[BUG] Semantic-guided read paths read chunk.value directly and break under an external ChunkStore

[noel-improv]

Package version: 3.18.5
Package: lexical-graph
Python version: 3.12
OS: Linux

Description

#437 moved the traversal-based read paths onto ChunkStore. The semantic-guided stack still reads chunk.value off the graph, so it breaks once a deployment configures an external chunk store and ChunkGraphBuilder stops writing that property (indexing/build/chunk_graph_builder.py:80-88).

Two queries fetch chunk nodes with no property list, which defaults to ['*'] (storage/graph/graph_utils.py:130) and drags the full text back on every call:

• retrieval/utils/chunk_utils.py:60 — get_chunks_query
• retrieval/utils/statement_utils.py:124 — get_statements_query

Three consumers index ['value'] on the result and raise KeyError once the property is gone:

• retrieval/retrievers/deprecated/semantic_guided_chunk_retriever.py:173
• retrieval/retrievers/deprecated/semantic_guided_retriever.py:218
• retrieval/post_processors/statement_enhancement.py:103, which feeds that text to the LLM as synthesis context

StatementEnhancementPostProcessor is not deprecated, and it ships in the docs, an example notebook, and the integration tests.

#437 skipped get_chunks_query on purpose: "left as-is since its only caller is deprecated." That held while the property was still written.

Steps to reproduce

Needs the S3 backend from #465. InGraphChunkStore is the only store on main and it still writes chunk.value.

Set GraphRAGConfig.s3_chunk_store, index a document set, then query through SemanticGuidedRetriever — with StatementEnhancementPostProcessor enabled, or with a chunk retriever. Both hit KeyError: 'value'.

Expected

The semantic-guided paths resolve chunk text through ChunkStore, the way keyword_vss_provider.py and traversal_based_base_retriever.py do.

Proposed fix

• Wire statement_enhancement.py to ChunkStore.
• Wire the semantic-guided retrievers, or delete them along with get_chunks_query, which has no other caller.
• Name the properties in whichever node_result calls survive, so these queries stop pulling text they may not use.

This should land before an external chunk store becomes the default.