The tree was parsed once, globally, and shared by every world -- so every
condition that needs the seed simply did not work. Compiling it per RandomState
fixes four of them at once.
noise_threshold sampled a per-column random draw and pretended it was
"minecraft:surface"; the other six noises it names were unsupported and returned
false. Each condition now holds its own seeded noise, sampled once per column
into a small cache the way vanilla's LazyXZCondition does. Powder snow, packed
ice and ice appear in the dump for the first time; calcite, swamp water windows
and gravel patches have their conditions back too.
vertical_gradient tapered through a per-column RNG shared with the other rules.
Vanilla rolls a positional random at the exact block, from a factory named by
the rule. More importantly the anchor decoder read only above_bottom and
discarded which kind of anchor it was, so the deepslate rule's absolute 0..8
collapsed onto y=-64 and **no deepslate existed anywhere in the world**. Anchors
now carry their kind and resolve against the real height bounds -- which also
retires a hardcoded 384 in y_above.
Two more stubs land with them: hole is surfaceDepth <= 0 rather than a constant
false, and steep reads the neighbouring column heights. steep needs the whole
chunk's heightmap, so the column pass is now two passes -- terrain and fluids
for all 256 columns, then surface rules -- which is the order vanilla uses
anyway (doFill, then buildSurface).
Deepslate was also missing from the block-ID table, and an unknown name resolved
to 0, which the caller read as "no block" and skipped. So even a correct rule
would have placed nothing. Unknown names are now a parse error, deepslate and
mud are in the table, and a rule that resolves to air genuinely places air --
the frozen-ocean surface asks for exactly that.
Below y=0 is now entirely deepslate, y=1..7 a scatter, above y=8 none.
