diff --git a/src/autorouter/autoroute.rs b/src/autorouter/autoroute.rs
index b2d1188..e391d2d 100644
--- a/src/autorouter/autoroute.rs
+++ b/src/autorouter/autoroute.rs
@@ -5,6 +5,7 @@ use crate::{
     drawing::graph::PrimitiveIndex,
     geometry::primitive::PrimitiveShape,
     router::{navmesh::Navmesh, route::Route, trace::Trace, Router, RouterStatus},
+    step::Step,
 };
 
 use super::{
@@ -40,10 +41,12 @@ impl Autoroute {
 
         Ok(this)
     }
+}
 
-    pub fn step(
+impl<M: AccessMesadata> Step<Autorouter<M>, AutorouterStatus, AutorouterError> for Autoroute {
+    fn step(
         &mut self,
-        autorouter: &mut Autorouter<impl AccessMesadata>,
+        autorouter: &mut Autorouter<M>,
     ) -> Result<AutorouterStatus, AutorouterError> {
         let Some(ref mut route) = self.route else {
             // Shouldn't happen.
diff --git a/src/autorouter/autorouter.rs b/src/autorouter/autorouter.rs
index 7a01d95..7d2afae 100644
--- a/src/autorouter/autorouter.rs
+++ b/src/autorouter/autorouter.rs
@@ -7,6 +7,7 @@ use crate::{
     drawing::{band::BandTermsegIndex, dot::FixedDotIndex, Infringement},
     layout::via::ViaWeight,
     router::{navmesh::NavmeshError, RouterError},
+    step::{IsFinished, Step},
     triangulation::GetTrianvertexNodeIndex,
 };
 
@@ -36,6 +37,12 @@ pub enum AutorouterStatus {
     Finished,
 }
 
+impl IsFinished for AutorouterStatus {
+    fn finished(&self) -> bool {
+        matches!(self, AutorouterStatus::Finished)
+    }
+}
+
 pub struct Autorouter<M: AccessMesadata> {
     pub(super) board: Board<M>,
     pub(super) ratsnest: Ratsnest,
diff --git a/src/autorouter/invoker.rs b/src/autorouter/invoker.rs
index a0b3181..10055be 100644
--- a/src/autorouter/invoker.rs
+++ b/src/autorouter/invoker.rs
@@ -9,6 +9,7 @@ use crate::{
     geometry::primitive::PrimitiveShape,
     layout::via::ViaWeight,
     router::{navmesh::Navmesh, trace::Trace},
+    step::{IsFinished, Step},
 };
 
 use super::{
@@ -54,6 +55,12 @@ pub enum InvokerStatus {
     Finished,
 }
 
+impl IsFinished for InvokerStatus {
+    fn finished(&self) -> bool {
+        matches!(self, InvokerStatus::Finished)
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub enum Command {
     Autoroute(PinSelection),
@@ -69,26 +76,6 @@ pub enum Execute {
 }
 
 impl Execute {
-    pub fn step<M: AccessMesadata>(
-        &mut self,
-        invoker: &mut Invoker<M>,
-    ) -> Result<InvokerStatus, InvokerError> {
-        match self.step_catch_err(invoker) {
-            Ok(InvokerStatus::Running) => Ok(InvokerStatus::Running),
-            Ok(InvokerStatus::Finished) => {
-                if let Some(command) = invoker.ongoing_command.take() {
-                    invoker.history.do_(command);
-                }
-
-                Ok(InvokerStatus::Finished)
-            }
-            Err(err) => {
-                invoker.ongoing_command = None;
-                Err(err)
-            }
-        }
-    }
-
     fn step_catch_err<M: AccessMesadata>(
         &mut self,
         invoker: &mut Invoker<M>,
@@ -111,6 +98,25 @@ impl Execute {
     }
 }
 
+impl<M: AccessMesadata> Step<Invoker<M>, InvokerStatus, InvokerError> for Execute {
+    fn step(&mut self, invoker: &mut Invoker<M>) -> Result<InvokerStatus, InvokerError> {
+        match self.step_catch_err(invoker) {
+            Ok(InvokerStatus::Running) => Ok(InvokerStatus::Running),
+            Ok(InvokerStatus::Finished) => {
+                if let Some(command) = invoker.ongoing_command.take() {
+                    invoker.history.do_(command);
+                }
+
+                Ok(InvokerStatus::Finished)
+            }
+            Err(err) => {
+                invoker.ongoing_command = None;
+                Err(err)
+            }
+        }
+    }
+}
+
 pub struct ExecuteWithStatus {
     execute: Execute,
     maybe_status: Option<InvokerStatus>,
diff --git a/src/lib.rs b/src/lib.rs
index 6084948..2e0434e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,4 +10,5 @@ pub mod layout;
 pub mod math;
 pub mod router;
 pub mod specctra;
+pub mod step;
 pub mod triangulation;
diff --git a/src/step.rs b/src/step.rs
new file mode 100644
index 0000000..09e79e2
--- /dev/null
+++ b/src/step.rs
@@ -0,0 +1,7 @@
+pub trait IsFinished {
+    fn finished(&self) -> bool;
+}
+
+pub trait Step<C, S: IsFinished, E> {
+    fn step(&mut self, context: &mut C) -> Result<S, E>;
+}