Building System

Building System

Describe a structure and Jarvis designs it, then builds it block by block. He can also paste schematics from a library, on every platform.

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Freeform building

/jarvis build a small stone cottage with a wooden roof
/jarvis build a 5x5 cobblestone tower

or in chat, or Building → Custom build in the bell menu, which asks for the description and runs the same thing.

The model is not asked for four hundred coordinates. There are two planners, chosen by build.planner:

• script (the shipped default) — the model writes a short JavaScript program that calls fill() and setBlock(), run in a sandbox with a block budget and a time limit. It needs a cloud model and GraalJS. Paper fetches GraalJS itself: plugin.yml lists it as a library, so the first start downloads about 60 MB from Maven into the server's libraries/ folder. If GraalJS cannot be loaded, Paper falls back to the json planner rather than failing.
• json — the model returns a short list of shapes — fill, walls, hollow, clear, set, door, bed, roof — which the core expands. A wall is therefore whole by construction, a door has both halves, a bed has its head, and a pitched roof is stairs stepping in to a ridge with its gables closed. Fabric and NeoForge carry no GraalJS, so the mods always use this one.

Either way the model spends its effort on the design instead of the arithmetic.

Builds come furnished. A dwelling gets a bed, a chest, a crafting table, light and something on the walls; a larger building gets rooms furnished for their purpose. Both planners' prompts require it rather than leave it to taste, because the first house built without that rule arrived with no door and a wall missing.

Mistakes are repaired rather than reported:

• Block ids are checked against the server's own registry.
• A door or window pane placed a block off the wall's line is moved into it.
• Glass panes and fences are joined to their neighbours; bed halves are made to agree.
• Anything that is not a block — a painting, an item frame — is left out and named in one warning line, rather than becoming a stray dirt block.

Underground requests carve their own space first.

/jarvis build undo       revert the last build
/jarvis build cancel     stop the one in progress
/jarvis build wall|floor|pillar|cube [size]    simple shapes, no AI

Build planning is the heavy AI tier: it prefers your cloud provider and gets a long timeout, because a plan runs to thousands of tokens. See AI Providers.

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The schematic library

Drop .schem or .schematic files into plugins/Jarvis/schematics/ on Paper, or config/jarvis/schematics/ on Fabric and NeoForge, and ask for one by name — matching is fuzzy, so exact filenames are not needed. Jarvis reads and pastes these files himself, so pasting works on every platform.

/jarvis schematic list
/jarvis schematic paste <name>         also: /jarvis paste <name>
/jarvis schematic scan                 rescan the folder
/jarvis schematic folder               where the folder is
/jarvis schematic save <name>          save your WorldEdit clipboard
/jarvis schematic rotate <name> 90

save and rotate, and pasting JSON-format schematics, need WorldEdit, so those are Paper only.

Litematica files convert in place:

/jarvis schematic litematic            list .litematic files
/jarvis schematic convert <name>
/jarvis schematic convertall

"jarvis, build me a house" picks the best match from the library when one fits, which is also the path a local-only server uses for large builds.

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He learns from what worked

Builds that went well are remembered and retrieved when you ask for something similar, matched on the request and on where you were standing — "build me a house" underground at y 12 is not the same request as on a plains surface. When something goes wrong he says why, in a sentence, rather than failing silently. See Experience memory in AI Providers.

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Upgrading

build.fallback-material is retired and ignored if it is still in your config. A block the server does not recognise is now skipped and named in the log instead of becoming dirt.