Check the elf2bin inputs at generation, quote cxx flags, add d1_wroom_02 to BOARDS

elf2bin.py and eboot.elf join the existence checks so a half-extracted
package fails by name before the compile instead of at the
second-to-last edge. get_project_cxx_compile_flags() values go through
_shell_token like every other flag source. d1_wroom_02 (2 MB, in
ESP8266_BOARD_BUILD and buildable under PlatformIO) joins BOARDS so the
native board guard stops rejecting it, and the guard comment states
what config validation actually checks.

esphome/build_gen/arduino8266.py

@@ -551,8 +551,8 @@ def write_project(paths: InstalledPaths) -> bool:
     config = _resolve_build_config(flag_defines)
     esp8266_data = CORE.data[KEY_ESP8266]
     board = esp8266_data[KEY_BOARD]
-    # Config-time validation rejects unsupported boards before this runs;
-    # guard anyway so a bypassing caller fails by name, not KeyError
+    # Config validation accepts the board as a bare string, so this is the
+    # first place an unknown board can fail by name instead of a KeyError
     if board not in BOARDS or board not in ESP8266_BOARD_BUILD:
         raise EsphomeError(f"Board '{board}' is not supported by the native toolchain")
     board_build = ESP8266_BOARD_BUILD[board]
@@ -590,6 +590,16 @@ def write_project(paths: InstalledPaths) -> bool:
             raise EsphomeError(
                 f"{_INCOMPLETE_INSTALL}: missing {required}; {_CLEAN_HINT}"
             )
+    # The elf2bin edge runs after the full compile and link; a
+    # half-extracted package must fail here, not an hour of wall-clock later
+    for required_file in (
+        framework / "tools" / "elf2bin.py",
+        framework / "bootloaders" / "eboot" / "eboot.elf",
+    ):
+        if not required_file.is_file():
+            raise EsphomeError(
+                f"{_INCOMPLETE_INSTALL}: missing {required_file}; {_CLEAN_HINT}"
+            )
     for lib in libraries:
         include_dirs += lib.include_dirs
 
@@ -611,7 +621,7 @@ def write_project(paths: InstalledPaths) -> bool:
         ["-fno-rtti", f"-std={cpp_standard}"]
         + ["-fexceptions" if config.exceptions else "-fno-exceptions"]
         + common
-        + get_project_cxx_compile_flags()
+        + [_shell_token(f) for f in get_project_cxx_compile_flags()]
     )
     # PlatformIO's ASPPCOM carries defines and includes but not CCFLAGS,
     # so only -D/-I user flags reach assembly there; match it. The tokens

esphome/components/esp8266/boards.py

@@ -199,6 +199,10 @@ BOARDS = {
         "name": "WeMos D1 mini Pro",
         "flash_size": FLASH_SIZE_16_MB,
     },
+    "d1_wroom_02": {
+        "name": "WeMos D1 ESP-WROOM-02",
+        "flash_size": FLASH_SIZE_2_MB,
+    },
     "d1": {
         "name": "WEMOS D1 R1",
         "flash_size": FLASH_SIZE_4_MB,

tests/unit_tests/build_gen/test_arduino8266.py

@@ -185,6 +185,10 @@ def _make_framework(tmp_path: Path) -> InstalledPaths:
     for sub in ("include", "ld", "lwip2/include", "lib"):
         (framework / "tools" / "sdk" / sub).mkdir(parents=True)
     (framework / "libraries").mkdir()
+    (framework / "tools" / "elf2bin.py").write_text("")
+    eboot = framework / "bootloaders" / "eboot"
+    eboot.mkdir(parents=True)
+    (eboot / "eboot.elf").write_text("")
     toolchain = tmp_path / "toolchain"
     (toolchain / "bin").mkdir(parents=True)
     (toolchain / "include").mkdir()
@@ -722,6 +726,23 @@ def test_write_project_returns_changed(tmp_path: Path) -> None:
         assert arduino8266.write_project(paths) is False
 
 
+def test_write_project_missing_elf2bin_raises(tmp_path: Path) -> None:
+    """A half-extracted package must fail by name at generation, not after
+    the full compile at the elf2bin edge."""
+    paths = _make_framework(tmp_path)
+    (paths.framework / "tools" / "elf2bin.py").unlink()
+    _set_flags()
+    src = CORE.relative_src_path()
+    (src / "main.cpp").parent.mkdir(parents=True, exist_ok=True)
+    (src / "main.cpp").write_text("")
+    with (
+        patch.object(arduino8266, "generate_ld_scripts"),
+        patch("esphome.arduino.library.resolve_libraries", return_value=[]),
+        pytest.raises(EsphomeError, match="elf2bin"),
+    ):
+        arduino8266.write_project(paths)
+
+
 def test_write_project_missing_src_dir_raises(tmp_path: Path) -> None:
     """A missing generated source tree is its own error, not an install one."""
     paths = _make_framework(tmp_path)