The guard tests used 3-char query tokens whose field tokens were literal
continuations ('car'/'carpet'), so the startsWith rule returned 0.9 before
the shared-prefix rule was reached. With MIN_SHARED_PREFIX=4 the rule is
unreachable for any 3-char token, making the assertion impossible to
satisfy. Swapped in cases where neither token is a true prefix of the
other, which actually exercise the guard.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
