Merge remote-tracking branch 'upstream/decouple_scheduler_loop_cadence' into integration

# Conflicts:
#	esphome/core/application.h

tests/integration/fixtures/loop_interval_decoupling.yaml

@@ -0,0 +1,60 @@
+esphome:
+  name: loop-interval-decouple
+  on_boot:
+    priority: -100
+    then:
+      - lambda: |-
+          // Raise loop_interval_ to 500ms. With the decoupling fix the
+          // component phase should run ~twice per second while the 50ms
+          // scheduler interval below still fires at its requested cadence.
+          App.set_loop_interval(500);
+      # Start measurement after 1s so boot transients settle.
+      - delay: 1000ms
+      - lambda: |-
+          id(loop_at_start) = id(loop_counter)->get_loop_count();
+          id(sched_at_start) = id(sched_count);
+          ESP_LOGI("test", "MEASUREMENT_STARTED loop=%d sched=%d",
+                   id(loop_at_start), id(sched_at_start));
+      # Observe for 2s.
+      - delay: 2000ms
+      - lambda: |-
+          int loop_delta = id(loop_counter)->get_loop_count() - id(loop_at_start);
+          int sched_delta = id(sched_count) - id(sched_at_start);
+          ESP_LOGI("test", "MEASUREMENT_DONE loop_delta=%d sched_delta=%d",
+                   loop_delta, sched_delta);
+
+host:
+api:
+logger:
+  level: INFO
+  logs:
+    loop_test_component: WARN   # Silence per-loop log spam
+
+external_components:
+  - source:
+      type: local
+      path: EXTERNAL_COMPONENT_PATH
+
+globals:
+  - id: sched_count
+    type: int
+    initial_value: "0"
+  - id: loop_at_start
+    type: int
+    initial_value: "0"
+  - id: sched_at_start
+    type: int
+    initial_value: "0"
+
+loop_test_component:
+  components:
+    - id: loop_counter
+      name: loop_counter
+
+interval:
+  # Fast scheduler interval — with the decoupling fix this should fire at
+  # its requested 50ms cadence regardless of loop_interval_.
+  - interval: 50ms
+    then:
+      - lambda: |-
+          id(sched_count) += 1;

tests/integration/test_loop_interval_decoupling.py

@@ -0,0 +1,73 @@
+"""Test that loop_interval_ no longer clamps scheduler cadence.
+
+Regression test for the decoupling of Application::loop() component-phase
+cadence from scheduler wake timing.
+
+Setup:
+- App.set_loop_interval(500) — raised for power-savings style cadence
+- Scheduler interval at 50ms — should fire at 50ms regardless of loop_interval_
+- Component loop (LoopTestComponent) — should run at 500ms cadence
+
+Before the decoupling fix the old `std::max(next_schedule, delay_time / 2)`
+floor clamped the sleep to ~250ms, so the 50ms scheduler only fired ~8 times
+per 2s (vs the ~40 expected). After the fix the scheduler fires close to its
+requested cadence while the component phase stays gated at loop_interval_.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import re
+
+import pytest
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_loop_interval_decoupling(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Raised loop_interval_ must not clamp scheduler item cadence."""
+    loop = asyncio.get_running_loop()
+    measurement_done: asyncio.Future[tuple[int, int]] = loop.create_future()
+
+    def on_log_line(line: str) -> None:
+        match = re.search(r"MEASUREMENT_DONE loop_delta=(\d+) sched_delta=(\d+)", line)
+        if match and not measurement_done.done():
+            measurement_done.set_result((int(match.group(1)), int(match.group(2))))
+
+    async with (
+        run_compiled(yaml_config, line_callback=on_log_line),
+        api_client_connected() as client,
+    ):
+        device_info = await client.device_info()
+        assert device_info is not None
+        assert device_info.name == "loop-interval-decouple"
+
+        try:
+            loop_delta, sched_delta = await asyncio.wait_for(
+                measurement_done, timeout=10.0
+            )
+        except TimeoutError:
+            pytest.fail("MEASUREMENT_DONE marker never appeared")
+
+        # Observation window = 2s, loop_interval_ = 500ms.
+        # Component phase should fire ~4 times in 2s. The upper bound must be
+        # less than 8: the pre-decoupling behavior clamped to ~250ms cadence
+        # giving ~8 loops/2s, so allowing 8 would let the old behavior pass.
+        assert 2 <= loop_delta <= 6, (
+            f"Component loop should fire ~4 times in 2s at loop_interval=500ms, "
+            f"got {loop_delta}"
+        )
+
+        # Scheduler interval = 50ms → ~40 fires in 2s. Before the decoupling
+        # fix this clamped to ~8 fires. Assert >= 20 to catch the old clamped
+        # behavior with comfortable jitter headroom for slow CI hosts.
+        assert sched_delta >= 20, (
+            f"50ms scheduler interval should fire ~40 times in 2s but only "
+            f"fired {sched_delta}. This indicates loop_interval_ is still "
+            f"clamping scheduler cadence."
+        )