Harden stacked CI scope and merge validation

scripts/ci-stack-scope.mjs

@@ -1,25 +0,0 @@
-import { appendFileSync, readFileSync } from "node:fs";
-import { fileURLToPath } from "node:url";
-
-export function requiresFullCi(eventName, event) {
-  if (eventName !== "pull_request") return true;
-  const pr = event?.pull_request;
-  const stackBase = pr?.stack?.base?.ref;
-  const prBase = pr?.base?.ref;
-  // Missing or incomplete stack metadata must retain full validation. The
-  // lowest unmerged layer targets the stack base; its position need not be 1.
-  return (
-    typeof stackBase !== "string" ||
-    stackBase.length === 0 ||
-    typeof prBase !== "string" ||
-    prBase.length === 0 ||
-    stackBase === prBase
-  );
-}
-
-if (process.argv[1] === fileURLToPath(import.meta.url)) {
-  const event = JSON.parse(readFileSync(process.env.GITHUB_EVENT_PATH, "utf8"));
-  const full = requiresFullCi(process.env.GITHUB_EVENT_NAME, event);
-  appendFileSync(process.env.GITHUB_OUTPUT, `full=${full}\n`);
-  console.log(full ? "Run full CI" : "Run code quality for an upper stack layer");
-}