search_graph returns null for list-valued requested fields despite stored graph properties #1284

Version

codebase-memory-mcp dev

Platform

Linux (x64)

What happened?

search_graph(fields=[...]) returns null for list-valued node properties even though the properties exist in the graph and query_graph returns their values correctly.

This was reproduced with:

• Class.base_classes
• Method.decorators
• Method.decorator_tags

Scalar requested fields such as signature render normally.

Public reproduction

Repository and commit:

• https://github.com/Enferlain/sd-scripts/tree/de2dd0ebae40174e8336157e8928e36cfd013284
• Example class: https://github.com/Enferlain/sd-scripts/blob/de2dd0ebae40174e8336157e8928e36cfd013284/library/strategies/sd/training.py#L19-L50
• Example decorated method: https://github.com/Enferlain/sd-scripts/blob/de2dd0ebae40174e8336157e8928e36cfd013284/library/strategies/base/contracts.py#L376-L403

A fresh full index reported:

12,131 nodes
70,850 edges
generation_matches=true

Reproduction: class bases

{
  "project": "home-imi-Projects-sd-scripts",
  "label": "Class",
  "name_pattern": "^(SdTrainingStrategy|Sd3TrainingStrategy|SdxlTrainingStrategy)$",
  "fields": ["base_classes"],
  "format": "json",
  "limit": 10,
  "offset": 0
}

Actual search_graph rows contain:

["SdTrainingStrategy", "Class", "19-50", 15, 13, null]
["Sd3TrainingStrategy", "Class", "17-63", 2, 12, null]
["SdxlTrainingStrategy", "Class", "20-58", 12, 13, null]

But the property is present and ordered in query_graph:

MATCH (c:Class)
WHERE c.name IN ['SdTrainingStrategy', 'Sd3TrainingStrategy', 'SdxlTrainingStrategy']
RETURN c.qualified_name, c.base_classes
ORDER BY c.qualified_name

For example, SdTrainingStrategy.base_classes returns:

[
  "SdModelLoadingStrategy",
  "SdTokenizeStrategy",
  "SdTextEncodingStrategy",
  "SdConditioningStrategy",
  "SdCachingStrategy",
  "SdSampleGenerationStrategy",
  "SdCheckpointingStrategy",
  "SdValidationStrategy",
  "SdDiffusionTrainingStrategy",
  "SdDenoiserCallingStrategy",
  "SdModelPreparationStrategy",
  "WeightedPromptStrategy",
  "TrainingStrategy"
]

Reproduction: method decorators

{
  "project": "home-imi-Projects-sd-scripts",
  "label": "Method",
  "name_pattern": "^process_batch$",
  "qn_pattern": "^home-imi-Projects-sd-scripts\\.library\\.strategies\\.base\\.contracts\\..*",
  "fields": ["decorators", "decorator_tags"],
  "format": "json",
  "limit": 10,
  "offset": 0
}

Actual row:

["process_batch", "Method", "380-403", 0, 10, null, null]

But query_graph returns:

decorators=["@abstractmethod"]
decorator_tags=["abstractmethod"]

The graph schema also lists base_classes, decorators, and decorator_tags as properties of their respective node labels.

All cited source paths returned no_recorded_issue with matching coverage metadata.

Expected behavior

Requested list-valued properties should be serialized in search_graph results, preserving order where the property is ordered:

["SdTrainingStrategy", "Class", "19-50", 15, 13, ["SdModelLoadingStrategy", "..."]]

If list-valued properties are intentionally unsupported, search_graph should return an explicit validation error or document the limitation rather than silently returning null for an existing property.

Impact

This is a smaller query-output issue; the underlying index data is intact and query_graph is a workaround. It still affects normal agent workflows because search_graph is the preferred discovery tool:

• inheritance order appears absent;
• abstract/decorator metadata appears absent;
• agents may draw false conclusions or issue unnecessary fallback queries;
• inheritance and framework audits become more expensive.

Confirmations

• Searched current open and closed issues; no exact duplicate found.
• Reproduced across three separate list-valued properties and two node labels.
• Scalar requested fields work.
• Underlying values are confirmed through query_graph.