Probe failures follow the compile branch's transient rules, strict on the native esp8266 job

tests/unit_tests/build_gen/test_arduino8266.py

@@ -1878,6 +1878,10 @@ def test_write_project_pch_strict_emits_probe_edge(
     )
     content = _write_ninja(paths, ccache="/usr/bin/ccache")
     assert "pchprobe esphome_pch.h.gch\n  flags = " in content
-    for line in content.splitlines():
-        if line.startswith("build obj/src/main.cpp.o:"):
-            assert line.endswith("| esphome_pch.h.gch esphome_pch.probe")
+    edges = [
+        line
+        for line in content.splitlines()
+        if line.startswith("build obj/src/") and ".cpp.o:" in line
+    ]
+    assert edges
+    assert all(line.endswith("| esphome_pch.h.gch esphome_pch.probe") for line in edges)

tests/unit_tests/build_gen/test_espidf.py

@@ -903,6 +903,32 @@ def test_prepare_pch_probe_spawn_failure_degrades(
         prepare_pch()
 
 
+def test_prepare_pch_probe_environmental_failures_do_not_latch(
+    tmp_path: Path,
+) -> None:
+    """A signal-killed or ENOSPC probe retries next build, no marker."""
+    from esphome.build_gen.espidf import prepare_pch
+
+    for stderr, code in (("", -9), ("fatal: No space left on device", 1)):
+        dev = _make_pch_device(tmp_path, f"dev_pe{code}")
+        CORE.build_path = dev
+        gch = dev / "build" / "esphome_pch.h.gch"
+
+        def env_probe(cmd, _gch=gch, _stderr=stderr, _code=code, **kwargs):
+            if "-fsyntax-only" in cmd:
+                return subprocess.CompletedProcess(cmd, _code, "", _stderr)
+            _gch.write_bytes(b"gch")
+            return subprocess.CompletedProcess(cmd, 0, "", "")
+
+        with (
+            patch.object(CORE, "name", "test"),
+            patch("esphome.build_helpers.pch.subprocess.run", side_effect=env_probe),
+        ):
+            prepare_pch()
+        assert not gch.exists()
+        assert not (dev / "build" / "esphome_pch.h.gch.failed").exists()
+
+
 def test_prepare_pch_signal_kill_strict_raises(
     tmp_path: Path, monkeypatch: pytest.MonkeyPatch
 ) -> None: