diff --git a/.gitignore b/.gitignore
index 68a0b4c0..c57675ff 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,6 @@ htmlcov/
 .coverage
 .idea/*
 .vscode/*
+venv
+.python-version
+.envrc
diff --git a/netqasm/sdk/connection.py b/netqasm/sdk/connection.py
index 2cd505e7..ecab5867 100644
--- a/netqasm/sdk/connection.py
+++ b/netqasm/sdk/connection.py
@@ -676,7 +676,7 @@ def loop_until(self, max_iterations: int) -> ContextManager[SdkLoopUntilContext]
 
         :param max_iterations: the maximum number of times to loop
         """
-        return self.builder.sdk_new_loop_until_context(max_iterations)
+        return self._builder.sdk_new_loop_until_context(max_iterations)
 
     def if_eq(self, a: T_CValue, b: T_CValue, body: T_BranchRoutine) -> None:
         """Execute a function if a == b.
diff --git a/netqasm/sdk/run/__init__.py b/netqasm/sdk/run/__init__.py
new file mode 100644
index 00000000..e8a25732
--- /dev/null
+++ b/netqasm/sdk/run/__init__.py
@@ -0,0 +1,2 @@
+from .context import Context
+from .program import Program
diff --git a/netqasm/sdk/run/context.py b/netqasm/sdk/run/context.py
new file mode 100644
index 00000000..8454b0c6
--- /dev/null
+++ b/netqasm/sdk/run/context.py
@@ -0,0 +1,17 @@
+"""
+External execution context interface.
+"""
+
+from abc import ABC, abstractmethod
+
+from netqasm.sdk.connection import BaseNetQASMConnection
+
+
+class Context(ABC):
+    def __init__(self):
+        pass
+
+    @property
+    @abstractmethod
+    def connection(self) -> BaseNetQASMConnection:
+        raise NotImplementedError
diff --git a/netqasm/sdk/run/program.py b/netqasm/sdk/run/program.py
new file mode 100644
index 00000000..594c34c5
--- /dev/null
+++ b/netqasm/sdk/run/program.py
@@ -0,0 +1,21 @@
+"""
+External program interface.
+"""
+
+from abc import ABC, abstractmethod
+from typing import Any, Dict
+
+from netqasm.sdk.run import Context
+
+
+class Program(ABC):
+    def __init__(self):
+        print(__name__)
+
+    @property
+    def parameters(self) -> Dict[str, Any]:
+        raise NotImplementedError
+
+    @abstractmethod
+    def run(self, context: Context):
+        raise NotImplementedError