diff --git a/esphome/espidf/size_summary.py b/esphome/espidf/size_summary.py
index 7a5305ff0c..7e3369fc3f 100644
--- a/esphome/espidf/size_summary.py
+++ b/esphome/espidf/size_summary.py
@@ -94,6 +94,12 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
         _LOGGER.debug("Skipping size summary: %s", e)
         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
+        _LOGGER.debug("Skipping size summary: unexpected shape in %s", size_json)
+        return
+
     memory_types = data.get("memory_types", {})
     ram_region = memory_types.get("DRAM") or memory_types.get("DIRAM") or {}
     ram_used = ram_region.get("used")
@@ -106,7 +112,12 @@ def print_summary(size_json: Path, partitions_csv: Path | None) -> None:
         return
     try:
         app_size = _find_app_partition_size(partitions_csv)
-    except ValueError as e:
+    except (ValueError, OSError) as e:
         _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
+        _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 933be88476..c5e0708539 100644
--- a/tests/unit_tests/test_size_summary.py
+++ b/tests/unit_tests/test_size_summary.py
@@ -126,3 +126,38 @@ def test_print_summary_handles_no_memory_types(
     size_json = _write_size_json(tmp_path, {"image_size": 0})
     print_summary(size_json, partitions_csv=None)
     assert capsys.readouterr().out == ""
+
+
+def test_print_summary_non_dict_json_is_skipped(tmp_path, capsys) -> None:
+    """Valid JSON that is not an object must not raise past a build that
+    already linked."""
+    size_json = tmp_path / "size.json"
+    size_json.write_text("[]")
+    print_summary(size_json, tmp_path / "partitions.csv")
+    assert capsys.readouterr().out == ""
+
+
+def test_print_summary_unreadable_partitions_is_skipped(tmp_path, capsys) -> None:
+    """An OSError reading the partition table is a skipped summary, not a
+    failed build."""
+    size_json = tmp_path / "size.json"
+    size_json.write_text(
+        '{"memory_types": {"DRAM": {"used": 1, "size": 2}}, "image_size": 100}'
+    )
+    print_summary(size_json, tmp_path / "missing" / "partitions.csv")
+    out = capsys.readouterr().out
+    assert "RAM:" in out and "Flash:" not in out
+
+
+def test_print_summary_zero_app_partition_is_skipped(tmp_path, capsys) -> None:
+    """A malformed partition row parsing to 0 must not render a 0% bar for
+    CI's memory-impact extraction to ingest."""
+    size_json = tmp_path / "size.json"
+    size_json.write_text(
+        '{"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