req: payload, rep: &mut reply };
+										let some = nfo.handle_req_ref(actx, key, Box::new(req)).await;
+										handle.reply(fwded, &some.then_some(reply)).await
+									},
 									api::AtomReq::CallRef(call @ api::CallRef(_, arg)) => {
 										let expr_store = BorrowedExprStore::new();
 										let expr_handle = ExprHandle::borrowed(*arg, &expr_store);
@@ -365,8 +399,6 @@ impl ExtensionBuilder {
 										expr_store.dispose().await;
 										handle.reply(call, &api_expr).await
 									},
-									api::AtomReq::Command(cmd @ api::Command(_)) =>
-										handle.reply(cmd, &encode_command_result(nfo.command(actx).await).await).await,
 								}
 							})
 							.await
@@ -380,7 +412,7 @@ impl ExtensionBuilder {
 									.map(|tk| Expr::from_handle(ExprHandle::deserialize(*tk)))
 									.collect_vec();
 								let id = AtomTypeId::decode_slice(read);
-								let nfo = (cted().inst().card().ops_by_atid(id))
+								let nfo = (dyn_cted().inst().card().ops_by_atid(id))
 									.expect("Deserializing atom with invalid ID");
 								handle.reply(&deser, &nfo.deserialize(read, &refs).await).await
 							})
diff --git a/orchid-extension/src/expr.rs b/orchid-extension/src/expr.rs
index 7507a24..c5d5fbe 100644
--- a/orchid-extension/src/expr.rs
+++ b/orchid-extension/src/expr.rs
@@ -6,23 +6,28 @@ use std::thread::panicking;
 
 use async_once_cell::OnceCell;
 use derive_destructure::destructure;
+use futures::future::join_all;
 use hashbrown::HashSet;
 use orchid_base::{FmtCtx, FmtUnit, Format, OrcErrv, Pos, stash};
 
-use crate::api;
-use crate::atom::ForeignAtom;
-use crate::entrypoint::{notify, request};
 use crate::gen_expr::{GExpr, GExprKind};
-use crate::system::sys_id;
+use crate::{ForeignAtom, api, notify, request, sys_id};
 
+/// Handle for a lifetime associated with an [ExprHandle], such as a function
+/// call. Can be passed into [ExprHandle::borrowed] as an optimization over
+/// [ExprHandle::from_ticket]
+///
+/// # Panics
+///
+/// The [Drop] of this type panics by default unless the stack is already
+/// unwinding. You need to make sure you dispose of it by calling
+/// [Self::dispose].
 pub struct BorrowedExprStore(RefCell<Option<HashSet<Rc<ExprHandle>>>>);
 impl BorrowedExprStore {
 	pub(crate) fn new() -> Self { Self(RefCell::new(Some(HashSet::new()))) }
 	pub async fn dispose(self) {
-		let elements = self.0.borrow_mut().take().unwrap();
-		for handle in elements {
-			handle.on_borrow_expire().await
-		}
+		let set = self.0.borrow_mut().take().expect("Double dispose of BorrowedExprStore!");
+		join_all(set.into_iter().map(ExprHandle::on_borrow_expire)).await;
 	}
 }
 impl Drop for BorrowedExprStore {
@@ -33,6 +38,10 @@ impl Drop for BorrowedExprStore {
 	}
 }
 
+/// A RAII wrapper over an [api::ExprTicket]. Extension authors usually use
+/// [Expr] for all purposes as this type does not deal with the details of the
+/// expression associated with the ticket, it merely ensures that [api::Acquire]
+/// and [api::Release] are sent at appropriate times.
 #[derive(destructure, PartialEq, Eq, Hash)]
 pub struct ExprHandle(api::ExprTicket);
 impl ExprHandle {
@@ -72,7 +81,7 @@ impl ExprHandle {
 	/// [ExprHandle::borrowed] or [ExprHandle::from_ticket]
 	pub fn ticket(&self) -> api::ExprTicket { self.0 }
 	async fn send_acq(&self) { notify(api::Acquire(sys_id(), self.0)).await }
-	/// If this is the last one reference, do nothing, otherwise send an Acquire
+	/// If this is the last reference, do nothing, otherwise send an Acquire
 	pub async fn on_borrow_expire(self: Rc<Self>) { self.serialize().await; }
 	/// Drop the handle and get the ticket without a release notification.
 	/// Use this with messages that imply ownership transfer. This function is
@@ -97,13 +106,20 @@ impl Drop for ExprHandle {
 	}
 }
 
+/// A smart object that keeps an expression alive in the interpreter until all
+/// references are dropped and provides information about that expression. These
+/// can be stored in any pattern, but care must be taken as adding new ones into
+/// a structure that is already visible to the interpreter can easily cause a
+/// memory leak.
 #[derive(Clone, Debug, destructure)]
 pub struct Expr {
 	handle: Rc<ExprHandle>,
 	data: Rc<OnceCell<ExprData>>,
 }
 impl Expr {
+	/// Wrap a handle in order to retrieve details about it
 	pub fn from_handle(handle: Rc<ExprHandle>) -> Self { Self { handle, data: Rc::default() } }
+	/// Wrap a handle the details of which are already known
 	pub fn from_data(handle: Rc<ExprHandle>, d: ExprData) -> Self {
 		Self { handle, data: Rc::new(OnceCell::from(d)) }
 	}
@@ -113,6 +129,8 @@ impl Expr {
 	pub async fn deserialize(tk: api::ExprTicket) -> Self {
 		Self::from_handle(ExprHandle::deserialize(tk))
 	}
+	/// Fetch the details of this expression via [api::Inspect] if not already
+	/// known, and return them
 	pub async fn data(&self) -> &ExprData {
 		(self.data.get_or_init(async {
 			let details = request(api::Inspect { target: self.handle.ticket() }).await;
@@ -127,15 +145,19 @@ impl Expr {
 		}))
 		.await
 	}
+	/// Attempt to downcast this to a [ForeignAtom]
 	pub async fn atom(self) -> Result<ForeignAtom, Self> {
 		match self.data().await {
 			ExprData { kind: ExprKind::Atom(atom), .. } => Ok(atom.clone()),
 			_ => Err(self),
 		}
 	}
+	/// Obtain code location info associated with this expression for logging.
 	pub async fn pos(&self) -> Pos { self.data().await.pos.clone() }
+	/// Clone out the handle for this expression
 	pub fn handle(&self) -> Rc<ExprHandle> { self.handle.clone() }
-
+	/// Wrap this expression in a [GExpr] synchronously as an escape hatch.
+	/// Otherwise identical to this type's [crate::ToExpr] impl
 	pub fn slot(&self) -> GExpr {
 		GExpr { pos: Pos::SlotTarget, kind: GExprKind::Slot(self.clone()) }
 	}
@@ -161,15 +183,23 @@ impl Hash for Expr {
 	fn hash<H: Hasher>(&self, state: &mut H) { self.handle.hash(state); }
 }
 
+/// Information about an expression
 #[derive(Clone, Debug)]
 pub struct ExprData {
+	/// Source code location data associated with the expression for debug logging
 	pub pos: Pos,
+	/// Limited information on the value available to extensions
 	pub kind: ExprKind,
 }
 
+/// All that is visible about a runtime value to extensions. This
+/// information is limited for the sake of extensibility
 #[derive(Clone, Debug)]
 pub enum ExprKind {
+	/// An atom, local or foreign
 	Atom(ForeignAtom),
+	/// A runtime error
 	Bottom(OrcErrv),
+	/// Some other value, possibly normalizes to one of the above
 	Opaque,
 }
diff --git a/orchid-extension/src/func_atom.rs b/orchid-extension/src/func_atom.rs
index 38c2872..1033ac4 100644
--- a/orchid-extension/src/func_atom.rs
+++ b/orchid-extension/src/func_atom.rs
@@ -15,14 +15,10 @@ use orchid_base::{FmtCtx, FmtUnit, OrcRes, Pos, Sym, clone};
 use task_local::task_local;
 use trait_set::trait_set;
 
-use crate::api;
-use crate::atom::Atomic;
-use crate::atom_owned::{DeserializeCtx, OwnedAtom, OwnedVariant};
-use crate::conv::ToExpr;
-use crate::coroutine_exec::{ExecHandle, exec};
-use crate::expr::Expr;
 use crate::gen_expr::{GExpr, new_atom};
-use crate::system::sys_id;
+use crate::{
+	Atomic, DeserializeCtx, ExecHandle, Expr, OwnedAtom, OwnedVariant, ToExpr, api, exec, sys_id,
+};
 
 trait_set! {
 	trait FunCB = Fn(Vec<Expr>) -> LocalBoxFuture<'static, OrcRes<GExpr>> + 'static;
@@ -32,6 +28,7 @@ task_local! {
 	static ARGV: Vec<Expr>;
 }
 
+/// Wihtin an [ExprFunc]'s body, access a raw argument by index
 pub fn get_arg(idx: usize) -> Expr {
 	ARGV
 		.try_with(|argv| {
@@ -41,16 +38,26 @@ pub fn get_arg(idx: usize) -> Expr {
 		.expect("get_arg called outside ExprFunc")
 }
 
+/// Find the number of arguments accepted by this [ExprFunc]
 pub fn get_argc() -> usize {
 	ARGV.try_with(|argv| argv.len()).expect("get_arg called outside ExprFunc")
 }
 
+/// Retrieve the code locations associated with specific arguments by index.
+/// This is intended to be the last argument to [orchid_base::mk_errv]
 pub async fn get_arg_posv(idxes: impl IntoIterator<Item = usize>) -> impl Iterator<Item = Pos> {
 	let args = (ARGV.try_with(|argv| idxes.into_iter().map(|i| &argv[i]).cloned().collect_vec()))
 		.expect("get_arg_posv called outside ExprFunc");
 	join_all(args.iter().map(|expr| expr.pos())).await.into_iter()
 }
 
+/// A Rust lambda that can be placed into an Orchid atom. This requires that
+///
+/// - the lambda is [Clone] and `'static`
+/// - All of its arguments are [crate::TryFromExpr]
+/// - Its return value is [crate::ToExpr]
+/// - For the sake of compilation time, at present the trait is only implemented
+///   for up to 6 arguments
 pub trait ExprFunc<I, O>: Clone + 'static {
 	fn argtyps() -> &'static [TypeId];
 	fn apply<'a>(&self, hand: ExecHandle<'a>, v: Vec<Expr>) -> impl Future<Output = OrcRes<GExpr>>;
@@ -152,13 +159,14 @@ impl OwnedAtom for Fun {
 /// An Atom representing a partially applied native lambda. These are not
 /// serializable.
 ///
-/// See [Fun] for the serializable variant
+/// See [crate::fun] for the serializable variant
 #[derive(Clone)]
 pub struct Lambda {
 	args: Vec<Expr>,
 	record: FunRecord,
 }
 impl Lambda {
+	/// Embed a lambda in an Orchid expression
 	pub fn new<I, O, F: ExprFunc<I, O>>(f: F) -> Self {
 		Self { args: vec![], record: process_args(f) }
 	}
diff --git a/orchid-extension/src/gen_expr.rs b/orchid-extension/src/gen_expr.rs
index 3a6c595..a71b6c9 100644
--- a/orchid-extension/src/gen_expr.rs
+++ b/orchid-extension/src/gen_expr.rs
@@ -7,16 +7,15 @@ use orchid_base::{
 	FmtCtx, FmtUnit, Format, OrcErr, OrcErrv, Pos, Sym, Variants, match_mapping, tl_cache,
 };
 
-use crate::api;
-use crate::atom::{AtomFactory, AtomicFeatures};
-use crate::conv::{ToExpr, ToExprFuture};
-use crate::entrypoint::request;
-use crate::expr::Expr;
-use crate::system::sys_id;
+use crate::{AtomFactory, AtomicFeatures, Expr, ToExpr, ToExprFuture, api, request, sys_id};
 
+/// Newly generated AST. Values of this type should not typically be constructed
+/// manually but through the helpers in this module
 #[derive(Clone, Debug)]
 pub struct GExpr {
+	/// AST node type
 	pub kind: GExprKind,
+	/// Code location associated with the expression for debugging purposes
 	pub pos: Pos,
 }
 impl GExpr {
@@ -38,7 +37,10 @@ impl GExpr {
 			}
 		}
 	}
+	/// Reassign location information. The typical default is [Pos::Inherit]
 	pub fn at(self, pos: Pos) -> Self { GExpr { pos, kind: self.kind } }
+	/// Send the expression to the interpreter to be compiled and to become
+	/// shareable across extensions
 	pub async fn create(self) -> Expr {
 		Expr::deserialize(request(api::Create(sys_id(), self.serialize().await)).await).await
 	}
@@ -49,20 +51,36 @@ impl Format for GExpr {
 	}
 }
 
+/// AST nodes recognized by the interpreter
 #[derive(Clone, Debug)]
 pub enum GExprKind {
+	/// Function call
 	Call(Box<GExpr>, Box<GExpr>),
+	/// Lambda expression. Argument numbers are matched when equal
 	Lambda(u64, Box<GExpr>),
+	/// Slot for a lambda argument
 	Arg(u64),
+	/// The second expression is only valid after the first one had already been
+	/// fully normalized. The main use case is the pattern `Lambda(0, Seq(0,
+	/// Call(foo, 0)))` where foo is an atom that attempts to downcast its
+	/// argument.
 	Seq(Box<GExpr>, Box<GExpr>),
+	/// A reference to a constant from the shared constant tree. It is best to
+	/// mark the system that provides named constants as a dependency, but this is
+	/// not required
 	Const(Sym),
+	/// A newly created atom. Since at this point the atom needs to be registered
+	/// inside the extension but doesn't yet have an [api::ExprTicket], atoms need
+	/// their own [api::Atom::drop] if they have an identity
 	#[allow(private_interfaces)]
 	NewAtom(AtomFactory),
+	/// An expression previously registered or coming from outside the extension
 	Slot(Expr),
+	/// A runtime error
 	Bottom(OrcErrv),
 }
 impl GExprKind {
-	pub async fn serialize(self) -> api::ExpressionKind {
+	async fn serialize(self) -> api::ExpressionKind {
 		match_mapping!(self, Self => api::ExpressionKind {
 			Call(
 				f => Box::new(f.serialize().await),
@@ -117,6 +135,8 @@ impl ToExpr for Sym {
 /// Creates an expression from a new atom that we own.
 pub fn new_atom<A: AtomicFeatures>(atom: A) -> GExpr { inherit(GExprKind::NewAtom(atom.factory())) }
 
+/// An expression which is only valid if a number of dependencies had already
+/// been normalized
 pub fn seq(
 	deps: impl IntoGExprStream,
 	val: impl ToExpr,
@@ -135,17 +155,24 @@ pub fn seq(
 	})
 }
 
+/// Argument bound by an enclosing [lam] or [dyn_lambda]
 pub fn arg(n: u64) -> GExpr { inherit(GExprKind::Arg(n)) }
 
+/// A lambda expression. The difference from [dyn_lambda] is purely aesthetic
 pub fn lam<const N: u64>(b: impl ToExpr) -> ToExprFuture<impl Future<Output = GExpr>> {
 	dyn_lambda(N, b)
 }
 
+/// A lambda expression. The difference from [lam] is purely aesthetic
 pub fn dyn_lambda(n: u64, b: impl ToExpr) -> ToExprFuture<impl Future<Output = GExpr>> {
 	ToExprFuture(async move { inherit(GExprKind::Lambda(n, Box::new(b.to_gen().await))) })
 }
 
+/// one or more items that are convertible to expressions. In practice, a
+/// [ToExpr], [Vec<GExpr>], or a tuple of types that all implement [ToExpr]. For
+/// compilation performance, the tuple's arity may not be more than 6
 pub trait IntoGExprStream {
+	/// Convert each item to an expression and return them
 	fn into_gexpr_stream(self) -> impl Stream<Item = GExpr>;
 }
 impl<T: ToExpr> IntoGExprStream for T {
@@ -184,6 +211,7 @@ mod tuple_impls {
 	tuple_impl!(A B C D E F);
 }
 
+/// Call a (curried) function
 pub fn call(
 	f: impl ToExpr,
 	argv: impl IntoGExprStream,
@@ -195,6 +223,7 @@ pub fn call(
 	})
 }
 
+/// Call a function on a dynamic number of arguments
 pub fn call_v(
 	f: impl ToExpr,
 	argv: impl IntoIterator<Item: ToExpr>,
@@ -208,6 +237,7 @@ pub fn call_v(
 	})
 }
 
+/// A runtime error
 pub fn bot(ev: impl IntoIterator<Item = OrcErr>) -> GExpr {
 	inherit(GExprKind::Bottom(OrcErrv::new(ev).unwrap()))
 }
diff --git a/orchid-extension/src/interner.rs b/orchid-extension/src/interner.rs
index 22934a6..f65bb64 100644
--- a/orchid-extension/src/interner.rs
+++ b/orchid-extension/src/interner.rs
@@ -5,8 +5,7 @@ use itertools::Itertools;
 use orchid_base::local_interner::{Int, StrBranch, StrvBranch};
 use orchid_base::{IStr, IStrv, InternerSrv};
 
-use crate::api;
-use crate::entrypoint::{MUTE_REPLY, request};
+use crate::{api, mute_reply, request};
 
 #[derive(Default)]
 struct ExtInterner {
@@ -17,9 +16,8 @@ impl InternerSrv for ExtInterner {
 	fn is<'a>(&'a self, v: &'a str) -> LocalBoxFuture<'a, IStr> {
 		match self.str.i(v) {
 			Ok(i) => Box::pin(ready(i)),
-			Err(e) => Box::pin(async {
-				e.set_if_empty(MUTE_REPLY.scope((), request(api::InternStr(v.to_owned()))).await)
-			}),
+			Err(e) =>
+				Box::pin(async { e.set_if_empty(mute_reply(request(api::InternStr(v.to_owned()))).await) }),
 		}
 	}
 	fn es(&self, t: api::TStr) -> LocalBoxFuture<'_, IStr> {
@@ -47,4 +45,4 @@ impl InternerSrv for ExtInterner {
 	}
 }
 
-pub fn new_interner() -> Rc<dyn InternerSrv> { Rc::<ExtInterner>::default() }
+pub(crate) fn new_interner() -> Rc<dyn InternerSrv> { Rc::<ExtInterner>::default() }
diff --git a/orchid-extension/src/lexer.rs b/orchid-extension/src/lexer.rs
index 2bbd3c0..f4ccdad 100644
--- a/orchid-extension/src/lexer.rs
+++ b/orchid-extension/src/lexer.rs
@@ -7,27 +7,30 @@ use futures::FutureExt;
 use futures::future::LocalBoxFuture;
 use orchid_base::{IStr, OrcErrv, OrcRes, Pos, SrcRange, Sym, is, mk_errv};
 
-use crate::api;
-use crate::entrypoint::request;
-use crate::expr::BorrowedExprStore;
-use crate::parser::PTokTree;
 use crate::tree::GenTokTree;
+use crate::{BorrowedExprStore, PTokTree, api, request};
 
-pub async fn ekey_cascade() -> IStr { is("An error cascading from a recursive call").await }
-pub async fn ekey_not_applicable() -> IStr {
+pub(crate) async fn ekey_cascade() -> IStr { is("An error cascading from a recursive call").await }
+pub(crate) async fn ekey_not_applicable() -> IStr {
 	is("Pseudo-error to communicate that the current branch in a dispatch doesn't apply").await
 }
 const MSG_INTERNAL_ERROR: &str = "This error is a sentinel for the extension library.\
 	it should not be emitted by the extension.";
 
-pub async fn err_cascade() -> OrcErrv {
+pub(crate) async fn err_cascade() -> OrcErrv {
 	mk_errv(ekey_cascade().await, MSG_INTERNAL_ERROR, [Pos::None])
 }
 
+/// Return this error if your lexer can determine that it is not applicable to
+/// this piece of syntax. This error will not be raised if another lexer
+/// matches, or if the piece of matched syntax is found to be valid until
+/// runtime
 pub async fn err_not_applicable() -> OrcErrv {
 	mk_errv(ekey_not_applicable().await, MSG_INTERNAL_ERROR, [Pos::None])
 }
 
+/// Object passed to lexers for recursion and position-related convenience
+/// methods
 pub struct LexContext<'a> {
 	pub(crate) exprs: &'a BorrowedExprStore,
 	pub text: &'a IStr,
@@ -36,7 +39,7 @@ pub struct LexContext<'a> {
 	pub(crate) src: Sym,
 }
 impl<'a> LexContext<'a> {
-	pub fn new(
+	pub(crate) fn new(
 		exprs: &'a BorrowedExprStore,
 		text: &'a IStr,
 		id: api::ParsId,
@@ -45,7 +48,11 @@ impl<'a> LexContext<'a> {
 	) -> Self {
 		Self { exprs, id, pos, src, text }
 	}
+	/// The logical path of the source file, also the path of the file's root
+	/// module
 	pub fn src(&self) -> &Sym { &self.src }
+	/// Lex an interpolated expression of some kind
+	///
 	/// This function returns [PTokTree] because it can never return
 	/// [orchid_base::Token::NewExpr]. You can use
 	/// [crate::parser::p_tree2gen] to convert this to [crate::tree::GenTokTree]
@@ -58,17 +65,23 @@ impl<'a> LexContext<'a> {
 		let tree = PTokTree::from_api(lx.tree, &mut { self.exprs }, &mut (), &self.src).await;
 		Ok((&self.text[lx.pos as usize..], tree))
 	}
-
+	/// Find the index of a cursor given the remaining, not-yet-consumed text
 	pub fn pos(&self, tail: &'a str) -> u32 { (self.text.len() - tail.len()) as u32 }
+	/// Convenience method to find the source position of a token given the text
+	/// it was found in and the text after it was parsed.
 	pub fn pos_tt(&self, tail_with: &'a str, tail_without: &'a str) -> SrcRange {
 		SrcRange::new(self.pos(tail_with)..self.pos(tail_without), &self.src)
 	}
-
+	/// Convenience method to find the source position of a token given its length
+	/// and the remaining text afterwards. The length can be any number type but
+	/// must convert to a u32 without errors
 	pub fn pos_lt(&self, len: impl TryInto<u32, Error: fmt::Debug>, tail: &'a str) -> SrcRange {
 		SrcRange::new(self.pos(tail) - len.try_into().unwrap()..self.pos(tail), &self.src)
 	}
 }
 
+/// One or more tokens returned by the parser. In practice, [GenTokTree],
+/// `Vec<GenTokTree>`, or `[GenTokTree; usize]`
 pub trait LexedData {
 	fn into_vec(self) -> Vec<GenTokTree>;
 }
@@ -82,16 +95,26 @@ impl<const N: usize> LexedData for [GenTokTree; N] {
 	fn into_vec(self) -> Vec<GenTokTree> { self.to_vec() }
 }
 
+/// A lexer plugin to extend the syntax of Orchid
 pub trait Lexer: Debug + Send + Sync + Sized + Default + 'static {
+	/// As an optimization, your lexer will only receive snippets that start with
+	/// a character included in one of these ranges. If you have a multi-character
+	/// discriminator, include all possible starting chars in this and return
+	/// [err_not_applicable] if the entire discriminator was not found
 	const CHAR_FILTER: &'static [RangeInclusive<char>];
+	/// Attempt to lex some custom syntax from the start of the tail string.
+	/// Return the remaining text and the lexed tokens.
 	fn lex<'a>(
 		tail: &'a str,
 		lctx: &'a LexContext<'a>,
 	) -> impl Future<Output = OrcRes<(&'a str, impl LexedData)>>;
 }
 
+/// Type-erased [Lexer]
 pub trait DynLexer: Debug + Send + Sync + 'static {
+	/// Type-erased [Lexer::CHAR_FILTER]
 	fn char_filter(&self) -> &'static [RangeInclusive<char>];
+	/// Type-erased [Lexer::lex]
 	fn lex<'a>(
 		&self,
 		tail: &'a str,
@@ -110,4 +133,6 @@ impl<T: Lexer> DynLexer for T {
 	}
 }
 
+/// Type-erased instance of a lexer that is returned by
+/// [crate::System::lexers]
 pub type LexerObj = &'static dyn DynLexer;
diff --git a/orchid-extension/src/lib.rs b/orchid-extension/src/lib.rs
index f5f4694..898b17f 100644
--- a/orchid-extension/src/lib.rs
+++ b/orchid-extension/src/lib.rs
@@ -3,27 +3,44 @@ use orchid_api as api;
 
 mod atom;
 pub use atom::*;
+mod cmd_atom;
+pub use cmd_atom::*;
 mod atom_owned;
 pub use atom_owned::*;
 mod atom_thin;
 pub use atom_thin::*;
 pub mod binary;
-pub mod conv;
-pub mod coroutine_exec;
-pub mod entrypoint;
-pub mod expr;
-pub mod ext_port;
-pub mod func_atom;
+mod conv;
+pub use conv::*;
+mod coroutine_exec;
+pub use coroutine_exec::*;
+mod entrypoint;
+pub use entrypoint::*;
+mod expr;
+pub use expr::*;
+mod ext_port;
+pub use ext_port::*;
+mod func_atom;
+pub use func_atom::*;
 pub mod gen_expr;
-pub mod interner;
-pub mod lexer;
-pub mod logger;
-pub mod other_system;
-pub mod parser;
-pub mod reflection;
-pub mod stream_reqs;
-pub mod system;
-pub mod system_ctor;
-pub mod tokio;
+mod interner;
+mod lexer;
+pub use lexer::*;
+mod logger;
+mod other_system;
+pub use other_system::*;
+mod parser;
+pub use parser::*;
+mod reflection;
+pub use reflection::*;
+pub mod std_reqs;
+mod system;
+pub use system::*;
+mod system_ctor;
+pub use system_ctor::*;
+mod system_card;
+pub use system_card::*;
+mod tokio;
+pub use tokio::*;
 pub mod tree;
 mod trivial_req;
diff --git a/orchid-extension/src/logger.rs b/orchid-extension/src/logger.rs
index ed0ab9a..0dea028 100644
--- a/orchid-extension/src/logger.rs
+++ b/orchid-extension/src/logger.rs
@@ -7,10 +7,9 @@ use futures::future::LocalBoxFuture;
 use hashbrown::HashMap;
 use orchid_base::{LogWriter, Logger, is};
 
-use crate::api;
-use crate::entrypoint::notify;
+use crate::{api, notify};
 
-pub struct LogWriterImpl {
+pub(crate) struct LogWriterImpl {
 	category: String,
 	strat: api::LogStrategy,
 }
@@ -33,7 +32,7 @@ impl LogWriter for LogWriterImpl {
 }
 
 #[derive(Clone)]
-pub struct LoggerImpl {
+pub(crate) struct LoggerImpl {
 	default: Option<api::LogStrategy>,
 	routing: HashMap<String, api::LogStrategy>,
 }
diff --git a/orchid-extension/src/other_system.rs b/orchid-extension/src/other_system.rs
index a50f1cf..b2713bc 100644
--- a/orchid-extension/src/other_system.rs
+++ b/orchid-extension/src/other_system.rs
@@ -1,25 +1,52 @@
-use crate::api;
-use crate::system::{DynSystemCard, SystemCard};
+use std::any::TypeId;
 
+use orchid_api_traits::{Decode, Encode, Request};
+
+use crate::system::{dyn_cted, sys_id};
+use crate::{DynSystemCard, SystemCard, api, request};
+
+/// A reference to an instance of an alternate system, passed to
+/// [crate::SystemCtor::inst] for dependencies. It can be accepted by functions
+/// that call [sys_req] to prove a dependency relationship.
 #[derive(Debug)]
 pub struct SystemHandle<C: SystemCard> {
-	pub(crate) card: C,
+	pub(crate) _card: C,
 	pub(crate) id: api::SysId,
 }
 impl<C: SystemCard> SystemHandle<C> {
-	pub(crate) fn new(id: api::SysId) -> Self { Self { card: C::default(), id } }
+	pub(crate) fn new(id: api::SysId) -> Self { Self { _card: C::default(), id } }
 	pub fn id(&self) -> api::SysId { self.id }
 }
 impl<C: SystemCard> Clone for SystemHandle<C> {
 	fn clone(&self) -> Self { Self::new(self.id) }
 }
 
+/// Type-erased system handle, not used for anything at the moment
 pub trait DynSystemHandle {
 	fn id(&self) -> api::SysId;
-	fn get_card(&self) -> &dyn DynSystemCard;
+	fn get_card(&self) -> Box<dyn DynSystemCard>;
 }
 
 impl<C: SystemCard> DynSystemHandle for SystemHandle<C> {
 	fn id(&self) -> api::SysId { self.id }
-	fn get_card(&self) -> &dyn DynSystemCard { &self.card }
+	fn get_card(&self) -> Box<dyn DynSystemCard> { Box::new(C::default()) }
+}
+
+/// Make a global request to a system that supports this request type. The
+/// target system must either be the system in which this function is called, or
+/// one of its direct dependencies.
+pub async fn sys_req<Sys: SystemCard, Req: Request + Into<Sys::Req>>(req: Req) -> Req::Response {
+	let mut msg = Vec::new();
+	req.into().encode_vec(&mut msg);
+	let cted = dyn_cted();
+	let own_inst = cted.inst();
+	let owner = if own_inst.card().type_id() == TypeId::of::<Sys>() {
+		sys_id()
+	} else {
+		(cted.deps().find(|s| s.get_card().type_id() == TypeId::of::<Sys>()))
+			.expect("System not in dependency array yet we have a handle somehow")
+			.id()
+	};
+	let reply = request(api::SysFwd(owner, msg)).await;
+	Req::Response::decode(std::pin::pin!(&reply[..])).await.unwrap()
 }
diff --git a/orchid-extension/src/parser.rs b/orchid-extension/src/parser.rs
index d92f1a2..5131fac 100644
--- a/orchid-extension/src/parser.rs
+++ b/orchid-extension/src/parser.rs
@@ -14,18 +14,23 @@ use orchid_base::{
 };
 use task_local::task_local;
 
-use crate::api;
-use crate::conv::ToExpr;
-use crate::entrypoint::request;
-use crate::expr::Expr;
 use crate::gen_expr::GExpr;
-use crate::system::sys_id;
 use crate::tree::{GenTok, GenTokTree};
+use crate::{Expr, ToExpr, api, request, sys_id};
 
+/// [PTokTree] without [orchid_base::Pos] metadata
 pub type PTok = Token<Expr, Never>;
+/// [TokTree] received by [Parser], or returned from recursive [crate::Lexer]
+/// call. It is different from [GenTok] because it cannot be [Token::NewExpr].
+/// Convert with [p_tok2gen], [p_tree2gen], [p_v2gen]
 pub type PTokTree = TokTree<Expr, Never>;
+/// Wrapper [Snippet] around a slice of [PTokTree] with a fallback item for
+/// [orchid_base::Pos] metadata
 pub type PSnippet<'a> = Snippet<'a, Expr, Never>;
 
+/// Convert ingress syntax tokens into egress for interpolation into the output
+///
+/// See also [p_tree2gen], [p_v2gen]
 pub fn p_tok2gen(tok: PTok) -> GenTok {
 	match_mapping!(tok, PTok => GenTok {
 		Comment(s), Name(n), BR, Handle(ex), Bottom(err),
@@ -36,15 +41,33 @@ pub fn p_tok2gen(tok: PTok) -> GenTok {
 		PTok::NewExpr(never) => match never {}
 	})
 }
+/// Convert ingress syntax tokens into egress for interpolation into the output
+///
+/// See also [p_tok2gen], [p_v2gen]
 pub fn p_tree2gen(tree: PTokTree) -> GenTokTree {
 	TokTree { tok: p_tok2gen(tree.tok), sr: tree.sr }
 }
+/// Convert ingress syntax tokens into egress for interpolation into the output
+///
+/// See also [p_tok2gen], [p_tree2gen]
 pub fn p_v2gen(v: impl IntoIterator<Item = PTokTree>) -> Vec<GenTokTree> {
 	v.into_iter().map(p_tree2gen).collect_vec()
 }
 
+/// A parser extension for the stage of parsing that converts source lines into
+/// a module tree. These are invoked by usercode intentionally through a custom
+/// keyword at the start of the line
+///
+/// Unlike [crate::Lexer]'s [crate::err_not_applicable], these don't have a
+/// mechanism to reject work. Each keyword must refer to one and exactly one
+/// parser
 pub trait Parser: Send + Sync + Sized + Default + 'static {
+	/// The keyword at the head of the line that invokes this parser
 	const LINE_HEAD: &'static str;
+	/// Parsing work. If the line head is preceded by the keyword "export", the
+	/// 2nd parameter is true. Both the line head and the optional export keyword
+	/// are trimmed off the 4th parameter. The parser should forward all comments
+	/// to the generated lines
 	fn parse<'a>(
 		ctx: ParsCtx<'a>,
 		exported: bool,
@@ -53,8 +76,11 @@ pub trait Parser: Send + Sync + Sized + Default + 'static {
 	) -> impl Future<Output = OrcRes<Vec<ParsedLine>>> + 'a;
 }
 
+/// Type-erased [Parser]
 pub trait DynParser: Send + Sync + 'static {
+	/// Type-erased [Parser::LINE_HEAD]
 	fn line_head(&self) -> &'static str;
+	/// Type-erased [Parser::parse]
 	fn parse<'a>(
 		&self,
 		ctx: ParsCtx<'a>,
@@ -77,14 +103,18 @@ impl<T: Parser> DynParser for T {
 	}
 }
 
+/// Trait-object of [Parser]
 pub type ParserObj = &'static dyn DynParser;
 
+/// Information about the parsing context
 pub struct ParsCtx<'a> {
 	_parse: PhantomData<&'a mut ()>,
 	module: Sym,
 }
 impl<'a> ParsCtx<'a> {
 	pub(crate) fn new(module: Sym) -> Self { Self { _parse: PhantomData, module } }
+	/// The full path of the module that contains the line the parser was invoked
+	/// with
 	pub fn module(&self) -> Sym { self.module.clone() }
 }
 
@@ -100,12 +130,19 @@ pub(crate) fn with_parsed_const_ctx<'a>(fut: LocalBoxFuture<'a, ()>) -> LocalBox
 	Box::pin(CONST_TBL.scope(RefCell::default(), NEXT_CONST_ID.scope(id_cell, fut)))
 }
 
+/// A logical subtree returned from a parser
 pub struct ParsedLine {
+	/// Source location associated with this item
 	pub sr: SrcRange,
+	/// Comments placed above this line
 	pub comments: Vec<Comment>,
+	/// Possible nodes in the logical tree
 	pub kind: ParsedLineKind,
 }
 impl ParsedLine {
+	/// Define a constant. The callback is only called later if the constant is
+	/// referenced, and it can call [crate::refl] to base its value on the module
+	/// tree or use its argument for context-specific queries
 	pub fn cnst<'a, R: ToExpr + 'static, F: AsyncFnOnce(ConstCtx) -> R + 'static>(
 		sr: &SrcRange,
 		comments: impl IntoIterator<Item = &'a Comment>,
@@ -118,6 +155,12 @@ impl ParsedLine {
 		let comments = comments.into_iter().cloned().collect();
 		ParsedLine { comments, sr: sr.clone(), kind }
 	}
+	/// Define a module containing additional items. `use_prelude` determines
+	/// whether the globally visible imports specified in the preludes of
+	/// extensions will be added to this module. In practice, it should typically
+	/// be enabled if you are interpolating any user-expressions or user-lines
+	/// into the module and disabled if your custom line parses all input and does
+	/// not interact with other plugins and macros
 	pub fn module<'a>(
 		sr: &SrcRange,
 		comments: impl IntoIterator<Item = &'a Comment>,
@@ -131,7 +174,7 @@ impl ParsedLine {
 		let comments = comments.into_iter().cloned().collect();
 		ParsedLine { comments, sr: sr.clone(), kind: line_kind }
 	}
-	pub async fn into_api(self) -> api::ParsedLine {
+	pub(crate) async fn into_api(self) -> api::ParsedLine {
 		api::ParsedLine {
 			comments: self.comments.into_iter().map(|c| c.to_api()).collect(),
 			source_range: self.sr.to_api(),
@@ -162,27 +205,50 @@ pub(crate) async fn linev_into_api(v: Vec<ParsedLine>) -> Vec<api::ParsedLine> {
 	join_all(v.into_iter().map(|l| l.into_api())).await
 }
 
+/// Lines in the logical tree returnable from parsers
 pub enum ParsedLineKind {
+	/// A single subtree in the logical tree. This kind can more conveniently be
+	/// generated with [ParsedLine::cnst] or [ParsedLine::module]
 	Mem(ParsedMem),
+	/// Additional syntax that will be passed to another line parser and may
+	/// evaluate to zero or more lines
 	Rec(Vec<GenTokTree>),
 }
 
+/// A single subtree in the logical tree, also visible via [crate::refl]
 pub struct ParsedMem {
+	/// Name must be unique
 	pub name: IStr,
+	/// Whether the subtree is visible outside its enclosing module. If not, only
+	/// siblings and their descendants will be able to import it
 	pub exported: bool,
+	/// Variants
 	pub kind: ParsedMemKind,
 }
 
+/// Kind of [ParsedMem]
 pub enum ParsedMemKind {
+	/// A constant
 	Const(BoxConstCallback),
-	Mod { lines: Vec<ParsedLine>, use_prelude: bool },
+	/// A module with additional descendants
+	Mod {
+		/// Logical lines inside the module
+		lines: Vec<ParsedLine>,
+		/// Whether the module will include prelude imports provided by all
+		/// extensions
+		use_prelude: bool,
+	},
 }
 
+/// Enable a generated constant to query about its environment
 #[derive(Clone)]
 pub struct ConstCtx {
 	constid: api::ParsedConstId,
 }
 impl ConstCtx {
+	/// Resolve a set of local names into the full names they would point to if
+	/// they were globally bound. Errors produced at this stage are soft, as the
+	/// names may still be found to be locally bound within the expression
 	pub fn names<'b>(
 		&'b self,
 		names: impl IntoIterator<Item = &'b Sym> + 'b,
@@ -202,6 +268,7 @@ impl ConstCtx {
 			}
 		})
 	}
+	/// Static-length version of [Self::names]
 	pub async fn names_n<const N: usize>(&self, names: [&Sym; N]) -> [OrcRes<Sym>; N] {
 		self.names(names).collect::<Vec<_>>().await.try_into().expect("Lengths must match")
 	}
diff --git a/orchid-extension/src/reflection.rs b/orchid-extension/src/reflection.rs
index d069989..c2dfac2 100644
--- a/orchid-extension/src/reflection.rs
+++ b/orchid-extension/src/reflection.rs
@@ -9,39 +9,45 @@ use memo_map::MemoMap;
 use orchid_base::{IStr, NameLike, VPath, es, iv};
 use task_local::task_local;
 
-use crate::api;
-use crate::entrypoint::request;
-use crate::system::sys_id;
+use crate::{api, request, sys_id};
 
 #[derive(Debug)]
-pub struct ReflMemData {
-	// None for inferred steps
+struct ReflMemData {
+	/// None for inferred steps
 	public: OnceCell<bool>,
 	kind: ReflMemKind,
 }
+/// Potentially partial reflected information about a member inside a module
 #[derive(Clone, Debug)]
 pub struct ReflMem(Rc<ReflMemData>);
 impl ReflMem {
 	pub fn kind(&self) -> ReflMemKind { self.0.kind.clone() }
 }
 
+/// The kind of [ReflMem]
 #[derive(Clone, Debug)]
 pub enum ReflMemKind {
+	/// A plain constant. Information about constants can be obtained by passing a
+	/// [crate::gen_expr::GExprKind::Const] to the interpreter
 	Const,
+	/// A module that can be reflected further
 	Mod(ReflMod),
 }
 
 #[derive(Debug)]
-pub struct ReflModData {
+struct ReflModData {
 	inferred: Mutex<bool>,
 	path: VPath,
 	members: MemoMap<IStr, ReflMem>,
 }
 
+/// A module whose members can be listed and inspected
 #[derive(Clone, Debug)]
 pub struct ReflMod(Rc<ReflModData>);
 impl ReflMod {
+	/// Retrieve the path of the module
 	pub fn path(&self) -> &[IStr] { &self.0.path[..] }
+	/// Whether this path is the root or if it has a parent
 	pub fn is_root(&self) -> bool { self.0.path.is_empty() }
 	async fn try_populate(&self) -> Result<(), api::LsModuleError> {
 		let path_tok = iv(&self.0.path[..]).await;
@@ -70,6 +76,7 @@ impl ReflMod {
 		}
 		Ok(())
 	}
+	/// Find a child by name within the module
 	pub async fn get_child(&self, key: &IStr) -> Option<ReflMem> {
 		let inferred_g = self.0.inferred.lock().await;
 		if let Some(mem) = self.0.members.get(key) {
@@ -90,6 +97,9 @@ impl ReflMod {
 		}
 		self.0.members.get(key).cloned()
 	}
+	/// Find a descendant by sub-path within the module. Note that this is not the
+	/// same as the paths accepted by import statements, as the `self` and `super`
+	/// keywords don't work
 	pub async fn get_by_path(&self, path: &[IStr]) -> Result<ReflMem, InvalidPathError> {
 		let (next, tail) = path.split_first().expect("Attempted to walk by empty path");
 		let inferred_g = self.0.inferred.lock().await;
@@ -138,8 +148,11 @@ task_local! {
 	static REFL_ROOTS: RefCell<HashMap<api::SysId, ReflMod>>
 }
 
+/// Indicates that the caller provided a path that does not exist
 #[derive(Clone, Debug)]
 pub struct InvalidPathError {
+	/// When unwinding a recursive path lookup, decides whether the temporary
+	/// member created for the parent object should be kept or deleted
 	keep_ancestry: bool,
 }
 
@@ -154,12 +167,18 @@ fn default_member(is_root: bool, kind: ReflMemKind) -> ReflMem {
 	}))
 }
 
+/// Obtains the root module for reflection. This function may only be called in
+/// callbacks provided by [crate::OwnedAtom] except for
+/// [crate::OwnedAtom::free], callbacks provided by [crate::ThinAtom], the
+/// callback for [crate::ParsedLine::cnst], [crate::gen_expr] callbacks, and
+/// other places where we know that the interpreter is running and holding a
+/// reference to the module tree
 pub fn refl() -> ReflMod {
 	REFL_ROOTS.with(|tbl| {
 		tbl.borrow_mut().entry(sys_id()).or_insert_with(|| default_module(VPath::new([]))).clone()
 	})
 }
 
-pub fn with_refl_roots<'a>(fut: LocalBoxFuture<'a, ()>) -> LocalBoxFuture<'a, ()> {
+pub(crate) fn with_refl_roots<'a>(fut: LocalBoxFuture<'a, ()>) -> LocalBoxFuture<'a, ()> {
 	Box::pin(REFL_ROOTS.scope(RefCell::default(), fut))
 }
diff --git a/orchid-extension/src/stream_reqs.rs b/orchid-extension/src/std_reqs.rs
similarity index 68%
rename from orchid-extension/src/stream_reqs.rs
rename to orchid-extension/src/std_reqs.rs
index fffba78..62ea3f0 100644
--- a/orchid-extension/src/stream_reqs.rs
+++ b/orchid-extension/src/std_reqs.rs
@@ -1,26 +1,52 @@
 use std::num::NonZero;
+use std::time::Duration;
 
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 
+use crate::api;
 use crate::atom::AtomMethod;
 
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
+pub struct Spawn(pub api::ExprTicket);
+impl Request for Spawn {
+	type Response = api::ExprTicket;
+}
+
+/// Execute the atom as a command.
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
+pub struct RunCommand;
+impl Request for RunCommand {
+	type Response = Option<api::Expression>;
+}
+impl AtomMethod for RunCommand {
+	const NAME: &str = "orchid::cmd::run";
+}
+
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
+pub struct AsDuration;
+impl Request for AsDuration {
+	type Response = Duration;
+}
+impl AtomMethod for AsDuration {
+	const NAME: &str = "orchid::time::as_duration";
+}
+
 /// Represents [std::io::ErrorKind] values that are produced while operating on
 /// already-opened files
 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding)]
 pub enum IoErrorKind {
-	BrokenPipe,
-	UnexpectedEof,
-	ConnectionAborted,
+	/// Produced when a stream ends prematurely due to an identifiably unintended
+	/// reason, such as a TCP socket timeout, the file becoming inaccessible or
+	/// disappearing, or
+	Interrupted,
 	Other,
 }
 impl IoErrorKind {
 	pub fn message(self) -> &'static str {
 		match self {
 			IoErrorKind::Other => "Failed to read from stream",
-			IoErrorKind::BrokenPipe => "Broken pipe",
-			IoErrorKind::UnexpectedEof => "Unexpected EOF",
-			IoErrorKind::ConnectionAborted => "Connection aborted",
+			IoErrorKind::Interrupted => "Stream interrupted",
 		}
 	}
 }
diff --git a/orchid-extension/src/system.rs b/orchid-extension/src/system.rs
index b1272c8..67a7e85 100644
--- a/orchid-extension/src/system.rs
+++ b/orchid-extension/src/system.rs
@@ -1,78 +1,21 @@
-use std::any::{Any, TypeId, type_name};
 use std::fmt::Debug;
 use std::future::Future;
-use std::num::NonZero;
+use std::rc::Rc;
 
 use futures::FutureExt;
 use futures::future::LocalBoxFuture;
-use orchid_api_traits::{Coding, Decode, Encode, Request};
-use orchid_base::{BoxedIter, Receipt, ReqHandle, ReqReader, ReqReaderExt, Sym};
+use orchid_base::{Receipt, ReqHandle, ReqReader, ReqReaderExt, Sym};
 use task_local::task_local;
 
-use crate::api;
-use crate::atom::{AtomOps, AtomTypeId, Atomic, AtomicFeatures};
-use crate::coroutine_exec::Replier;
-use crate::entrypoint::request;
-use crate::func_atom::{Fun, Lambda};
-use crate::lexer::LexerObj;
-use crate::parser::ParserObj;
-use crate::system_ctor::{CtedObj, SystemCtor};
 use crate::tree::GenMember;
+use crate::{Cted, CtedObj, DynSystemCard, LexerObj, ParserObj, SystemCard, SystemCtor, api};
 
-/// Description of a system. This is a distinct object because [SystemCtor]
-/// isn't [Default]
-pub trait SystemCard: Debug + Default + 'static {
-	type Ctor: SystemCtor;
-	type Req: Coding;
-	fn atoms() -> impl IntoIterator<Item = Option<Box<dyn AtomOps>>>;
-}
-
-/// Type-erased [SystemCard]
-pub trait DynSystemCard: Any + 'static {
-	fn name(&self) -> &'static str;
-	/// Atoms explicitly defined by the system card. Do not rely on this for
-	/// querying atoms as it doesn't include the general atom types
-	fn atoms(&'_ self) -> BoxedIter<'_, Option<Box<dyn AtomOps>>>;
-}
-
-impl<T: DynSystemCard + ?Sized> DynSystemCardExt for T {}
-pub(crate) trait DynSystemCardExt: DynSystemCard {
-	fn ops_by_tid(&self, tid: TypeId) -> Option<(AtomTypeId, Box<dyn AtomOps>)> {
-		(self.atoms().enumerate().map(|(i, o)| (NonZero::new(i as u32 + 1).unwrap(), o)))
-			.chain(general_atoms().enumerate().map(|(i, o)| (NonZero::new(!(i as u32)).unwrap(), o)))
-			.filter_map(|(i, o)| o.map(|a| (AtomTypeId(i), a)))
-			.find(|ent| ent.1.tid() == tid)
-	}
-	fn ops_by_atid(&self, tid: AtomTypeId) -> Option<Box<dyn AtomOps>> {
-		if (u32::from(tid.0) >> (u32::BITS - 1)) & 1 == 1 {
-			general_atoms().nth(!u32::from(tid.0) as usize).unwrap()
-		} else {
-			self.atoms().nth(u32::from(tid.0) as usize - 1).unwrap()
-		}
-	}
-	fn ops<A: Atomic>(&self) -> (AtomTypeId, Box<dyn AtomOps>) {
-		self
-			.ops_by_tid(TypeId::of::<A>())
-			.unwrap_or_else(|| panic!("{} is not an atom in {}", type_name::<A>(), self.name()))
-	}
-}
-
-/// Atoms supported by this package which may appear in all extensions.
-/// The indices of these are bitwise negated, such that the MSB of an atom index
-/// marks whether it belongs to this package (0) or the importer (1)
-fn general_atoms() -> impl Iterator<Item = Option<Box<dyn AtomOps>>> {
-	[Some(Fun::ops()), Some(Lambda::ops()), Some(Replier::ops())].into_iter()
-}
-
-impl<T: SystemCard> DynSystemCard for T {
-	fn name(&self) -> &'static str { T::Ctor::NAME }
-	fn atoms(&'_ self) -> BoxedIter<'_, Option<Box<dyn AtomOps>>> {
-		Box::new(Self::atoms().into_iter())
-	}
-}
+pub type CardForSystem<T> = <<T as System>::Ctor as SystemCtor>::Card;
+pub type ReqForSystem<T> = <CardForSystem<T> as SystemCard>::Req;
 
 /// System as defined by author
-pub trait System: SystemCard + 'static {
+pub trait System: Debug + 'static {
+	type Ctor: SystemCtor<Instance = Self>;
 	fn prelude(&self) -> impl Future<Output = Vec<Sym>>;
 	fn env(&self) -> impl Future<Output = Vec<GenMember>>;
 	fn lexers(&self) -> Vec<LexerObj>;
@@ -80,11 +23,11 @@ pub trait System: SystemCard + 'static {
 	fn request<'a>(
 		&self,
 		hand: Box<dyn ReqHandle<'a> + 'a>,
-		req: Self::Req,
+		req: ReqForSystem<Self>,
 	) -> impl Future<Output = Receipt<'a>>;
 }
 
-pub trait DynSystem: DynSystemCard + 'static {
+pub trait DynSystem: Debug + 'static {
 	fn dyn_prelude(&self) -> LocalBoxFuture<'_, Vec<Sym>>;
 	fn dyn_env(&self) -> LocalBoxFuture<'_, Vec<GenMember>>;
 	fn dyn_lexers(&self) -> Vec<LexerObj>;
@@ -93,7 +36,7 @@ pub trait DynSystem: DynSystemCard + 'static {
 		&'a self,
 		hand: Box<dyn ReqReader<'b> + 'b>,
 	) -> LocalBoxFuture<'a, Receipt<'b>>;
-	fn card(&self) -> &dyn DynSystemCard;
+	fn card(&self) -> Box<dyn DynSystemCard>;
 }
 
 impl<T: System> DynSystem for T {
@@ -106,11 +49,11 @@ impl<T: System> DynSystem for T {
 		mut hand: Box<dyn ReqReader<'b> + 'b>,
 	) -> LocalBoxFuture<'a, Receipt<'b>> {
 		Box::pin(async move {
-			let value = hand.read_req::<<Self as SystemCard>::Req>().await.unwrap();
+			let value = hand.read_req().await.unwrap();
 			self.request(hand.finish().await, value).await
 		})
 	}
-	fn card(&self) -> &dyn DynSystemCard { self }
+	fn card(&self) -> Box<dyn DynSystemCard> { Box::new(CardForSystem::<Self>::default()) }
 }
 
 #[derive(Clone)]
@@ -125,23 +68,7 @@ pub(crate) async fn with_sys<F: Future>(sys: SysCtx, fut: F) -> F::Output {
 }
 
 pub fn sys_id() -> api::SysId { SYS_CTX.with(|cx| cx.0) }
-pub fn cted() -> CtedObj { SYS_CTX.with(|cx| cx.1.clone()) }
-
-/// Make a global request to a system that supports this request type. The
-/// target system must either be the system in which this function is called, or
-/// one of its direct dependencies.
-pub async fn sys_req<Sys: SystemCard, Req: Request + Into<Sys::Req>>(req: Req) -> Req::Response {
-	let mut msg = Vec::new();
-	req.into().encode_vec(&mut msg);
-	let cted = cted();
-	let own_inst = cted.inst();
-	let owner = if own_inst.card().type_id() == TypeId::of::<Sys>() {
-		sys_id()
-	} else {
-		(cted.deps().find(|s| s.get_card().type_id() == TypeId::of::<Sys>()))
-			.expect("System not in dependency array")
-			.id()
-	};
-	let reply = request(api::SysFwd(owner, msg)).await;
-	Req::Response::decode(std::pin::pin!(&reply[..])).await.unwrap()
+pub fn dyn_cted() -> CtedObj { SYS_CTX.with(|cx| cx.1.clone()) }
+pub fn cted<C: SystemCtor>() -> Cted<C> {
+	Rc::downcast::<Cted<C>>(dyn_cted().as_any()).unwrap().as_ref().clone()
 }
diff --git a/orchid-extension/src/system_card.rs b/orchid-extension/src/system_card.rs
new file mode 100644
index 0000000..19e958e
--- /dev/null
+++ b/orchid-extension/src/system_card.rs
@@ -0,0 +1,60 @@
+use std::any::{Any, TypeId, type_name};
+use std::fmt::Debug;
+use std::num::NonZero;
+
+use orchid_api_traits::Coding;
+use orchid_base::BoxedIter;
+
+use crate::{AtomOps, AtomTypeId, Atomic, AtomicFeatures, Fun, Lambda, Replier, SystemCtor};
+
+/// Description of a system. This is intended to be a ZST storing the static
+/// properties of a [SystemCtor] which should be known to foreign systems
+pub trait SystemCard: Debug + Default + 'static {
+	type Ctor: SystemCtor;
+	type Req: Coding;
+	fn atoms() -> impl IntoIterator<Item = Option<Box<dyn AtomOps>>>;
+}
+
+/// Type-erased [SystemCard]
+pub trait DynSystemCard: Any + 'static {
+	fn name(&self) -> &'static str;
+	/// Atoms explicitly defined by the system card. Do not rely on this for
+	/// querying atoms as it doesn't include the general atom types
+	fn atoms(&'_ self) -> BoxedIter<'_, Option<Box<dyn AtomOps>>>;
+}
+
+impl<T: SystemCard> DynSystemCard for T {
+	fn name(&self) -> &'static str { T::Ctor::NAME }
+	fn atoms(&'_ self) -> BoxedIter<'_, Option<Box<dyn AtomOps>>> {
+		Box::new(Self::atoms().into_iter())
+	}
+}
+
+impl<T: DynSystemCard + ?Sized> DynSystemCardExt for T {}
+pub(crate) trait DynSystemCardExt: DynSystemCard {
+	fn ops_by_tid(&self, tid: TypeId) -> Option<(AtomTypeId, Box<dyn AtomOps>)> {
+		(self.atoms().enumerate().map(|(i, o)| (NonZero::new(i as u32 + 1).unwrap(), o)))
+			.chain(general_atoms().enumerate().map(|(i, o)| (NonZero::new(!(i as u32)).unwrap(), o)))
+			.filter_map(|(i, o)| o.map(|a| (AtomTypeId(i), a)))
+			.find(|ent| ent.1.tid() == tid)
+	}
+	fn ops_by_atid(&self, tid: AtomTypeId) -> Option<Box<dyn AtomOps>> {
+		if (u32::from(tid.0) >> (u32::BITS - 1)) & 1 == 1 {
+			general_atoms().nth(!u32::from(tid.0) as usize).unwrap()
+		} else {
+			self.atoms().nth(u32::from(tid.0) as usize - 1).unwrap()
+		}
+	}
+	fn ops<A: Atomic>(&self) -> (AtomTypeId, Box<dyn AtomOps>) {
+		self
+			.ops_by_tid(TypeId::of::<A>())
+			.unwrap_or_else(|| panic!("{} is not an atom in {}", type_name::<A>(), self.name()))
+	}
+}
+
+/// Atoms supported by this package which may appear in all extensions.
+/// The indices of these are bitwise negated, such that the MSB of an atom index
+/// marks whether it belongs to this package (0) or the importer (1)
+pub(crate) fn general_atoms() -> impl Iterator<Item = Option<Box<dyn AtomOps>>> {
+	[Some(Fun::ops()), Some(Lambda::ops()), Some(Replier::ops())].into_iter()
+}
diff --git a/orchid-extension/src/system_ctor.rs b/orchid-extension/src/system_ctor.rs
index f5c5b66..407f802 100644
--- a/orchid-extension/src/system_ctor.rs
+++ b/orchid-extension/src/system_ctor.rs
@@ -1,33 +1,31 @@
 use std::any::Any;
 use std::fmt::Debug;
-use std::sync::Arc;
+use std::rc::Rc;
 
 use orchid_base::{BoxedIter, box_empty, box_once};
 use ordered_float::NotNan;
 
-use crate::api;
-use crate::other_system::{DynSystemHandle, SystemHandle};
-use crate::system::{DynSystem, System, SystemCard};
+use crate::{DynSystem, DynSystemHandle, System, SystemCard, SystemHandle, api};
 
 #[derive(Debug)]
 pub struct Cted<Ctor: SystemCtor + ?Sized> {
 	pub deps: <Ctor::Deps as DepDef>::Sat,
-	pub inst: Arc<Ctor::Instance>,
+	pub inst: Rc<Ctor::Instance>,
 }
 impl<C: SystemCtor + ?Sized> Clone for Cted<C> {
 	fn clone(&self) -> Self { Self { deps: self.deps.clone(), inst: self.inst.clone() } }
 }
 pub trait DynCted: Debug + 'static {
-	fn as_any(&self) -> &dyn Any;
+	fn as_any(self: Rc<Self>) -> Rc<dyn Any>;
 	fn deps<'a>(&'a self) -> BoxedIter<'a, &'a (dyn DynSystemHandle + 'a)>;
-	fn inst(&self) -> Arc<dyn DynSystem>;
+	fn inst(&self) -> Rc<dyn DynSystem>;
 }
 impl<C: SystemCtor + ?Sized> DynCted for Cted<C> {
-	fn as_any(&self) -> &dyn Any { self }
+	fn as_any(self: Rc<Self>) -> Rc<dyn Any> { self }
 	fn deps<'a>(&'a self) -> BoxedIter<'a, &'a (dyn DynSystemHandle + 'a)> { self.deps.iter() }
-	fn inst(&self) -> Arc<dyn DynSystem> { self.inst.clone() }
+	fn inst(&self) -> Rc<dyn DynSystem> { self.inst.clone() }
 }
-pub type CtedObj = Arc<dyn DynCted>;
+pub type CtedObj = Rc<dyn DynCted>;
 
 pub trait DepSat: Debug + Clone + 'static {
 	fn iter<'a>(&'a self) -> BoxedIter<'a, &'a (dyn DynSystemHandle + 'a)>;
@@ -61,7 +59,8 @@ impl DepDef for () {
 
 pub trait SystemCtor: Debug + 'static {
 	type Deps: DepDef;
-	type Instance: System;
+	type Instance: System<Ctor = Self>;
+	type Card: SystemCard<Ctor = Self>;
 	const NAME: &'static str;
 	const VERSION: f64;
 	/// Create a system instance.
@@ -85,8 +84,8 @@ impl<T: SystemCtor> DynSystemCtor for T {
 	fn new_system(&self, api::NewSystem { system: _, id: _, depends }: &api::NewSystem) -> CtedObj {
 		let mut ids = depends.iter().copied();
 		let deps = T::Deps::create(&mut || ids.next().unwrap());
-		let inst = Arc::new(self.inst(deps.clone()));
-		Arc::new(Cted::<T> { deps, inst })
+		let inst = Rc::new(self.inst(deps.clone()));
+		Rc::new(Cted::<T> { deps, inst })
 	}
 }
 
diff --git a/orchid-extension/src/tokio.rs b/orchid-extension/src/tokio.rs
index e06466d..8075a79 100644
--- a/orchid-extension/src/tokio.rs
+++ b/orchid-extension/src/tokio.rs
@@ -1,7 +1,6 @@
 use std::rc::Rc;
 
-use crate::entrypoint::ExtensionBuilder;
-use crate::ext_port::ExtPort;
+use crate::{ExtPort, ExtensionBuilder};
 /// Run an extension inside a Tokio localset. Since the extension API does not
 /// provide a forking mechanism, it can safely abort once the localset is
 /// exhausted. If an extension absolutely needs a parallel thread, it can import
@@ -10,7 +9,7 @@ use crate::ext_port::ExtPort;
 /// value returned by [crate::system_ctor::SystemCtor::inst] to initiate
 /// shutdown.
 #[cfg(feature = "tokio")]
-pub async fn tokio_entrypoint(builder: ExtensionBuilder) {
+pub async fn __tokio_entrypoint(builder: ExtensionBuilder) {
 	use std::cell::RefCell;
 
 	use async_event::Event;
@@ -61,6 +60,6 @@ pub async fn tokio_entrypoint(builder: ExtensionBuilder) {
 macro_rules! tokio_main {
 	($builder:expr) => {
 		#[tokio::main]
-		pub async fn main() { $crate::tokio::tokio_entrypoint($builder).await }
+		pub async fn main() { $crate::__tokio_entrypoint($builder).await }
 	};
 }
diff --git a/orchid-extension/src/tree.rs b/orchid-extension/src/tree.rs
index 8e7717e..d189b8e 100644
--- a/orchid-extension/src/tree.rs
+++ b/orchid-extension/src/tree.rs
@@ -13,13 +13,16 @@ use substack::Substack;
 use task_local::task_local;
 use trait_set::trait_set;
 
-use crate::api;
-use crate::conv::ToExpr;
-use crate::expr::{BorrowedExprStore, Expr, ExprHandle};
-use crate::func_atom::{ExprFunc, Fun};
 use crate::gen_expr::{GExpr, new_atom};
+use crate::{BorrowedExprStore, Expr, ExprFunc, ExprHandle, Fun, ToExpr, api};
 
+/// Tokens generated by lexers and parsers
+///
+/// See: [GenTok], [Token], [crate::Lexer], [crate::Parser]
 pub type GenTokTree = TokTree<Expr, GExpr>;
+/// Tokens generated by lexers and parsers - without location data
+///
+/// See: [GenTokTree], [Token], [crate::Lexer], [crate::Parser]
 pub type GenTok = Token<Expr, GExpr>;
 
 impl TokenVariant<api::Expression> for GExpr {
@@ -41,9 +44,15 @@ impl TokenVariant<api::ExprTicket> for Expr {
 	async fn into_api(self, (): &mut Self::ToApiCtx<'_>) -> api::ExprTicket { self.handle().ticket() }
 }
 
+/// Embed a literal value in generated syntax.
 pub async fn x_tok(x: impl ToExpr) -> GenTok { GenTok::NewExpr(x.to_gen().await) }
+/// Embed a reference to a constant in generated syntax. The constant doesn't
+/// need to be visible per export rules, and if it doesn't exist, the expression
+/// will raise a runtime error
 pub async fn ref_tok(path: Sym) -> GenTok { GenTok::NewExpr(path.to_gen().await) }
 
+/// Create a new subtree that is evaluated as-needed, asynchronously, and can
+/// use its own path to determine its value
 pub fn lazy(
 	public: bool,
 	name: &str,
@@ -51,30 +60,32 @@ pub fn lazy(
 ) -> Vec<GenMember> {
 	vec![GenMember {
 		name: name.to_string(),
-		kind: MemKind::Lazy(LazyMemberFactory::new(cb)),
+		kind: LazyMemKind::Lazy(LazyMemberFactory::new(cb)),
 		comments: vec![],
 		public,
 	}]
 }
+/// A constant node in the module tree
 pub fn cnst(public: bool, name: &str, value: impl ToExpr + Clone + 'static) -> Vec<GenMember> {
 	lazy(public, name, async |_| MemKind::Const(value.to_gen().await))
 }
+/// A module in the tree. These can be merged by [merge_trivial]
 pub fn module(
 	public: bool,
 	name: &str,
 	mems: impl IntoIterator<Item = Vec<GenMember>>,
 ) -> Vec<GenMember> {
-	let (name, kind) = root_mod(name, mems);
+	let (name, kind) = (name.to_string(), LazyMemKind::Mod(mems.into_iter().flatten().collect()));
 	vec![GenMember { name, kind, public, comments: vec![] }]
 }
-pub fn root_mod(name: &str, mems: impl IntoIterator<Item = Vec<GenMember>>) -> (String, MemKind) {
-	(name.to_string(), MemKind::module(mems))
-}
+/// A Rust function that is passed to Orchid via [Fun]
 pub fn fun<I, O>(public: bool, name: &str, xf: impl ExprFunc<I, O>) -> Vec<GenMember> {
 	let fac =
 		LazyMemberFactory::new(async move |sym| MemKind::Const(new_atom(Fun::new(sym, xf).await)));
-	vec![GenMember { name: name.to_string(), kind: MemKind::Lazy(fac), public, comments: vec![] }]
+	vec![GenMember { name: name.to_string(), kind: LazyMemKind::Lazy(fac), public, comments: vec![] }]
 }
+/// A chain of nested modules with names taken from the duble::colon::delimited
+/// path ultimately containing the elements
 pub fn prefix(path: &str, items: impl IntoIterator<Item = Vec<GenMember>>) -> Vec<GenMember> {
 	let mut items = items.into_iter().flatten().collect_vec();
 	for step in path.split("::").collect_vec().into_iter().rev() {
@@ -82,7 +93,7 @@ pub fn prefix(path: &str, items: impl IntoIterator<Item = Vec<GenMember>>) -> Ve
 	}
 	items
 }
-
+/// Add comments to a set of members
 pub fn comments<'a>(
 	cmts: impl IntoIterator<Item = &'a str>,
 	mut val: Vec<GenMember>,
@@ -101,20 +112,20 @@ pub fn comments<'a>(
 /// - Duplicate constants result in an error
 /// - A combination of lazy and anything results in an error
 pub fn merge_trivial(trees: impl IntoIterator<Item = Vec<GenMember>>) -> Vec<GenMember> {
-	let mut all_members = HashMap::<String, (MemKind, Vec<String>)>::new();
+	let mut all_members = HashMap::<String, (LazyMemKind, Vec<String>)>::new();
 	for mem in trees.into_iter().flatten() {
 		assert!(mem.public, "Non-trivial merge in {}", mem.name);
 		match mem.kind {
-			unit @ (MemKind::Const(_) | MemKind::Lazy(_)) => {
+			unit @ (LazyMemKind::Const(_) | LazyMemKind::Lazy(_)) => {
 				let prev = all_members.insert(mem.name.clone(), (unit, mem.comments.into_iter().collect()));
 				assert!(prev.is_none(), "Conflict in trivial tree merge on {}", mem.name);
 			},
-			MemKind::Mod(members) => match all_members.entry(mem.name.clone()) {
+			LazyMemKind::Mod(members) => match all_members.entry(mem.name.clone()) {
 				hashbrown::hash_map::Entry::Vacant(slot) => {
-					slot.insert((MemKind::Mod(members), mem.comments.into_iter().collect()));
+					slot.insert((LazyMemKind::Mod(members), mem.comments.into_iter().collect()));
 				},
 				hashbrown::hash_map::Entry::Occupied(mut old) => match old.get_mut() {
-					(MemKind::Mod(old_items), old_cmts) => {
+					(LazyMemKind::Mod(old_items), old_cmts) => {
 						let mut swap = vec![];
 						std::mem::swap(&mut swap, old_items);
 						*old_items = merge_trivial([swap, members]);
@@ -135,7 +146,7 @@ trait_set! {
 	trait LazyMemberCallback =
 		FnOnce(Sym) -> LocalBoxFuture<'static, MemKind> + DynClone
 }
-pub struct LazyMemberFactory(Box<dyn LazyMemberCallback>);
+pub(crate) struct LazyMemberFactory(Box<dyn LazyMemberCallback>);
 impl LazyMemberFactory {
 	pub fn new(cb: impl AsyncFnOnce(Sym) -> MemKind + Clone + 'static) -> Self {
 		Self(Box::new(|s| cb(s).boxed_local()))
@@ -147,10 +158,10 @@ impl Clone for LazyMemberFactory {
 }
 
 pub struct GenMember {
-	pub name: String,
-	pub kind: MemKind,
-	pub public: bool,
-	pub comments: Vec<String>,
+	pub(crate) name: String,
+	pub(crate) kind: LazyMemKind,
+	pub(crate) public: bool,
+	pub(crate) comments: Vec<String>,
 }
 impl GenMember {
 	pub(crate) async fn into_api(self, tia_cx: &mut impl TreeIntoApiCtx) -> api::Member {
@@ -161,16 +172,24 @@ impl GenMember {
 	}
 }
 
+/// Items in the tree after deferrals have been resolved
 pub enum MemKind {
 	Const(GExpr),
 	Mod(Vec<GenMember>),
-	Lazy(LazyMemberFactory),
 }
 impl MemKind {
 	pub async fn cnst(val: impl ToExpr) -> Self { Self::Const(val.to_gen().await) }
 	pub fn module(mems: impl IntoIterator<Item = Vec<GenMember>>) -> Self {
 		Self::Mod(mems.into_iter().flatten().collect())
 	}
+}
+
+pub(crate) enum LazyMemKind {
+	Const(GExpr),
+	Mod(Vec<GenMember>),
+	Lazy(LazyMemberFactory),
+}
+impl LazyMemKind {
 	pub(crate) async fn into_api(self, ctx: &mut impl TreeIntoApiCtx) -> api::MemberKind {
 		match self {
 			Self::Lazy(lazy) => api::MemberKind::Lazy(add_lazy(ctx, lazy)),
@@ -189,7 +208,7 @@ impl MemKind {
 	}
 }
 
-pub enum MemberRecord {
+pub(crate) enum MemberRecord {
 	Gen(Vec<IStr>, LazyMemberFactory),
 	Res,
 }
@@ -201,7 +220,7 @@ task_local! {
 	static LAZY_MEMBERS: LazyMemberStore;
 }
 
-pub fn with_lazy_member_store<'a>(fut: LocalBoxFuture<'a, ()>) -> LocalBoxFuture<'a, ()> {
+pub(crate) fn with_lazy_member_store<'a>(fut: LocalBoxFuture<'a, ()>) -> LocalBoxFuture<'a, ()> {
 	Box::pin(LAZY_MEMBERS.scope(LazyMemberStore::default(), fut))
 }
 
@@ -215,7 +234,7 @@ fn add_lazy(cx: &impl TreeIntoApiCtx, fac: LazyMemberFactory) -> api::TreeId {
 	})
 }
 
-pub async fn get_lazy(id: api::TreeId) -> (Sym, MemKind) {
+pub(crate) async fn get_lazy(id: api::TreeId) -> (Sym, LazyMemKind) {
 	let (path, cb) =
 		LAZY_MEMBERS.with(|tbl| match tbl.0.borrow_mut().insert(id, MemberRecord::Res) {
 			None => panic!("Tree for ID not found"),
@@ -223,7 +242,10 @@ pub async fn get_lazy(id: api::TreeId) -> (Sym, MemKind) {
 			Some(MemberRecord::Gen(path, cb)) => (path, cb),
 		});
 	let path = Sym::new(path).await.unwrap();
-	(path.clone(), cb.build(path).await)
+	(path.clone(), match cb.build(path).await {
+		MemKind::Const(c) => LazyMemKind::Const(c),
+		MemKind::Mod(m) => LazyMemKind::Mod(m),
+	})
 }
 
 pub(crate) trait TreeIntoApiCtx {
@@ -231,7 +253,7 @@ pub(crate) trait TreeIntoApiCtx {
 	fn path(&self) -> impl Iterator<Item = IStr>;
 }
 
-pub struct TreeIntoApiCtxImpl<'a> {
+pub(crate) struct TreeIntoApiCtxImpl<'a> {
 	pub basepath: &'a [IStr],
 	pub path: Substack<'a, IStr>,
 }
diff --git a/orchid-host/Cargo.toml b/orchid-host/Cargo.toml
index 6208cac..7958c06 100644
--- a/orchid-host/Cargo.toml
+++ b/orchid-host/Cargo.toml
@@ -27,6 +27,7 @@ orchid-extension = { version = "0.1.0", path = "../orchid-extension", optional =
 ordered-float = "5.1.0"
 pastey = "0.2.1"
 substack = "1.1.1"
+task-local = "0.1.0"
 tokio = { version = "1.49.0", features = ["process"], optional = true }
 tokio-util = { version = "0.7.18", features = ["compat"], optional = true }
 trait-set = "0.3.0"
diff --git a/orchid-host/src/atom.rs b/orchid-host/src/atom.rs
index cbf65ac..f2f76b4 100644
--- a/orchid-host/src/atom.rs
+++ b/orchid-host/src/atom.rs
@@ -94,7 +94,7 @@ impl AtomHand {
 	#[must_use]
 	pub fn ext(&self) -> &Extension { self.sys().ext() }
 	pub async fn req(&self, key: api::TStrv, req: Vec<u8>) -> Option<Vec<u8>> {
-		self.0.owner.client().request(api::Fwded(self.0.api_ref(), key, req)).await.unwrap()
+		self.0.owner.client().request(api::FinalFwded(self.0.api_ref(), key, req)).await.unwrap()
 	}
 	#[must_use]
 	pub fn api_ref(&self) -> api::Atom { self.0.api_ref() }
diff --git a/orchid-host/src/cmd_system.rs b/orchid-host/src/cmd_system.rs
new file mode 100644
index 0000000..7172c9e
--- /dev/null
+++ b/orchid-host/src/cmd_system.rs
@@ -0,0 +1,249 @@
+use std::borrow::Cow;
+use std::cell::RefCell;
+use std::collections::VecDeque;
+use std::fmt::Debug;
+use std::pin::pin;
+use std::rc::Rc;
+
+use async_event::Event;
+use async_fn_stream::stream;
+use futures::channel::mpsc;
+use futures::future::LocalBoxFuture;
+use futures::stream::FuturesUnordered;
+use futures::{SinkExt, StreamExt, select};
+use never::Never;
+use orchid_base::{OrcErrv, Receipt, ReqHandle, Sym};
+use orchid_extension::{self as ox, AtomicFeatures as _};
+
+use crate::ctx::Ctx;
+use crate::execute::{ExecCtx, ExecResult};
+use crate::expr::{Expr, ExprFromApiCtx, PathSetBuilder};
+use crate::tree::Root;
+
+struct CommandQueueState {
+	new: VecDeque<Expr>,
+	added: Rc<Event>,
+	wants_exit: bool,
+	ctx: Ctx,
+}
+#[derive(Clone)]
+struct CommandQueue(Rc<RefCell<CommandQueueState>>);
+impl CommandQueue {
+	fn new(ctx: Ctx, init: impl IntoIterator<Item = Expr>) -> Self {
+		Self(Rc::new(RefCell::new(CommandQueueState {
+			new: init.into_iter().collect(),
+			added: Rc::default(),
+			wants_exit: false,
+			ctx,
+		})))
+	}
+	pub fn push(&self, expr: Expr) {
+		let was_empty = {
+			let mut g = self.0.borrow_mut();
+			g.new.push_back(expr);
+			g.new.len() == 1
+		};
+		if was_empty {
+			let added = self.0.borrow_mut().added.clone();
+			added.notify_one();
+		}
+	}
+	pub async fn get_new(&self) -> Expr {
+		let added = {
+			let mut g = self.0.borrow_mut();
+			if let Some(waiting) = g.new.pop_front() {
+				return waiting;
+			}
+			g.added.clone()
+		};
+		added.wait_until(|| self.0.borrow_mut().new.pop_front()).await
+	}
+}
+impl Debug for CommandQueue {
+	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+		f.debug_struct("CommandQueue").finish_non_exhaustive()
+	}
+}
+
+pub enum CmdResult {
+	/// All command sequences settled
+	Settled,
+	/// Exit was requested explicitly by usercode
+	Exit,
+	/// Ran out of gas
+	Gas,
+	/// Received a value that wasn't a command
+	///
+	/// This is potentially user error, but implementors may choose to well-define
+	/// certain responses
+	NonCommand(Expr),
+	/// Received an Orchid error
+	///
+	/// This is definitely user error, but implementors may choose to continue
+	/// running other chains of execution after handling it
+	Err(OrcErrv),
+}
+
+pub struct CmdRunner {
+	root: Root,
+	queue: CommandQueue,
+	gas: Option<u64>,
+	interrupted: Option<ExecCtx>,
+	futures: FuturesUnordered<LocalBoxFuture<'static, Option<CmdResult>>>,
+}
+impl CmdRunner {
+	pub async fn new(root: Root, ctx: Ctx, init: impl IntoIterator<Item = Expr>) -> Self {
+		Self {
+			futures: FuturesUnordered::new(),
+			gas: None,
+			root,
+			interrupted: None,
+			queue: CommandQueue::new(ctx, init),
+		}
+	}
+	#[must_use]
+	pub fn get_gas(&self) -> u64 { self.gas.expect("queried gas but no gas was set") }
+	pub fn set_gas(&mut self, gas: u64) { self.gas = Some(gas) }
+	pub fn disable_gas(&mut self) { self.gas = None }
+	pub async fn execute(&mut self) -> CmdResult {
+		let waiting_on_queue = RefCell::new(false);
+		let (mut spawn, mut on_spawn) = mpsc::channel(1);
+		let mut normalize_stream = pin!(
+			stream(async |mut h| {
+				loop {
+					if self.queue.0.borrow().wants_exit {
+						h.emit(CmdResult::Exit).await;
+						break;
+					}
+					waiting_on_queue.replace(false);
+					let mut xctx = match self.interrupted.take() {
+						None => ExecCtx::new(self.root.clone(), self.queue.get_new().await).await,
+						Some(xctx) => xctx,
+					};
+					waiting_on_queue.replace(true);
+					xctx.set_gas(self.gas);
+					let res = xctx.execute().await;
+					match res {
+						ExecResult::Err(e, gas) => {
+							self.gas = gas;
+							h.emit(CmdResult::Err(e)).await;
+						},
+						ExecResult::Gas(exec) => {
+							self.interrupted = Some(exec);
+							h.emit(CmdResult::Gas).await;
+						},
+						ExecResult::Value(val, gas) => {
+							self.gas = gas;
+							let Some(atom) = val.as_atom().await else {
+								h.emit(CmdResult::NonCommand(val)).await;
+								continue;
+							};
+							let queue = self.queue.clone();
+							let ctx = queue.0.borrow_mut().ctx.clone();
+							spawn
+								.send(Box::pin(async move {
+									match atom.ipc(ox::std_reqs::RunCommand).await {
+										None => Some(CmdResult::NonCommand(val)),
+										Some(None) => None,
+										Some(Some(expr)) => {
+											let from_api_cx = ExprFromApiCtx { ctx, sys: atom.api_ref().owner };
+											queue.push(Expr::from_api(expr, PathSetBuilder::new(), from_api_cx).await);
+											None
+										},
+									}
+								}))
+								.await
+								.expect("Receiver is owned by the layer that polls this");
+						},
+					}
+				}
+			})
+			.fuse()
+		);
+		loop {
+			if self.queue.0.borrow().wants_exit {
+				break CmdResult::Exit;
+			}
+			let task = select!(
+				r_opt = self.futures.by_ref().next() => match r_opt {
+					Some(Some(r)) => break r,
+					None if *waiting_on_queue.borrow() => break CmdResult::Settled,
+					None | Some(None) => continue,
+				},
+				r = normalize_stream.by_ref().next() => break r.expect("infinite stream"),
+				task = on_spawn.by_ref().next() => task.expect("sender moved into infinite stream"),
+			);
+			self.futures.push(task)
+		}
+	}
+}
+
+#[derive(Default, Debug)]
+pub struct CmdSystemCard;
+impl ox::SystemCard for CmdSystemCard {
+	type Ctor = CmdSystemCtor;
+	type Req = Never;
+	fn atoms() -> impl IntoIterator<Item = Option<Box<dyn ox::AtomOps>>> {
+		[Some(CommandQueue::ops())]
+	}
+}
+
+#[derive(Debug)]
+pub struct CmdSystemCtor {
+	queue: CommandQueue,
+}
+impl ox::SystemCtor for CmdSystemCtor {
+	const NAME: &'static str = "orchid::cmd";
+	const VERSION: f64 = 0.1;
+	type Card = CmdSystemCard;
+	type Deps = ();
+	type Instance = CmdSystemInst;
+	fn inst(&self, _: <Self::Deps as orchid_extension::DepDef>::Sat) -> Self::Instance {
+		CmdSystemInst { queue: self.queue.clone() }
+	}
+}
+
+fn ox_get_queue() -> CommandQueue { ox::cted::<CmdSystemCtor>().inst.queue.clone() }
+
+#[derive(Debug)]
+pub struct CmdSystemInst {
+	queue: CommandQueue,
+}
+impl ox::System for CmdSystemInst {
+	type Ctor = CmdSystemCtor;
+	async fn env(&self) -> Vec<ox::tree::GenMember> {
+		ox::tree::prefix("orchid::cmd", [
+			ox::tree::cnst(false, "queue", ox::gen_expr::new_atom(ox_get_queue())),
+			ox::tree::fun(true, "spawn", async |side: ox::Expr, cont: ox::Expr| {
+				ox::cmd(async move || {
+					let queue = ox_get_queue();
+					let side_xtk = side.serialize().await;
+					let mut g = queue.0.borrow_mut();
+					let host_ex =
+						g.ctx.exprs.take_expr(side_xtk).expect("Host could not locate leaked expr by ID ");
+					g.new.push_back(host_ex);
+					Some(cont)
+				})
+			}),
+		])
+	}
+	async fn prelude(&self) -> Vec<Sym> { vec![] }
+	fn lexers(&self) -> Vec<ox::LexerObj> { vec![] }
+	fn parsers(&self) -> Vec<ox::ParserObj> { vec![] }
+	async fn request<'a>(
+		&self,
+		_hand: Box<dyn ReqHandle<'a> + 'a>,
+		req: ox::ReqForSystem<Self>,
+	) -> Receipt<'a> {
+		match req {}
+	}
+}
+
+impl ox::Atomic for CommandQueue {
+	type Data = ();
+	type Variant = ox::OwnedVariant;
+}
+impl ox::OwnedAtom for CommandQueue {
+	type Refs = Never;
+	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
+}
diff --git a/orchid-host/src/execute.rs b/orchid-host/src/execute.rs
index 5965d30..31f3697 100644
--- a/orchid-host/src/execute.rs
+++ b/orchid-host/src/execute.rs
@@ -20,9 +20,9 @@ enum StackOp {
 }
 
 pub enum ExecResult {
-	Value(Expr),
+	Value(Expr, Option<u64>),
 	Gas(ExecCtx),
-	Err(OrcErrv),
+	Err(OrcErrv, Option<u64>),
 }
 
 pub struct ExecCtx {
@@ -46,17 +46,6 @@ impl ExecCtx {
 	#[must_use]
 	pub fn idle(&self) -> bool { self.did_pop }
 	#[must_use]
-	pub fn result(self) -> ExecResult {
-		if self.idle() {
-			match &*self.cur {
-				ExprKind::Bottom(errv) => ExecResult::Err(errv.clone()),
-				_ => ExecResult::Value(*self.cur.unbind()),
-			}
-		} else {
-			ExecResult::Gas(self)
-		}
-	}
-	#[must_use]
 	pub fn use_gas(&mut self, amount: u64) -> bool {
 		if let Some(gas) = &mut self.gas {
 			*gas -= amount;
@@ -79,7 +68,7 @@ impl ExecCtx {
 			Err(TryLockError) => panic!("Cycle encountered!"),
 		}
 	}
-	pub async fn execute(&mut self) {
+	pub async fn execute(mut self) -> ExecResult {
 		while self.use_gas(1) {
 			let mut kind_swap = ExprKind::Missing;
 			mem::swap(&mut kind_swap, &mut self.cur);
@@ -135,7 +124,7 @@ impl ExecCtx {
 				StackOp::Nop => (),
 				StackOp::Pop => match self.stack.pop() {
 					Some(top) => self.cur = top,
-					None => return,
+					None => return ExecResult::Value(*self.cur.unbind(), self.gas),
 				},
 				StackOp::Push(sub) => {
 					self.cur_pos = sub.pos();
@@ -150,10 +139,11 @@ impl ExecCtx {
 					}
 					*self.cur = ExprKind::Bottom(err.clone());
 					self.stack = vec![];
-					return;
+					return ExecResult::Err(err.clone(), self.gas);
 				},
 			}
 		}
+		ExecResult::Gas(self)
 	}
 }
 
diff --git a/orchid-host/src/extension.rs b/orchid-host/src/extension.rs
index e95025b..6a2e075 100644
--- a/orchid-host/src/extension.rs
+++ b/orchid-host/src/extension.rs
@@ -162,8 +162,10 @@ impl Extension {
 										let sys =
 											ctx.system_inst(atom.owner).await.expect("owner of live atom dropped");
 										let client = sys.client();
-										let reply =
-											client.request(api::Fwded(fw.0.clone(), *key, body.clone())).await.unwrap();
+										let reply = client
+											.request(api::FinalFwded(fw.0.clone(), *key, body.clone()))
+											.await
+											.unwrap();
 										handle.reply(fw, &reply).await
 									},
 									api::ExtHostReq::SysFwd(ref fw @ api::SysFwd(id, ref body)) => {
diff --git a/orchid-host/src/inline.rs b/orchid-host/src/inline.rs
index b8b6c89..9d91307 100644
--- a/orchid-host/src/inline.rs
+++ b/orchid-host/src/inline.rs
@@ -1,28 +1,18 @@
-#[cfg(feature = "orchid-extension")]
+use std::io;
+use std::rc::Rc;
 use std::time::Duration;
 
-#[cfg(feature = "orchid-extension")]
-use orchid_base::on_drop;
-#[cfg(feature = "orchid-extension")]
+use futures::io::BufReader;
+use futures::{AsyncBufReadExt, StreamExt};
+use orchid_base::{log, on_drop};
 use orchid_extension as ox;
+use unsync_pipe::pipe;
 
-#[cfg(feature = "orchid-extension")]
 use crate::ctx::Ctx;
-#[cfg(feature = "orchid-extension")]
 use crate::extension::ExtPort;
-#[cfg(feature = "orchid-extension")]
 use crate::task_set::TaskSet;
 
-#[cfg(feature = "orchid-extension")]
-pub async fn ext_inline(builder: ox::entrypoint::ExtensionBuilder, ctx: Ctx) -> ExtPort {
-	use std::io;
-	use std::rc::Rc;
-
-	use futures::io::BufReader;
-	use futures::{AsyncBufReadExt, StreamExt};
-	use orchid_base::log;
-	use unsync_pipe::pipe;
-
+pub async fn ext_inline(builder: ox::ExtensionBuilder, ctx: Ctx) -> ExtPort {
 	let (in_stdin, out_stdin) = pipe(1024);
 	let (in_stdout, out_stdout) = pipe(1024);
 	let (in_stderr, out_stderr) = pipe(1024);
@@ -48,7 +38,7 @@ pub async fn ext_inline(builder: ox::entrypoint::ExtensionBuilder, ctx: Ctx) ->
 	std::mem::drop(ctx.clone().spawn(Duration::ZERO, async move {
 		let task_set2 = task_set1.clone();
 		builder
-			.run(ox::ext_port::ExtPort {
+			.run(ox::ExtPort {
 				input: Box::pin(out_stdin),
 				output: Box::pin(in_stdout),
 				log: Box::pin(in_stderr),
diff --git a/orchid-host/src/lib.rs b/orchid-host/src/lib.rs
index 24633dd..db26601 100644
--- a/orchid-host/src/lib.rs
+++ b/orchid-host/src/lib.rs
@@ -2,6 +2,8 @@ use orchid_api as api;
 
 pub mod atom;
 pub mod ctx;
+#[cfg(feature = "orchid-extension")]
+pub mod cmd_system;
 pub mod dealias;
 #[cfg(feature = "tokio")]
 pub mod dylib;
@@ -9,6 +11,7 @@ pub mod execute;
 pub mod expr;
 pub mod expr_store;
 pub mod extension;
+#[cfg(feature = "orchid-extension")]
 pub mod inline;
 pub mod lex;
 pub mod logger;
diff --git a/orchid-std/src/lib.rs b/orchid-std/src/lib.rs
index 67c0113..a79931d 100644
--- a/orchid-std/src/lib.rs
+++ b/orchid-std/src/lib.rs
@@ -13,11 +13,10 @@ pub use std::tuple::{HomoTpl, Tpl, Tuple, UntypedTuple};
 pub use macros::macro_system::MacroSystem;
 pub use macros::mactree::{MacTok, MacTree};
 use orchid_api as api;
-use orchid_extension::dylib_main;
-use orchid_extension::entrypoint::ExtensionBuilder;
+use orchid_extension::{ExtensionBuilder, dylib_main};
 
 pub fn builder() -> ExtensionBuilder {
-	ExtensionBuilder::new("orchid-std::main").system(StdSystem::default()).system(MacroSystem)
+	ExtensionBuilder::new("orchid-std::main").system(StdSystem).system(MacroSystem)
 }
 
 dylib_main! { builder() }
diff --git a/orchid-std/src/macros/instantiate_tpl.rs b/orchid-std/src/macros/instantiate_tpl.rs
index 3810311..0856338 100644
--- a/orchid-std/src/macros/instantiate_tpl.rs
+++ b/orchid-std/src/macros/instantiate_tpl.rs
@@ -2,11 +2,9 @@ use std::borrow::Cow;
 
 use never::Never;
 use orchid_base::fmt;
-use orchid_extension::conv::ToExpr;
-use orchid_extension::coroutine_exec::exec;
-use orchid_extension::expr::Expr;
+use orchid_extension::Expr;
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::{Atomic, OwnedAtom, OwnedVariant, TAtom};
+use orchid_extension::{Atomic, OwnedAtom, OwnedVariant, TAtom, ToExpr, exec};
 
 use crate::macros::mactree::{MacTok, MacTree};
 
diff --git a/orchid-std/src/macros/let_line.rs b/orchid-std/src/macros/let_line.rs
index e3b3c16..470e7e8 100644
--- a/orchid-std/src/macros/let_line.rs
+++ b/orchid-std/src/macros/let_line.rs
@@ -7,10 +7,10 @@ use orchid_base::{
 	Comment, OrcRes, Paren, Parsed, Snippet, Sym, expect_tok, is, report, sym, token_errv,
 	try_pop_no_fluff, with_reporter,
 };
-use orchid_extension::TAtom;
-use orchid_extension::conv::TryFromExpr;
 use orchid_extension::gen_expr::{call, new_atom};
-use orchid_extension::parser::{ConstCtx, PSnippet, PTok, PTokTree, ParsCtx, ParsedLine, Parser};
+use orchid_extension::{
+	ConstCtx, PSnippet, PTok, PTokTree, ParsCtx, ParsedLine, Parser, TAtom, TryFromExpr,
+};
 
 use crate::macros::mactree::{MacTok, MacTree, MacTreeSeq};
 use crate::macros::ph_lexer::PhAtom;
diff --git a/orchid-std/src/macros/macro_lib.rs b/orchid-std/src/macros/macro_lib.rs
index 6ed97cf..5957d5c 100644
--- a/orchid-std/src/macros/macro_lib.rs
+++ b/orchid-std/src/macros/macro_lib.rs
@@ -1,8 +1,7 @@
 use orchid_base::sym;
-use orchid_extension::TAtom;
-use orchid_extension::coroutine_exec::exec;
 use orchid_extension::gen_expr::{call, new_atom};
 use orchid_extension::tree::{GenMember, fun, prefix};
+use orchid_extension::{TAtom, exec};
 
 use crate::macros::mactree::MacTree;
 use crate::macros::resolve::resolve;
diff --git a/orchid-std/src/macros/macro_line.rs b/orchid-std/src/macros/macro_line.rs
index d36cf78..869282b 100644
--- a/orchid-std/src/macros/macro_line.rs
+++ b/orchid-std/src/macros/macro_line.rs
@@ -9,9 +9,9 @@ use orchid_base::{
 	mk_errv, report, sym, token_errv, try_pop_no_fluff, with_reporter,
 };
 use orchid_extension::TAtom;
-use orchid_extension::conv::{ToExpr, TryFromExpr};
+use orchid_extension::{ToExpr, TryFromExpr};
 use orchid_extension::gen_expr::{call, new_atom};
-use orchid_extension::parser::{PSnippet, ParsCtx, ParsedLine, Parser};
+use orchid_extension::{PSnippet, ParsCtx, ParsedLine, Parser};
 
 use crate::macros::let_line::{dealias_mac_v, parse_tokv};
 use crate::macros::macro_value::{Macro, MacroData, Rule};
diff --git a/orchid-std/src/macros/macro_system.rs b/orchid-std/src/macros/macro_system.rs
index 60925f4..9e5b216 100644
--- a/orchid-std/src/macros/macro_system.rs
+++ b/orchid-std/src/macros/macro_system.rs
@@ -1,12 +1,9 @@
 use never::Never;
 use orchid_base::{Receipt, ReqHandle, Sym, sym};
-use orchid_extension::{AtomOps, AtomicFeatures};
-use orchid_extension::lexer::LexerObj;
-use orchid_extension::other_system::SystemHandle;
-use orchid_extension::parser::ParserObj;
-use orchid_extension::system::{System, SystemCard};
-use orchid_extension::system_ctor::SystemCtor;
 use orchid_extension::tree::{GenMember, merge_trivial};
+use orchid_extension::{
+	AtomOps, AtomicFeatures, LexerObj, ParserObj, System, SystemCard, SystemCtor, SystemHandle,
+};
 
 use crate::macros::instantiate_tpl::InstantiateTplCall;
 use crate::macros::let_line::LetLine;
@@ -24,10 +21,11 @@ use crate::{MacTree, StdSystem};
 pub struct MacroSystem;
 impl SystemCtor for MacroSystem {
 	type Deps = StdSystem;
-	type Instance = Self;
+	type Instance = MacroSystemInst;
+	type Card = Self;
 	const NAME: &'static str = "orchid::macros";
 	const VERSION: f64 = 0.00_01;
-	fn inst(&self, _: SystemHandle<StdSystem>) -> Self::Instance { Self }
+	fn inst(&self, std: SystemHandle<StdSystem>) -> Self::Instance { MacroSystemInst { _std: std } }
 }
 impl SystemCard for MacroSystem {
 	type Ctor = Self;
@@ -43,7 +41,13 @@ impl SystemCard for MacroSystem {
 		]
 	}
 }
-impl System for MacroSystem {
+
+#[derive(Debug)]
+pub struct MacroSystemInst {
+	_std: SystemHandle<StdSystem>,
+}
+impl System for MacroSystemInst {
+	type Ctor = MacroSystem;
 	async fn request<'a>(&self, _: Box<dyn ReqHandle<'a> + 'a>, req: Never) -> Receipt<'a> {
 		match req {}
 	}
diff --git a/orchid-std/src/macros/mactree.rs b/orchid-std/src/macros/mactree.rs
index 044c983..a809967 100644
--- a/orchid-std/src/macros/mactree.rs
+++ b/orchid-std/src/macros/mactree.rs
@@ -10,7 +10,7 @@ use orchid_base::{
 	FmtCtx, FmtUnit, Format, IStr, OrcErrv, Paren, Pos, Sym, Variants, indent, tl_cache,
 };
 use orchid_extension::Atomic;
-use orchid_extension::expr::Expr;
+use orchid_extension::Expr;
 use orchid_extension::{OwnedAtom, OwnedVariant};
 
 fn union_rc_sets(seq: impl IntoIterator<Item = Rc<HashSet<Sym>>>) -> Rc<HashSet<Sym>> {
diff --git a/orchid-std/src/macros/mactree_lexer.rs b/orchid-std/src/macros/mactree_lexer.rs
index e201737..2402722 100644
--- a/orchid-std/src/macros/mactree_lexer.rs
+++ b/orchid-std/src/macros/mactree_lexer.rs
@@ -5,8 +5,8 @@ use itertools::chain;
 use orchid_base::Paren;
 use orchid_base::{OrcRes, PARENS, is, mk_errv};
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::lexer::{LexContext, Lexer, err_not_applicable};
-use orchid_extension::parser::p_tree2gen;
+use orchid_extension::{LexContext, Lexer, err_not_applicable};
+use orchid_extension::p_tree2gen;
 use orchid_extension::tree::{GenTok, GenTokTree, x_tok};
 
 use crate::macros::instantiate_tpl::InstantiateTplCall;
diff --git a/orchid-std/src/macros/match_macros.rs b/orchid-std/src/macros/match_macros.rs
index edec506..fe0d4cb 100644
--- a/orchid-std/src/macros/match_macros.rs
+++ b/orchid-std/src/macros/match_macros.rs
@@ -6,9 +6,9 @@ use futures::{Stream, StreamExt, stream};
 use never::Never;
 use orchid_api_derive::Coding;
 use orchid_base::{OrcRes, Sym, fmt, is, mk_errv, sym};
-use orchid_extension::conv::ToExpr;
-use orchid_extension::coroutine_exec::{ExecHandle, exec};
-use orchid_extension::expr::{Expr, ExprHandle};
+use orchid_extension::ToExpr;
+use orchid_extension::{ExecHandle, exec};
+use orchid_extension::{Expr, ExprHandle};
 use orchid_extension::gen_expr::{GExpr, arg, bot, call, call_v, lam, new_atom};
 use orchid_extension::tree::{GenMember, fun, prefix};
 use orchid_extension::{Atomic, OwnedAtom, OwnedVariant, TAtom};
diff --git a/orchid-std/src/macros/ph_lexer.rs b/orchid-std/src/macros/ph_lexer.rs
index 7678d29..6306e0e 100644
--- a/orchid-std/src/macros/ph_lexer.rs
+++ b/orchid-std/src/macros/ph_lexer.rs
@@ -2,7 +2,7 @@ use orchid_api_derive::Coding;
 use orchid_base::{FmtUnit, OrcRes, es, is, mk_errv, name_char, name_start};
 use orchid_extension::Atomic;
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::lexer::{LexContext, Lexer, err_not_applicable};
+use orchid_extension::{LexContext, Lexer, err_not_applicable};
 use orchid_extension::tree::{GenTokTree, x_tok};
 use orchid_extension::{ThinAtom, ThinVariant};
 
diff --git a/orchid-std/src/macros/resolve.rs b/orchid-std/src/macros/resolve.rs
index 0d5c757..0847778 100644
--- a/orchid-std/src/macros/resolve.rs
+++ b/orchid-std/src/macros/resolve.rs
@@ -6,11 +6,8 @@ use futures::{FutureExt, StreamExt, stream};
 use hashbrown::{HashMap, HashSet};
 use itertools::Itertools;
 use orchid_base::{NameLike, Paren, Pos, Sym, VPath, fmt, is, log, mk_errv};
-use orchid_extension::TAtom;
-use orchid_extension::conv::ToExpr;
-use orchid_extension::coroutine_exec::exec;
 use orchid_extension::gen_expr::{GExpr, arg, bot, call, call_v, dyn_lambda, new_atom};
-use orchid_extension::reflection::{ReflMemKind, refl};
+use orchid_extension::{ReflMemKind, TAtom, ToExpr, exec, refl};
 use subslice_offset::SubsliceOffset;
 use substack::Substack;
 
diff --git a/orchid-std/src/macros/stdlib/option.rs b/orchid-std/src/macros/stdlib/option.rs
index 8d1d11c..0d12223 100644
--- a/orchid-std/src/macros/stdlib/option.rs
+++ b/orchid-std/src/macros/stdlib/option.rs
@@ -1,11 +1,8 @@
 use futures::StreamExt;
 use orchid_base::sym;
-use orchid_extension::TAtom;
-use orchid_extension::conv::ToExpr;
-use orchid_extension::coroutine_exec::exec;
-use orchid_extension::expr::Expr;
 use orchid_extension::gen_expr::{call, new_atom};
 use orchid_extension::tree::{GenMember, fun, prefix};
+use orchid_extension::{Expr, TAtom, ToExpr, exec};
 
 use crate::macros::match_macros::MatcherAtom;
 use crate::macros::resolve::resolve;
diff --git a/orchid-std/src/macros/stdlib/record.rs b/orchid-std/src/macros/stdlib/record.rs
index ba18384..cd27344 100644
--- a/orchid-std/src/macros/stdlib/record.rs
+++ b/orchid-std/src/macros/stdlib/record.rs
@@ -1,8 +1,8 @@
 use orchid_base::sym;
 use orchid_extension::TAtom;
-use orchid_extension::conv::ToExpr;
-use orchid_extension::coroutine_exec::exec;
-use orchid_extension::expr::Expr;
+use orchid_extension::ToExpr;
+use orchid_extension::exec;
+use orchid_extension::Expr;
 use orchid_extension::gen_expr::{call, new_atom};
 use orchid_extension::tree::{GenMember, prefix};
 
diff --git a/orchid-std/src/macros/stdlib/tuple.rs b/orchid-std/src/macros/stdlib/tuple.rs
index 7efc692..297fa7b 100644
--- a/orchid-std/src/macros/stdlib/tuple.rs
+++ b/orchid-std/src/macros/stdlib/tuple.rs
@@ -1,9 +1,9 @@
 use futures::{StreamExt, stream};
 use orchid_base::{OrcRes, sym};
 use orchid_extension::TAtom;
-use orchid_extension::conv::ToExpr;
-use orchid_extension::coroutine_exec::exec;
-use orchid_extension::expr::Expr;
+use orchid_extension::ToExpr;
+use orchid_extension::exec;
+use orchid_extension::Expr;
 use orchid_extension::gen_expr::{GExpr, call, new_atom};
 use orchid_extension::tree::{GenMember, fun, prefix};
 
diff --git a/orchid-std/src/macros/utils.rs b/orchid-std/src/macros/utils.rs
index 3beafa2..27dbd0a 100644
--- a/orchid-std/src/macros/utils.rs
+++ b/orchid-std/src/macros/utils.rs
@@ -7,7 +7,7 @@ use futures::future::LocalBoxFuture;
 use itertools::{Itertools, chain};
 use never::Never;
 use orchid_base::{NameLike, Sym, VPath, is};
-use orchid_extension::conv::ToExpr;
+use orchid_extension::ToExpr;
 use orchid_extension::gen_expr::{GExpr, new_atom};
 use orchid_extension::tree::{GenMember, MemKind, cnst, lazy};
 use orchid_extension::{Atomic, OwnedAtom, OwnedVariant, TAtom};
@@ -32,13 +32,13 @@ impl Atomic for MacroBodyArgCollector {
 impl OwnedAtom for MacroBodyArgCollector {
 	type Refs = Never;
 	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
-	async fn call_ref(&self, arg: orchid_extension::expr::Expr) -> GExpr {
+	async fn call_ref(&self, arg: orchid_extension::Expr) -> GExpr {
 		if !self.args.is_empty() {
 			eprintln!("This is an intermediary value. It should never be copied");
 		}
 		self.clone().call(arg).await
 	}
-	async fn call(mut self, arg: orchid_extension::expr::Expr) -> GExpr {
+	async fn call(mut self, arg: orchid_extension::Expr) -> GExpr {
 		let atom = (TAtom::<MacTree>::downcast(arg.handle()).await).unwrap_or_else(|_| {
 			panic!("This is an intermediary value, the argument types are known in advance")
 		});
diff --git a/orchid-std/src/std/binary/binary_lib.rs b/orchid-std/src/std/binary/binary_lib.rs
index f0ea6c5..e8bcd95 100644
--- a/orchid-std/src/std/binary/binary_lib.rs
+++ b/orchid-std/src/std/binary/binary_lib.rs
@@ -1,10 +1,9 @@
 use std::rc::Rc;
 
 use orchid_base::{OrcErrv, is, mk_errv};
-use orchid_extension::TAtom;
-use orchid_extension::func_atom::get_arg_posv;
 use orchid_extension::gen_expr::new_atom;
 use orchid_extension::tree::{GenMember, comments, fun, prefix};
+use orchid_extension::{TAtom, get_arg_posv};
 
 use crate::std::binary::binary_atom::BlobAtom;
 use crate::std::boolean::Bool;
diff --git a/orchid-std/src/std/boolean.rs b/orchid-std/src/std/boolean.rs
index 90bf7e3..3bb5f1f 100644
--- a/orchid-std/src/std/boolean.rs
+++ b/orchid-std/src/std/boolean.rs
@@ -1,7 +1,7 @@
 use orchid_api_derive::Coding;
 use orchid_base::{FmtUnit, OrcRes, sym};
-use orchid_extension::conv::{ToExpr, TryFromExpr};
-use orchid_extension::expr::Expr;
+use orchid_extension::{ToExpr, TryFromExpr};
+use orchid_extension::Expr;
 use orchid_extension::gen_expr::GExpr;
 use orchid_extension::tree::{GenMember, cnst, comments, fun, prefix};
 use orchid_extension::{Atomic, TAtom, ThinAtom, ThinVariant};
diff --git a/orchid-std/src/std/future/future_lib.rs b/orchid-std/src/std/future/future_lib.rs
index 3d1ab43..352215f 100644
--- a/orchid-std/src/std/future/future_lib.rs
+++ b/orchid-std/src/std/future/future_lib.rs
@@ -19,15 +19,14 @@ use never::Never;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 use orchid_base::{FmtCtxImpl, OrcRes};
-use orchid_extension::conv::ToExpr;
+use orchid_extension::ToExpr;
 use orchid_extension::entrypoint::spawn;
-use orchid_extension::expr::Expr;
+use orchid_extension::Expr;
 use orchid_extension::gen_expr::{GExpr, IntoGExprStream, call, new_atom};
 use orchid_extension::system::cted;
 use orchid_extension::tree::{GenMember, cnst, comments, fun, prefix};
 use orchid_extension::{
-	Atomic, CmdResult, Continuation, ForeignAtom, Next, OwnedAtom, OwnedVariant, err_not_callable,
-	err_not_command,
+	Atomic, ForeignAtom, OwnedAtom, OwnedVariant, err_not_callable, err_not_command,
 };
 use rust_decimal::prelude::Zero;
 use tokio::task::{JoinHandle, spawn_local};
diff --git a/orchid-std/src/std/future/mod.rs b/orchid-std/src/std/future/mod.rs
index 59e5c02..853d551 100644
--- a/orchid-std/src/std/future/mod.rs
+++ b/orchid-std/src/std/future/mod.rs
@@ -1 +1 @@
-pub mod future_lib;
+// pub mod future_lib;
diff --git a/orchid-std/src/std/number/num_atom.rs b/orchid-std/src/std/number/num_atom.rs
index af7ae84..6ebdaef 100644
--- a/orchid-std/src/std/number/num_atom.rs
+++ b/orchid-std/src/std/number/num_atom.rs
@@ -3,10 +3,10 @@ use std::io;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 use orchid_base::{FmtUnit, Numeric, OrcRes, Receipt, ReqHandle, ReqHandleExt, Sym, sym};
-use orchid_extension::conv::{ToExpr, TryFromExpr};
-use orchid_extension::expr::Expr;
-use orchid_extension::system::sys_req;
-use orchid_extension::{Atomic, MethodSetBuilder, Supports, TAtom, ThinAtom, ThinVariant};
+use orchid_extension::{
+	Atomic, Expr, MethodSetBuilder, Supports, TAtom, ThinAtom, ThinVariant, ToExpr, TryFromExpr,
+	sys_req,
+};
 use ordered_float::NotNan;
 use rust_decimal::prelude::Zero;
 
diff --git a/orchid-std/src/std/number/num_lexer.rs b/orchid-std/src/std/number/num_lexer.rs
index b5985f2..756a1e0 100644
--- a/orchid-std/src/std/number/num_lexer.rs
+++ b/orchid-std/src/std/number/num_lexer.rs
@@ -1,9 +1,8 @@
 use std::ops::RangeInclusive;
 
 use orchid_base::{OrcRes, num_to_errv, parse_num};
-use orchid_extension::conv::ToExpr;
-use orchid_extension::lexer::{LexContext, Lexer};
 use orchid_extension::tree::{GenTokTree, x_tok};
+use orchid_extension::{LexContext, Lexer};
 
 use super::num_atom::Num;
 
diff --git a/orchid-std/src/std/number/num_lib.rs b/orchid-std/src/std/number/num_lib.rs
index 1775c84..efdc758 100644
--- a/orchid-std/src/std/number/num_lib.rs
+++ b/orchid-std/src/std/number/num_lib.rs
@@ -1,5 +1,5 @@
 use orchid_base::{Numeric, is, mk_errv};
-use orchid_extension::func_atom::get_arg;
+use orchid_extension::get_arg;
 use orchid_extension::tree::{GenMember, fun, prefix};
 use ordered_float::NotNan;
 use rust_decimal::prelude::ToPrimitive;
diff --git a/orchid-std/src/std/ops/subscript_lexer.rs b/orchid-std/src/std/ops/subscript_lexer.rs
index eb52894..b251b2a 100644
--- a/orchid-std/src/std/ops/subscript_lexer.rs
+++ b/orchid-std/src/std/ops/subscript_lexer.rs
@@ -1,7 +1,7 @@
 use orchid_base::{name_char, name_start};
 use orchid_base::{OrcRes, is};
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::lexer::{LexContext, LexedData, Lexer, err_not_applicable};
+use orchid_extension::{LexContext, LexedData, Lexer, err_not_applicable};
 use orchid_extension::tree::GenTok;
 
 use crate::std::string::str_atom::IntStrAtom;
diff --git a/orchid-std/src/std/option.rs b/orchid-std/src/std/option.rs
index cda3a5a..6931220 100644
--- a/orchid-std/src/std/option.rs
+++ b/orchid-std/src/std/option.rs
@@ -4,8 +4,8 @@ use std::pin::Pin;
 use futures::AsyncWrite;
 use orchid_api_traits::Encode;
 use orchid_base::{is, mk_errv, sym};
-use orchid_extension::conv::{ToExpr, TryFromExpr};
-use orchid_extension::expr::{Expr, ExprHandle};
+use orchid_extension::{ToExpr, TryFromExpr};
+use orchid_extension::{Expr, ExprHandle};
 use orchid_extension::gen_expr::{call, new_atom};
 use orchid_extension::tree::{GenMember, cnst, fun, prefix};
 use orchid_extension::{Atomic, DeserializeCtx, ForeignAtom, OwnedAtom, OwnedVariant, TAtom};
diff --git a/orchid-std/src/std/protocol/parse_impls.rs b/orchid-std/src/std/protocol/parse_impls.rs
index a948a44..bbb7ae3 100644
--- a/orchid-std/src/std/protocol/parse_impls.rs
+++ b/orchid-std/src/std/protocol/parse_impls.rs
@@ -5,7 +5,7 @@ use orchid_base::{
 };
 use orchid_base::{Paren, Token};
 use orchid_base::{IStr, OrcRes, is, mk_errv};
-use orchid_extension::parser::{
+use orchid_extension::{
 	PTokTree, ParsCtx, ParsedLine, ParsedLineKind, p_tree2gen, p_v2gen,
 };
 
diff --git a/orchid-std/src/std/protocol/proto_parser.rs b/orchid-std/src/std/protocol/proto_parser.rs
index c380c6a..56fdf2a 100644
--- a/orchid-std/src/std/protocol/proto_parser.rs
+++ b/orchid-std/src/std/protocol/proto_parser.rs
@@ -2,9 +2,9 @@ use std::rc::Rc;
 
 use hashbrown::HashMap;
 use orchid_base::{Comment, OrcRes, Parsed, Token, expect_end, is, mk_errv, sym, try_pop_no_fluff};
-use orchid_extension::conv::ToExpr;
+use orchid_extension::ToExpr;
 use orchid_extension::gen_expr::{call, new_atom};
-use orchid_extension::parser::{PSnippet, ParsCtx, ParsedLine, Parser};
+use orchid_extension::{PSnippet, ParsCtx, ParsedLine, Parser};
 
 use crate::std::protocol::parse_impls::parse_impls;
 use crate::std::protocol::types::Tag;
diff --git a/orchid-std/src/std/protocol/type_parser.rs b/orchid-std/src/std/protocol/type_parser.rs
index a83ee86..52f992c 100644
--- a/orchid-std/src/std/protocol/type_parser.rs
+++ b/orchid-std/src/std/protocol/type_parser.rs
@@ -2,9 +2,9 @@ use std::rc::Rc;
 
 use hashbrown::HashMap;
 use orchid_base::{Comment, OrcRes, Parsed, Token, expect_end, is, mk_errv, sym, try_pop_no_fluff};
-use orchid_extension::conv::ToExpr;
+use orchid_extension::ToExpr;
 use orchid_extension::gen_expr::{call, new_atom};
-use orchid_extension::parser::{PSnippet, ParsCtx, ParsedLine, Parser};
+use orchid_extension::{PSnippet, ParsCtx, ParsedLine, Parser};
 
 use crate::std::protocol::parse_impls::parse_impls;
 use crate::std::protocol::types::Tag;
diff --git a/orchid-std/src/std/protocol/types.rs b/orchid-std/src/std/protocol/types.rs
index 2044eaf..c35f351 100644
--- a/orchid-std/src/std/protocol/types.rs
+++ b/orchid-std/src/std/protocol/types.rs
@@ -11,14 +11,11 @@ use never::Never;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 use orchid_base::{NameLike, OrcRes, ReqHandleExt, Sym, VName, ev, fmt, is, mk_errv};
-use orchid_extension::conv::{ClonableToExprDyn, ToExpr};
-use orchid_extension::coroutine_exec::exec;
-use orchid_extension::expr::{Expr, ExprHandle};
 use orchid_extension::gen_expr::{GExpr, call, new_atom};
-use orchid_extension::system::sys_req;
 use orchid_extension::tree::{GenMember, MemKind, cnst, fun, lazy, prefix};
 use orchid_extension::{
-	AtomMethod, Atomic, ForeignAtom, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports, TAtom,
+	AtomMethod, Atomic, ClonableToExprDyn, Expr, ExprHandle, ForeignAtom, MethodSetBuilder,
+	OwnedAtom, OwnedVariant, Supports, TAtom, ToExpr, exec, sys_req,
 };
 
 use crate::std::std_system::StdReq;
diff --git a/orchid-std/src/std/record/record_atom.rs b/orchid-std/src/std/record/record_atom.rs
index acaf0d6..d890535 100644
--- a/orchid-std/src/std/record/record_atom.rs
+++ b/orchid-std/src/std/record/record_atom.rs
@@ -9,8 +9,8 @@ use hashbrown::HashMap;
 use orchid_api_derive::Coding;
 use orchid_api_traits::{Encode, Request};
 use orchid_base::{IStr, Receipt, ReqHandle, ReqHandleExt, Sym, es, sym};
-use orchid_extension::conv::ToExpr;
-use orchid_extension::expr::Expr;
+use orchid_extension::ToExpr;
+use orchid_extension::Expr;
 use orchid_extension::{
 	Atomic, DeserializeCtx, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports,
 };
diff --git a/orchid-std/src/std/record/record_lib.rs b/orchid-std/src/std/record/record_lib.rs
index fa90f3c..a0a1c28 100644
--- a/orchid-std/src/std/record/record_lib.rs
+++ b/orchid-std/src/std/record/record_lib.rs
@@ -4,7 +4,7 @@ use hashbrown::HashMap;
 use itertools::Itertools;
 use orchid_base::{is, mk_errv};
 use orchid_extension::TAtom;
-use orchid_extension::expr::Expr;
+use orchid_extension::Expr;
 use orchid_extension::gen_expr::{arg, new_atom};
 use orchid_extension::tree::{GenMember, cnst, fun, prefix};
 
diff --git a/orchid-std/src/std/reflection/sym_atom.rs b/orchid-std/src/std/reflection/sym_atom.rs
index 57633d6..f4a3782 100644
--- a/orchid-std/src/std/reflection/sym_atom.rs
+++ b/orchid-std/src/std/reflection/sym_atom.rs
@@ -3,12 +3,11 @@ use std::borrow::Cow;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 use orchid_base::{NameLike, ReqHandleExt, Sym, es, is, mk_errv};
-use orchid_extension::{Atomic, Supports, TAtom};
-use orchid_extension::{OwnedAtom, OwnedVariant};
-use orchid_extension::expr::{Expr, ExprHandle};
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::system::sys_req;
 use orchid_extension::tree::{GenMember, fun, prefix};
+use orchid_extension::{
+	Atomic, Expr, ExprHandle, OwnedAtom, OwnedVariant, Supports, TAtom, sys_req,
+};
 
 use crate::std::std_system::StdReq;
 use crate::std::string::str_atom::IntStrAtom;
diff --git a/orchid-std/src/std/std_system.rs b/orchid-std/src/std/std_system.rs
index 7b149aa..68509f0 100644
--- a/orchid-std/src/std/std_system.rs
+++ b/orchid-std/src/std/std_system.rs
@@ -1,18 +1,14 @@
-use std::cell::OnceCell;
 use std::rc::Rc;
 
 use futures::future::join_all;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_base::{Receipt, ReqHandle, ReqHandleExt, Sym, es, sym};
-use orchid_extension::{AtomOps, AtomicFeatures};
-use orchid_extension::conv::ToExpr;
-use orchid_extension::expr::Expr;
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::lexer::LexerObj;
-use orchid_extension::parser::ParserObj;
-use orchid_extension::system::{System, SystemCard};
-use orchid_extension::system_ctor::SystemCtor;
+use orchid_extension::ParserObj;
 use orchid_extension::tree::{GenMember, merge_trivial};
+use orchid_extension::{
+	AtomOps, AtomicFeatures, Expr, LexerObj, ReqForSystem, System, SystemCard, SystemCtor, ToExpr,
+};
 
 use super::number::num_lib::gen_num_lib;
 use super::string::str_atom::{IntStrAtom, StrAtom};
@@ -20,7 +16,6 @@ use super::string::str_lib::gen_str_lib;
 use crate::std::binary::binary_atom::BlobAtom;
 use crate::std::binary::binary_lib::gen_binary_lib;
 use crate::std::boolean::gen_bool_lib;
-use crate::std::future::future_lib::{FutureReq, Scheduler, gen_future_lib};
 use crate::std::number::num_atom::{CreateFloat, CreateInt};
 use crate::std::number::num_lexer::NumLexer;
 use crate::std::ops::gen_ops_lib;
@@ -49,19 +44,17 @@ pub enum StdReq {
 	CreateTuple(CreateTuple),
 	CreateRecord(CreateRecord),
 	CreateSymAtom(CreateSymAtom),
-	FutureReq(FutureReq),
 }
 
 #[derive(Debug, Default)]
-pub struct StdSystem {
-	pub(crate) sched: OnceCell<Scheduler>,
-}
+pub struct StdSystem;
 impl SystemCtor for StdSystem {
 	type Deps = ();
+	type Card = Self;
 	type Instance = Self;
 	const NAME: &'static str = "orchid::std";
 	const VERSION: f64 = 0.00_01;
-	fn inst(&self, _: ()) -> Self::Instance { Self::default() }
+	fn inst(&self, _: ()) -> Self::Instance { Self }
 }
 impl SystemCard for StdSystem {
 	type Ctor = Self;
@@ -83,16 +76,13 @@ impl SystemCard for StdSystem {
 	}
 }
 impl System for StdSystem {
-	async fn request<'a>(&self, xreq: Box<dyn ReqHandle<'a> + 'a>, req: Self::Req) -> Receipt<'a> {
+	type Ctor = Self;
+	async fn request<'a>(
+		&self,
+		xreq: Box<dyn ReqHandle<'a> + 'a>,
+		req: ReqForSystem<Self>,
+	) -> Receipt<'a> {
 		match req {
-			StdReq::FutureReq(req) => {
-				let sched = self.sched.get_or_init(Scheduler::default);
-				match req {
-					FutureReq::AddAsyncWork(req) => xreq.reply(&req, &sched.add(&req).await).await.unwrap(),
-					FutureReq::FinishAsyncWork(req) =>
-						xreq.reply(&req, &sched.finish(&req).await).await.unwrap(),
-				}
-			},
 			StdReq::CreateInt(ref req @ CreateInt(int)) =>
 				xreq.reply(req, &new_atom(int).to_expr().await.serialize().await).await.unwrap(),
 			StdReq::CreateFloat(ref req @ CreateFloat(float)) =>
@@ -151,7 +141,6 @@ impl System for StdSystem {
 			gen_binary_lib(),
 			gen_stream_lib(),
 			gen_time_lib(),
-			gen_future_lib(),
 		])
 	}
 	async fn prelude(&self) -> Vec<Sym> {
diff --git a/orchid-std/src/std/stream/stream_cmds.rs b/orchid-std/src/std/stream/stream_cmds.rs
index b5a3d9f..adeae3b 100644
--- a/orchid-std/src/std/stream/stream_cmds.rs
+++ b/orchid-std/src/std/stream/stream_cmds.rs
@@ -1,12 +1,12 @@
 use std::borrow::Cow;
+use std::io;
 use std::rc::Rc;
 
 use never::Never;
-use orchid_base::{OrcRes, fmt, is, mk_errv};
-use orchid_extension::expr::Expr;
-use orchid_extension::gen_expr::{GExpr, bot, call, new_atom};
-use orchid_extension::stream_reqs::{ReadLimit, ReadReq};
-use orchid_extension::{Atomic, ForeignAtom, OwnedAtom, OwnedVariant};
+use orchid_base::{ReqHandleExt, fmt, is, mk_errv};
+use orchid_extension::gen_expr::{bot, call, new_atom};
+use orchid_extension::std_reqs::{ReadLimit, ReadReq, RunCommand};
+use orchid_extension::{Atomic, Expr, ForeignAtom, OwnedAtom, OwnedVariant, Supports, ToExpr};
 
 use crate::std::binary::binary_atom::BlobAtom;
 
@@ -24,16 +24,22 @@ impl Atomic for ReadStreamCmd {
 impl OwnedAtom for ReadStreamCmd {
 	type Refs = Never;
 	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
-	async fn command(self) -> OrcRes<Option<GExpr>> {
-		match self.hand.call(ReadReq(self.limit)).await {
+}
+impl Supports<RunCommand> for ReadStreamCmd {
+	async fn handle<'a>(
+		&self,
+		hand: Box<dyn orchid_base::ReqHandle<'a> + '_>,
+		req: RunCommand,
+	) -> io::Result<orchid_base::Receipt<'a>> {
+		let ret = match self.hand.call(ReadReq(self.limit.clone())).await {
 			None => Err(mk_errv(
 				is("Atom is not readable").await,
 				format!("Expected a readable stream handle, found {}", fmt(&self.hand).await),
 				[self.hand.pos()],
 			)),
-			Some(Err(e)) => Ok(Some(
+			Some(Err(e)) => Ok(
 				call(
-					self.fail,
+					self.fail.clone(),
 					bot(mk_errv(
 						is(e.kind.message()).await,
 						format!("An error occurred while reading: {}", e.message),
@@ -41,8 +47,9 @@ impl OwnedAtom for ReadStreamCmd {
 					)),
 				)
 				.await,
-			)),
-			Some(Ok(v)) => Ok(Some(call(self.succ, new_atom(BlobAtom(Rc::new(v)))).await)),
-		}
+			),
+			Some(Ok(v)) => Ok(call(self.succ.clone(), new_atom(BlobAtom(Rc::new(v)))).await),
+		};
+		hand.reply(&req, &Some(ret.to_gen().await.serialize().await)).await
 	}
 }
diff --git a/orchid-std/src/std/stream/stream_lib.rs b/orchid-std/src/std/stream/stream_lib.rs
index d29305d..745af9d 100644
--- a/orchid-std/src/std/stream/stream_lib.rs
+++ b/orchid-std/src/std/stream/stream_lib.rs
@@ -1,12 +1,14 @@
+use std::num::NonZero;
+use std::rc::Rc;
+
 use orchid_base::{is, mk_errv};
-use orchid_extension::ForeignAtom;
-use orchid_extension::expr::Expr;
-use orchid_extension::func_atom::get_arg;
-use orchid_extension::gen_expr::new_atom;
-use orchid_extension::stream_reqs::ReadLimit;
+use orchid_extension::gen_expr::{call, new_atom};
+use orchid_extension::std_reqs::ReadLimit;
 use orchid_extension::tree::{GenMember, comments, fun, prefix};
+use orchid_extension::{Expr, ForeignAtom, get_arg};
 
 use crate::Int;
+use crate::std::binary::binary_atom::BlobAtom;
 use crate::std::stream::stream_cmds::ReadStreamCmd;
 
 pub fn gen_stream_lib() -> Vec<GenMember> {
@@ -30,7 +32,16 @@ pub fn gen_stream_lib() -> Vec<GenMember> {
 				Ok(new_atom(ReadStreamCmd { hand, succ, fail, limit: ReadLimit::Delimiter(end) }))
 			}),
 			fun(true, "read_bytes", async |hand: ForeignAtom, count: Int, succ: Expr, fail: Expr| {
-				Int(todo!())
+				match count.0.try_into().map(NonZero::new) {
+					Ok(Some(nzlen)) =>
+						Ok(new_atom(ReadStreamCmd { hand, succ, fail, limit: ReadLimit::Length(nzlen) })),
+					Ok(None) => Ok(call(succ, new_atom(BlobAtom(Rc::default()))).await),
+					Err(_) => Err(mk_errv(
+						is("Length cannot be negative").await,
+						format!("{} is negative and cannot be used as a length", count.0),
+						[get_arg(1).pos().await],
+					)),
+				}
 			}),
 		]),
 	)])
diff --git a/orchid-std/src/std/string/str_atom.rs b/orchid-std/src/std/string/str_atom.rs
index 315508c..c7ad1aa 100644
--- a/orchid-std/src/std/string/str_atom.rs
+++ b/orchid-std/src/std/string/str_atom.rs
@@ -10,8 +10,8 @@ use orchid_api_traits::{Encode, Request};
 use orchid_base::{
 	FmtCtx, FmtUnit, IStr, OrcRes, Receipt, ReqHandle, ReqHandleExt, Sym, es, is, mk_errv, sym,
 };
-use orchid_extension::conv::{ToExpr, TryFromExpr};
-use orchid_extension::expr::Expr;
+use orchid_extension::{ToExpr, TryFromExpr};
+use orchid_extension::Expr;
 use orchid_extension::{
 	AtomMethod, Atomic, DeserializeCtx, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports, TAtom,
 };
diff --git a/orchid-std/src/std/string/str_lexer.rs b/orchid-std/src/std/string/str_lexer.rs
index d3cf925..d3f4fc0 100644
--- a/orchid-std/src/std/string/str_lexer.rs
+++ b/orchid-std/src/std/string/str_lexer.rs
@@ -1,9 +1,9 @@
 use itertools::Itertools;
 use orchid_base::{OrcErr, OrcErrv, OrcRes, Paren, SrcRange, Sym, is, mk_errv, sym, wrap_tokv};
-use orchid_extension::conv::ToExpr;
+use orchid_extension::ToExpr;
 use orchid_extension::gen_expr::new_atom;
-use orchid_extension::lexer::{LexContext, Lexer, err_not_applicable};
-use orchid_extension::parser::p_tree2gen;
+use orchid_extension::{LexContext, Lexer, err_not_applicable};
+use orchid_extension::p_tree2gen;
 use orchid_extension::tree::{GenTok, GenTokTree, ref_tok, x_tok};
 
 use super::str_atom::IntStrAtom;
diff --git a/orchid-std/src/std/string/str_lib.rs b/orchid-std/src/std/string/str_lib.rs
index 57582da..4617701 100644
--- a/orchid-std/src/std/string/str_lib.rs
+++ b/orchid-std/src/std/string/str_lib.rs
@@ -1,12 +1,9 @@
 use std::rc::Rc;
 
 use orchid_base::{fmt, is, mk_errv, sym};
-use orchid_extension::ForeignAtom;
-use orchid_extension::coroutine_exec::exec;
-use orchid_extension::expr::Expr;
-use orchid_extension::func_atom::get_arg;
 use orchid_extension::gen_expr::{call, new_atom};
 use orchid_extension::tree::{GenMember, comments, fun, prefix};
+use orchid_extension::{Expr, ForeignAtom, exec, get_arg};
 use unicode_segmentation::UnicodeSegmentation;
 
 use super::str_atom::StrAtom;
diff --git a/orchid-std/src/std/time.rs b/orchid-std/src/std/time.rs
index dee0cba..18515ec 100644
--- a/orchid-std/src/std/time.rs
+++ b/orchid-std/src/std/time.rs
@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::io;
 use std::time::Instant;
 
 use chrono::TimeDelta;
@@ -6,13 +7,14 @@ use never::Never;
 use orchid_api::ExprTicket;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
-use orchid_base::{Numeric, OrcRes};
-use orchid_extension::conv::{ToExpr, TryFromExpr};
-use orchid_extension::expr::Expr;
+use orchid_base::{Numeric, OrcRes, Receipt, ReqHandle, ReqHandleExt};
 use orchid_extension::gen_expr::{GExpr, call, new_atom};
-use orchid_extension::system::sys_req;
+use orchid_extension::std_reqs::{AsDuration, RunCommand};
 use orchid_extension::tree::{GenMember, fun, prefix};
-use orchid_extension::{Atomic, OwnedAtom, OwnedVariant, TAtom, ThinAtom, ThinVariant};
+use orchid_extension::{
+	Atomic, Expr, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports, TAtom, ThinAtom, ThinVariant,
+	ToExpr, TryFromExpr, sys_req,
+};
 use ordered_float::NotNan;
 
 use crate::std::std_system::StdReq;
@@ -42,6 +44,15 @@ impl TryFromExpr for OrcDT {
 		Ok(TAtom::<OrcDT>::try_from_expr(expr).await?.value)
 	}
 }
+impl Supports<AsDuration> for OrcDT {
+	async fn handle<'a>(
+		&self,
+		hand: Box<dyn ReqHandle<'a> + '_>,
+		req: AsDuration,
+	) -> std::io::Result<Receipt<'a>> {
+		hand.reply(&req, &self.0.to_std().unwrap()).await
+	}
+}
 
 #[derive(Clone)]
 pub struct InstantAtom(Instant);
@@ -59,12 +70,20 @@ struct Now(Expr);
 impl Atomic for Now {
 	type Variant = OwnedVariant;
 	type Data = ();
+	fn reg_methods() -> MethodSetBuilder<Self> { MethodSetBuilder::new().handle::<RunCommand>() }
 }
 impl OwnedAtom for Now {
 	type Refs = Never;
 	async fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
-	async fn command(self) -> OrcRes<Option<GExpr>> {
-		Ok(Some(call(self.0, new_atom(InstantAtom(Instant::now())))))
+}
+impl Supports<RunCommand> for Now {
+	async fn handle<'a>(
+		&self,
+		hand: Box<dyn ReqHandle<'a> + '_>,
+		req: RunCommand,
+	) -> io::Result<Receipt<'a>> {
+		let cont = call(self.0.clone(), new_atom(InstantAtom(Instant::now()))).await.serialize().await;
+		hand.reply(&req, &Some(cont)).await
 	}
 }
 
diff --git a/orchid-std/src/std/tuple.rs b/orchid-std/src/std/tuple.rs
index 9458e82..b9381d5 100644
--- a/orchid-std/src/std/tuple.rs
+++ b/orchid-std/src/std/tuple.rs
@@ -9,13 +9,11 @@ use never::Never;
 use orchid_api_derive::{Coding, Hierarchy};
 use orchid_api_traits::Request;
 use orchid_base::{FmtCtx, FmtUnit, Format, OrcRes, ReqHandleExt, Sym, Variants, is, mk_errv, sym};
-use orchid_extension::conv::{ToExpr, TryFromExpr};
-use orchid_extension::expr::{Expr, ExprHandle};
 use orchid_extension::gen_expr::{GExpr, new_atom};
-use orchid_extension::system::sys_req;
 use orchid_extension::tree::{GenMember, cnst, fun, prefix};
 use orchid_extension::{
-	Atomic, DeserializeCtx, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports, TAtom,
+	Atomic, DeserializeCtx, Expr, ExprHandle, MethodSetBuilder, OwnedAtom, OwnedVariant, Supports,
+	TAtom, ToExpr, TryFromExpr, sys_req,
 };
 
 use crate::std::protocol::types::{GetImpl, ProtocolMethod};
@@ -171,9 +169,8 @@ pub struct Tpl<T>(pub T);
 mod tpl_impls {
 	use itertools::Itertools;
 	use orchid_base::{OrcRes, is, mk_errv};
-	use orchid_extension::conv::{ToExpr, TryFromExpr};
-	use orchid_extension::expr::Expr;
 	use orchid_extension::gen_expr::GExpr;
+	use orchid_extension::{Expr, ToExpr, TryFromExpr};
 
 	use super::{Tpl, UntypedTuple};
 
diff --git a/orcx/src/main.rs b/orcx/src/main.rs
index 5289a90..8b914cc 100644
--- a/orcx/src/main.rs
+++ b/orcx/src/main.rs
@@ -169,8 +169,8 @@ impl JoinHandle for JoinHandleImpl {
 
 struct SpawnerImpl;
 impl Spawner for SpawnerImpl {
-	fn spawn_obj(&self, fut: LocalBoxFuture<'static, ()>) -> Box<dyn JoinHandle> {
-		Box::new(JoinHandleImpl(spawn_local(fut)))
+	fn spawn_obj(&self, delay: Duration, fut: LocalBoxFuture<'static, ()>) -> Box<dyn JoinHandle> {
+		Box::new(JoinHandleImpl(spawn_local(tokio::time::sleep(delay).then(|()| fut))))
 	}
 }
 
@@ -317,13 +317,14 @@ async fn main() -> io::Result<ExitCode> {
 						let mut xctx = ExecCtx::new(root.clone(), entrypoint).await;
 						eprintln!("executed");
 						xctx.set_gas(Some(1000));
-						xctx.execute().await;
-						match xctx.result() {
-							ExecResult::Value(val) => println!(
-								"{const_name} = {}",
-								take_first(&val.print(&FmtCtxImpl::default()).await, false)
-							),
-							ExecResult::Err(e) => println!("error: {e}"),
+						match xctx.execute().await {
+							ExecResult::Value(val, _) => {
+								println!(
+									"{const_name} = {}",
+									take_first(&val.print(&FmtCtxImpl::default()).await, false)
+								)
+							},
+							ExecResult::Err(e, _) => println!("error: {e}"),
 							ExecResult::Gas(_) => println!("Ran out of gas!"),
 						}
 					}
@@ -436,12 +437,11 @@ async fn main() -> io::Result<ExitCode> {
 					let expr = ExprKind::Const(sym!(usercode::entrypoint)).at(prefix_sr.pos());
 					let mut xctx = ExecCtx::new(root.clone(), expr).await;
 					xctx.set_gas(Some(10_000));
-					xctx.execute().await;
-					match xctx.result() {
-						ExecResult::Value(val) => {
+					match xctx.execute().await {
+						ExecResult::Value(val, _) => {
 							println!("{}", take_first(&val.print(&FmtCtxImpl::default()).await, false))
 						},
-						ExecResult::Err(e) => println!("error: {e}"),
+						ExecResult::Err(e, _) => println!("error: {e}"),
 						ExecResult::Gas(_) => println!("Ran out of gas!"),
 					}
 				},