docs: clarify property-query index coverage

[contrueCT]

Summary

Clarify the property-index query rules beside the existing properties parameters in the English and Chinese Vertex and Edge REST API pages.

• Define query-visible candidate labels, including empty labels and the parent/sub-edge coverage rule. A parent index can cover sub-labels only when the parent is visible to the query.
• Distinguish no/partial/complete compatible coverage for type-valid values and the empty-result exception for type-incompatible values after an index matches.
• Explain labeled PRIMARY_KEY direct lookup, rejection of range conditions when all primary-key fields are supplied, and vertex_id-bounded adjacency.
• Wrap added prose close to 160 characters per line, allowing shorter paragraph endings; keep Chinese line breaks at sentence endings and related conditions in the same paragraph.

Related code: apache/hugegraph#3243. Related scope: apache/hugegraph#3201; its selective fallback optimization remains open. Publish this documentation with or after #3243: released versions can still silently omit matches under partial coverage.

Validation

• git diff --check and added-prose line-length / Chinese sentence-boundary checks passed.
• bash dist/validate-links.sh passed.
• Strict production scripts/hugo.sh build passed locally on macOS arm64 with Hugo Extended 0.165.0 and Go 1.27.1; the pinned OINK v1.1.0 module and checksums were verified with scripts/oink_module.py.
• Rendered English/Chinese Vertex/Edge paragraphs checked for the primary-key range restriction and parent visibility qualification, including placement next to the existing rules and Chinese whitespace.
• Content-only change; routes, navigation, configuration and visual assets are unchanged.

[imbajin]

Blocking: no. Summary: The index-coverage guidance matches the paired query fix, with one exception for labeled primary-key lookups. Evidence: In apache/hugegraph#3243 head f435a1f, GraphTransaction.optimizeQuery() converts a labeled query containing every primary-key field into an IdQuery, bypassing property-index lookup.

[imbajin]

Blocking: no. Summary: The index-coverage guidance is clear overall, with two minor edge cases noted inline. Evidence: Static review against GraphIndexTransaction.java and SourceIndexCoverageTest.java at apache/hugegraph#3243 head 0de33ed.

[bitflicker64]

Blocking: no. Summary: The coverage rules match GraphIndexTransaction.checkIndexCoverage() and GraphTransaction.optimizeQuery() at apache/hugegraph#3243 head 0de33ed, including the PRIMARY_KEY direct lookup and the vertex_id adjacency path; one Chinese line break renders as a stray space. The two open Minor threads on invalid values and parent edge labels still apply at this head and are not repeated here. Evidence: static review of 1e67982 against GraphIndexTransaction.java (queryIndex, queryByUserprop, collectMatchedIndexes, checkIndexCoverage), GraphTransaction.optimizeQuery(), HugeVertexStep (resetUserpropConditions for adjacency filters), EdgeAPI.list and SourceIndexCoverageTest at 0de33ed; hugo.yaml markup.goldmark has no cjk extension.

[bitflicker64]

Blocking: no. Summary: The coverage rules match GraphIndexTransaction at apache/hugegraph#3243 head 7f5a917, including the new hidden/deleting label filter, the father-label skip and the invalid-value ordering. One gap remains: a labeled PRIMARY_KEY query with a non-exact condition on a primary-key field is rejected by the server, not routed to a property index as the new text implies. Evidence: static review of c87d249 against GraphTransaction.optimizeQuery(), ConditionQuery.matchUserpropKeys() and ConditionQuery.userpropValuesString() at 7f5a917; no server was run.

[imbajin]

Blocking: no. Summary: The edge coverage guidance needs one visibility qualification for parent indexes. Evidence: apache/hugegraph#3243 at 7f5a917; GraphIndexTransaction.collectMatchedIndexes() filters labels using rootOriginQuery() visibility before checkIndexCoverage().