diff --git a/c/coli b/c/coli
index 8c89caf..9408281 100755
--- a/c/coli
+++ b/c/coli
@@ -161,6 +161,34 @@ def resource_request(a, env):
 
 def env_for(a):
     e = dict(os.environ, SNAP=a.model)
+    if sys.platform == "win32":
+        # COLI_NO_OMP_TUNE spegne SOLO il blocco OMP (stesso perimetro del
+        # self-exec di glm.c; presence-based come nel motore: impostarla a
+        # qualsiasi valore, anche 0, disattiva). I default I/O piu' sotto
+        # restano attivi: kill-switch dedicati = le var stesse (DIRECT=0 ecc.)
+        if not e.get("COLI_NO_OMP_TUNE"):
+            # parita' col tuning OMP self-exec di glm.c (solo Linux/FreeBSD, e
+            # comunque saltato sotto CUDA/Metal): libgomp legge queste variabili
+            # prima di main, quindi su Windows vanno nell'ambiente del figlio.
+            # niente OMP_PROC_BIND/OMP_PLACES: la libgomp di MinGW non supporta
+            # l'affinity su Windows ("Affinity not supported on this configuration")
+            from resource_plan import physical_cpu_count
+            for k, v in (("OMP_WAIT_POLICY", "active"),
+                         ("GOMP_SPINCOUNT", "200000"),
+                         ("OMP_DYNAMIC", "FALSE"),
+                         ("OMP_NUM_THREADS", str(physical_cpu_count()))):
+                e.setdefault(k, v)
+        # Default Windows misurati sul box di riferimento (docs/tuning-9950x3d-5090.md),
+        # tutti lossless e tutti setdefault (un override esplicito vince sempre):
+        # - DIRECT=1: 10.7 GB/s O_DIRECT vs 9.0 buffered (iobench, anche a cache
+        #   calda); nel motore 0.48 -> 1.02 tok/s. Upstream #162: 1.47x.
+        # - PIPE=1: overlap load/matmul, +8% sopra DIRECT (byte-identico, riordina
+        #   solo l'I/O). PIPE_WORKERS resta al default 8 (sweep 4/8/16 piatto).
+        # - PILOT_REAL=1: prefetch cross-layer con load veri (unico prefetch
+        #   funzionante su Windows: fadvise e' no-op), +11%, hit rate +19 punti.
+        e.setdefault("DIRECT", "1")
+        e.setdefault("PIPE", "1")
+        e.setdefault("PILOT_REAL", "1")
     e["COLI_POLICY"]=a.policy
     if a.ram:  e["RAM_GB"]=str(a.ram)
     if a.ngen: e["NGEN"]=str(a.ngen)
diff --git a/c/resource_plan.py b/c/resource_plan.py
index 7258180..6b3f2fe 100644
--- a/c/resource_plan.py
+++ b/c/resource_plan.py
@@ -313,8 +313,11 @@ def environment_for_plan(plan, env=None, cuda_enabled=True):
     result = dict(env or {})
     result.setdefault("COLI_POLICY", plan["policy"]["name"])
     result.setdefault("OMP_NUM_THREADS", str(plan["cpu"]["physical_cores"]))
-    result.setdefault("OMP_PROC_BIND", "spread")
-    result.setdefault("OMP_PLACES", "cores")
+    if sys.platform != "win32":
+        # la libgomp di MinGW non supporta l'affinity su Windows
+        # ("Affinity not supported on this configuration"): non impostarle li'.
+        result.setdefault("OMP_PROC_BIND", "spread")
+        result.setdefault("OMP_PLACES", "cores")
     if plan["policy"]["name"] == "balanced":
         result.setdefault("REPIN", "64")
     ram = plan["tiers"]["ram"]
diff --git a/c/tests/test_env_defaults.py b/c/tests/test_env_defaults.py
new file mode 100644
index 0000000..12a3c99
--- /dev/null
+++ b/c/tests/test_env_defaults.py
@@ -0,0 +1,68 @@
+"""env_for: default Windows misurati (DIRECT/PIPE/PILOT_REAL + blocco OMP).
+
+Carica `coli` come modulo (ha la guardia __main__) e verifica il contratto:
+- win32: i tre default I/O e il blocco OMP sono setdefault
+- un override esplicito dell'utente vince sempre
+- COLI_NO_OMP_TUNE spegne SOLO il blocco OMP, non i default I/O
+- non-win32: env_for non tocca nulla di tutto questo
+"""
+import importlib.machinery
+import importlib.util
+import os
+import sys
+import types
+import unittest
+from pathlib import Path
+from unittest import mock
+
+HERE = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(HERE))
+
+_loader = importlib.machinery.SourceFileLoader("coli_cli", str(HERE / "coli"))
+_spec = importlib.util.spec_from_loader("coli_cli", _loader)
+coli = importlib.util.module_from_spec(_spec)
+_loader.exec_module(coli)
+
+
+def args(**over):
+    base = dict(model="X", policy="quality", ram=0, ngen=0, topp=0, topk=0,
+                temp=None, repin=0, ctx=0, auto_tier=False, gpu=None, vram=0)
+    base.update(over)
+    return types.SimpleNamespace(**base)
+
+
+class EnvDefaultsTest(unittest.TestCase):
+    def env_for_with(self, environ, platform):
+        with mock.patch.dict(os.environ, environ, clear=True), \
+             mock.patch.object(sys, "platform", platform):
+            return coli.env_for(args())
+
+    def test_win32_sets_measured_defaults(self):
+        e = self.env_for_with({}, "win32")
+        self.assertEqual(e["DIRECT"], "1")
+        self.assertEqual(e["PIPE"], "1")
+        self.assertEqual(e["PILOT_REAL"], "1")
+        self.assertEqual(e["OMP_WAIT_POLICY"], "active")
+        self.assertNotIn("OMP_PROC_BIND", e)  # MinGW libgomp: niente affinity
+
+    def test_explicit_override_wins(self):
+        e = self.env_for_with({"DIRECT": "0", "PIPE": "0"}, "win32")
+        self.assertEqual(e["DIRECT"], "0")
+        self.assertEqual(e["PIPE"], "0")
+        self.assertEqual(e["PILOT_REAL"], "1")  # non overridden -> default
+
+    def test_kill_switch_scope_is_omp_only(self):
+        e = self.env_for_with({"COLI_NO_OMP_TUNE": "1"}, "win32")
+        self.assertNotIn("OMP_WAIT_POLICY", e)
+        self.assertNotIn("OMP_NUM_THREADS", e)
+        self.assertEqual(e["DIRECT"], "1")   # i default I/O restano attivi
+        self.assertEqual(e["PIPE"], "1")
+
+    def test_non_windows_untouched(self):
+        e = self.env_for_with({}, "linux")
+        for k in ("DIRECT", "PIPE", "PILOT_REAL", "OMP_WAIT_POLICY"):
+            self.assertNotIn(k, e)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/c/tests/test_resource_plan.py b/c/tests/test_resource_plan.py
index 5a89773..023cb93 100644
--- a/c/tests/test_resource_plan.py
+++ b/c/tests/test_resource_plan.py
@@ -112,8 +112,13 @@ class ResourcePlanTest(unittest.TestCase):
         self.assertEqual(env["COLI_CUDA"], "1")
         self.assertEqual(env["COLI_GPUS"], "1")
         self.assertEqual(env["OMP_NUM_THREADS"], str(plan["cpu"]["physical_cores"]))
-        self.assertEqual(env["OMP_PROC_BIND"], "spread")
-        self.assertEqual(env["OMP_PLACES"], "cores")
+        if sys.platform == "win32":
+            # MinGW libgomp: niente affinity su Windows, le chiavi non vanno emesse
+            self.assertNotIn("OMP_PROC_BIND", env)
+            self.assertNotIn("OMP_PLACES", env)
+        else:
+            self.assertEqual(env["OMP_PROC_BIND"], "spread")
+            self.assertEqual(env["OMP_PLACES"], "cores")
         self.assertEqual(env["PIN_GB"], env["CUDA_EXPERT_GB"])
 
         explicit_threads = environment_for_plan(plan, {"OMP_NUM_THREADS": "7",