Per-statement work no longer allocates where it does not need to: parseKeyPath returns the first key component directly, absolute paths and key buffers sit on the parser, the definition maps are created on first write, arrays presize, and a string without escapes is copied out in one piece instead of built byte by byte. Repeated keys share one string across array-of-tables elements through a parser-local intern table whose lookup works on the bytes, so a repeated key costs no allocation.
UTF-8 validity is no longer a whole-input pass before the parser runs: the scan validates where it meets a multi-byte sequence, and a SyntaxError now names the line the invalid byte sits on. TestParseRejectsInvalidUTF8 covers nine positions; docs/API.md describes the new reporting.
Long document: 67 664 to 31 765 allocations per parse, about 51 to about 106 MB/s; representative document: 157 to 104 allocations.
petrbalvin
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