diff --git a/tests/integration/_support/mcp.py b/tests/integration/_support/mcp.py
index e6ae70f27e9..2d88a77a037 100644
--- a/tests/integration/_support/mcp.py
+++ b/tests/integration/_support/mcp.py
@@ -58,7 +58,16 @@ class McpPeer:
 
     def registration(self) -> dict[str, object]:
         if self.transport == "stdio":
-            return {"transport": "stdio", "command": self.command, "args": list(self.args)}
+            return {
+                "transport": "stdio",
+                "command": self.command,
+                "args": list(self.args),
+                **(
+                    {"env": {"COVERAGE_PROCESS_CONFIG": os.environ["COVERAGE_PROCESS_CONFIG"]}}
+                    if os.environ.get("COVERAGE_PROCESS_CONFIG")
+                    else {}
+                ),
+            }
         if self.spec_path is not None:
             return {"transport": "http", "url": self.url, "spec_path": str(self.spec_path)}
         return {"transport": self.transport, "url": self.url}
diff --git a/tests/unit/integration_support/test_conformance.py b/tests/unit/integration_support/test_conformance.py
index 9471adee8dd..aaa8bfa07b1 100644
--- a/tests/unit/integration_support/test_conformance.py
+++ b/tests/unit/integration_support/test_conformance.py
@@ -52,6 +52,26 @@ async def test_negotiation_records_preserve_the_peer_call_contract(monkeypatch:
     assert records[0]["negotiation"] == {"requested": "2025-03-26", "returned": "2025-03-26"}
 
 
+@pytest.mark.parametrize("covered", (False, True))
+def test_stdio_registration_forwards_only_explicit_coverage(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, covered: bool
+) -> None:
+    monkeypatch.syspath_prepend(str(Path(__file__).resolve().parents[2]))
+    from integration._support.mcp import stdio_peer
+
+    monkeypatch.delenv("COVERAGE_PROCESS_CONFIG", raising=False)
+    monkeypatch.setenv("OPENAI_API_KEY", "must-not-reach-peer")
+    if covered:
+        monkeypatch.setenv("COVERAGE_PROCESS_CONFIG", "coverage-config")
+    with stdio_peer(tmp_path) as peer:
+        assert peer.registration() == {
+            "transport": "stdio",
+            "command": peer.command,
+            "args": list(peer.args),
+            **({"env": {"COVERAGE_PROCESS_CONFIG": "coverage-config"}} if covered else {}),
+        }
+
+
 @pytest.mark.parametrize("file_backed", (False, True))
 def test_peer_drain_preserves_received_requests(
     tmp_path: Path, file_backed: bool, monkeypatch: pytest.MonkeyPatch