Ship only the assets each platform needs

One flutter: assets list used to mean every platform received every file. From 3.41 you can filter:

flutter:
  assets:
    - path: assets/logo.png
    - path: assets/web_worker.js
      platforms: [web]
    - path: assets/desktop_icon.png
      platforms: [windows, linux, macos]

Why this is not optional for multi-platform apps

• Mobile users should not download desktop help PDFs or web workers.
• Store size metrics and download friction improve immediately.
• CI can assert platform asset matrices in tests.

Practical split

Asset type	Platforms
Shared branding	all
Web workers / wasm helpers	web
High-res print templates	desktop
iOS/Android notification sounds	android, ios

Pitfalls

• Conditional rootBundle.load of a missing platform asset throws — guard with a platform check.
• This is packaging filtering, not runtime theming.