diff --git a/esphome/espidf/size_summary.py b/esphome/espidf/size_summary.py
index 7e3369fc3f..1006655791 100644
--- a/esphome/espidf/size_summary.py
+++ b/esphome/espidf/size_summary.py
@@ -35,7 +35,9 @@ _SIZE_SUFFIXES = {"K": 1024, "M": 1024 * 1024}
 def _parse_size(token: str) -> int:
     token = token.strip()
     if not token:
-        return 0
+        # A blank size cell is a malformed row; naming it beats a
+        # meaningless "from 0 bytes" bar downstream
+        raise ValueError("blank partition size cell")
     if token.startswith(("0x", "0X")):
         return int(token, 16)
     suffix = token[-1].upper()
@@ -85,6 +87,15 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
     Failures are non-fatal: the build has already succeeded, we just couldn't
     summarize. Logs the cause at debug level.
     """
+    try:
+        _print_summary(size_json, partitions_csv)
+    except Exception as e:  # noqa: BLE001  # pylint: disable=broad-exception-caught
+        # The named guards below cover the known shapes; this net keeps the
+        # promise for the rest (nested non-dict values, non-numeric sizes)
+        _LOGGER.debug("Skipping size summary: %s", e)
+
+
+def _print_summary(size_json: Path, partitions_csv: Path | None) -> None:
     if not size_json.is_file():
         _LOGGER.debug("Skipping size summary: %s not found", size_json)
         return
@@ -95,8 +106,8 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
         return
 
     if not isinstance(data, dict):
-        # Valid JSON that is not an object (truncated tool output) must
-        # not raise past a build that already linked
+        # Valid JSON that is not an object (a hand-edited or tool-emitted
+        # array) has no .get; skip with the file named
         _LOGGER.debug("Skipping size summary: unexpected shape in %s", size_json)
         return
 
@@ -116,8 +127,10 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
         _LOGGER.debug("Skipping Flash summary: %s", e)
         return
     if app_size <= 0:
-        # A malformed partition row parses to 0; a 0% bar would feed CI's
-        # memory-impact extraction fabricated data
+        # Defensive backstop behind _parse_size's blank-cell rejection: a
+        # "from 0 bytes" denominator is meaningless to a reader. Note the
+        # skip costs CI's memory-impact extraction its Flash match, which
+        # is the loud outcome a broken partition table deserves.
         _LOGGER.debug("Skipping Flash summary: app partition size is 0")
         return
     print(f"Flash: {_format_bar(image_size, app_size)}")
diff --git a/tests/unit_tests/test_size_summary.py b/tests/unit_tests/test_size_summary.py
index cd4b52fc6f..efe33dd7d5 100644
--- a/tests/unit_tests/test_size_summary.py
+++ b/tests/unit_tests/test_size_summary.py
@@ -177,3 +177,52 @@ def test_print_summary_zero_app_partition_is_skipped(
     print_summary(size_json, partitions)
     out = capsys.readouterr().out
     assert "RAM:" in out and "Flash:" not in out
+
+
+def test_print_summary_happy_path_prints_both_bars(
+    tmp_path: Path, capsys: pytest.CaptureFixture[str]
+) -> None:
+    """A well-formed size report and partition table print both bars."""
+    size_json = tmp_path / "size.json"
+    size_json.write_text(
+        '{"memory_types": {"DRAM": {"used": 1000, "size": 2000}}, "image_size": 100000}'
+    )
+    partitions = tmp_path / "partitions.csv"
+    partitions.write_text("app0, app, ota_0, 0x10000, 0x180000,\n")
+    print_summary(size_json, partitions)
+    out = capsys.readouterr().out
+    assert "RAM:" in out and "Flash:" in out
+
+
+@pytest.mark.parametrize(
+    "payload",
+    [
+        {"memory_types": []},
+        {"memory_types": {"DRAM": 5}},
+        {"memory_types": {"DRAM": {"used": "x", "size": "y"}}, "image_size": 1},
+    ],
+)
+def test_print_summary_nested_bad_shapes_never_raise(
+    tmp_path: Path, capsys: pytest.CaptureFixture[str], payload: dict
+) -> None:
+    """The blanket guard keeps nested non-dict values and non-numeric sizes
+    from raising past a linked build."""
+    size_json = _write_size_json(tmp_path, payload)
+    print_summary(size_json, None)
+    assert "Traceback" not in capsys.readouterr().err
+
+
+def test_print_summary_blank_size_cell_names_the_row(
+    tmp_path: Path, capsys: pytest.CaptureFixture[str]
+) -> None:
+    """A blank size cell is reported as the malformed input it is, via the
+    ValueError path, instead of parsing to 0."""
+    size_json = _write_size_json(
+        tmp_path,
+        {"memory_types": {"DRAM": {"used": 1, "size": 2}}, "image_size": 100},
+    )
+    partitions = tmp_path / "partitions.csv"
+    partitions.write_text("app0, app, ota_0, 0x10000, ,\n")
+    print_summary(size_json, partitions)
+    out = capsys.readouterr().out
+    assert "RAM:" in out and "Flash:" not in out