fix(nrf52): avoid CCCD flash reset on Full Companion

platformio.ini

@@ -155,6 +155,7 @@ platform_packages =
 extra_scripts = create-uf2.py
   pre:scripts/nrf52_usb_power_fix.py
   pre:scripts/nrf52_internal_flash_fix.py
+  pre:scripts/nrf52_ble_cccd_fix.py
   pre:scripts/nrf52_internal_bootloader_link.py
   ; Nordic's builder otherwise overwrites the LTO-aware archive tools.
   pre:scripts/nrf52_lto_toolchain.py

scripts/nrf52_ble_cccd_fix.py

@@ -0,0 +1,53 @@
+"""Avoid Bluefruit's unstable live CCCD persistence on nRF52 Full Companions.
+
+The pinned core saves every bonded CCCD write from its callback worker into
+InternalFS. On a T1000-E Full Companion this reproducibly resets the radio as
+the client enables notifications, even after formatting InternalFS. Bond-key
+persistence still works. The Companion client re-subscribes on connection;
+this workaround sacrifices CCCD persistence, not key-based reconnection.
+Patch a private build copy; never edit PlatformIO's shared framework cache.
+"""
+
+from pathlib import Path
+
+
+OLD_SAVE = """      {
+        conn->saveCccd();
+      }
+"""
+FIXED_SAVE = """      {
+#if !defined(COMPANION_RADIO_FULL) || !COMPANION_RADIO_FULL
+        conn->saveCccd();
+#endif
+      }
+"""
+
+
+def patched_source(source):
+    source = source.replace("\r\n", "\n")
+    if FIXED_SAVE in source and OLD_SAVE not in source:
+        return source
+    if source.count(OLD_SAVE) != 1:
+        raise RuntimeError(
+            "nRF52 BLE CCCD fix: unrecognized framework source; review before building"
+        )
+    return source.replace(OLD_SAVE, FIXED_SAVE)
+
+
+def replace_framework_source(build_env, node):
+    source = Path(node.srcnode().get_abspath())
+    if source.name != "BLEGatt.cpp" or source.parent.name != "src":
+        return node
+    patched = patched_source(source.read_text(encoding="utf-8"))
+    build_env.AppendUnique(CPPPATH=[str(source.parent)])
+    destination = Path(build_env.subst("$BUILD_DIR")) / "patched-nrf52-ble" / "BLEGatt.cpp"
+    destination.parent.mkdir(parents=True, exist_ok=True)
+    if not destination.exists() or destination.read_text(encoding="utf-8") != patched:
+        destination.write_text(patched, encoding="utf-8")
+    print("nRF52 BLE: Full Companion CCCD persistence workaround enabled")
+    return build_env.File(str(destination))
+
+
+if "Import" in globals():
+    Import("env")
+    env.AddBuildMiddleware(replace_framework_source, "*BLEGatt.cpp")

test/test_nrf52_ble_cccd_fix.py

@@ -0,0 +1,32 @@
+"""Guard the nRF52 Full Companion CCCD build-local workaround."""
+
+from importlib.util import module_from_spec, spec_from_file_location
+from pathlib import Path
+import unittest
+
+
+ROOT = Path(__file__).resolve().parents[1]
+SCRIPT = ROOT / "scripts/nrf52_ble_cccd_fix.py"
+spec = spec_from_file_location("nrf52_ble_cccd_fix", SCRIPT)
+module = module_from_spec(spec)
+spec.loader.exec_module(module)
+
+
+class Nrf52BleCccdFixTest(unittest.TestCase):
+    def test_only_full_companions_skip_persistence(self):
+        patched = module.patched_source("before\n" + module.OLD_SAVE + "after\n")
+        self.assertIn("!defined(COMPANION_RADIO_FULL) || !COMPANION_RADIO_FULL", patched)
+        self.assertIn("conn->saveCccd();", patched)
+        self.assertEqual(module.patched_source(patched), patched)
+
+    def test_unrecognized_core_fails_closed(self):
+        with self.assertRaises(RuntimeError):
+            module.patched_source("changed SDK layout")
+
+    def test_nrf52_base_loads_workaround(self):
+        ini = (ROOT / "platformio.ini").read_text(encoding="utf-8")
+        self.assertIn("pre:scripts/nrf52_ble_cccd_fix.py", ini)
+
+
+if __name__ == "__main__":
+    unittest.main()