fix: EXISTS {} inner anonymous node with properties no longer raises ValidationError

[DecisionNerd]

Closes #474

Summary

• EXISTS { MATCH (:Label {prop: outer.var}) } raised ValidationError: PropertyAccess requires either 'variable' or 'base' when the inner node was anonymous (no explicit variable name)
• Root cause: _plan_match passed node_pattern.variable (which is None for anonymous nodes) to _properties_to_predicate, but var_name on the line above already resolves the correct name (real or generated anon)
• One-line fix: use var_name instead of node_pattern.variable at the call site

Test plan

• test_anonymous_inner_node_with_outer_property — exact failure case from issue
• test_outer_variable_in_inner_where — outer var referenced in inner WHERE
• test_outer_variable_in_in_expression — outer var in IN expression
• test_ontology_conformance_query — full repro from issue, domain-violation rows correct
• All existing EXISTS TCK scenarios still pass
• make pre-push green (87.08% total coverage)

🤖 Generated with Claude Code

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Summary by CodeRabbit

• Bug Fixes
  • Fixed a critical bug in EXISTS subquery evaluation that prevented proper handling of outer-scope variable references and property access from parent queries. Enhanced the query planner's handling of anonymous nodes in MATCH patterns to ensure all property predicates and filter operations correctly reference the intended internal variables (issue fix: EXISTS {} subquery fails in planner when outer variable used in inner MATCH property #474).

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 79726d9 and d148eb4.

📒 Files selected for processing (2)

• src/graphforge/planner/planner.py
• tests/integration/test_exists_is_empty.py

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Walkthrough

The planner's single-node MATCH pattern builder now uses the resolved internal variable name when constructing inline property predicates, fixing a bug where anonymous pattern nodes (lacking explicit variables) would fail with validation errors during EXISTS subquery planning.

Changes

Planner Fix for EXISTS Subqueries with Outer Variables

Layer / File(s)	Summary
Core Logic Fix src/graphforge/planner/planner.py	_plan_match uses the resolved var_name (including auto-generated names for anonymous nodes) instead of node_pattern.variable (which can be None) when building inline property predicates for single-node patterns.
Integration Tests tests/integration/test_exists_is_empty.py	New TestExistsSubqueryOuterVariable suite with four tests validates EXISTS subqueries correctly resolve outer-scope variables in inner node properties, WHERE clauses, and IN expressions; includes an ontology conformance query test.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• DecisionNerd/graphforge#376: Related work on pattern predicates and variable binding in planner logic for OPTIONAL MATCH and pattern-variable handling.
• DecisionNerd/graphforge#396: Related planner updates for correlated EXISTS subqueries and outer-scope variable handling in planner.py.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and accurately describes the main fix: resolving a ValidationError when EXISTS subqueries use anonymous inner nodes with properties.
Description check	✅ Passed	The PR description includes a clear summary, root cause analysis, test plan with checkmarks, and references the issue (#474), meeting all key template requirements despite not using the full checklist format.
Linked Issues check	✅ Passed	The PR fully addresses all acceptance criteria from #474: fixes the ValidationError for anonymous inner nodes with outer variables, adds comprehensive tests (anonymous node with outer property, outer var in WHERE/IN), confirms existing EXISTS TCK scenarios pass, and verifies the ontology conformance query works correctly.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the EXISTS subquery bug: the one-line fix in _plan_match and the four integration tests validating the fix against acceptance criteria from #474.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

📝 Generate docstrings

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/474-exists-subquery-outer-variable

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.02%. Comparing base (79726d9) to head (d148eb4).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #496      +/-   ##
==========================================
- Coverage   88.02%   88.02%   -0.01%     
==========================================
  Files          40       40              
  Lines       14471    14470       -1     
  Branches     3434     3434              
==========================================
- Hits        12738    12737       -1     
  Misses       1142     1142              
  Partials      591      591              

Flag	Coverage Δ
full-coverage	88.02% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
parser	95.67% <ø> (ø)
planner	82.88% <100.00%> (-0.01%)	⬇️
executor	83.63% <ø> (ø)
storage	91.25% <ø> (ø)
ast	98.20% <ø> (ø)
types	94.75% <ø> (ø)

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