fix(runner): scope internal Node notices to the supervisor (#7020)

scripts/run-exclusive.mjs

@@ -8,6 +8,10 @@ let shutdownSignal;
 const supervisor = spawn(
   process.execPath,
   [
+    // SQLite and Windows source transforms are internal supervisor APIs. This
+    // process-only flag keeps their notices out of command stderr without
+    // changing the command's arguments, environment, or warning behavior.
+    "--disable-warning=ExperimentalWarning",
     fileURLToPath(new URL("./run-exclusive-command.mjs", import.meta.url)),
     ...process.argv.slice(2),
   ],

tests/process-global/runnerCancellation.test.ts

@@ -318,6 +318,33 @@ it("preserves executable arguments through the public runner", async () => {
   });
 });
 
+it("preserves command stderr, warnings and exit status independently of supervisor notices", async () => {
+  const directory = await createTestTempDirectory("rea-runner-diagnostics-");
+  const stderr = 'authored command stderr: \"quotes\" & 雪\n';
+  const result = await execute(directory, process.execPath, [
+    "-e",
+    `
+process.stdout.write(JSON.stringify({
+  disabledWarnings: process.execArgv.filter((argument) => argument.startsWith("--disable-warning")),
+}));
+process.stderr.write(${JSON.stringify(stderr)});
+process.emitWarning("authored command experiment", { type: "ExperimentalWarning" });
+process.emitWarning("authored command deprecation", { type: "DeprecationWarning" });
+process.exitCode = 7;
+`,
+  ]);
+  expect(result.code).toBe(7);
+  expect(JSON.parse(result.stdout)).toEqual({ disabledWarnings: [] });
+  expect(result.stderr).toContain(stderr);
+  expect(result.stderr).toContain(
+    "ExperimentalWarning: authored command experiment",
+  );
+  expect(result.stderr).toContain(
+    "DeprecationWarning: authored command deprecation",
+  );
+  expect(result.stderr).not.toContain("stripTypeScriptTypes");
+});
+
 it.runIf(process.platform === "win32")(
   "launches an executable from a path containing spaces",
   async () => {