Expose lazy UART tables in dir() and pin the contract with a test

tests/unit_tests/components/test_logger.py

@@ -0,0 +1,24 @@
+"""Tests for the logger component's lazy platform tables."""
+
+import sys
+
+
+def test_uart_selection_tables_exposed_for_external_tooling() -> None:
+    """device-builder introspects these names off the module; keep them
+    accessible (and discoverable) without importing the platform packages."""
+    for mod in ("esphome.components.esp32", "esphome.components.libretiny"):
+        sys.modules.pop(mod, None)
+
+    from esphome.components import logger
+
+    assert "UART_SELECTION_ESP32" in dir(logger)
+    assert "UART_SELECTION_LIBRETINY" in dir(logger)
+    assert logger.UART_SELECTION_ESP32["ESP32C3"] == [
+        "UART0",
+        "UART1",
+        "USB_CDC",
+        "USB_SERIAL_JTAG",
+    ]
+    assert "bk72xx" in logger.UART_SELECTION_LIBRETINY
+    # Repeated access returns the same cached object
+    assert logger.UART_SELECTION_ESP32 is logger.UART_SELECTION_ESP32