diff --git a/services/hermes/agent-deployment.yaml b/services/hermes/agent-deployment.yaml
index 31e1df4b6..77228b6e6 100644
--- a/services/hermes/agent-deployment.yaml
+++ b/services/hermes/agent-deployment.yaml
@@ -25,7 +25,7 @@ spec:
         ai.bstein.dev/execution: Hermes Kanban with durable direct Codex and Claude Code CLI workers
         ai.bstein.dev/model-policy: Jetson-assisted AUTO routing, low through xhigh, cross-provider fallback
         ai.bstein.dev/placement: rpi5 preferred; Jetson deferred until state storage is available
-        ai.bstein.dev/config-rev: "20260812-tool-call-failover"
+        ai.bstein.dev/config-rev: "20260812-stream-tool-failover"
         vault.hashicorp.com/agent-inject: "true"
         vault.hashicorp.com/role: hermes-agent
         vault.hashicorp.com/agent-inject-secret-anthropic-token: kv/data/atlas/hermes/agent-tokens
diff --git a/services/hermes/scripts/codex_broker.py b/services/hermes/scripts/codex_broker.py
index a4a8a447a..6f34c4520 100644
--- a/services/hermes/scripts/codex_broker.py
+++ b/services/hermes/scripts/codex_broker.py
@@ -160,7 +160,31 @@ def _completed_response(lines: Iterable[str]) -> dict[str, Any]:
     """Collapse a Codex SSE stream for a non-streaming Responses caller."""
     terminal_response: dict[str, Any] | None = None
     output_items: dict[int, dict[str, Any]] = {}
+    function_argument_deltas: dict[str, list[str]] = {}
+    completed_function_arguments: set[str] = set()
     upstream_error = ""
+
+    def function_key(event: dict[str, Any]) -> str:
+        """Identify one streamed function call without retaining its content."""
+        item_id = str(event.get("item_id") or "").strip()
+        if item_id:
+            return item_id
+        output_index = event.get("output_index")
+        return f"output:{output_index}" if isinstance(output_index, int) else ""
+
+    def validate_arguments(arguments: Any) -> None:
+        """Reject an incomplete JSON object so Switchyard can fail over."""
+        if not isinstance(arguments, str):
+            raise RuntimeError("Codex returned malformed function arguments")
+        try:
+            parsed_arguments = json.loads(arguments)
+        except (TypeError, ValueError, json.JSONDecodeError) as exc:
+            raise RuntimeError(
+                "Codex returned retryable malformed function arguments"
+            ) from exc
+        if not isinstance(parsed_arguments, dict):
+            raise RuntimeError("Codex returned malformed function arguments")
+
     for line in lines:
         if not line.startswith("data:"):
             continue
@@ -175,6 +199,19 @@ def _completed_response(lines: Iterable[str]) -> dict[str, Any]:
             continue
         event_type = str(event.get("type") or "")
         response = event.get("response")
+        if event_type == "response.function_call_arguments.delta":
+            key = function_key(event)
+            delta = event.get("delta")
+            if key and isinstance(delta, str):
+                function_argument_deltas.setdefault(key, []).append(delta)
+        elif event_type == "response.function_call_arguments.done":
+            key = function_key(event)
+            arguments = event.get("arguments")
+            if not isinstance(arguments, str) and key:
+                arguments = "".join(function_argument_deltas.get(key, []))
+            validate_arguments(arguments)
+            if key:
+                completed_function_arguments.add(key)
         if event_type == "response.output_item.done":
             item = event.get("item")
             output_index = event.get("output_index")
@@ -192,6 +229,9 @@ def _completed_response(lines: Iterable[str]) -> dict[str, Any]:
                 upstream_error = str(error.get("message") or error.get("type") or "")
             else:
                 upstream_error = str(error or "")
+    for key, deltas in function_argument_deltas.items():
+        if key not in completed_function_arguments:
+            validate_arguments("".join(deltas))
     if terminal_response is not None:
         status = str(terminal_response.get("status") or "").lower()
         if status != "completed":
@@ -224,16 +264,7 @@ def _completed_response(lines: Iterable[str]) -> dict[str, Any]:
             if str(item.get("status") or "completed").lower() == "incomplete":
                 raise RuntimeError("Codex returned a retryable incomplete tool call")
             arguments = item.get("arguments")
-            if not isinstance(arguments, str):
-                raise RuntimeError("Codex returned malformed function arguments")
-            try:
-                parsed_arguments = json.loads(arguments)
-            except (TypeError, ValueError, json.JSONDecodeError) as exc:
-                raise RuntimeError(
-                    "Codex returned retryable malformed function arguments"
-                ) from exc
-            if not isinstance(parsed_arguments, dict):
-                raise RuntimeError("Codex returned malformed function arguments")
+            validate_arguments(arguments)
         return terminal_response
     raise RuntimeError(upstream_error or "Codex stream ended without a terminal response")
 
diff --git a/services/hermes/switchyard-configmap.yaml b/services/hermes/switchyard-configmap.yaml
index 2d1388cc0..864c04533 100644
--- a/services/hermes/switchyard-configmap.yaml
+++ b/services/hermes/switchyard-configmap.yaml
@@ -311,7 +311,7 @@ data:
     classifier_target = "classifier"
     # Switchyard falls through this list after a request-local target failure.
     # Keep both xhigh providers first so recovery can escalate, never downgrade.
-    targets = ["claude_opus_xhigh", "codex_sol_xhigh", "claude_sonnet_high", "codex_sol_high", "claude_opus_high", "codex_terra_high", "claude_sonnet_medium", "codex_sol_medium", "codex_terra_medium", "claude_haiku_low", "codex_luna_low", "codex_terra_low"]
+    targets = ["claude_opus_xhigh", "codex_sol_xhigh", "claude_sonnet_high", "codex_sol_high", "claude_opus_high", "codex_terra_high", "claude_sonnet_medium", "codex_sol_medium", "codex_terra_medium"]
     default_target = "claude_sonnet_high"
     session_affinity = false
     recent_turn_window = 12
@@ -353,14 +353,15 @@ data:
     unavailable, failed, exhausted, rate-limited, or out of capacity; use the
     other provider at the same floor.
 
-    4. Map exactly: Codex low=codex_luna_low, medium=codex_terra_medium,
-    high=codex_sol_high, xhigh=codex_sol_xhigh; Claude low=claude_haiku_low,
+    4. Map exactly: Codex medium=codex_terra_medium,
+    high=codex_sol_high, xhigh=codex_sol_xhigh; Claude
     medium=claude_sonnet_medium, high=claude_sonnet_high,
-    xhigh=claude_opus_xhigh. Re-evaluate every boundary and resolve "continue"
-    or "do it" from recent context.
+    xhigh=claude_opus_xhigh. Low-tier targets are intentionally unavailable on
+    this route. Re-evaluate every boundary and resolve "continue" or "do it"
+    from recent context.
     """
     response_schema = '''
-    {"type":"object","properties":{"decision":{"type":"object","properties":{"target":{"type":"string","enum":["claude_sonnet_high","codex_sol_high","codex_terra_medium","claude_sonnet_medium","codex_terra_high","codex_sol_medium","claude_opus_high","codex_sol_xhigh","claude_opus_xhigh","codex_luna_low","claude_haiku_low","codex_terra_low"]}},"required":["target"],"additionalProperties":false}},"required":["decision"],"additionalProperties":false}
+    {"type":"object","properties":{"decision":{"type":"object","properties":{"target":{"type":"string","enum":["claude_sonnet_high","codex_sol_high","codex_terra_medium","claude_sonnet_medium","codex_terra_high","codex_sol_medium","claude_opus_high","codex_sol_xhigh","claude_opus_xhigh"]}},"required":["target"],"additionalProperties":false}},"required":["decision"],"additionalProperties":false}
     '''
 
     [routes.auto_deep.policy]
@@ -374,7 +375,7 @@ data:
     classifier_target = "classifier"
     # Switchyard falls through this list after a request-local target failure.
     # Keep both xhigh providers first so recovery can escalate, never downgrade.
-    targets = ["codex_sol_xhigh", "claude_opus_xhigh", "codex_sol_high", "claude_opus_high", "claude_sonnet_high", "codex_terra_high", "codex_sol_medium", "claude_sonnet_medium", "codex_terra_medium", "codex_luna_low", "claude_haiku_low", "codex_terra_low"]
+    targets = ["codex_sol_xhigh", "claude_opus_xhigh", "codex_sol_high", "claude_opus_high", "claude_sonnet_high", "codex_terra_high", "codex_sol_medium", "claude_sonnet_medium", "codex_terra_medium"]
     default_target = "codex_sol_high"
     session_affinity = false
     recent_turn_window = 16
@@ -416,14 +417,15 @@ data:
     unavailable, failed, exhausted, rate-limited, or out of capacity; use the
     other provider at the same floor.
 
-    4. Map exactly: Codex low=codex_luna_low, medium=codex_terra_medium,
-    high=codex_sol_high, xhigh=codex_sol_xhigh; Claude low=claude_haiku_low,
+    4. Map exactly: Codex medium=codex_terra_medium,
+    high=codex_sol_high, xhigh=codex_sol_xhigh; Claude
     medium=claude_sonnet_medium, high=claude_sonnet_high,
-    xhigh=claude_opus_xhigh. Re-evaluate every boundary and resolve "continue"
-    or "do it" from recent context.
+    xhigh=claude_opus_xhigh. Low-tier targets are intentionally unavailable on
+    this route. Re-evaluate every boundary and resolve "continue" or "do it"
+    from recent context.
     """
     response_schema = '''
-    {"type":"object","properties":{"decision":{"type":"object","properties":{"target":{"type":"string","enum":["codex_sol_high","claude_opus_high","claude_sonnet_high","codex_terra_high","codex_sol_xhigh","claude_opus_xhigh","codex_terra_medium","claude_sonnet_medium","codex_sol_medium","codex_luna_low","claude_haiku_low","codex_terra_low"]}},"required":["target"],"additionalProperties":false}},"required":["decision"],"additionalProperties":false}
+    {"type":"object","properties":{"decision":{"type":"object","properties":{"target":{"type":"string","enum":["codex_sol_high","claude_opus_high","claude_sonnet_high","codex_terra_high","codex_sol_xhigh","claude_opus_xhigh","codex_terra_medium","claude_sonnet_medium","codex_sol_medium"]}},"required":["target"],"additionalProperties":false}},"required":["decision"],"additionalProperties":false}
     '''
 
     [routes.auto_maximum.policy]
diff --git a/services/hermes/switchyard-deployment.yaml b/services/hermes/switchyard-deployment.yaml
index 57ba23e75..80b4cb210 100644
--- a/services/hermes/switchyard-deployment.yaml
+++ b/services/hermes/switchyard-deployment.yaml
@@ -22,7 +22,7 @@ spec:
       labels:
         app: hermes-switchyard
       annotations:
-        ai.bstein.dev/config-rev: "20260812-tool-call-effort-floor"
+        ai.bstein.dev/config-rev: "20260812-enforced-tool-floor"
         prometheus.io/scrape: "true"
         prometheus.io/port: "9005"
         prometheus.io/path: /metrics
diff --git a/testing/tests/test_hermes_chat_quality.py b/testing/tests/test_hermes_chat_quality.py
index ff0265d4a..2532d6333 100644
--- a/testing/tests/test_hermes_chat_quality.py
+++ b/testing/tests/test_hermes_chat_quality.py
@@ -743,6 +743,34 @@ def test_codex_broker_auth_and_request_contract(tmp_path: Path, monkeypatch):
             + json.dumps({"type": "response.completed", "response": completed}),
         ]
     )["output"] == [valid_tool_item]
+    with pytest.raises(RuntimeError, match="malformed function arguments"):
+        module._completed_response(
+            [
+                "event: response.function_call_arguments.delta",
+                'data: {"type":"response.function_call_arguments.delta",'
+                '"item_id":"call_1","output_index":0,'
+                '"delta":"{\\"path\\":\\"/tmp\\",\\"offset\\":"}',
+                "event: response.completed",
+                "data: "
+                + json.dumps({"type": "response.completed", "response": completed}),
+            ]
+        )
+    streamed_tool = module._completed_response(
+        [
+            "event: response.function_call_arguments.delta",
+            'data: {"type":"response.function_call_arguments.delta",'
+            '"item_id":"call_2","output_index":0,'
+            '"delta":"{\\"path\\":\\"/tmp\\",\\"offset\\":"}',
+            "event: response.function_call_arguments.done",
+            'data: {"type":"response.function_call_arguments.done",'
+            '"item_id":"call_2","output_index":0,'
+            '"arguments":"{\\"path\\":\\"/tmp\\",\\"offset\\":0}"}',
+            "event: response.completed",
+            "data: "
+            + json.dumps({"type": "response.completed", "response": completed}),
+        ]
+    )
+    assert streamed_tool["status"] == "completed"
 
     auth_dir = tmp_path / ".codex"
     auth_dir.mkdir()
@@ -981,8 +1009,8 @@ def test_local_flux_runtime_and_gpu_handoff_are_flux_managed():
     assert "Claude xhigh=worker_claude_opus_xhigh" in switchyard
     assert "Anthropic and Claude name the same provider" in switchyard
     assert "OpenAI and Codex name the same provider" in switchyard
-    assert switchyard.count("Codex low=codex_luna_low") == 4
-    assert switchyard.count("Claude low=claude_haiku_low") == 4
+    assert switchyard.count("Codex low=codex_luna_low") == 2
+    assert switchyard.count("Claude low=claude_haiku_low") == 2
     assert switchyard.count('Treat "think hard"') == 4
     assert switchyard.count("Never choose below the") >= 5
     routes = tomllib.loads(switchyard)["routes"]
@@ -994,7 +1022,9 @@ def test_local_flux_runtime_and_gpu_handoff_are_flux_managed():
         targets = routes[route_name]["targets"]
         selector_targets = routes[route_name]["response_schema"]
         assert not any(target.startswith("local_") for target in targets)
+        assert not any(target.endswith("_low") for target in targets)
         assert "local_qwen" not in selector_targets
+        assert "_low" not in selector_targets
         assert "not eligible for foreground" in routes[route_name]["prompt"]
     for route_name in ("auto_fast", "auto_balanced", "manual_local_qwen"):
         assert any(