diff --git a/esphome/build_gen/arduino8266.py b/esphome/build_gen/arduino8266.py
index c6a6ca7855..deb48f6d54 100644
--- a/esphome/build_gen/arduino8266.py
+++ b/esphome/build_gen/arduino8266.py
@@ -495,8 +495,11 @@ def write_project(paths: InstalledPaths) -> bool:
     flag_defines = _flag_defines()
     config = _resolve_build_config(flag_defines)
     esp8266_data = CORE.data[KEY_ESP8266]
-    # Board support was validated at config time (_validate_native_toolchain).
     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
+    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]
     flash_ld_name = _flash_ld_name(board)
 
@@ -557,12 +560,13 @@ def write_project(paths: InstalledPaths) -> bool:
         + 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.
+    # so only -D/-I user flags reach assembly there; match it. The tokens
+    # are already shell-quoted, so test past a leading quote too.
     asflags = (
         _ASFLAGS
         + defines
         + includes
-        + [f for f in project_compile_flags if f.startswith(("-D", "-I"))]
+        + [f for f in project_compile_flags if f.lstrip('"').startswith(("-D", "-I"))]
     )
 
     # build_unflags applies to the framework flag sets too (compile and link),
@@ -654,6 +658,7 @@ def write_project(paths: InstalledPaths) -> bool:
         core_exclude |= _CORE_EXCLUDE_WAVEFORM
 
     archives = []
+    direct_objs: list[str] = []
     # variant_dir existence was already enforced with the include dirs
     variant_sources = _collect_sources(variant_dir)
     if variant_sources:
@@ -690,6 +695,12 @@ def write_project(paths: InstalledPaths) -> bool:
             f"lib/{lib.name}",
             flags=" ".join(_shell_token(f) for f in lib.flags),
         )
+        if not lib.lib_archive:
+            # libArchive: false / dot_a_linkage=false: hand the objects to
+            # the linker directly so unreferenced-but-required symbols
+            # (exception handlers, weak overrides) survive
+            direct_objs.extend(objs)
+            continue
         archive = f"lib{lib.name}.a"
         lines.append(f"build {_e(archive)}: ar {' '.join(objs)}")
         archives.append(archive)
@@ -706,10 +717,10 @@ def write_project(paths: InstalledPaths) -> bool:
     if CORE.testing_mode:
         ld_deps.append(f"ld/{flash_ld}")
     lines.append(
-        f"build firmware.elf: link {' '.join(src_objs)} | "
+        f"build firmware.elf: link {' '.join(src_objs + direct_objs)} | "
         f"{' '.join(_e(a) for a in archives)} {' '.join(_e(d) for d in ld_deps)}"
     )
-    lines.append(f"  archives = {' '.join(archives)}")
+    lines.append(f"  archives = {' '.join(_shell_token(a) for a in archives)}")
     lines.append("build firmware.bin: elf2bin firmware.elf")
     lines.append("build firmware.factory.bin: copy firmware.bin")
     lines.append("build firmware.ota.bin: copy firmware.bin")
diff --git a/tests/unit_tests/build_gen/test_arduino8266.py b/tests/unit_tests/build_gen/test_arduino8266.py
index 8d9894e3ce..87093ce3e7 100644
--- a/tests/unit_tests/build_gen/test_arduino8266.py
+++ b/tests/unit_tests/build_gen/test_arduino8266.py
@@ -772,3 +772,47 @@ def test_generate_ld_scripts_missing_compiler_is_clean(tmp_path: Path) -> None:
     _set_flags()
     with pytest.raises(EsphomeError, match="Could not run"):
         _run_generate_ld_scripts(paths)
+
+
+def test_write_project_asm_keeps_quoted_defines(tmp_path: Path) -> None:
+    """A spaced -D/-I user flag arrives shell-quoted; assembly must still
+    receive it."""
+    paths = _make_framework(tmp_path)
+    _set_flags('-DGREETING="hello world"', "-Wno-volatile")
+    content = _write_ninja(paths)
+    asflags = next(line for line in content.splitlines() if line.startswith("asflags"))
+    assert '"-DGREETING=hello world"' in asflags
+    assert "-Wno-volatile" not in asflags
+
+
+def test_write_project_unarchived_library_links_objects(tmp_path: Path) -> None:
+    """A libArchive:false library's objects reach the link directly."""
+    from esphome.arduino.library import ArduinoLibrary
+
+    paths = _make_framework(tmp_path)
+    lib_src = tmp_path / "gdb" / "src"
+    lib_src.mkdir(parents=True)
+    (lib_src / "GDBStub.cpp").write_text("")
+    _set_flags()
+    lib = ArduinoLibrary(
+        name="GDBStub",
+        sources=[lib_src / "GDBStub.cpp"],
+        include_dirs=[lib_src],
+        lib_archive=False,
+    )
+    content = _write_ninja(paths, libraries=[lib])
+    assert "libGDBStub.a" not in content
+    link_line = next(
+        line for line in content.splitlines() if line.startswith("build firmware.elf")
+    )
+    assert "GDBStub.cpp.o" in link_line
+
+
+def test_write_project_unknown_board_fails_by_name(tmp_path: Path) -> None:
+    """A caller bypassing config validation gets the board named, not a
+    KeyError."""
+    paths = _make_framework(tmp_path)
+    _set_flags()
+    CORE.data[KEY_ESP8266][KEY_BOARD] = "not_a_board"
+    with pytest.raises(EsphomeError, match="'not_a_board' is not supported"):
+        _write_ninja(paths)