Treat dot-prefixed top-level keys as block boundaries in the line scanners

esphome_device_builder/helpers/device_yaml/_parsing.py

@@ -386,7 +386,8 @@ def extract_directly_referenced_integrations(
         return []
     out: set[str] = set()
     for key, value in config.items():
-        if not isinstance(key, str):
+        # esphome ignores dot-prefixed top-level keys (anchor containers).
+        if not isinstance(key, str) or key.startswith("."):
             continue
         out.add(key)
         if isinstance(value, list):

esphome_device_builder/helpers/yaml/scan.py

@@ -49,7 +49,9 @@ def block_end_index(lines: list[str], start: int) -> int:
     """First line after *start* that opens the next top-level block; ``len(lines)`` at EOF."""
     for idx in range(start + 1, len(lines)):
         stripped = lines[idx].rstrip("\n\r")
-        if stripped and stripped[0].isalpha() and not stripped.startswith(" "):
+        # A dot-prefixed key (esphome-ignored anchor container) opens a
+        # block too; comments deliberately don't.
+        if stripped and (stripped[0].isalpha() or stripped[0] == "."):
             return idx
     return len(lines)
 

esphome_device_builder/helpers/yaml/writing_layout.py

@@ -76,7 +76,7 @@ def _locate_singleton_block(
         if not stripped:
             continue
         if not stripped.startswith(" "):
-            if stripped[0].isalpha():
+            if stripped[0].isalpha() or stripped[0] == ".":
                 end = idx
                 break
             # Column-0 comment ends the block only when the next

tests/test_directly_referenced_integrations.py

@@ -37,6 +37,15 @@ def test_extracts_top_level_keys() -> None:
     ]
 
 
+def test_skips_dot_prefixed_keys() -> None:
+    """esphome-ignored anchor containers never count as integrations."""
+    config = {
+        "esphome": {"name": "x"},
+        ".defaultfilters": [{"throttle": "60s"}],
+    }
+    assert extract_directly_referenced_integrations(config) == ["esphome"]
+
+
 def test_extracts_platform_stems_from_list() -> None:
     """``- platform: <name>`` entries under a list-shaped block.
 

tests/test_yaml_helpers.py

@@ -68,7 +68,12 @@
     _plain_is_fast_safe,
     _plain_is_safe,
 )
-from esphome_device_builder.helpers.yaml.scan import find_block_header, top_level_key_index
+from esphome_device_builder.helpers.yaml.scan import (
+    block_end_index,
+    find_block_header,
+    top_level_key_index,
+)
+from esphome_device_builder.helpers.yaml.writing_layout import _locate_singleton_block
 from esphome_device_builder.models import ErrorCode
 from esphome_device_builder.models.common import ConfigEntry, ConfigEntryType
 from esphome_device_builder.models.components import (
@@ -1291,6 +1296,22 @@ def test_merge_component_yaml_preserves_following_blocks_after_splice() -> None:
     assert result.count("sensor:\n") == 1
 
 
+def test_merge_component_yaml_splice_stops_at_dot_prefixed_key() -> None:
+    """A dot-prefixed anchor block after the domain block ends the splice range."""
+    component = _component(component_id="sensor.dht", category=ComponentCategory.SENSOR)
+    fields: dict[str, Any] = {"pin": "GPIO4", "name": "Inside"}
+
+    existing = (
+        "esphome:\n  name: kitchen\n\n"
+        "sensor:\n  - platform: bme280\n    address: 0x76\n\n"
+        ".defaultfilters:\n  - &throttle_time\n    throttle: 60s\n"
+    )
+    result = merge_component_yaml(existing, component, fields)
+
+    assert result.endswith(".defaultfilters:\n  - &throttle_time\n    throttle: 60s\n")
+    assert result.index("- platform: dht") < result.index(".defaultfilters:")
+
+
 def test_merge_component_yaml_appends_non_platform_component() -> None:
     """A non-platform component (e.g. ``i2c``) emits as a top-level mapping.
 
@@ -2432,6 +2453,23 @@ def test_child_block_end_trims_shallow_banner_but_keeps_deep_comment() -> None:
     assert _cbe(text, 1, "  ") == 4
 
 
+def test_block_end_index_stops_at_dot_prefixed_key() -> None:
+    lines = ["sensor:\n", "  - platform: bme280\n", ".defaultfilters:\n", "  - &throttle\n"]
+    assert block_end_index(lines, 0) == 2
+
+
+def test_block_end_index_skips_column_zero_comments() -> None:
+    lines = ["sensor:\n", "  - platform: bme280\n", "# banner\n", "logger:\n"]
+    assert block_end_index(lines, 0) == 3
+
+
+def test_locate_singleton_block_ends_at_dot_prefixed_key() -> None:
+    lines = ["api:\n", "  reboot_timeout: 0s\n", ".anchors:\n", "  - &throttle\n"]
+    span = _locate_singleton_block(lines, "api")
+    assert span is not None
+    assert span[:2] == (0, 2)
+
+
 def test_top_level_key_index_matches_find_block_header() -> None:
     lines = [
         "esphome:\n",