Blank lines between a block scalar header and its first content line come
before the indent token, so the earlier blank-line capture skipped them.
Buffer leading blanks while the block indentation is still pending and
flush them as empty content once the indent is established, in the shared
indentation path used by both scan loops. Also fix folded bodies to emit
a break for a leading blank rather than folding it into a leading space.
This closes the last block-scalar blank-line edge from #57.
A folded block scalar folded every non-blank line into the surrounding
text, including more-indented lines, which YAML keeps literal with their
line breaks. Detect a more-indented line by its retained leading
whitespace and keep the breaks adjacent to it instead of folding them.
Plain and blank-line folding are unchanged.
The scanner dropped every blank line within and after a block scalar, so
a literal block lost internal blank lines, a folded block turned a blank
line into a space rather than a newline, and the keep indicator could not
preserve trailing blank lines. Capture blank lines as empty content in
both the batch scan loop and the streaming TokenCursor loop, which had
drifted as duplicate copies. Rework blockScalarValue to apply literal
versus folded line semantics and clip/strip/keep chomping over the
captured lines; content without blank lines is unchanged. Re-pin the
multiline-scalar test whose expectation encoded the old dropped-blank
behavior, and add a chomping-and-folding test matrix.
The scanner consumed the `+` indicator of a `|+` / `>+` block scalar but
mapped it to nothing, so keep was silently treated as clip, and a scanner
test baked that in. Add a `keep` case to BlockScalarChomping, recognize
`+` in the header scanner, and correct the test. Full keep value semantics
(preserving trailing blank lines) depend on scanner blank-line capture and
are tracked in #57; this commit fixes the token classification only.
Add structured validation diagnostics, JSON and Yams comparison gates, and lazy token/event parsing so production behavior is measured without retaining full intermediate parser arrays.
