| name | latitude-biome-selection-contract |
| description | Defines the contract between vanilla “base” biomes and Latitude “out” biomes. Prevents incorrect assumptions about F3 biome, temperature/precip flags, and feature placement. Provides the required debugging interpretation for LAT_PICK logs. |
Latitude — Biome Selection Contract (Authoritative)
This skill prevents a common error:
“F3 says biome = jungle, therefore cold/snow features cannot trigger.”
That is false when:
- vanilla selects a cold base biome, and
- Latitude overrides to a warm out biome, but
- some vanilla systems still consult base-biome temperature/precip rules during placement.
Definitions
- Base biome: the vanilla biome prior to Latitude override. Logged as
base=... in [LAT_PICK].
- Out biome: the biome Latitude returns to worldgen. Logged as
out=... and typically what F3 shows.
- Wrapper illusion: you can see
out while generation decisions still reference base.
Contract rules (must be respected)
- Latitude may override biome output by latitude band (Z-based), but vanilla may still:
- consult base biome temperature,
- consult precipitation flags,
- run features keyed off base-biome climate.
- Therefore:
- Seeing cold blocks/features in a warm F3 biome implies base leakage or write-path placement, not that F3 is “wrong”.
- Fixes must be either:
- ensure temperature/precip checks use out-biome (harder), OR
- block the offending feature/write path in disallowed bands (preferred for robustness).
How to interpret [LAT_PICK] logs
Given a log line like:
zone=EQUATOR base=minecraft:snowy_taiga out=minecraft:jungle
Interpretation:
- Vanilla asked for a biome and would have used
snowy_taiga.
- Latitude returned
jungle.
- Any system that still consults base-biome climate may try to place snow/ice even though out-biome is warm.
This is expected in the presence of base leakage and does not mean Latitude selection failed.
Representative [LAT_PICK] template
[LAT_PICK]
x=<x> z=<z> absZ=<absZ> radius=<radius> t=<t>
zone=<EQUATOR|TROPICS|ARID|TEMPERATE|SUBPOLAR|POLAR>
base=<minecraft:...>
out=<minecraft:...>
beachOverride=<true|false>
rareOverride=<true|false>
mangroveDecision=<...> cont=<...> ero=<...> weird=<...>
How to read it:
- If
out is warm but base is cold, vanilla temperature-driven features may still attempt cold placements unless guarded (e.g., FreezeTopLayer).
- That’s not a biome-table bug; it’s a base-leakage / write-path issue.
Debugging obligations
When a “contradiction” occurs (warm biome but cold artifacts):
- Capture coords + F3 out-biome.
- Find nearby
[LAT_PICK] entries:
- confirm
zone and compare base vs out.
- Identify write path:
- feature hook logs (e.g.,
FreezeTopLayerFeature)
- ChunkRegion/ProtoChunk traps
- Apply minimal fix (feature cancel / write-path rewrite).
Do not propose band-table changes based only on F3.
Canonical example: warm-band snow
Observed:
- F3:
minecraft:jungle
- Snow blocks or powder snow appear at cave mouths.
Common cause:
[LAT_PICK] base=snowy_plains out=jungle- Vanilla
FreezeTopLayerFeature consults base biome climate → attempts snow.
- LatitudeSnowGuard blocks/cancels in warm bands.
Forbidden assumptions
- “Out biome implies all placements consult out biome.”
- “If snow appears, Latitude chose the wrong biome.”
- “Fix by moving snowy biomes out of authority table.”
- “Fix by rewriting MaterialRules first.”
Required assistant output when diagnosing biome contradictions
The assistant must provide:
- base vs out interpretation
- suspected offender (feature or write path)
- the minimum guard/cancel plan
- a proof plan (log/counter) gated behind a debug flag
