MobWalk

A client-side Fabric mod that shows where a chosen mob can safely stand and walk.

Right-click a block with the wand and MobWalk paints every surface the chosen mob could reach from there, and marks inescapable holes and hazards such as soul sand.

Every color, and whether each hazard is marked at all, is configurable.

Requirements

• Minecraft 26.x with Fabric Loader
• Fabric API, MaLiLib, and ModMenu

MobWalk is purely client-side.

Controls

The wand is a stick by default, and you can set it to any item.

• Right-click a block with the wand: paint the surfaces around it.
• Right-click air: clear the selection.
• Sneak + scroll while holding the wand: grow or shrink how far it checks.
• Sneak + right-click air: switch to the next mob.
• Sneak: see the painted surfaces through walls.
• Auto Update: Automatically recalculates around the selection or your location.

Some mobs are built in (eg Player, Ravager, Warden), and you can add your own with a width, height, and vertical reach. Surfaces show while you hold the wand, or can be set to always show.

More details of each setting may be found in the menu tooltips.

Known limitations

• Classification near the edge of the flood fill may be inaccurate, due to missing neighbors.
• An unreachable ledge between two reachable surfaces may be marked as a "hole", since technically it is unreachable from both directions.
• Single tick floods over large areas can stutter. Multi-ticks flood may desync.
• The visual vs collision hitbox of honey is inconsistent horizontally as well as vertically; this is not adjusted for, since usually it is within the dilated radius, so is not visible.
• Reachability assumes zero horizontal velocity. Otherwise this becomes modeling all of parkour. Most mobs do not make horizontal jumps, so the surfaces found are generally accurate.
• Soul sand slows through a slab; currently this is not taken into account. (Same with honey etc)

Disclaimers

The hazard markers can be set to display through walls, which might violate Modrinth content rule 3.3.a (X-ray). If this is a hard blocker, I could change it to not allow on servers by default.

AI usage

The code was written with Cursor, primarily using Opus and Grok. Mainly because it saves me having to learn the Fabric API. I also used this project to learn how to use coding agents. Planning artefacts can be found in git history.

90%+ of the actual design and scope is mine: the walkability geometry and logic, what gets drawn and how, all the settings options, etc. After all, that's the fun part. Also, even Opus still sucks at abstract planning.