The stack-based substitute_script_path() rewrite left quoteEmpty set while emitting literal content inside a single-quoted region, so a template like '\<field>' wrongly took the exact-wrap branch and dropped the backslash (ScriptSubstitutionMatrix 'shell 56'). Clear the frame's quoteEmpty whenever a single-quoted character is emitted, matching the pre-rewrite fallthrough.
ScriptSubstitutionMatrix.php: add 8 explicit parser cases exercising the \/backtick nested contexts and escaped \$ / backtick pairing so every rewritten line is covered by the changed-coverage probe (1285 -> 1293).
TheWitness