cypher parser: NOT binds tighter than comparison — `NOT n.age = 30` parses as `(NOT n.age) = 30`

[ruvnet]

Defect

ruvector-graph's Cypher parser gives NOT higher precedence than the comparison operators. In Cypher, NOT binds looser than comparison, so NOT n.age = 30 must parse as NOT (n.age = 30).

Verified

Dumping MatchClause.where_clause for MATCH (n) WHERE NOT n.age = 30 RETURN n on c6bb23c84:

BinaryOp {
    left:  UnaryOp { op: Not, operand: Property { object: Variable("n"), property: "age" } },
    op:    Equal,
    right: Integer(30),
}

The NOT has captured only n.age, and the whole thing is an Equal comparing a boolean against 30. Correct would be:

UnaryOp { op: Not, operand: BinaryOp { left: Property{..}, op: Equal, right: Integer(30) } }

Consequence

Any executor evaluating this tree faithfully returns the wrong rows. (NOT n.age) evaluates to a boolean, comparing it to 30 is false for every node, so WHERE NOT <comparison> silently matches nothing. It does not error — it returns an empty result, which reads as "no matching rows" rather than "your query was misparsed".

<> is unaffected (n.age <> 30 parses correctly), so the workaround is to use <> and De Morgan the rest by hand.

Scope

This is in the shared parser (crates/ruvector-graph/src/cypher/parser.rs), so it affects every consumer of parse_cypher, not just the Node binding. Fixing it means moving NOT below the comparison level in the precedence climb, and checking the existing parser tests don't encode the current behaviour.

Found while implementing #879's WHERE evaluation (PR #938). Deliberately left out of that PR — a precedence change in a shared parser has a wider blast radius than the binding fix and deserves its own review. PR #938 documents the gap next to the test it had to drop.

Related

• graph-node: persisted writes invisible to stats()/query() across handles/processes; MATCH without label unimplemented #879 — query() ignored WHERE entirely, so this was unreachable before now
• PR fix(graph-node): execute Cypher MATCH properly and defer hydration (#879, #826) #938 — implements WHERE evaluation; cypher_exec.rs notes this precedence gap