Fix string/list handling in PII column detection macros

- Fix get_column_tags to properly handle string tags vs lists
- Fix pii_tags processing to handle scalar strings correctly
- Apply consistent string/list normalization to model tags
- Addresses CodeRabbit comments r2250021209 and r2250021214

The core issue was that Jinja2's 'is iterable' test returns True for strings,
causing scalar string tags like 'pii' to be treated as character arrays
['p','i','i'] instead of single-element lists ['pii']. Fixed by using
explicit string checking with 'src is string' to properly distinguish
between strings and actual lists/arrays.

Co-Authored-By: Yosef Arbiv <[email protected]>

Author: devin-ai-integration[bot]

macros/edr/system/system_utils/get_pii_columns_from_parent_model.sql

@@ -1,17 +1,17 @@
 {% macro get_column_tags(column_node) %}
-  {# column -> tags #}
-  {% set column_tags = column_node.get('tags', []) %}
+  {% set _tags_sources = [
+    column_node.get('tags', []),
+    column_node.get('config', {}).get('tags', []),
+    column_node.get('meta', {}).get('tags', []),
+  ] %}
 
-  {# column -> config -> tags #}
-  {% set config_dict = column_node.get('config', {}) %}
-  {% set config_tags = config_dict.get('tags', []) %}
-
-  {# column -> meta -> tags #}
-  {% set meta_dict = column_node.get('meta', {}) %}
-  {% set meta_tags = meta_dict.get('tags', []) %}
+  {% set all_column_tags = [] %}
+  {% for src in _tags_sources %}
+    {% set tags_list = src if src is iterable and not (src is string) else [src] %}
+    {% do all_column_tags.extend(tags_list) %}
+  {% endfor %}
 
-  {% set all_column_tags = config_tags + column_tags + meta_tags %}
-  {% do return(all_column_tags | map('lower') | list) %}
+  {% do return(all_column_tags | map('lower') | unique | list) %}
 {% endmacro %}
 
 {% macro get_pii_columns_from_parent_model(flattened_test) %}
@@ -29,13 +29,24 @@
   {% endif %}
 
   {% set raw_pii_tags = elementary.get_config_var('pii_tags') %}
-  {% set pii_tags = (raw_pii_tags if raw_pii_tags is iterable else [raw_pii_tags]) | map('lower') | list %}
+  {% if raw_pii_tags is string %}
+    {% set pii_tags = [raw_pii_tags|lower] %}
+  {% else %}
+    {% set pii_tags = (raw_pii_tags or []) | map('lower') | list %}
+  {% endif %}
 
   {# Check if the model itself has PII tags - if so, all columns are considered PII #}
-  {% set model_tags = parent_model.get('tags', []) %}
-  {% set model_config_tags = parent_model.get('config', {}).get('tags', []) %}
-  {% set model_meta_tags = parent_model.get('meta', {}).get('tags', []) %}
-  {% set all_model_tags = (model_tags + model_config_tags + model_meta_tags) | map('lower') | list %}
+  {% set _model_tags_sources = [
+    parent_model.get('tags', []),
+    parent_model.get('config', {}).get('tags', []),
+    parent_model.get('meta', {}).get('tags', [])
+  ] %}
+  {% set all_model_tags = [] %}
+  {% for src in _model_tags_sources %}
+    {% set tags_list = src if src is iterable and not (src is string) else [src] %}
+    {% do all_model_tags.extend(tags_list) %}
+  {% endfor %}
+  {% set all_model_tags = all_model_tags | map('lower') | unique | list %}
 
   {% for pii_tag in pii_tags %}
     {% if pii_tag in all_model_tags %}