Inconsistent Behavior When Using Regex Variables in JSONata 2.0.6

[sartian]

Problem

Shared regex variables from higher scopes used with $replace function produce different results on repeated use, violating immutability. Works correctly in 1.8.7/2.0.1, broken in 2.0.6.

Reproduction

( 
  /* input and expected output values */
  $input := "a,b,c";

  /* regex variable mutations within subcontexts */ 
  $pattern := /[,-]/;

  $calledOnce := [
    $input ~> $replace($pattern, "|")
  ];
  
  $calledTwice := [
    $replace($input, $pattern, "|"), $replace($input, $pattern, "|")
  ];

  $calledTwiceTwice := [
    $replace($input, $pattern, "|"), $replace($input, $pattern, "|")
  ];

  $calledThrice := [
    $replace($input, $pattern, "|"), $replace($input, $pattern, "|"), $replace($input, $pattern, "|")
  ];

  /* some test runs with multiple calls */
  {
    "1x": $calledOnce,
    "2x": $calledTwice,
    "3x": $calledThrice
  }
)

Expected Output (works in 1.8.7/2.0.1):

{
  "1x": [
    "a|b|c"
  ],
  "2x": [
    "a|b|c",
    "a|b|c"
  ],
  "3x": [
    "a|b|c",
    "a|b|c",
    "a|b|c"
  ]
}

Actual Output (fails in 2.0.6):

{
  "1x": [
    "a|b|c"
  ],
  "2x": [
    "a|b|,b,|b|c",
    "a|b,c"
  ],
  "3x": [
    "a|b|,|,b,|b|c",
    "a|b,c",
    "a|,|b,c"
  ]
}

Workarounds

• Use inline regex: $replace(/[,;]/, "|")
• Create fresh instances: $fresh := function() { /[,;]/ }

Impact

Breaks immutability and consistency guarantees - same input gives different output. Silent failure makes it problematic at best for production use.

Root Cause

Regex internal state isn't reset between uses? May be related to Issue #177 regex architecture.