fix(python): reverse directional operators in PEP 508 reversed marker form

When a marker comparison is written as 'value' op variable (e.g.,
'3.8' >= python_version), parseAtom swaps the operands but must also
reverse directional operators: < ↔ >, <= ↔ >=. Symmetric operators
(==, !=) remain unchanged.

Resolves TC-4314

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ruromero

src/providers/marker_evaluator.js

@@ -103,9 +103,13 @@ function parseAtom(expr) {
 	let m = expr.match(/^\s*([\w.]+)\s*(~=|!=|==|>=|<=|>|<|not\s+in|in)\s*["']([^"']*)["']\s*$/)
 	if (m) { return { variable: m[1], op: m[2].replace(/\s+/g, ' '), value: m[3] } }
 
-	// Reversed form: 'value' op variable
+	// Reversed form: 'value' op variable — reverse directional operators
 	let mReverse = expr.match(/^\s*["']([^"']*)['"]\s*(~=|!=|==|>=|<=|>|<|not\s+in|in)\s*([\w.]+)\s*$/)
-	if (mReverse) { return { variable: mReverse[3], op: mReverse[2].replace(/\s+/g, ' '), value: mReverse[1] } }
+	if (mReverse) {
+		let reverseOp = { '<': '>', '>': '<', '<=': '>=', '>=': '<=' }
+		let op = mReverse[2].replace(/\s+/g, ' ')
+		return { variable: mReverse[3], op: reverseOp[op] || op, value: mReverse[1] }
+	}
 
 	return null
 }

test/providers/marker_evaluator.test.js

@@ -44,4 +44,42 @@ suite('PEP 508 marker evaluator', () => {
 			expect(evaluateMarker("sys_platform not in 'lin'")).to.be.true
 		})
 	})
+
+	suite('reversed form — directional operator reversal', () => {
+		test('>= is reversed to <= when operands are swapped', () => {
+			expect(evaluateMarker("'3.8' >= python_version")).to.equal(
+				evaluateMarker("python_version <= '3.8'")
+			)
+		})
+
+		test('< is reversed to > when operands are swapped', () => {
+			expect(evaluateMarker("'3.8' < python_version")).to.equal(
+				evaluateMarker("python_version > '3.8'")
+			)
+		})
+
+		test('> is reversed to < when operands are swapped', () => {
+			expect(evaluateMarker("'3.8' > python_version")).to.equal(
+				evaluateMarker("python_version < '3.8'")
+			)
+		})
+
+		test('<= is reversed to >= when operands are swapped', () => {
+			expect(evaluateMarker("'3.8' <= python_version")).to.equal(
+				evaluateMarker("python_version >= '3.8'")
+			)
+		})
+
+		test('== is unchanged when operands are swapped', () => {
+			expect(evaluateMarker("'linux' == sys_platform")).to.equal(
+				evaluateMarker("sys_platform == 'linux'")
+			)
+		})
+
+		test('!= is unchanged when operands are swapped', () => {
+			expect(evaluateMarker("'win32' != sys_platform")).to.equal(
+				evaluateMarker("sys_platform != 'win32'")
+			)
+		})
+	})
 })