diff --git a/tests/e2e/AGENTS.md b/tests/e2e/AGENTS.md
index 72f9b5e39b1..b654d2dc4ef 100644
--- a/tests/e2e/AGENTS.md
+++ b/tests/e2e/AGENTS.md
@@ -315,6 +315,8 @@ other.<area>.<case>.<assertion>
 ```
 
 ## Hard Rules
+- no comments in code unless they are truly necessary
+
 - no unit tests of a product feature under `tests/e2e`, and no mock tests or monkeypatching of code anywhere in it: a product feature is proven end to end against a live proxy, never with a unit test. if a contributor asks you to write an end to end test, do NOT stage a unit test with it. If you find a product gap, call it out in the PR description. the harness's own plumbing is tested outside the suite, in `tests/e2e_harness/` (mirroring this folder's layout), because the Buildkite e2e run copies `tests/e2e/` into the runner image and runs every test in it, so a harness test in here would count as a product test in the nightly numbers. those tests run without a proxy and take their inputs as arguments or env vars (setting an env var through pytest's `monkeypatch` fixture is fine, patching a function, class, or module is not), and no coverage-registry or compat-matrix cell rests on them. judge a change inside one of them by that standard, not as a misplaced product test
 
 - use model management endpoints to create new models for a test. this could be in a conftest / inline for each test. ask the user what they want.
diff --git a/tests/e2e/codex/setups.py b/tests/e2e/codex/setups.py
index 523f94febb1..19c92fae51b 100644
--- a/tests/e2e/codex/setups.py
+++ b/tests/e2e/codex/setups.py
@@ -97,21 +97,31 @@ def with_expected_failure(setup_id: SetupId, *, reason: str) -> tuple[ParameterS
     )
 
 
-def also_driving(setups: tuple[ParameterSet, ...], extra: Mapping[str, Subject]) -> tuple[ParameterSet, ...]:
+@dataclass(frozen=True, slots=True)
+class ExtraModel:
+    provider: Provider
+    litellm_params: LiteLLMParamsBody
+
+
+def also_driving(setups: tuple[ParameterSet, ...], extra: Mapping[str, ExtraModel]) -> tuple[ParameterSet, ...]:
     return tuple(_also_driving(setup, extra) for setup in setups)
 
 
-def _also_driving(setup: ParameterSet, extra: Mapping[str, Subject]) -> ParameterSet:
+def _also_driving(setup: ParameterSet, extra: Mapping[str, ExtraModel]) -> ParameterSet:
     deployment: Final = setup.values[0]
     assert isinstance(deployment, Deployment)
     added: Final = extra[deployment.litellm_params.model]
     return pytest.param(*setup.values, id=setup.id, marks=tuple(_widened(mark, added) for mark in setup.marks))
 
 
-def _widened(mark: pytest.MarkDecorator | pytest.Mark, added: Subject) -> pytest.MarkDecorator | pytest.Mark:
+def _widened(mark: pytest.MarkDecorator | pytest.Mark, added: ExtraModel) -> pytest.MarkDecorator | pytest.Mark:
     subject: Final = mark.args[0] if mark.name == "meta" and mark.args else None
     if not isinstance(subject, Subject):
         return mark
     return meta(
-        replace(subject, providers=(*subject.providers, *added.providers), models=(*subject.models, *added.models))
+        replace(
+            subject,
+            providers=(*subject.providers, added.provider),
+            models=(*subject.models, added.litellm_params.model),
+        )
     )
diff --git a/tests/e2e/codex/test_switch_model_e2e.py b/tests/e2e/codex/test_switch_model_e2e.py
index 5ff375e3730..ea8225ce281 100644
--- a/tests/e2e/codex/test_switch_model_e2e.py
+++ b/tests/e2e/codex/test_switch_model_e2e.py
@@ -3,7 +3,6 @@
 from __future__ import annotations
 
 from collections.abc import Callable
-from dataclasses import dataclass
 from types import MappingProxyType
 from typing import Final
 
@@ -17,44 +16,34 @@ from codex.setups import (
     GPT_ON_BEDROCK_RUNTIME,
     GPT_ON_OPENAI,
     Deployment,
+    ExtraModel,
     ModelSetup,
     also_driving,
     with_expected_failure,
 )
 from e2e_config import unique_marker
-from e2e_metadata import Provider, Subject
+from e2e_metadata import Provider
 from models import LiteLLMParamsBody
 
 pytestmark = pytest.mark.e2e
 
-OTHER_GPT_ON_BEDROCK_MANTLE: Final = "bedrock_mantle/openai.gpt-6-luna"
-OTHER_GPT_ON_BEDROCK_RUNTIME: Final = "bedrock/us.openai.gpt-6-luna"
-OTHER_GPT_ON_OPENAI: Final = "openai/gpt-6.1-terra"
-OTHER_CLAUDE_ON_BEDROCK: Final = "bedrock/us.anthropic.claude-haiku-5-5"
-
-
-@dataclass(frozen=True, slots=True)
-class SwitchTo:
-    provider: Provider
-    litellm_params: LiteLLMParamsBody
-
-
-TO_OTHER_GPT_ON_OPENAI: Final = SwitchTo(
-    Provider.OPENAI, LiteLLMParamsBody(model=OTHER_GPT_ON_OPENAI, api_key="os.environ/OPENAI_API_KEY")
+TERRA_ON_OPENAI: Final = ExtraModel(
+    Provider.OPENAI, LiteLLMParamsBody(model="openai/gpt-6.1-terra", api_key="os.environ/OPENAI_API_KEY")
 )
 SWITCH_TO: Final = MappingProxyType(
     {
-        GPT_ON_BEDROCK_MANTLE: SwitchTo(
+        GPT_ON_BEDROCK_MANTLE: ExtraModel(
             Provider.BEDROCK_MANTLE,
-            LiteLLMParamsBody(model=OTHER_GPT_ON_BEDROCK_MANTLE, aws_region_name=BEDROCK_REGION),
+            LiteLLMParamsBody(model="bedrock_mantle/openai.gpt-6-luna", aws_region_name=BEDROCK_REGION),
         ),
-        GPT_ON_BEDROCK_RUNTIME: SwitchTo(
-            Provider.BEDROCK, LiteLLMParamsBody(model=OTHER_GPT_ON_BEDROCK_RUNTIME, aws_region_name=BEDROCK_REGION)
+        GPT_ON_BEDROCK_RUNTIME: ExtraModel(
+            Provider.BEDROCK, LiteLLMParamsBody(model="bedrock/us.openai.gpt-6-luna", aws_region_name=BEDROCK_REGION)
         ),
-        GPT_ON_AZURE_OPENAI: TO_OTHER_GPT_ON_OPENAI,
-        GPT_ON_OPENAI: TO_OTHER_GPT_ON_OPENAI,
-        CLAUDE_ON_BEDROCK: SwitchTo(
-            Provider.BEDROCK, LiteLLMParamsBody(model=OTHER_CLAUDE_ON_BEDROCK, aws_region_name=BEDROCK_REGION)
+        GPT_ON_AZURE_OPENAI: TERRA_ON_OPENAI,
+        GPT_ON_OPENAI: TERRA_ON_OPENAI,
+        CLAUDE_ON_BEDROCK: ExtraModel(
+            Provider.BEDROCK,
+            LiteLLMParamsBody(model="bedrock/us.anthropic.claude-haiku-5-5", aws_region_name=BEDROCK_REGION),
         ),
     }
 )
@@ -78,12 +67,7 @@ def key_models(setup: ModelSetup, second_model: str) -> tuple[str, ...]:
             reason="LiteLLM forwards the reasoning Azure encrypted to OpenAI, which cannot decrypt another account's"
             " reasoning and rejects the turn with invalid_encrypted_content (#41792)",
         ),
-        MappingProxyType(
-            {
-                model: Subject(providers=(to.provider,), models=(to.litellm_params.model,))
-                for model, to in SWITCH_TO.items()
-            }
-        ),
+        SWITCH_TO,
     ),
 )
 class TestCodexSwitchModel:
diff --git a/tests/e2e_harness/codex/test_codex_setups.py b/tests/e2e_harness/codex/test_codex_setups.py
index cae8aa5e49a..40f4522635d 100644
--- a/tests/e2e_harness/codex/test_codex_setups.py
+++ b/tests/e2e_harness/codex/test_codex_setups.py
@@ -4,8 +4,9 @@ from types import MappingProxyType
 from typing import Final
 
 from _pytest.mark.structures import ParameterSet
-from codex.setups import SETUPS, Deployment, also_driving, with_expected_failure
+from codex.setups import SETUPS, Deployment, ExtraModel, also_driving, with_expected_failure
 from e2e_metadata import Provider, Subject
+from models import LiteLLMParamsBody
 
 SECOND_MODEL: Final = "openai/second-model"
 
@@ -28,11 +29,10 @@ def _model(setup: ParameterSet) -> str:
 
 
 def test_also_driving_declares_the_extra_model_on_every_setup_and_keeps_the_xfail() -> None:
+    second: Final = ExtraModel(Provider.OPENAI, LiteLLMParamsBody(model=SECOND_MODEL))
     setups: Final = also_driving(
         with_expected_failure("azure_openai", reason="known bug"),
-        MappingProxyType(
-            {_model(setup): Subject(providers=(Provider.OPENAI,), models=(SECOND_MODEL,)) for setup in SETUPS}
-        ),
+        MappingProxyType({_model(setup): second for setup in SETUPS}),
     )
 
     assert tuple(setup.id for setup in setups) == tuple(setup.id for setup in SETUPS)