Cypher MATCH after WITH rejects re-binding a carried secondary alias as a node variable in trailing MATCH

[lmeyerov]

Summary

Cypher queries that carry a secondary alias through a WITH and then bind it as a node variable in a trailing MATCH are rejected by the GFQL lowering. This blocks the LDBC SNB IC1 shortestPath shape and similar re-entry patterns.

Repro (minimal, fails on master 41d865ac9)

MATCH (p:Person {id: $pid}), (friend:Person)
WHERE NOT p = friend
WITH p, friend
MATCH path = shortestPath((p)-[:KNOWS*1..3]-(friend))
RETURN friend.id AS friendId, length(path) AS dist

Expected vs observed

• Expected: shortestPath is computed with friend already constrained from the prefix WITH.
• Observed: GFQLValidationError: [unsupported-cypher-query] Cypher MATCH after WITH does not yet support re-binding a carried secondary alias as a node variable in the trailing MATCH | field: match | value: ['friend']

Source

• Guard: graphistry/compute/gfql/cypher/lowering.py:7181
• Asserting test: graphistry/tests/compute/gfql/cypher/test_lowering.py:9082 (pytest.raises(... match="re-binding a carried secondary alias"))

Benchmark evidence

• pyg-bench artifact: results/runs/dgx-spark-ic1-conformance-2026-04-05/probe-results.json
• LDBC SNB lane: interactive-complex-1 / named-shortest-friends
• Probe semantic_scope: adapter_shortest_path_join_workaround — adapter currently splits this into a workaround pass because the direct shape is rejected here.
• Official query at third_party/ldbc_snb_interactive_v1_impls/cypher/queries/interactive-complex-1.cypher uses exactly this WITH p, friend MATCH path = shortestPath((p)-[:KNOWS*1..3]-(friend)) shape.

Acceptance criteria

• The minimal repro above succeeds end-to-end with a row per (p, friend) pair carrying the shortestPath length.
• The secondary-alias rebinding guard at lowering.py:7181 is retired or scoped down (e.g., admit when the rebound alias is the trailing pattern endpoint of a shortestPath() / regular-pattern MATCH).
• At least one regression test under graphistry/tests/compute/gfql/cypher/ exercises the IC1 shape directly.
• The blocking xfail-style test asserting the guard fires can be deleted or repurposed as a positive test.

Subsystem / scope

• graphistry/compute/gfql/cypher/lowering.py (alias rebinding gate)
• graphistry/compute/gfql/cypher/reentry/runtime.py + cypher/reentry_plan.py (carry plumbing for the rebound alias)
• Out of scope: full row-carrier IR (Cypher/GFQL: introduce a first-class row-carrier IR for multi-stage vectorized row semantics #989) — this issue scopes the rebinding gap narrowly so it can land independently.

Related

• Parent umbrella: [FEA] GFQL bindings_table (row bindings) from chain using Yannakakis prune #880 (benchmark residual row-bindings)
• Architectural follow-up: Cypher/GFQL: introduce a first-class row-carrier IR for multi-stage vectorized row semantics #989 (row-carrier IR)
• Coordination: Meta: benchmark coverage unlock plan for GFQL and GFQL/Cypher #992, Meta: GFQL compiler/planner post-M4 execution DAG (active wave) #1259