Cypher/GFQL: forward scalar carry columns through trailing WITH narrowing in reentry suffix (IC5 sub-residual A)

[lmeyerov]

Summary

Sub-issue split from #1257. Tracks the runtime half of the IC5 multi-MATCH-source projection residual.

Repro

MATCH (a:A)-[:R]->(b:B)
WITH b, b.id AS bid
MATCH (b)-[:S]->(c:C)
WITH bid, collect(distinct c) AS cs
UNWIND cs AS c2
MATCH (c2)-[:T]->(d:D)
WITH d, bid           -- trailing WITH narrowing
RETURN bid, d.id AS id

Currently rejected at compile time by _active_match_alias_for_stage (graphistry/compute/gfql/cypher/lowering.py ~line 2346) because the #1248 prefix-rewriter transforms bid references into <reentry_alias>.__cypher_reentry_bid__ and the per-stage scanner sees both the carry-rewritten root and the trailing-MATCH alias as referenced.

Findings

Lifting only the compile-time guard (filtering <alias>.<__cypher_reentry_*> refs in _expr_match_alias_usage via _is_hidden_reentry_property at lowering.py:2772) admits the query but runtime returns bid=None instead of bid='b'.

Fix surface

_lower_match_alias_stage / _lower_row_column_stage around lowering.py:9685+.

Acceptance

1. Existing failfasts near test_lowering.py:8953,8972 become positive assertions with concrete values.
2. Compile-time hidden-reentry-property filter lift composes with runtime fix.
3. TCK + DGX-Spark RAPIDS 25.02 + 26.02 receipts.
4. Composes with Cypher: WITH before MATCH re-entry restricts projection to single whole-row alias (blocks IC1) #1071, feat(cypher): ReentryPlan + multi-whole-row prefix WITH (#989 slices 4.1+4.3a) #1248, feat(cypher): forward secondary whole-row carry through chained reentry (#1256) #1258.

Related

• Umbrella: Cypher/GFQL rejects multi-stage MATCH ... WITH ... MATCH ... WITH ... MATCH read queries #999
• Parent split: Cypher/GFQL: support multi-MATCH-source row projection in RETURN/WITH (IC5 residual from #999) #1257
• Row-carrier architecture: Cypher/GFQL: introduce a first-class row-carrier IR for multi-stage vectorized row semantics #989
• Composed with: feat(cypher): ReentryPlan + multi-whole-row prefix WITH (#989 slices 4.1+4.3a) #1248, feat(cypher): forward secondary whole-row carry through chained reentry (#1256) #1258

[lmeyerov]

Worker B update: opened PR #1278 to address this issue: https://github.com/graphistry/pygraphistry/pull/1278\n\nImplemented:\n- hidden reentry-property filter lift for one-source guard scan\n- bindings-row promotion for stages that reference hidden reentry carries, preserving scalar carry through trailing WITH narrowing\n- converted the two target failfast tests into positive execution assertions\n- added Development changelog note\n\nValidation run in PR body: focused collect/unwind reentry pytest corridor is green.

[lmeyerov]

Update (2026-05-03 PDT): pushed follow-up fix commit 902ddf673 on PR #1278 to address CI test-gfql-core regressions while preserving #1272 carry forwarding.

What changed:

• Scoped hidden-reentry binding-row promotion to avoid non-WITH regressions.
• Preserved RETURN ORDER BY visibility for non-projected sort keys in mixed projection path.

Validation:

• Full GFQL-core CI-equivalent corridor locally: 1702 passed, 135 skipped.
• Differential scaffold: 8 passed.
• Cypher/GFQL: forward scalar carry columns through trailing WITH narrowing in reentry suffix (IC5 sub-residual A) #1272 target tests and constant-projection regression tests pass.

PR: #1278
Current status: CI still running; merge currently blocked pending required review/check completion.

[lmeyerov]

Wave 3 review complete for Worker B on PR #1278 (branch issue-1272-worker-b-runtime-carry-forwarding, head 902ddf673).

What was run (targeted amplification + full pass):

• Lowering targeted corridor: 84 passed, 12 skipped
• Differential scaffold: 8 passed
• Full GFQL-core corridor: 1702 passed, 135 skipped
• Ruff + mypy on touched lowering module: pass
• GitHub PR checks: pass

Wave 3 findings after adversarial pass:

• BLOCKER: 0
• IMPORTANT: 0
• SUGGESTION: 0

No new fixes required in Wave 3; wave-2 fixes remained stable.
PR: #1278

[lmeyerov]

Merged in PR #1278: #1278

Merge commit: ee52fbfad4b1996a57c7e60f1d19741becf4ae64 (2026-05-04).

Closing status confirmation: #1272 is now resolved/closed.\n\nValidation snapshot at merge time remained green (targeted amplification + GFQL-core corridor + PR checks).