DC-067: [WIP] jest failing at grade time

.gitignore-extra

@@ -0,0 +1 @@
+node_modules

dashcaddy-api/__tests__/shutdown-coordinator.test.js

@@ -409,6 +409,32 @@ describe('ShutdownCoordinator (DC-067)', () => {
   });
 
   describe('installSignalHandlers()', () => {
+    // Track listeners added during each test so we can remove them in
+    // afterEach. process.on() listeners leak across tests otherwise.
+    let addedListeners;
+    let originalProcessOn;
+
+    beforeEach(() => {
+      addedListeners = [];
+      originalProcessOn = process.on;
+      // Wrap process.on to record every (signal, listener) pair we add.
+      // Must capture originalProcessOn at wrap time so we can call it.
+      const realOn = originalProcessOn;
+      process.on = function patchedOn(signal, listener) {
+        addedListeners.push({ signal, listener });
+        return realOn.call(process, signal, listener);
+      };
+    });
+
+    afterEach(() => {
+      process.on = originalProcessOn;
+      for (const { signal, listener } of addedListeners) {
+        originalProcessOn.call(process, signal, listener);  // ensure clean slate
+        process.removeListener(signal, listener);
+      }
+      addedListeners = [];
+    });
+
     test('registers listeners on the given signals', () => {
       const c = createShutdownCoordinator({
         server: makeFakeServer(),