Go's `TokenChunker` previously ignored **bare (non-backtick)
delimiters** such as `::`, `.`, or `；`. `compileDelimPattern` compiled
them with `keepBare=false`, so a bare delimiter produced a `nil` pattern
and the payload was routed to the single-section merge that never split
on it — diverging from Python's `naive_merge`, which splits on bare
delimiters and then merges by token size.
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