Skill Rust Report

[Standing-Storm]

Describe the bug

#79884 asked for a report about the functioning of the SKILL_RUST_RESIST enchant. This is such a report

Attach save file

Without enchant
Rustworld-trimmed.tar.gz

With 5x enchant:
Rustworld-trimmed.tar.gz

Steps to reproduce

1. Place the following JSON somewhere so it loads:
   { "type": "mutation", "id": "FORGETFUL2", "name": { "str": "Super Forgetful" }, "points": 0, "description": "You have a very hard time remembering things. Your skills will erode slightly faster than usual, and you have trouble keeping your story straight when lying.", "enchantments": [ { "values": [ { "value": "SKILL_RUST_RESIST", "multiply": 4 } ] } ] }
2. Load each game and wait 24 hours. Check the rust of the Food Handling or Applied Science skills
3. In the first game, they were originally at 0.25 before rust, 0.21 after one day. In the second game they rusted down to 0.05, as expected from current documentation on how SKILL_RUST_RESIST works

Expected behavior

The linked PR intends to remove SKILL_RUST_RESIST because

this enchantment is completely useless.

But that appears not to be the case.

Screenshots

No response

Versions and configuration

• OS: Windows
  • OS Version: 10.0.22631.4890 (23H2)
• Game Version: 0d12391 [64-bit]
• Graphics Version: Tiles
• Game Language: English [en]
• Mods loaded: [
  Dark Days Ahead [dda],
  Disable NPC Needs [no_npc_food],
  Portal Storms Ignore NPCs [personal_portal_storms]
  ]

Additional context

One thing I did discover that might have led to confusion is that skill rust seems to be hardcapped to X.99, where X is one level below the skill's theoretical level. If you're part-way through a level, you can rust down all the way to the 99% point of the previous level, but if you're exactly at 00% you'll never rust more than that 1% down to X.99.