diff --git a/script/helpers.py b/script/helpers.py
index f897ab3053..199660b6a8 100644
--- a/script/helpers.py
+++ b/script/helpers.py
@@ -1126,7 +1126,7 @@ def get_fixture_to_test_files() -> dict[str, frozenset[str]]:
             result.setdefault(base_name, set()).add(rel_path)
         # Shared fixtures are named by marker, not by a test function
         names = _SHARED_YAML_RE.findall(content)
-        if len(names) != content.count("shared_yaml("):
+        if len(names) != content.count("pytest.mark.shared_yaml("):
             # A wrapped or non-literal marker would silently drop the mapping
             # and CI would select no tests for that fixture
             raise ValueError(
diff --git a/tests/integration/conftest.py b/tests/integration/conftest.py
index 15fecb9b62..2318dab39f 100644
--- a/tests/integration/conftest.py
+++ b/tests/integration/conftest.py
@@ -362,7 +362,8 @@ def _prune_stale_builds(name: str, keep: Path) -> None:
     for stale in SHARED_BUILDS_ROOT.iterdir():
         if stale == keep:
             continue
-        if not stale.name.startswith(prefix) and not _unused_since(stale, cutoff):
+        same_fixture = stale.name.startswith(prefix)
+        if not same_fixture and not _unused_since(stale, cutoff):
             continue
         try:
             lock_file = (stale / ".lock").open("w")
@@ -376,6 +377,10 @@ def _prune_stale_builds(name: str, keep: Path) -> None:
                 fcntl.flock(lock_file.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
             except BlockingIOError:
                 continue  # still in use by another run
+            # Re-probe under the lock: a worker freshens its dir before
+            # locking, so a just-claimed dir no longer looks unused
+            if not same_fixture and not _unused_since(stale, cutoff):
+                continue
             # rmtree tolerates races; a leftover partial tree only costs a
             # rebuild, since the ELF is deleted before every compile
             try:
@@ -464,6 +469,9 @@ async def compile_esphome(
         # pay one full compile and later only a main.cpp (port) rebuild + relink
         shared_dir = _shared_build_dir(name)
         shared_dir.mkdir(parents=True, exist_ok=True)
+        # Freshen the dir before locking so a concurrent age sweep, which
+        # re-probes under the lock, never reaps a dir a worker just claimed
+        os.utime(shared_dir)
         if shared_dir not in _pruned_dirs:
             _pruned_dirs.add(shared_dir)
             await loop.run_in_executor(None, _prune_stale_builds, name, shared_dir)
diff --git a/tests/integration/host_prefs.py b/tests/integration/host_prefs.py
index c7f21d8a01..82569a5d66 100644
--- a/tests/integration/host_prefs.py
+++ b/tests/integration/host_prefs.py
@@ -11,13 +11,19 @@ boot (e.g. forcing safe mode) or to clear stale state between runs.
 
 from __future__ import annotations
 
+import os
 from pathlib import Path
 import struct
 
 
 def host_prefs_path(device_name: str) -> Path:
-    """Return the on-disk prefs file path for a host-platform device."""
-    return Path.home() / ".esphome" / "prefs" / f"{device_name}.prefs"
+    """Return the on-disk prefs file path for a host-platform device.
+
+    Honors ESPHOME_PREFDIR, which the autouse isolated_preferences fixture
+    sets, so seeds land where the binary will look."""
+    prefdir = os.environ.get("ESPHOME_PREFDIR")
+    base = Path(prefdir) if prefdir else Path.home() / ".esphome" / "prefs"
+    return base / f"{device_name}.prefs"
 
 
 def clear_host_prefs(device_name: str) -> None:
diff --git a/tests/script/test_helpers.py b/tests/script/test_helpers.py
index 99a795a5c1..8f82a121c6 100644
--- a/tests/script/test_helpers.py
+++ b/tests/script/test_helpers.py
@@ -2141,11 +2141,11 @@ def test_no_orphan_integration_fixtures() -> None:
     helpers.get_fixture_to_test_files.cache_clear()
     mapping = helpers.get_fixture_to_test_files()
     fixtures_dir = (Path(__file__).parent.parent / "integration" / "fixtures").resolve()
+    fixtures = list(fixtures_dir.glob("*.yaml"))
+    assert fixtures, f"no fixtures found under {fixtures_dir}"
     # cache_init is covered via INTEGRATION_TESTS_TRIGGER_FILES instead
     orphans = [
-        f.stem
-        for f in fixtures_dir.glob("*.yaml")
-        if f.stem != "cache_init" and f.stem not in mapping
+        f.stem for f in fixtures if f.stem != "cache_init" and f.stem not in mapping
     ]
     assert not orphans, f"fixtures invisible to CI test selection: {orphans}"