Fix false custom warning for default Fix heading detection

CHANGELOG.md

@@ -25,6 +25,10 @@ Releases are tagged in the [GitHub repository](https://github.com/Community-Acce
 
 ## [Unreleased]
 
+### Fixed
+
+- **Web Fix: default ACB runs no longer get mislabeled as custom due to heading detection.** `web/src/acb_large_print_web/customization_warning.py` now treats `detect_headings=True` with `heading_accuracy=balanced` as the default behavior and only flags heading detection when it is disabled or switched to a non-default accuracy mode. Added regression coverage in `web/tests/test_customization_warning.py` for both default behavior and disabled heading detection.
+
 ## [7.6.0] - 2026-05-19
 
 ### Added

web/src/acb_large_print_web/customization_warning.py

@@ -169,14 +169,19 @@ def detect_fix_customizations(form_data) -> tuple[bool, list[str]]:
     if _get_bool(form_data, "preserve_heading_alignment"):
         customizations.append("Heading alignment preservation enabled")
 
-    if _get_bool(form_data, "detect_headings"):
+    detect_headings = (
+        _get_bool(form_data, "detect_headings")
+        if "detect_headings" in form_data
+        else True
+    )
+    if not detect_headings:
+        customizations.append("Heading detection disabled")
+    else:
         heading_accuracy = form_data.get("heading_accuracy", "balanced")
         if heading_accuracy != "balanced":
             customizations.append(
                 f"Heading detection enabled ({heading_accuracy} accuracy)"
             )
-        else:
-            customizations.append("Heading detection enabled")
 
     # Check suppressed rules via the rule_policy if available
     suppressed_ids: list[str] = []

web/tests/test_customization_warning.py

@@ -13,7 +13,8 @@ def test_detect_fix_customizations_ignores_default_fix_options():
             "para_indent_in": 0.0,
             "first_line_indent_in": 0.0,
             "preserve_heading_alignment": False,
-            "detect_headings": False,
+            "detect_headings": True,
+            "heading_accuracy": "balanced",
             "suppress_link_text": False,
             "suppress_missing_alt_text": False,
             "suppress_faux_heading": False,
@@ -36,6 +37,18 @@ def test_detect_fix_customizations_flags_non_default_list_indent():
     assert reasons == ['Document formatting customizations: List indent changed to 0.5"']
 
 
+def test_detect_fix_customizations_flags_heading_detection_disabled():
+    has_customizations, reasons = detect_fix_customizations(
+        {
+            "mode": "full",
+            "detect_headings": False,
+        }
+    )
+
+    assert has_customizations is True
+    assert reasons == ["Document formatting customizations: Heading detection disabled"]
+
+
 def test_generate_customization_warning_uses_plain_paragraphs_without_hard_wraps():
     warning = generate_customization_warning(
         ['Document formatting customizations: List indent changed to 0.5"']
@@ -44,4 +57,4 @@ def test_generate_customization_warning_uses_plain_paragraphs_without_hard_wraps
     assert "<br" not in warning
     assert "specification). Your customizations may result" in warning
     assert "The ACB Large Print Guidelines define specific requirements for typography" in warning
-    assert "• Document formatting customizations: List indent changed to 0.5\"" in warning
+    assert "• Document formatting customizations: List indent changed to 0.5\"" in warning