initial implementation

Signed-off-by: Maria Teresa Ortega <teresa.ortega0903@gmail.com>

Author: teresa-ortega

src/lambkin/core/ctx/context.py

@@ -23,6 +23,8 @@
 from types import SimpleNamespace
 from typing import Any
 
+from lambkin.core.shell import ShellProxy
+
 from .source import Source
 
 
@@ -176,7 +178,7 @@ def __init__(
         # as parameters.
 
         # ctx.shell
-        # TODO(teresa-ortega): self.shell = Shell(self)
+        self.shell = ShellProxy()
 
     def _setup_directories(self) -> None:
         """Create variant and iteration directories."""

src/lambkin/core/shell/__init__.py

@@ -0,0 +1,26 @@
+# Copyright 2026 Ekumen, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Shell subpackage for the lambkin SDK.
+
+Provides shell abstractions for executing system commands within benchmarks.
+Each shell implementation exposes the same interface, allowing benchmarks to
+switch between dry-run and real execution without changing any benchmark code.
+"""
+
+from .proxy import ShellProxy
+
+__all__ = [
+    "ShellProxy",
+]

src/lambkin/core/shell/proxy.py

@@ -17,3 +17,50 @@
 Provides an abstraction over shell command dispatch, allowing benchmark
 processes to be launched and managed through a consistent interface.
 """
+
+from __future__ import annotations
+
+import shlex
+from typing import Any
+
+
+class _CommandProxy:
+    """Builds a shell command lazily by chaining attribute access and calls."""
+
+    def __init__(self, parts: list[str]) -> None:
+        """Initialize the proxy with the command words accumulated so far."""
+        self._parts = parts
+
+    def __getattr__(self, name: str) -> _CommandProxy:
+        """Append a new word to the command and return a new proxy."""
+        return _CommandProxy(self._parts + [name])
+
+    def __call__(self, *args: Any, **kwargs: Any) -> None:
+        """Finalize and print the command.
+
+        Positional args are appended as plain tokens. Keyword args are
+        converted to --flag value pairs, with underscores replaced by hyphens.
+        Boolean True values produce a standalone flag, False values are ignored.
+        """
+        extra = []
+
+        for arg in args:
+            extra.append(str(arg))
+
+        for key, value in kwargs.items():
+            flag = "--" + key.replace("_", "-")
+            if value is True:
+                extra.append(flag)
+            elif value is not False:
+                extra.extend([flag, shlex.quote(str(value))])
+
+        command = " ".join(self._parts + extra)
+        print(f"[CMD]: {command}")
+
+
+class ShellProxy:
+    """Dry-run mock shell that prints commands instead of executing them."""
+
+    def __getattr__(self, name: str) -> _CommandProxy:
+        """Start building a new command from the given top-level tool name."""
+        return _CommandProxy([name])