NativeScript
diff --git a/test-app/app/src/main/assets/app/mainpage.js b/test-app/app/src/main/assets/app/mainpage.js
@@ -21,6 +21,7 @@ shared.runWorkerTests();
 shared.runPerformanceTests();
 shared.runStructuredCloneTests();
 require("./tests/testWebAssembly");
+require("./tests/testEventLoop");
 require("./tests/testMultithreadedJavascript");
 require("./tests/testWorkerTerminateDuringLoad");
 require("./tests/testInterfaceDefaultMethods");

diff --git a/test-app/app/src/main/assets/app/tests/eventLoopEchoWorker.js b/test-app/app/src/main/assets/app/tests/eventLoopEchoWorker.js
@@ -0,0 +1,3 @@
+onmessage = function (msg) {
+    postMessage(msg.data);
+};
diff --git a/test-app/app/src/main/assets/app/tests/testEventLoop.js b/test-app/app/src/main/assets/app/tests/testEventLoop.js
@@ -0,0 +1,273 @@
+// V8 delivers these resolutions as platform foreground tasks, so they only
+// settle if the runtime pumps its foreground task runner (EventLoopHandler).
+describe("event loop foreground tasks", function () {
+    it("resolves Atomics.waitAsync when notified on the same thread", function (done) {
+        const sab = new SharedArrayBuffer(4);
+        const i32 = new Int32Array(sab);
+
+        const result = Atomics.waitAsync(i32, 0, 0);
+        expect(result.async).toBe(true);
+
+        result.value.then(value => {
+            expect(value).toBe("ok");
+            done();
+        }).catch(e => {
+            // jasmine 2.0.1: done has no .fail - record the failure, then complete
+            expect("resolved").toBe("rejected: " + e);
+            done();
+        });
+
+        const woken = Atomics.notify(i32, 0);
+        expect(woken).toBe(1);
+    });
+
+    it("resolves Atomics.waitAsync with 'timed-out' after the timeout", function (done) {
+        const sab = new SharedArrayBuffer(4);
+        const i32 = new Int32Array(sab);
+
+        const result = Atomics.waitAsync(i32, 0, 0, 50);
+        expect(result.async).toBe(true);
+
+        result.value.then(value => {
+            expect(value).toBe("timed-out");
+            done();
+        }).catch(e => {
+            // jasmine 2.0.1: done has no .fail - record the failure, then complete
+            expect("resolved").toBe("rejected: " + e);
+            done();
+        });
+    });
+
+    it("resolves Atomics.waitAsync synchronously on value mismatch", function () {
+        const sab = new SharedArrayBuffer(4);
+        const i32 = new Int32Array(sab);
+        i32[0] = 42;
+
+        const result = Atomics.waitAsync(i32, 0, 0);
+        expect(result.async).toBe(false);
+        expect(result.value).toBe("not-equal");
+    });
+
+    it("keeps ordinary promise chains working alongside foreground tasks", function (done) {
+        const sab = new SharedArrayBuffer(4);
+        const i32 = new Int32Array(sab);
+        const order = [];
+
+        Atomics.waitAsync(i32, 0, 0).value.then(() => {
+            order.push("waitAsync");
+            return Promise.resolve();
+        }).then(() => {
+            order.push("chained");
+            expect(order).toEqual(["waitAsync", "chained"]);
+            done();
+        }).catch(e => {
+            expect("resolved").toBe("rejected: " + e);
+            done();
+        });
+
+        Atomics.notify(i32, 0);
+    });
+});
+
+// The ordered lane rides the Java MessageQueue, so these callbacks must be
+// strict macrotasks: after the current turn's microtasks, FIFO with timers.
+describe("event loop ordered macrotasks", function () {
+    it("__ns__queueMacrotask runs the callback asynchronously", function (done) {
+        let ran = false;
+        __ns__queueMacrotask(() => {
+            ran = true;
+            done();
+        });
+        expect(ran).toBe(false);
+    });
+
+    it("runs after the current turn's microtasks", function (done) {
+        const order = [];
+        __ns__queueMacrotask(() => {
+            order.push("macrotask");
+            expect(order).toEqual(["microtask", "macrotask"]);
+            done();
+        });
+        Promise.resolve().then(() => order.push("microtask"));
+    });
+
+    // native timers (__ns__*): the app-level `setTimeout` global in this test
+    // app is an old Handler-based polyfill, not the runtime timers
+    it("stays FIFO-ordered with native setTimeout(0)", function (done) {
+        const order = [];
+        __ns__queueMacrotask(() => order.push("macro1"));
+        __ns__setTimeout(() => order.push("timeout"), 0);
+        __ns__queueMacrotask(() => {
+            order.push("macro2");
+            expect(order).toEqual(["macro1", "timeout", "macro2"]);
+            done();
+        });
+    });
+
+    it("rejects non-function arguments", function () {
+        expect(() => __ns__queueMacrotask("nope")).toThrowError(TypeError);
+        expect(() => __ns__queueMacrotask()).toThrowError(TypeError);
+    });
+
+    it("runs on the main thread when posted from a background JS thread", function (done) {
+        const mainThreadId = java.lang.Thread.currentThread().getId();
+        new java.lang.Thread(new java.lang.Runnable({
+            run() {
+                expect(java.lang.Thread.currentThread().getId()).not.toEqual(mainThreadId);
+                __ns__queueMacrotask(() => {
+                    expect(java.lang.Thread.currentThread().getId()).toEqual(mainThreadId);
+                    done();
+                });
+            }
+        })).start();
+    });
+});
+
+// clearTimeout leaves a tombstone in the merged ordered domain, so the
+// cleared timer's already-queued token consumes its own slot as a no-op
+// instead of running a later-scheduled item ahead of Java messages queued
+// between the two tokens' positions.
+describe("event loop ordered tombstones", function () {
+    it("cleared timeout's token does not run a later timer ahead of java posts", function (done) {
+        const order = [];
+        const handler = new android.os.Handler(android.os.Looper.myLooper());
+        const t1 = __ns__setTimeout(() => order.push("cleared"), 0);
+        __ns__clearTimeout(t1);
+        handler.post(new java.lang.Runnable({
+            run: () => order.push("java")
+        }));
+        __ns__setTimeout(() => {
+            order.push("t2");
+            expect(order).toEqual(["java", "t2"]);
+            done();
+        }, 0);
+    });
+
+    it("cleared timeout's token does not run a queued macrotask ahead of java posts", function (done) {
+        const order = [];
+        const handler = new android.os.Handler(android.os.Looper.myLooper());
+        const t1 = __ns__setTimeout(() => order.push("cleared"), 0);
+        __ns__clearTimeout(t1);
+        handler.post(new java.lang.Runnable({
+            run: () => order.push("java")
+        }));
+        __ns__queueMacrotask(() => {
+            order.push("macro");
+            expect(order).toEqual(["java", "macro"]);
+            done();
+        });
+    });
+});
+
+// Long (>=32ms) timers carry an identified token whose clear removes the
+// queued wakeup; short timers carry a native claim cell whose clear is a
+// single CAS. Both must keep exact clear semantics under any thread.
+describe("event loop token cancellation", function () {
+    it("cleared identified (long) timeout never fires and later timers are unaffected", function (done) {
+        let fired = false;
+        const t = __ns__setTimeout(() => { fired = true; }, 100);
+        __ns__clearTimeout(t);
+        __ns__setTimeout(() => {
+            expect(fired).toBe(false);
+            done();
+        }, 150);
+    });
+
+    it("background-thread clear racing dispatch neither jumps java posts nor ghost-fires", function (done) {
+        // only iterations whose clear provably ran count toward the quota, so
+        // the spec can't pass on 30 runs where the thread never raced at all
+        let remaining = 30;
+        let attempts = 0;
+        (function iter() {
+            if (++attempts > 300) {
+                expect("background clears raced " + (30 - remaining) + "/30 times")
+                    .toBe("background clears raced 30/30 times");
+                done();
+                return;
+            }
+            const order = [];
+            const cleared = new java.util.concurrent.atomic.AtomicBoolean(false);
+            const handler = new android.os.Handler(android.os.Looper.myLooper());
+            const t1 = __ns__setTimeout(() => order.push("t1"), 0);
+            new java.lang.Thread(new java.lang.Runnable({
+                run() {
+                    __ns__clearTimeout(t1);
+                    cleared.set(true);
+                }
+            })).start();
+            handler.post(new java.lang.Runnable({
+                run: () => order.push("java")
+            }));
+            __ns__setTimeout(() => {
+                order.push("t2");
+                const observed = order.join(">");
+                // t1 either fired before the clear landed (at its own legal
+                // slot, ahead of "java") or never; t2 must never jump "java"
+                expect(observed === "java>t2" || observed === "t1>java>t2").toBe(true);
+                if (cleared.get() && --remaining === 0) {
+                    done();
+                } else {
+                    iter();
+                }
+            }, 5);
+        })();
+    });
+
+    it("clearing an identified interval stops it", function (done) {
+        let ticks = 0;
+        const iv = __ns__setInterval(() => {
+            ticks++;
+            if (ticks === 2) {
+                __ns__clearInterval(iv);
+                __ns__setTimeout(() => {
+                    expect(ticks).toBe(2);
+                    done();
+                }, 120);
+            }
+        }, 40);
+    });
+});
+
+describe("event loop internal lane", function () {
+    // Regression for the eventfd unit-accounting bug: a worker reply's wakeup
+    // arriving while an overdue waitAsync timeout is still unsignaled must not
+    // be spent on the timeout entry, or the reply starves.
+    it("delivers worker messages whose wakeup raced an overdue waitAsync timeout", function (done) {
+        const worker = new Worker("./eventLoopEchoWorker.js");
+        let warm = false;
+        worker.onmessage = function (msg) {
+            if (msg.data === "warmup") {
+                warm = true;
+                const i32 = new Int32Array(new SharedArrayBuffer(4));
+                Atomics.waitAsync(i32, 0, 0, 50);
+                worker.postMessage("ping");
+                // block the looper until both the timeout and the reply are
+                // pending, so their wakeups are serviced from the same poll
+                const start = Date.now();
+                while (Date.now() - start < 150) { }
+            } else {
+                expect(warm).toBe(true);
+                expect(msg.data).toBe("ping");
+                worker.terminate();
+                done();
+            }
+        };
+        worker.postMessage("warmup");
+    });
+
+    it("keeps event loops healthy across worker churn", function (done) {
+        let remaining = 8;
+        (function cycle() {
+            const worker = new Worker("./eventLoopEchoWorker.js");
+            worker.onmessage = function () {
+                worker.terminate();
+                if (--remaining === 0) {
+                    __ns__queueMacrotask(done);
+                } else {
+                    cycle();
+                }
+            };
+            worker.postMessage("alive");
+        })();
+    });
+});
diff --git a/test-app/runtime/CMakeLists.txt b/test-app/runtime/CMakeLists.txt
@@ -69,7 +69,6 @@ set(RUNTIME_BUILTIN_JS
         ${RUNTIME_BUILTIN_JS_DIR}/events.js
         ${RUNTIME_BUILTIN_JS_DIR}/inspect.js
         ${RUNTIME_BUILTIN_JS_DIR}/json-helper.js
-        ${RUNTIME_BUILTIN_JS_DIR}/message-loop-timer.js
         ${RUNTIME_BUILTIN_JS_DIR}/node-util.js
         ${RUNTIME_BUILTIN_JS_DIR}/ns-util.js
         ${RUNTIME_BUILTIN_JS_DIR}/performance.js
@@ -152,8 +151,9 @@ add_library(
         src/main/cpp/Constants.cpp
         src/main/cpp/DirectBuffer.cpp
         src/main/cpp/ErrorEvents.cpp
-        src/main/cpp/FrameCallbacks.cpp
+        src/main/cpp/EventLoop.cpp
         src/main/cpp/Events.cpp
+        src/main/cpp/FrameCallbacks.cpp
         src/main/cpp/FieldAccessor.cpp
         src/main/cpp/File.cpp
         src/main/cpp/Interop.cpp
@@ -166,9 +166,7 @@ add_library(
         src/main/cpp/JsArgToArrayConverter.cpp
         src/main/cpp/JSONObjectHelper.cpp
         src/main/cpp/Logger.cpp
-        src/main/cpp/LooperTasks.cpp
         src/main/cpp/ManualInstrumentation.cpp
-        src/main/cpp/MessageLoopTimer.cpp
         src/main/cpp/MetadataMethodInfo.cpp
         src/main/cpp/MetadataNode.cpp
         src/main/cpp/MetadataReader.cpp
@@ -179,6 +177,7 @@ add_library(
         src/main/cpp/ModuleInternal.cpp
         src/main/cpp/ModuleInternalCallbacks.cpp
         src/main/cpp/NativeScriptException.cpp
+        src/main/cpp/NativeScriptPlatform.cpp
         src/main/cpp/NsBuiltinModules.cpp
         src/main/cpp/NumericCasts.cpp
         src/main/cpp/ObjectManager.cpp