diff --git a/pkgs/clan-cli/clan_cli/completions.py b/pkgs/clan-cli/clan_cli/completions.py
index ce32a7c62..aad1b9ebf 100644
--- a/pkgs/clan-cli/clan_cli/completions.py
+++ b/pkgs/clan-cli/clan_cli/completions.py
@@ -23,6 +23,9 @@ from .secrets.users import list_users
 This module provides dynamic completions.
 The completions should feel fast.
 We target a maximum of 1second on our average machine.
+
+Note: All completion functions have 'prefix' as their first parameter (required
+by argcomplete's API) but don't use it internally.
 """
 
 
@@ -44,7 +47,7 @@ def clan_dir(flake: str | None) -> str | None:
 
 
 def complete_machines(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -77,7 +80,7 @@ def complete_machines(
 
 
 def complete_services_for_machine(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -121,7 +124,7 @@ def complete_services_for_machine(
 
 
 def complete_backup_providers_for_machine(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -164,7 +167,7 @@ def complete_backup_providers_for_machine(
 
 
 def complete_state_services_for_machine(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -207,7 +210,7 @@ def complete_state_services_for_machine(
 
 
 def complete_secrets(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -225,7 +228,7 @@ def complete_secrets(
 
 
 def complete_users(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -243,7 +246,7 @@ def complete_users(
 
 
 def complete_groups(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -262,7 +265,7 @@ def complete_groups(
 
 
 def complete_templates_disko(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -283,7 +286,7 @@ def complete_templates_disko(
 
 
 def complete_templates_clan(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -304,7 +307,7 @@ def complete_templates_clan(
 
 
 def complete_templates_machine(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -325,7 +328,7 @@ def complete_templates_machine(
 
 
 def complete_vars_for_machine(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -366,7 +369,7 @@ def complete_vars_for_machine(
 
 
 def complete_target_host(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
@@ -407,7 +410,7 @@ def complete_target_host(
 
 
 def complete_tags(
-    _prefix: str,
+    prefix: str,  # noqa: ARG001
     parsed_args: argparse.Namespace,
     **_kwargs: Any,
 ) -> Iterable[str]:
diff --git a/pkgs/clan-cli/clan_cli/completions_test.py b/pkgs/clan-cli/clan_cli/completions_test.py
new file mode 100644
index 000000000..fc2f0b70a
--- /dev/null
+++ b/pkgs/clan-cli/clan_cli/completions_test.py
@@ -0,0 +1,113 @@
+"""Tests for dynamic completion functionality.
+
+These tests verify that dynamic completions work correctly for various commands.
+The tests directly call completion functions rather than simulating shell completion.
+"""
+
+import argparse
+import inspect
+
+import pytest
+from clan_lib.flake import Flake
+
+from .completions import complete_machines
+from .tests import fixtures_flakes
+from .tests.helpers import cli
+
+
+@pytest.mark.with_core
+def test_complete_machines(
+    test_flake_with_core: fixtures_flakes.FlakeForTest,
+) -> None:
+    """Test that complete_machines returns the correct machine names."""
+    parsed_args = argparse.Namespace(flake=Flake(str(test_flake_with_core.path)))
+
+    completions = complete_machines(prefix="", parsed_args=parsed_args)
+
+    completion_list = (
+        list(completions.keys()) if isinstance(completions, dict) else list(completions)
+    )
+
+    assert "vm1" in completion_list, (
+        f"Expected 'vm1' in completions, got: {completion_list}"
+    )
+    assert "vm2" in completion_list, (
+        f"Expected 'vm2' in completions, got: {completion_list}"
+    )
+
+
+@pytest.mark.with_core
+def test_complete_machines_with_prefix(
+    test_flake_with_core: fixtures_flakes.FlakeForTest,
+) -> None:
+    parsed_args = argparse.Namespace(flake=Flake(str(test_flake_with_core.path)))
+
+    completions = complete_machines(prefix="vm", parsed_args=parsed_args)
+    completion_list = (
+        list(completions.keys()) if isinstance(completions, dict) else list(completions)
+    )
+
+    assert len(completion_list) > 0, "Should return machine names"
+
+
+@pytest.mark.with_core
+def test_complete_machines_without_flake(
+    test_flake_with_core: fixtures_flakes.FlakeForTest,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Test that complete_machines works when flake is not explicitly set.
+
+    When no --flake argument is provided, completions should use the current
+    directory or CLAN_DIR environment variable.
+    """
+    monkeypatch.chdir(test_flake_with_core.path)
+
+    parsed_args = argparse.Namespace()
+
+    completions = complete_machines(prefix="", parsed_args=parsed_args)
+    completion_list = (
+        list(completions.keys()) if isinstance(completions, dict) else list(completions)
+    )
+
+    assert "vm1" in completion_list
+    assert "vm2" in completion_list
+
+
+@pytest.mark.with_core
+def test_complete_machines_with_created_machine(
+    test_flake_with_core: fixtures_flakes.FlakeForTest,
+) -> None:
+    """Test that completions include dynamically created machines."""
+    # Create a new machine
+    cli.run(
+        [
+            "machines",
+            "create",
+            "--flake",
+            str(test_flake_with_core.path),
+            "test-machine",
+        ],
+    )
+
+    parsed_args = argparse.Namespace(flake=Flake(str(test_flake_with_core.path)))
+    completions = complete_machines(prefix="", parsed_args=parsed_args)
+    completion_list = (
+        list(completions.keys()) if isinstance(completions, dict) else list(completions)
+    )
+
+    # Should include the newly created machine
+    assert "test-machine" in completion_list, (
+        f"Expected 'test-machine' in {completion_list}"
+    )
+    assert "vm1" in completion_list
+    assert "vm2" in completion_list
+
+
+def test_complete_machines_signature() -> None:
+    """Test that complete_machines has the correct signature for argcomplete."""
+    sig = inspect.signature(complete_machines)
+    params = list(sig.parameters.keys())
+
+    assert params[0] == "prefix", (
+        f"First parameter should be 'prefix' for argcomplete compatibility, got: {params[0]}"
+    )