Add build info to image (#12425)

Co-authored-by: J. Nick Koston <nick+github@koston.org>
Co-authored-by: J. Nick Koston <nick@home-assistant.io>
Co-authored-by: J. Nick Koston <nick@koston.org>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

tests/unit_tests/core/test_config.py

@@ -892,3 +892,74 @@ async def test_add_includes_overwrites_existing_files(
     mock_copy_file_if_changed.assert_called_once_with(
         include_file, CORE.build_path / "src" / "header.h"
     )
+
+
+def test_config_hash_returns_int() -> None:
+    """Test that config_hash returns an integer."""
+    CORE.reset()
+    CORE.config = {"esphome": {"name": "test"}}
+    assert isinstance(CORE.config_hash, int)
+
+
+def test_config_hash_is_cached() -> None:
+    """Test that config_hash is computed once and cached."""
+    CORE.reset()
+    CORE.config = {"esphome": {"name": "test"}}
+
+    # First access computes the hash
+    hash1 = CORE.config_hash
+
+    # Modify config (without resetting cache)
+    CORE.config = {"esphome": {"name": "different"}}
+
+    # Second access returns cached value
+    hash2 = CORE.config_hash
+
+    assert hash1 == hash2
+
+
+def test_config_hash_reset_clears_cache() -> None:
+    """Test that reset() clears the cached config_hash."""
+    CORE.reset()
+    CORE.config = {"esphome": {"name": "test"}}
+    hash1 = CORE.config_hash
+
+    # Reset clears the cache
+    CORE.reset()
+    CORE.config = {"esphome": {"name": "different"}}
+
+    hash2 = CORE.config_hash
+
+    # After reset, hash should be recomputed
+    assert hash1 != hash2
+
+
+def test_config_hash_deterministic_key_order() -> None:
+    """Test that config_hash is deterministic regardless of key insertion order."""
+    CORE.reset()
+    # Create two configs with same content but different key order
+    config1 = {"z_key": 1, "a_key": 2, "nested": {"z_nested": "z", "a_nested": "a"}}
+    config2 = {"a_key": 2, "z_key": 1, "nested": {"a_nested": "a", "z_nested": "z"}}
+
+    CORE.config = config1
+    hash1 = CORE.config_hash
+
+    CORE.reset()
+    CORE.config = config2
+    hash2 = CORE.config_hash
+
+    # Hashes should be equal because keys are sorted during serialization
+    assert hash1 == hash2
+
+
+def test_config_hash_different_for_different_configs() -> None:
+    """Test that different configs produce different hashes."""
+    CORE.reset()
+    CORE.config = {"esphome": {"name": "test1"}}
+    hash1 = CORE.config_hash
+
+    CORE.reset()
+    CORE.config = {"esphome": {"name": "test2"}}
+    hash2 = CORE.config_hash
+
+    assert hash1 != hash2