diff --git a/tests/test_codex_runner_variant_dispatch.py b/tests/test_codex_runner_variant_dispatch.py
new file mode 100644
index 0000000..8074229
--- /dev/null
+++ b/tests/test_codex_runner_variant_dispatch.py
@@ -0,0 +1,85 @@
+from __future__ import annotations
+
+import inspect
+import json
+from pathlib import Path
+import sys
+import tempfile
+import unittest
+from unittest import mock
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT / "tools"))
+
+import codex_runner_variant_matrix as matrix
+
+
+class CodexRunnerVariantDispatchTests(unittest.TestCase):
+    def test_run_matrix_call_shapes_bind_to_variant_helpers(self) -> None:
+        inspect.signature(matrix._hook_variant).bind(
+            Path("fixtures"),
+            Path("output"),
+            "hook_json_bash_bypass",
+            "^Bash$",
+            "json",
+            True,
+            True,
+            False,
+        )
+        inspect.signature(matrix._compact_variant).bind(
+            Path("fixtures"),
+            "compact_body_after_prefix_no_budget_single",
+            "body_after_prefix",
+            False,
+            False,
+        )
+        inspect.signature(matrix._subagent_variant).bind(
+            Path("fixtures"),
+            Path("output"),
+            "subagent_v1_explicit",
+            False,
+            True,
+            False,
+        )
+
+    def test_run_matrix_dispatches_all_fourteen_variants_without_codex(self) -> None:
+        def result(name: str, log_path: str) -> dict[str, object]:
+            return {
+                "variant": name,
+                "returncode": 0,
+                "local_hook_records": {log_path: []},
+            }
+
+        def fake_hook(_root: Path, _output: Path, name: str, *_args: object) -> dict[str, object]:
+            return result(name, ".diag/pretool.jsonl")
+
+        def fake_compact(_root: Path, name: str, *_args: object) -> dict[str, object]:
+            return result(name, ".diag/compact.jsonl")
+
+        def fake_subagent(_root: Path, _output: Path, name: str, *_args: object) -> dict[str, object]:
+            return result(name, ".diag/subagent.jsonl")
+
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp) / "runtime"
+            output = Path(tmp) / "artifact"
+            with (
+                mock.patch.object(matrix, "_hook_variant", side_effect=fake_hook) as hook,
+                mock.patch.object(matrix, "_compact_variant", side_effect=fake_compact) as compact,
+                mock.patch.object(matrix, "_subagent_variant", side_effect=fake_subagent) as subagent,
+            ):
+                results = matrix.run_matrix(root, output)
+
+            self.assertEqual([item["variant"] for item in results], list(matrix.VARIANT_NAMES))
+            self.assertEqual(hook.call_count, 6)
+            self.assertEqual(compact.call_count, 4)
+            self.assertEqual(subagent.call_count, 4)
+
+            files = sorted(path.name for path in output.glob("*.json"))
+            self.assertEqual(files, sorted(f"{name}.json" for name in matrix.VARIANT_NAMES))
+            for path in output.glob("*.json"):
+                payload = json.loads(path.read_text(encoding="utf-8"))
+                self.assertEqual(payload["returncode"], 0)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tools/codex_runner_variant_matrix.py b/tools/codex_runner_variant_matrix.py
index c3b9be3..f530968 100644
--- a/tools/codex_runner_variant_matrix.py
+++ b/tools/codex_runner_variant_matrix.py
@@ -410,7 +410,7 @@ def _execute_variant(
     return base.sanitize(payload)
 
 
-def _hook_variant(root: Path, output: Path, name: str, *, matcher: str, representation: str, bypass: bool, hooks_enabled: bool, sidecar_env: bool) -> dict[str, Any]:
+def _hook_variant(root: Path, output: Path, name: str, matcher: str, representation: str, bypass: bool, hooks_enabled: bool, sidecar_env: bool) -> dict[str, Any]:
     repo = root / name
     _init_repo(repo)
     _seed_pretool(repo, matcher=matcher, representation=representation)
@@ -424,7 +424,7 @@ def _hook_variant(root: Path, output: Path, name: str, *, matcher: str, represen
     return _execute_variant(name, repo, args, env=env, local_logs=(".diag/pretool.jsonl",), sidecar=sidecar if sidecar_env else None)
 
 
-def _compact_variant(root: Path, name: str, *, scope: str, token_budget: bool, two_step: bool) -> dict[str, Any]:
+def _compact_variant(root: Path, name: str, scope: str, token_budget: bool, two_step: bool) -> dict[str, Any]:
     repo = root / name
     _init_repo(repo)
     _seed_compaction(repo)
@@ -444,7 +444,7 @@ def _compact_variant(root: Path, name: str, *, scope: str, token_budget: bool, t
     return _execute_variant(name, repo, args, timeout=900, local_logs=(".diag/compact.jsonl",))
 
 
-def _subagent_variant(root: Path, output: Path, name: str, *, v2: bool, explicit: bool, home_non_ephemeral: bool = False) -> dict[str, Any]:
+def _subagent_variant(root: Path, output: Path, name: str, v2: bool, explicit: bool, home_non_ephemeral: bool = False) -> dict[str, Any]:
     repo = root / name
     _init_repo(repo)
     _seed_subagent(repo, project_agent=not home_non_ephemeral)