#3996 fix(cypher): CALL...YIELD preserves variables carried in from WITH

[robfrank]

Summary

• CALL db.labels() YIELD label (and all other procedures) were silently dropping variables bound by a preceding WITH or MATCH clause - x returned null on every row instead of its bound value.
• Root cause: CallStep.executeChainedCall() collected procedure result iterators into a flat List<Iterator<?>> with no link back to the originating input row, so outer-scope variables were never merged into the yielded results.
• Fix: changed to List<Map.Entry<Result, Iterator<?>>> pairs; the lazy iterator now tracks currentInputRow and calls the existing mergeWithInputRow() helper for every yielded result, restoring standard Cypher semantics.

Test plan

• CypherCallYieldWithVariablesTest - 4 new regression tests covering db.labels(), db.relationshipTypes(), db.propertyKeys(), and aggregated count(*) carried through WITH
• OpenCypherUnionCallProfileTest - existing CALL tests still pass
• Full Cypher test suite - no regressions

Fixes #3996

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Coverage 86.67% diff coverage · -7.85% coverage variation

Metric	Results
Coverage variation	✅ -7.85% coverage variation
Diff coverage	✅ 86.67% diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (983da3f)	120063	87787	73.12%
Head commit (5851530)	151308 (+31245)	98751 (+10964)	65.26% (-7.85%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#4009)	15	13	86.67%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[gemini-code-assist]

Code Review

This pull request addresses an issue where variables from preceding clauses were lost after a CALL ... YIELD statement by tracking and merging the original input row with procedure results. A comprehensive regression test suite has been added to verify this behavior across various database procedures. The review feedback suggests avoiding redundant merging in optional calls to prevent potential variable shadowing and recommends a performance optimization for the allPairs list initialization by setting an initial capacity.

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.23%. Comparing base (983da3f) to head (5851530).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...dedb/query/opencypher/executor/steps/CallStep.java	80.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4009      +/-   ##
==========================================
+ Coverage   64.20%   64.23%   +0.03%     
==========================================
  Files        1597     1597              
  Lines      120063   120069       +6     
  Branches    25556    25557       +1     
==========================================
+ Hits        77083    77125      +42     
+ Misses      32306    32276      -30     
+ Partials    10674    10668       -6     

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