Name the unreadable report's file, tighten the number and region checks

The corrupt-report arm names its file with wording distinct from the
backstop, so tests can tell them apart (and now do, plus the non-UTF-8
half). _is_number rejects bool and non-finite floats, and the RAM
region selects by key presence, so a falsy-but-present DRAM value is
malformed rather than absent -- the size report is the one input
nothing upstream validates, so these stay hardened. The not-app_size
comment carries the zero case it also swallows.

esphome/espidf/size_summary.py

@@ -26,6 +26,7 @@ from __future__ import annotations
 import csv
 import json
 import logging
+import math
 from pathlib import Path
 
 _LOGGER = logging.getLogger(__name__)
@@ -104,7 +105,7 @@ def _print_summary(size_json: Path, partitions_csv: Path | None) -> None:
         data = json.loads(size_json.read_text(encoding="utf-8"))
     except (OSError, ValueError) as e:
         # ValueError covers JSONDecodeError and a non-UTF-8 (truncated) file
-        _LOGGER.warning("Skipping size summary: %s", e)
+        _LOGGER.warning("Skipping size summary: cannot read %s: %s", size_json, e)
         return
     if not isinstance(data, dict):
         # Non-object JSON has no .get
@@ -127,13 +128,25 @@ def _present_but_not_dict(value: object) -> bool:
 
 
 def _is_number(value: object) -> bool:
-    return isinstance(value, (int, float))
+    # bool subclasses int; NaN/Infinity are valid JSON for json.loads
+    return (
+        isinstance(value, (int, float))
+        and not isinstance(value, bool)
+        and math.isfinite(value)
+    )
 
 
 def _ram_line(data: dict, size_json: Path) -> str | None:
     """The formatted RAM line, or None (already logged) to skip it."""
     memory_types = data.get("memory_types")
-    ram_region = _dict_get(memory_types, "DRAM") or _dict_get(memory_types, "DIRAM")
+    ram_region = None
+    if isinstance(memory_types, dict):
+        # Key presence, not truthiness: a falsy DRAM value is corrupt, not
+        # absent, and must not fall through to DIRAM
+        for key in ("DRAM", "DIRAM"):
+            if key in memory_types:
+                ram_region = memory_types[key]
+                break
     used = _dict_get(ram_region, "used")
     total = _dict_get(ram_region, "size")
     if _is_number(used) and _is_number(total) and total > 0:
@@ -170,7 +183,8 @@ def _flash_line(data: dict, size_json: Path, partitions_csv: Path | None) -> str
         return None
     app_size = _find_app_partition_size(partitions_csv)
     if not app_size:
-        # No table or no qualifying row: legitimate for non-app layouts
+        # No qualifying row (a zero-size row has nothing to report either):
+        # legitimate for non-app layouts
         _LOGGER.debug("Skipping Flash summary: no app partition in %s", partitions_csv)
         return None
     return f"Flash: {_format_bar(int(image_size), app_size)}"

tests/unit_tests/test_size_summary.py

@@ -133,7 +133,8 @@ def test_print_summary_handles_missing_json(
     """Missing size json is non-fatal and prints nothing."""
     print_summary(tmp_path / "does_not_exist.json", partitions_csv=None)
     assert capsys.readouterr().out == ""
-    assert "Skipping size summary" in caplog.text
+    assert "cannot read" in caplog.text
+    assert "Skipping size summary for" not in caplog.text
 
 
 def test_print_summary_handles_no_memory_types(
@@ -196,6 +197,8 @@ def test_print_summary_happy_path_prints_both_bars(
         {"memory_types": []},
         {"memory_types": {"DRAM": 5}},
         {"memory_types": {"DRAM": {"used": "x", "size": "y"}}, "image_size": 1},
+        {"memory_types": {"DRAM": []}},
+        {"memory_types": {"DRAM": {"used": True, "size": True}}},
     ],
 )
 def test_print_summary_nested_bad_shapes_never_raise(
@@ -303,8 +306,12 @@ def test_print_summary_corrupt_size_json_warns(
     size_json = tmp_path / "size.json"
     size_json.write_text("not json {{{")
     print_summary(size_json, None)
+    size_json.write_bytes(b"\xff\xfe\x00")
+    print_summary(size_json, None)
     assert capsys.readouterr().out == ""
-    assert "Skipping size summary" in caplog.text
+    # The named arm, not the blanket, for both damage classes
+    assert caplog.text.count("cannot read") == 2
+    assert "Skipping size summary for" not in caplog.text
 
 
 def test_print_summary_missing_partitions_named_in_backstop(