Custom Outside World icon for extfs volume

[bryanwintermute]

Background

Infinite Mac ships a custom volume icon (in third_party/infinite-mac/Images/The Outside World.dsk.zip with source art at third_party/infinite-mac/Art/The Outside World.acorn) for their equivalent concept. We should apply that icon to our BasiliskII extfs volume so the kid sees a friendly themed icon instead of the generic Mac volume icon.

Mechanism

• Write Icon\r file to outside-world/ root with resource fork containing icl8/ICN# resources
• Set the "custom icon" attribute bit in the volume's Finder Info (storage location TBD on extfs)
• Pair with Patch BasiliskII to allow custom extfs volume name (default Unix → Outside World) #4 (Unix → Outside World) since both require source-level BasiliskII work

Depends on

• Patch BasiliskII to allow custom extfs volume name (default Unix → Outside World) #4 — they're naturally paired (rename + icon together)

Discovered

2026-05-14 during kid-shortlist curation; we noticed the "Unix" volume on the kid's Desktop and discussed visual differentiation.