fix: handle quoted picoschema enum strings in YAML frontmatter (#612)

The picoschema enum-with-description syntax `[val1, val2], description`
is invalid YAML. Users must quote it so YAML parses it as a string.
This adds `_parse_enum_string()` to extract enum values and description
from the resulting string value (e.g., "[active, blocked], current state").

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: phernandez <paul@basicmachines.co>

Author: phernandez

src/basic_memory/schema/parser.py

@@ -14,6 +14,7 @@
   EntityName as type (capitalized)  # entity reference
 """
 
+import re
 from dataclasses import dataclass, field
 
 
@@ -124,6 +125,31 @@ def _is_entity_ref_type(type_str: str) -> bool:
     return len(type_str) > 0 and type_str[0].isupper()
 
 
+# --- Enum String Parsing ---
+
+
+def _parse_enum_string(value: str) -> tuple[list[str], str | None]:
+    """Parse a string-typed enum value into enum values and optional description.
+
+    When picoschema enum values are quoted in YAML frontmatter (required when a
+    description follows the list), YAML parses the whole thing as a string. This
+    function extracts the enum values and description from that string.
+
+    Examples:
+        "[active, blocked, done], current state" -> (['active', 'blocked', 'done'], 'current state')
+        "[active, blocked]"                      -> (['active', 'blocked'], None)
+        "active"                                 -> (['active'], None)
+    """
+    # Match bracketed list with optional trailing description
+    m = re.match(r"\[([^\]]+)\](?:\s*,\s*(.+))?", value)
+    if m:
+        items = [item.strip() for item in m.group(1).split(",")]
+        description = m.group(2).strip() if m.group(2) else None
+        return items, description
+    # Plain string — single enum value
+    return [value.strip()], None
+
+
 # --- Main Parser ---
 
 
@@ -147,18 +173,25 @@ def parse_picoschema(yaml_dict: dict) -> list[SchemaField]:
         name, required, is_array, is_enum, is_object = _parse_field_key(key)
 
         # --- Enum fields ---
-        # Trigger: value is a list (e.g., [active, inactive])
-        # Why: enums declare allowed values directly as a YAML list
+        # Trigger: value is a list or a string containing bracketed enum values
+        # Why: enums declare allowed values directly as a YAML list, or as a quoted
+        #   string when a description follows (e.g., "[a, b], desc" must be quoted
+        #   in YAML to avoid parse errors)
         # Outcome: SchemaField with is_enum=True and enum_values populated
         if is_enum:
-            enum_values = value if isinstance(value, list) else [str(value)]
+            description = None
+            if isinstance(value, list):
+                enum_values = [str(v) for v in value]
+            else:
+                enum_values, description = _parse_enum_string(str(value))
             fields.append(
                 SchemaField(
                     name=name,
                     type="enum",
                     required=required,
                     is_enum=True,
-                    enum_values=[str(v) for v in enum_values],
+                    enum_values=enum_values,
+                    description=description,
                 )
             )
             continue

tests/schema/test_parser.py

@@ -8,6 +8,7 @@
     parse_schema_note,
     _parse_field_key,
     _parse_type_and_description,
+    _parse_enum_string,
     _is_entity_ref_type,
     SCALAR_TYPES,
 )
@@ -105,6 +106,26 @@ def test_empty_string(self):
         assert _is_entity_ref_type("") is False
 
 
+# --- _parse_enum_string ---
+
+
+class TestParseEnumString:
+    def test_bracketed_list_with_description(self):
+        values, desc = _parse_enum_string("[active, blocked, done, abandoned], current state")
+        assert values == ["active", "blocked", "done", "abandoned"]
+        assert desc == "current state"
+
+    def test_bracketed_list_without_description(self):
+        values, desc = _parse_enum_string("[active, blocked]")
+        assert values == ["active", "blocked"]
+        assert desc is None
+
+    def test_plain_string(self):
+        values, desc = _parse_enum_string("active")
+        assert values == ["active"]
+        assert desc is None
+
+
 # --- parse_picoschema ---
 
 
@@ -153,6 +174,21 @@ def test_enum_values_coerced_to_string(self):
         fields = parse_picoschema({"year?(enum)": [2020, 2021, 2022]})
         assert fields[0].enum_values == ["2020", "2021", "2022"]
 
+    def test_enum_string_with_brackets_and_description(self):
+        """Quoted picoschema enum string parsed from YAML frontmatter."""
+        fields = parse_picoschema(
+            {"status?(enum)": "[active, blocked, done, abandoned], current state"}
+        )
+        assert fields[0].is_enum is True
+        assert fields[0].enum_values == ["active", "blocked", "done", "abandoned"]
+        assert fields[0].description == "current state"
+
+    def test_enum_string_with_brackets_no_description(self):
+        fields = parse_picoschema({"status?(enum)": "[active, blocked]"})
+        assert fields[0].is_enum is True
+        assert fields[0].enum_values == ["active", "blocked"]
+        assert fields[0].description is None
+
     def test_object_field(self):
         fields = parse_picoschema(
             {