fix(cypher): translate collect() to json_group_array with typed decode

[ManSio]

Summary

• collect() in the Cypher SQL translator now lowers to json_group_array(expr) FILTER (WHERE expr IS NOT NULL) — Neo4j semantics: null-ignored, empty match → [].
• collect(*) and nested collect raise explicit ValueError; DISTINCT inside collect is rejected by the parser layer.
• Translator marks collect columns (collect_cols); cypher_executor decodes json.loads only for marked string columns — collision-safe (a collected string that looks like JSON stays a string), warning-only on decode failure.

Evidence

• 13 new SQL/E2E/error tests incl. decode-collision guard: file 93 passed.
• Full pytest: 1663 passed / 6 skipped / 91 deselected (verified 5×, incl. a sanitized-env replica of the gate-zero run).
• ruff clean; verify_diary 16 ✅ / 0 ❌; negative controls: stale_detector PROVEN (after reverting a stray stale_config.json edit that broke gate-zero + negative controls — root-caused and reverted).
• Red Team 5/5 attacks covered: empty match, nulls, unicode/quotes, DISTINCT, nested/*.
• Experiments G1/G2 raw-verified on sqlite 3.50.4 / Python 3.14.3: FILTER semantics and empty→[] confirmed.

Notes

• Known hook-environment issue documented: pre-commit hook launched under a non-venv interpreter (no pytest) made gate-zero fail with an empty summary; commits require venv-first PATH until the hook resolves sys.executable explicitly (follow-up).
• Refs KNOWN_ISSUES 2026-09-07: collect() open → fixed.

fixes the collect() item tracked in KNOWN_ISSUES; closes #23 follow-up not included (LSP wrong-root stays open).

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 05d62007-6cb0-4c05-badc-e412c0981d34

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}