diff --git a/.github/workflows/run-unit-tests.yml b/.github/workflows/run-unit-tests.yml
index 3d65e7542..6bd6de21d 100644
--- a/.github/workflows/run-unit-tests.yml
+++ b/.github/workflows/run-unit-tests.yml
@@ -804,6 +804,7 @@ jobs:
           python3 -B test/test_notification_settings.py
           python3 -B test/test_notification_led_ownership.py -v
           python3 -B test/test_mono_led_rollover.py -v
+          python3 -B test/test_backlight_poll_rollover.py -v
           python3 -B test/test_display_power.py
           python3 -B test/test_legacy_ui_version_bounds.py -v
           python3 -B test/test_ssd1306_power.py -v
diff --git a/examples/companion_radio/ui-new/UITask.cpp b/examples/companion_radio/ui-new/UITask.cpp
index 2d05211a6..2e1d3d1dd 100644
--- a/examples/companion_radio/ui-new/UITask.cpp
+++ b/examples/companion_radio/ui-new/UITask.cpp
@@ -2444,13 +2444,17 @@ void UITask::loop() {
   }
 #endif
 #if defined(BACKLIGHT_BTN)
-  if (millis() > next_backlight_btn_check) {
-    static bool was_pressed = false;
+  // First-poll state must not collide with a completed poll at timestamp zero.
+  enum class BacklightButtonState : uint8_t { Unseen, Released, Pressed };
+  static BacklightButtonState button_state = BacklightButtonState::Unseen;
+  const uint32_t backlight_now = millis();
+  if (button_state == BacklightButtonState::Unseen ? backlight_now > 0
+      : static_cast<uint32_t>(backlight_now - last_backlight_btn_check) > 300) {
     const bool pressed = digitalRead(PIN_BUTTON2) == LOW;
-    if (pressed && !was_pressed && _display != NULL)
+    if (pressed && button_state != BacklightButtonState::Pressed && _display != NULL)
       _display->wake(mesh::ui::DisplayWake::Button);
-    was_pressed = pressed;
-    next_backlight_btn_check = millis() + 300;
+    button_state = pressed ? BacklightButtonState::Pressed : BacklightButtonState::Released;
+    last_backlight_btn_check = millis();
   }
 #endif
 
diff --git a/examples/companion_radio/ui-new/UITask.h b/examples/companion_radio/ui-new/UITask.h
index e9186fca8..ad0bab61c 100644
--- a/examples/companion_radio/ui-new/UITask.h
+++ b/examples/companion_radio/ui-new/UITask.h
@@ -48,7 +48,7 @@ class UITask : public AbstractUITask {
   int _msgcount;
   unsigned long ui_started_at;
   uint32_t next_batt_chck;
-  int next_backlight_btn_check = 0;
+  uint32_t last_backlight_btn_check = 0;
 #ifdef HAS_TOUCH
   #ifndef TOUCH_CENTER_ZONE_PERCENT
     #define TOUCH_CENTER_ZONE_PERCENT 34
diff --git a/examples/companion_radio/ui-tiny/UITask.cpp b/examples/companion_radio/ui-tiny/UITask.cpp
index 515db50e6..5ef36b6fa 100644
--- a/examples/companion_radio/ui-tiny/UITask.cpp
+++ b/examples/companion_radio/ui-tiny/UITask.cpp
@@ -940,13 +940,17 @@ void UITask::loop() {
   }
 #endif
 #if defined(BACKLIGHT_BTN)
-  if (millis() > next_backlight_btn_check) {
-    static bool was_pressed = false;
+  // First-poll state must not collide with a completed poll at timestamp zero.
+  enum class BacklightButtonState : uint8_t { Unseen, Released, Pressed };
+  static BacklightButtonState button_state = BacklightButtonState::Unseen;
+  const uint32_t backlight_now = millis();
+  if (button_state == BacklightButtonState::Unseen ? backlight_now > 0
+      : static_cast<uint32_t>(backlight_now - last_backlight_btn_check) > 300) {
     const bool pressed = digitalRead(PIN_BUTTON2) == LOW;
-    if (pressed && !was_pressed && _display != NULL)
+    if (pressed && button_state != BacklightButtonState::Pressed && _display != NULL)
       _display->wake(mesh::ui::DisplayWake::Button);
-    was_pressed = pressed;
-    next_backlight_btn_check = millis() + 300;
+    button_state = pressed ? BacklightButtonState::Pressed : BacklightButtonState::Released;
+    last_backlight_btn_check = millis();
   }
 #endif
 #if defined(HAS_TORCH)
diff --git a/examples/companion_radio/ui-tiny/UITask.h b/examples/companion_radio/ui-tiny/UITask.h
index 25d0fd08e..e92705413 100644
--- a/examples/companion_radio/ui-tiny/UITask.h
+++ b/examples/companion_radio/ui-tiny/UITask.h
@@ -47,7 +47,7 @@ class UITask : public AbstractUITask {
   int _msgcount;
   unsigned long ui_started_at;
   uint32_t next_batt_chck;
-  int next_backlight_btn_check = 0;
+  uint32_t last_backlight_btn_check = 0;
   uint16_t _cached_batt_mv;
 #ifdef PIN_STATUS_LED
   int led_state = 0;
diff --git a/test/fixtures/backlight_poll_rollover.cpp b/test/fixtures/backlight_poll_rollover.cpp
new file mode 100644
index 000000000..30cb143b7
--- /dev/null
+++ b/test/fixtures/backlight_poll_rollover.cpp
@@ -0,0 +1,181 @@
+// Actual guarded loop block and timer field are injected without rewriting.
+// Only Arduino clock/GPIO and display wake are host boundary adapters.
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+static uint32_t clock_ms = 0;
+uint32_t millis() { return clock_ms; }
+static unsigned reads = 0, wakes = 0;
+static uint32_t read_duration = 0, wake_duration = 0;
+static bool pin_pressed = false;
+static const char* active_case = "startup";
+static unsigned checks = 0;
+#define CHECK(value) do { \
+  ++checks; \
+  if (!(value)) { \
+    std::fprintf(stderr, "FAIL %s: %s (line %d)\n", active_case, #value, __LINE__); \
+    std::exit(1); \
+  } \
+} while (0)
+
+#if defined(BACKLIGHT_BTN)
+constexpr unsigned LOW = 0, HIGH = 1;
+int digitalRead(unsigned pin) {
+  CHECK(pin == PIN_BUTTON2);
+  ++reads;
+  clock_ms += read_duration;
+  return pin_pressed ? LOW : HIGH;
+}
+#endif
+
+namespace mesh { namespace ui { enum class DisplayWake { Button }; } }
+struct DisplayDriver {
+  void wake(mesh::ui::DisplayWake reason) {
+    CHECK(reason == mesh::ui::DisplayWake::Button);
+    ++wakes;
+    clock_ms += wake_duration;
+  }
+} display;
+
+struct UITask {
+  @FIELD@
+  DisplayDriver* _display = &display;
+  void poll() {
+@BLOCK@
+  }
+};
+
+static void at(UITask& ui, uint32_t now, bool pressed,
+               unsigned expected_reads, unsigned expected_wakes) {
+  clock_ms = now;
+  pin_pressed = pressed;
+  ui.poll();
+  CHECK(reads == expected_reads);
+  CHECK(wakes == expected_wakes);
+}
+
+#if defined(BACKLIGHT_BTN)
+static void cadence(UITask& ui, uint32_t start, bool initially_pressed) {
+  const unsigned first_wake = initially_pressed ? 1 : 0;
+  at(ui, start, initially_pressed, 1, first_wake);
+  at(ui, start, initially_pressed, 1, first_wake);
+  at(ui, start + 1, !initially_pressed, 1, first_wake);
+  at(ui, start + 300, !initially_pressed, 1, first_wake);
+  at(ui, start + 301, !initially_pressed, 2, 1);
+  at(ui, start + 301, !initially_pressed, 2, 1);
+}
+#endif
+
+// Every case is a fresh process: real static sampled-button state is retained.
+int main(int argc, char** argv) {
+  CHECK(argc == 2);
+  active_case = argv[1];
+  UITask ui;
+  const char* name = argv[1];
+#if defined(BACKLIGHT_BTN)
+  if (!std::strcmp(name, "zero")) {
+    at(ui, 0, true, 0, 0);
+    cadence(ui, 1, true);
+  } else if (!std::strcmp(name, "upper")) {
+    cadence(ui, 0x80000000u, false);
+  } else if (!std::strcmp(name, "upper-pressed")) {
+    cadence(ui, 0x80000000u, true);
+  } else if (!std::strcmp(name, "max")) {
+    cadence(ui, UINT32_MAX, false);
+  } else if (!std::strcmp(name, "normal")) {
+    cadence(ui, 100, false);
+  } else if (!std::strcmp(name, "signed-boundary")) {
+    cadence(ui, 0x7fffffffu - 150, false);
+  } else if (!std::strcmp(name, "wrap-visible")) {
+    cadence(ui, UINT32_MAX - 15, false);
+  } else if (!std::strcmp(name, "wrap-wake")) {
+    at(ui, UINT32_MAX - 310, false, 1, 0);
+    at(ui, 20, true, 2, 1);
+    at(ui, 20, true, 2, 1);
+  } else if (!std::strcmp(name, "deadline-zero")) {
+    cadence(ui, uint32_t(0u - 300u), false);
+  } else if (!std::strcmp(name, "held")) {
+    at(ui, 1, true, 1, 1);
+    at(ui, 302, true, 2, 1);
+    at(ui, 603, true, 3, 1);
+    at(ui, 904, false, 4, 1);
+    at(ui, 1205, true, 5, 2);
+  } else if (!std::strcmp(name, "unobserved-release")) {
+    at(ui, 1, true, 1, 1);
+    at(ui, 100, false, 1, 1);
+    at(ui, 101, true, 1, 1);
+    at(ui, 302, true, 2, 1);
+  } else if (!std::strcmp(name, "null-pressed")) {
+    ui._display = nullptr;
+    at(ui, 1, true, 1, 0);
+    ui._display = &display;
+    at(ui, 302, true, 2, 0);
+    at(ui, 603, false, 3, 0);
+    at(ui, 904, true, 4, 1);
+  } else if (!std::strcmp(name, "null-released")) {
+    ui._display = nullptr;
+    at(ui, 1, false, 1, 0);
+    ui._display = &display;
+    at(ui, 302, true, 2, 1);
+  } else if (!std::strcmp(name, "completion")) {
+    read_duration = 7;
+    wake_duration = 37;
+    at(ui, 100, true, 1, 1);
+    CHECK(clock_ms == 144);
+    read_duration = wake_duration = 0;
+    at(ui, 444, false, 1, 1);
+    at(ui, 445, false, 2, 1);
+    at(ui, 745, true, 2, 1);
+    at(ui, 746, true, 3, 2);
+  } else if (!std::strcmp(name, "completion-zero-wake")) {
+    wake_duration = 11;
+    at(ui, UINT32_MAX - 10, true, 1, 1);
+    CHECK(clock_ms == 0);
+    wake_duration = 0;
+    at(ui, 0, true, 1, 1);
+    at(ui, 1, true, 1, 1);
+    at(ui, 300, false, 1, 1);
+    at(ui, 301, false, 2, 1);
+  } else if (!std::strcmp(name, "completion-zero-read")) {
+    read_duration = 11;
+    at(ui, UINT32_MAX - 10, false, 1, 0);
+    CHECK(clock_ms == 0);
+    read_duration = 0;
+    at(ui, 0, true, 1, 0);
+    at(ui, 300, true, 1, 0);
+    at(ui, 301, true, 2, 1);
+  } else if (!std::strcmp(name, "long-released")) {
+    at(ui, 1, false, 1, 0);
+    at(ui, 1u + 26u * 24u * 60u * 60u * 1000u, true, 2, 1);
+  } else if (!std::strcmp(name, "long-pressed")) {
+    at(ui, 1, true, 1, 1);
+    const uint32_t later = 1u + 26u * 24u * 60u * 60u * 1000u;
+    at(ui, later, true, 2, 1);
+    at(ui, later + 301, false, 3, 1);
+    at(ui, later + 602, true, 4, 2);
+  } else if (!std::strcmp(name, "near-full-cycle")) {
+    at(ui, 100, false, 1, 0);
+    at(ui, uint32_t(100u + UINT32_MAX - 1000u), true, 2, 1);
+  } else if (!std::strcmp(name, "late-one-poll")) {
+    at(ui, 1, false, 1, 0);
+    at(ui, 100000, true, 2, 1);
+    at(ui, 100000, false, 2, 1);
+    at(ui, 100300, false, 2, 1);
+    at(ui, 100301, false, 3, 1);
+  } else {
+    std::fprintf(stderr, "unknown case: %s\n", name);
+    return 2;
+  }
+#else
+  CHECK(std::strcmp(name, "no-feature") == 0);
+  const uint32_t stamps[] = {0u, 1u, 0x7fffffffu, 0x80000000u, UINT32_MAX};
+  for (uint32_t stamp : stamps) {
+    at(ui, stamp, true, 0, 0);
+    at(ui, stamp, false, 0, 0);
+  }
+  CHECK(read_duration == 0 && wake_duration == 0);
+#endif
+  std::printf("PASS %s: %u checks\n", name, checks);
+}
diff --git a/test/test_backlight_poll_rollover.py b/test/test_backlight_poll_rollover.py
new file mode 100644
index 000000000..a370e3f5d
--- /dev/null
+++ b/test/test_backlight_poll_rollover.py
@@ -0,0 +1,114 @@
+"""Compile actual guarded backlight polling with original timer initialization.
+
+Both UI paths are fixture-enabled, plus feature-disabled controls. Current
+normal BACKLIGHT_BTN recipes select ui-new; ui-tiny is consistency coverage.
+Arduino clock/GPIO and display wake are host fakes, not hardware sleep tests.
+"""
+from pathlib import Path
+import os
+import re
+import shutil
+import subprocess
+import tempfile
+import unittest
+
+from test_replay_reset_integration import extract_braced
+
+ROOT = Path(__file__).resolve().parents[1]
+FIXTURE = ROOT / 'test/fixtures/backlight_poll_rollover.cpp'
+UIS = ('ui-new', 'ui-tiny')
+CASES = ('zero', 'upper', 'upper-pressed', 'max', 'normal', 'signed-boundary',
+         'wrap-visible', 'wrap-wake', 'deadline-zero', 'held', 'unobserved-release',
+         'null-pressed', 'null-released', 'completion', 'completion-zero-wake',
+         'completion-zero-read', 'long-released', 'long-pressed', 'near-full-cycle',
+         'late-one-poll')
+
+
+def production(ui):
+    prefix = ROOT / 'examples/companion_radio' / ui
+    source = (prefix / 'UITask.cpp').read_text(encoding='ascii')
+    header = (prefix / 'UITask.h').read_text(encoding='ascii')
+    first = source.index('#if defined(BACKLIGHT_BTN)')
+    block = source[first:source.index('#endif', first) + len('#endif')]
+    field = re.search(r'^  (?:int|uint32_t) (?:next|last)_backlight_btn_check = 0;',
+                      header, re.MULTILINE).group()
+    return source, field, block
+
+
+def harness(ui, mutation=None):
+    _, field, block = production(ui)
+    if mutation == 'level-wake':
+        block, count = re.subn(r'pressed\s*&&\s*button_state\s*!=\s*BacklightButtonState::Pressed\s*&&',
+                               'pressed &&', block, count=1)
+        if count != 1:
+            raise AssertionError('backlight wake must recognize a newly sampled press')
+    elif mutation == 'entry-anchor':
+        old = 'last_backlight_btn_check = millis();'
+        if block.count(old) != 1:
+            raise AssertionError('backlight timestamp must be anchored after I/O and wake')
+        block = block.replace(old, 'last_backlight_btn_check = backlight_now;', 1)
+    return FIXTURE.read_text(encoding='ascii').replace('@FIELD@', field).replace('@BLOCK@', block)
+
+
+class BacklightPollRolloverTest(unittest.TestCase):
+    def test_actual_polling_wrap_cadence_and_button_state(self):
+        self.run_variants()
+
+    def test_block_remains_in_live_loop_with_32bit_timer(self):
+        for ui in UIS:
+            with self.subTest(ui=ui):
+                source, field, block = production(ui)
+                self.assertEqual(field.strip(), 'uint32_t last_backlight_btn_check = 0;')
+                loop = extract_braced(source, 'void UITask::loop()')
+                self.assertEqual(loop.count(block), 1)
+                self.assertLess(loop.index(block), loop.index('userLedHandler();'))
+                self.assertIn('digitalRead(PIN_BUTTON2) == LOW', block)
+                self.assertIn('_display->wake(mesh::ui::DisplayWake::Button)', block)
+
+    def test_held_level_wake_regression_is_rejected(self):
+        self.run_variants('level-wake', ('held',), 'FAIL held: wakes == expected_wakes')
+
+    def test_entry_anchoring_regression_is_rejected(self):
+        self.run_variants('entry-anchor', ('completion',), 'FAIL completion: reads == expected_reads')
+
+    def run_variants(self, mutation=None, cases=CASES, expected_failure=None):
+        compiler = shutil.which('g++') or shutil.which('clang++')
+        if compiler is None:
+            self.skipTest('a host C++17 compiler is required')
+        sanitize = [] if os.name == 'nt' else [
+            '-fsanitize=address,undefined', '-fno-sanitize-recover=all', '-fno-pie', '-no-pie']
+        with tempfile.TemporaryDirectory(prefix='backlight-poll-rollover-') as directory:
+            work = Path(directory)
+            for ui in UIS:
+                source = work / (ui + '.cpp')
+                source.write_text(harness(ui, mutation), encoding='ascii')
+                for enabled in (True,) if mutation else (True, False):
+                    with self.subTest(ui=ui, enabled=enabled):
+                        binary = work / (ui + '-' + str(int(enabled)) +
+                                         ('.exe' if os.name == 'nt' else ''))
+                        # A disabled build deliberately has no PIN_BUTTON2/LOW
+                        # definitions: accidental unguarded I/O cannot compile.
+                        macros = ['-DBACKLIGHT_BTN=PIN_BUTTON2', '-DPIN_BUTTON2=14'] if enabled else []
+                        built = subprocess.run([
+                            compiler, '-std=c++17', '-O1', '-g', '-Wall', '-Wextra', '-Werror',
+                            *sanitize, *macros, str(source), '-o', str(binary),
+                        ], capture_output=True, text=True, timeout=60)
+                        self.assertEqual(built.returncode, 0, built.stdout + built.stderr)
+                        # Preserve the real function-static sampled state by
+                        # launching a fresh process, not resetting fake statics.
+                        for case in cases if enabled else ('no-feature',):
+                            with self.subTest(case=case):
+                                tested = subprocess.run([str(binary), case], capture_output=True,
+                                                        text=True, timeout=10)
+                                if expected_failure:
+                                    self.assertEqual(tested.returncode, 1, tested.stdout + tested.stderr)
+                                    self.assertIn(expected_failure, tested.stderr)
+                                    self.assertNotIn('AddressSanitizer:', tested.stderr)
+                                    self.assertNotIn('runtime error:', tested.stderr)
+                                else:
+                                    self.assertEqual(tested.returncode, 0, tested.stdout + tested.stderr)
+                                    self.assertRegex(tested.stdout, r'PASS ' + case + r': \d+ checks')
+
+
+if __name__ == '__main__':
+    unittest.main()