[wifi/rp2040] Add stable wifi-capability helpers for device-builder

Add public helpers so the device-builder dashboard backend
(esphome/device-builder) doesn't have to import the internal
NO_WIFI_VARIANTS list / BOARDS dict to decide whether its basic-
setup wizard should emit a wifi: block:

- esphome.components.wifi.has_native_wifi(*, platform, board=None,
  variant=None) - central dispatcher that takes whichever
  platform-relevant fields the caller has and routes to the right
  per-platform check internally. As ESPHome adds new platforms
  (5-6 planned), this is the single place to teach them about
  Wi-Fi capability - external tooling does not have to grow a
  parallel per-platform switch.
- esphome.components.wifi.variant_has_wifi(variant) - building
  block for the ESP32 branch (False for H2 / P4 which require
  esp32_hosted).
- esphome.components.rp2040.board_id_has_wifi(board_id) - building
  block for the RP2040 branch (existing no-arg board_has_wifi()
  unchanged, now delegates to the new helper). New name (rather
  than overloading board_has_wifi) so device-builder can feature-
  detect ESPHome support via try/except ImportError on the new
  symbol - an older ESPHome would import board_has_wifi
  successfully but raise TypeError on the explicit-arg call,
  defeating the fallback.

All three wrap implementation-detail tables (NO_WIFI_VARIANTS,
the generated BOARDS dict) with explicit-arg signatures + tests,
so device-builder pins against a stable surface and a future
refactor of the underlying tables doesn't silently break the
wizard.

Same shape as the device-builder API stabilisation in #16206
and #16290.

esphome/components/rp2040/__init__.py

@@ -48,7 +48,21 @@ def board_has_wifi() -> bool:
     Returns True for unknown/custom boards to avoid rejecting valid
     configurations for boards not in the generated list.
     """
-    board_info = boards.BOARDS.get(get_board())
+    return board_id_has_wifi(get_board())
+
+
+def board_id_has_wifi(board_id: str) -> bool:
+    """Return True if *board_id* has WiFi (CYW43 wireless chip).
+
+    Returns True for unknown/custom boards to avoid rejecting valid
+    configurations for boards not in the generated list.
+
+    Used by device-builder (esphome/device-builder) — separate
+    explicit-arg helper so callers outside the compile pipeline
+    don't need ``CORE`` set up to query the board map. Please keep
+    the signature stable.
+    """
+    board_info = boards.BOARDS.get(board_id)
     if board_info is None:
         return True
     return board_info.get("wifi", False)

esphome/components/wifi/__init__.py

@@ -67,9 +67,66 @@ _LOGGER = logging.getLogger(__name__)
 
 AUTO_LOAD = ["network"]
 
-_LOGGER = logging.getLogger(__name__)
-
 NO_WIFI_VARIANTS = [const.VARIANT_ESP32H2, const.VARIANT_ESP32P4]
+
+
+def variant_has_wifi(variant: str) -> bool:
+    """Return True if *variant* has a native WiFi PHY.
+
+    Variants without a native PHY (ESP32-H2, ESP32-P4) need the
+    ``esp32_hosted`` co-processor to use ``wifi:``.
+
+    Used by device-builder (esphome/device-builder) to decide whether
+    its basic-setup wizard emits a ``wifi:`` block — please keep the
+    signature stable.
+    """
+    return variant not in NO_WIFI_VARIANTS
+
+
+_WIFI_FIRST_PLATFORMS: frozenset[str] = frozenset(
+    {
+        Platform.ESP8266,
+        Platform.BK72XX,
+        Platform.RTL87XX,
+        Platform.LN882X,
+        # Legacy umbrella key for the LibreTiny families (bk72xx /
+        # rtl87xx / ln882x); still produced by older configs that
+        # haven't migrated to the per-family keys.
+        Platform.LIBRETINY_OLDSTYLE,
+    }
+)
+
+
+def has_native_wifi(
+    *, platform: str, board: str | None = None, variant: str | None = None
+) -> bool:
+    """Return True when the given platform/board/variant has native WiFi.
+
+    Single dispatch entry point for tooling that needs to decide
+    whether emitting a ``wifi:`` block produces a compilable
+    config. Caller passes whichever platform-relevant fields they
+    have (``variant`` for ESP32, ``board`` for RP2040), and this
+    function routes to the right per-platform check internally.
+
+    Allowlist-based: unknown / Wi-Fi-less platforms (``host``,
+    ``nrf52``) return False so a future platform added to ESPHome
+    fails closed in external tooling rather than silently emitting
+    a ``wifi:`` block the new platform's component would reject.
+
+    Used by device-builder (esphome/device-builder)'s basic-setup
+    wizard. Centralised here so callers don't have to special-case
+    each platform — as ESPHome adds new platforms, this dispatcher
+    is the one place to teach them about Wi-Fi capability.
+    """
+    if platform == Platform.ESP32:
+        return variant_has_wifi(variant) if variant else True
+    if platform == Platform.RP2040:
+        from esphome.components.rp2040 import board_id_has_wifi
+
+        return board_id_has_wifi(board) if board else True
+    return platform in _WIFI_FIRST_PLATFORMS
+
+
 CONF_SAVE = "save"
 CONF_BAND_MODE = "band_mode"
 CONF_MIN_AUTH_MODE = "min_auth_mode"

tests/unit_tests/components/test_rp2040.py

@@ -0,0 +1,29 @@
+"""Tests for RP2040 component public helpers."""
+
+from esphome.components.rp2040 import board_id_has_wifi
+
+
+def test_board_id_has_wifi_for_known_wifi_board() -> None:
+    """``rpipicow`` is the canonical Pico W → True."""
+    assert board_id_has_wifi("rpipicow") is True
+
+
+def test_board_id_has_wifi_for_known_non_wifi_board() -> None:
+    """Plain ``rpipico`` has no CYW43 → False."""
+    assert board_id_has_wifi("rpipico") is False
+
+
+def test_board_id_has_wifi_for_rp2350_w_variant() -> None:
+    """``rpipico2w`` is the RP2350 Pico 2 W → True."""
+    assert board_id_has_wifi("rpipico2w") is True
+
+
+def test_board_id_has_wifi_for_unknown_board_returns_true() -> None:
+    """Unknown ids fail open so a custom board is not rejected.
+
+    The validator falls back to ESPHome's compile-time check; the
+    helper returning True here means the wizard emits a ``wifi:``
+    block and any genuinely-unsupported config trips the existing
+    "no CYW43" guard at compile time.
+    """
+    assert board_id_has_wifi("not-a-real-board-id") is True

tests/unit_tests/components/test_wifi.py

@@ -0,0 +1,96 @@
+"""Tests for WiFi component public helpers."""
+
+import pytest
+
+from esphome.components.esp32 import const
+from esphome.components.wifi import has_native_wifi, variant_has_wifi
+from esphome.const import Platform
+
+
+@pytest.mark.parametrize(
+    "variant",
+    [
+        const.VARIANT_ESP32,
+        const.VARIANT_ESP32S2,
+        const.VARIANT_ESP32S3,
+        const.VARIANT_ESP32C3,
+        const.VARIANT_ESP32C6,
+    ],
+)
+def test_variant_has_wifi_for_native_phy_variants(variant: str) -> None:
+    """Variants with a native WiFi PHY → True."""
+    assert variant_has_wifi(variant) is True
+
+
+@pytest.mark.parametrize(
+    "variant",
+    [
+        const.VARIANT_ESP32H2,
+        const.VARIANT_ESP32P4,
+    ],
+)
+def test_variant_has_wifi_for_no_phy_variants(variant: str) -> None:
+    """Variants that need ``esp32_hosted`` → False."""
+    assert variant_has_wifi(variant) is False
+
+
+def test_has_native_wifi_dispatches_esp32_to_variant_check() -> None:
+    """ESP32 platform routes through ``variant_has_wifi``."""
+    assert (
+        has_native_wifi(platform=Platform.ESP32, variant=const.VARIANT_ESP32C3) is True
+    )
+    assert (
+        has_native_wifi(platform=Platform.ESP32, variant=const.VARIANT_ESP32H2) is False
+    )
+
+
+def test_has_native_wifi_dispatches_rp2040_to_board_check() -> None:
+    """RP2040 platform routes through ``rp2040.board_id_has_wifi``."""
+    assert has_native_wifi(platform=Platform.RP2040, board="rpipicow") is True
+    assert has_native_wifi(platform=Platform.RP2040, board="rpipico") is False
+
+
+def test_has_native_wifi_returns_false_for_nrf52() -> None:
+    """nRF52 family is BLE-only — no Wi-Fi PHY in the platform."""
+    assert has_native_wifi(platform=Platform.NRF52) is False
+
+
+def test_has_native_wifi_returns_false_for_host() -> None:
+    """``host`` platform compiles ESPHome to a host binary — no radio at all."""
+    assert has_native_wifi(platform=Platform.HOST) is False
+
+
+def test_has_native_wifi_returns_false_for_unknown_platform() -> None:
+    """Unknown platform string fails closed.
+
+    A future platform added to ESPHome that's missed here returns
+    False rather than silently emitting a ``wifi:`` block external
+    tooling would have to compile and reject — fail-closed surfaces
+    the gap as an obvious "needs wifi support added" signal.
+    """
+    assert has_native_wifi(platform="not-a-real-platform") is False
+
+
+@pytest.mark.parametrize(
+    "platform",
+    [
+        Platform.ESP8266,
+        Platform.BK72XX,
+        Platform.RTL87XX,
+        Platform.LN882X,
+        Platform.LIBRETINY_OLDSTYLE,
+    ],
+)
+def test_has_native_wifi_returns_true_for_wifi_first_platforms(platform: str) -> None:
+    """Catch-all Wi-Fi-first platforms → True regardless of board / variant."""
+    assert has_native_wifi(platform=platform) is True
+
+
+def test_has_native_wifi_esp32_without_variant_assumes_wifi() -> None:
+    """ESP32 without a variant id falls open to True (the chip family default)."""
+    assert has_native_wifi(platform=Platform.ESP32) is True
+
+
+def test_has_native_wifi_rp2040_without_board_assumes_wifi() -> None:
+    """RP2040 without a board id falls open to True (custom-board default)."""
+    assert has_native_wifi(platform=Platform.RP2040) is True