Kglite

Added

- **MCP Servers guide** — new docs page covering server setup, core tools, FORMAT CSV export, security, semantic search, and a minimal template

Added

- **`FORMAT CSV` Cypher clause** — append `FORMAT CSV` to any query to get results as a CSV string instead of a ResultView. Good for large data transfers and token-efficient output in MCP servers.

Added

- **`add_connections` query mode** — `add_connections(None, ..., query='MATCH ... RETURN ...')` creates edges from Cypher query results instead of a DataFrame. `extra_properties=` stamps static properties onto every edge.
- **`'sum'` conflict handling mode** — `conflict_handling='sum'` adds numeric edge properties on conflict (Int64+Int64, Float64+Float64, mixed promotes to Float64). Non-numeric properties overwrite like `'update'`. For nodes, `'sum'` behaves identically to `'update'`.

Fixed

- **`add_connections` query-mode param validation** — `columns`, `skip_columns`, and `column_types` now raise `ValueError` in query mode (previously silently ignored)
- **`describe()` incomplete `add_connections` signature** — now shows `query`, `extra_properties`, `conflict_handling` params and query-mode example

Fixed

- **Cypher edge traversal without ORDER BY** — queries like `MATCH (a)-[r:REL]->(b) RETURN ... LIMIT N` returned wrong row count, NULL target/edge properties, and ignored LIMIT. Root cause: `push_limit_into_match` pushed LIMIT into the pattern executor for edge patterns, causing early termination before edge expansion. Now only pushes for node-only patterns.
- **`create_connections()` silently creating 0 edges** — two sub-bugs: (1) `ConnectionBatchProcessor.flush_chunk` used `find_edge()` which matches ANY edge type, so creating PERSON_AT edges would update existing WORKS_AT edges instead. Now uses type-aware `edges_connecting` lookup. (2) Parent map in `maintain_graph::create_connections` used `HashMap<NodeIndex, NodeIndex>` (single parent per child), losing multi-parent relationships. Now uses `Vec<NodeIndex>` per child and iterates group parents directly.
- **`describe(fluent=['loading'])` wrong parameter name** — documented `properties=` for `add_connections()`, actual parameter is `columns=`
- **`traverse()` with `method='contains'` ignoring `target_type=`** — when spatial method was specified, `target_type=` keyword was ignored and only the first positional arg was used as target type. Now prefers explicit `target_type=` over positional arg.
- **`geometry_contains_geometry` missing combinations** — added `(MultiPolygon, LineString)` and `(MultiPolygon, MultiPolygon)` match arms that previously fell through to `false`

Added

- **`fold_or_to_in` optimizer pass** — folds `WHERE n.x = 'A' OR n.x = 'B' OR n.x = 'C'` into `WHERE n.x IN ['A', 'B', 'C']` for pushdown and index acceleration
- **`InLiteralSet` AST node** — pre-evaluated literal IN with HashSet for O(1) membership testing instead of per-row list evaluation
- **TypeSchema-based fast property key discovery** — `to_df()`, `ResultView`, and `describe()` use TypeSchema for O(1) key lookup when all nodes share a type (>50 nodes)
- **Sampled property stats** — `describe()` and `properties()` sample large types (>1000 nodes) for faster response
- **`StringInterner::try_resolve()`** — fallible key resolution for TypeSchema-based paths
- **`rebuild_type_indices_and_compact` metadata fallback** — scans nodes to build TypeSchemas when metadata is empty (loaded from file)

Fixed

- **FusedMatchReturnAggregate output columns** — built from return clause items instead of reusing pre-existing columns, fixing wrong column names in fused aggregation results
- **FusedMatchReturnAggregate top-k sort order** — removed erroneous `top.reverse()` calls that inverted DESC/ASC order in `ORDER BY ... LIMIT` queries
- **FusedMatchReturnAggregate zero-count rows** — exclude nodes with zero matching edges (MATCH semantics require at least one match)
- **Path binding variable lookup** — path assignments now find the correct variable-length edge variable instead of grabbing the first available binding
- **UNWIND null produces zero rows** — `UNWIND null AS x` now correctly produces no rows per Cypher spec instead of emitting a null row
- **InLiteralSet cross-type equality** — `WHERE n.id IN [1, 2, 3]` now matches float values via `values_equal` fallback
- **NULL = NULL returns false in WHERE** — implements Cypher three-valued logic where NULL comparisons are falsy; grouping/DISTINCT unaffected
- **Property push-down no longer overwrites** — `apply_property_to_patterns` uses `entry().or_insert()` to preserve earlier matchers
- **Pattern reversal skips path assignments** — `optimize_pattern_start_node` no longer reverses patterns bound to path variables
- **Fuse guard: HAVING clause** — `fuse_match_return_aggregate` bails out when HAVING is present
- **Fuse guard: vector score aggregation** — `fuse_vector_score_order_limit` bails out when return items contain aggregate functions
- **Fuse guard: bidirectional edge count** — `fuse_count_short_circuits` skips undirected patterns that could produce wrong counts
- **Fuse guard: dead SKIP check removed** — `fuse_order_by_top_k` no longer checks wrong clause index for SKIP
- **Parallel expansion error propagation** — errors in rayon parallel edge expansion are now propagated instead of silently returning empty results
- **Variable-length paths min_hops=0** — source node is now yielded at depth 0 when `min_hops=0` (e.g., `[*0..2]`)
- **Parallel distinct target dedup** — parallel expansion path now applies `distinct_target_var` deduplication matching the serial path
- **Unterminated string/backtick detection** — tokenizer now returns errors for unclosed string literals and backtick identifiers
- **String reconstruction preserves escapes** — `CypherToken::StringLit` re-escapes quotes and backslashes during reconstruction

Changed

- **zstd compression for save/load** — replaced gzip level 3 with zstd level 1; Save 9.5s → 1.1s (8.6×), Load 2.3s → 1.0s (2.2×), file 7% smaller. Backward-compatible: old gzip files load transparently
- **Vectorized pandas series extraction** — `convert_pandas_series()` uses `series.tolist()` + `PyList.get_item()` instead of per-cell `Series.get_item()`, plus batch `extract::<Vec<Option<T>>>()` for Float64/Boolean/String. Build 24.7s → 19.3s
- **Fast lookup constructors** — `TypeLookup::from_id_indices()` and `CombinedTypeLookup::from_id_indices()` reuse pre-built `DirGraph.id_indices` instead of scanning all nodes
- **Skip edge existence check on initial load** — `ConnectionBatchProcessor.skip_existence_check` flag bypasses `find_edge()` when no edges of that type exist yet
- **Pre-interned property keys** — intern column name strings once before the row loop, use `Vec<(InternedKey, Value)>` instead of per-row `HashMap<String, Value>` for node creation
- **Single-pass load finalize** — `rebuild_type_indices_and_compact()` combines type index rebuild + Map→Compact property conversion in one pass, with TypeSchemas built from metadata instead of scanning nodes
- **Zero-alloc InternedKey deserialization** — custom serde Visitor hashes borrowed `&str` from the decompressed buffer, eliminating ~5.6M String allocations per load
- **Remove unnecessary `.copy()` on first CSV read** in blueprint loader