From f072685a696d362103915a79c8d6b3de48b28be7 Mon Sep 17 00:00:00 2001
From: jenkins <jenkins@bstein.dev>
Date: Sat, 15 Aug 2026 04:07:30 -0300
Subject: [PATCH] hermes: resolve durable lane model ids

---
 services/hermes/scripts/cli_lane_runner.py    | 18 ++++-
 testing/tests/test_hermes_cli_lane_routing.py | 81 +++++++++++++++++++
 2 files changed, 98 insertions(+), 1 deletion(-)
 create mode 100644 testing/tests/test_hermes_cli_lane_routing.py

diff --git a/services/hermes/scripts/cli_lane_runner.py b/services/hermes/scripts/cli_lane_runner.py
index 5faa2351..d1116626 100644
--- a/services/hermes/scripts/cli_lane_runner.py
+++ b/services/hermes/scripts/cli_lane_runner.py
@@ -169,10 +169,26 @@ def select_route(
         with open_request(request, timeout=60) as response:
             selected = str(response.headers.get("x-model-router-selected-model") or "")
             rationale = str(response.headers.get("x-model-router-rationale") or "")
-            response.read()
+            response_body = response.read()
     except (OSError, urllib.error.URLError) as exc:
         raise RuntimeError(f"Switchyard worker routing failed: {exc}") from exc
     provider, model, effort = _decode_worker_target(selected)
+    # Switchyard preserves the stable tier target in the selection header and
+    # top-level response model. The worker broker's assistant content contains
+    # the steward-resolved provider model required by the native CLI.
+    try:
+        response_document = json.loads(response_body)
+        resolved_target = str(response_document["choices"][0]["message"]["content"] or "")
+        resolved_provider, resolved_model, resolved_effort = _decode_worker_target(resolved_target)
+        required_prefix = "gpt-" if provider == "codex" else "claude-"
+        if (
+            resolved_provider == provider
+            and resolved_effort == effort
+            and resolved_model.startswith(required_prefix)
+        ):
+            model = resolved_model
+    except (AttributeError, IndexError, KeyError, RuntimeError, TypeError, ValueError, json.JSONDecodeError):
+        pass
     if exclude_provider and provider == exclude_provider:
         raise RuntimeError(
             f"Switchyard selected excluded provider {exclude_provider} for retry"
diff --git a/testing/tests/test_hermes_cli_lane_routing.py b/testing/tests/test_hermes_cli_lane_routing.py
new file mode 100644
index 00000000..5aac2f4e
--- /dev/null
+++ b/testing/tests/test_hermes_cli_lane_routing.py
@@ -0,0 +1,81 @@
+"""Regression tests for durable Hermes worker-route model resolution."""
+
+from __future__ import annotations
+
+import importlib.util
+import json
+import sys
+from pathlib import Path
+
+
+SCRIPT = (
+    Path(__file__).parents[2] / "services/hermes/scripts/cli_lane_runner.py"
+)
+SPEC = importlib.util.spec_from_file_location("cli_lane_routing", SCRIPT)
+assert SPEC and SPEC.loader
+lanes = importlib.util.module_from_spec(SPEC)
+sys.modules[SPEC.name] = lanes
+SPEC.loader.exec_module(lanes)
+
+
+class SwitchyardResponse:
+    """Return a tier header and independently resolved broker content."""
+
+    def __init__(self, selected: str, resolved_target: str):
+        self.headers = {
+            "x-model-router-selected-model": selected,
+            "x-model-router-rationale": "test route",
+        }
+        self.resolved_target = resolved_target
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_args):
+        return False
+
+    def read(self) -> bytes:
+        return json.dumps(
+            {
+                "model": self.headers["x-model-router-selected-model"],
+                "choices": [
+                    {"message": {"content": self.resolved_target}}
+                ],
+            }
+        ).encode()
+
+
+def test_switchyard_tier_is_resolved_before_invoking_codex():
+    """Codex receives the exact account-visible ID, not a tier shorthand."""
+    route = lanes.select_route(
+        "Repair the failing implementation.",
+        "cli-auto",
+        open_request=lambda *_args, **_kwargs: SwitchyardResponse(
+            "worker/codex/terra/xhigh",
+            "worker/codex/gpt-5.6-terra/xhigh",
+        ),
+    )
+
+    assert (route.provider, route.model, route.effort) == (
+        "codex",
+        "gpt-5.6-terra",
+        "xhigh",
+    )
+
+
+def test_mismatched_broker_resolution_cannot_change_route_decision():
+    """Resolved content cannot change Switchyard's provider or effort."""
+    route = lanes.select_route(
+        "Repair it.",
+        "cli-auto",
+        open_request=lambda *_args, **_kwargs: SwitchyardResponse(
+            "worker/codex/terra/xhigh",
+            "worker/claude/claude-opus-5/high",
+        ),
+    )
+
+    assert (route.provider, route.model, route.effort) == (
+        "codex",
+        "terra",
+        "xhigh",
+    )