Unable to assign `FontSource` values in `bsn!` : `FontSource` does not implement `Into<FontSourceTemplate>`

Bevy version and features

Bevy 0.19.1, no defaults with 3D, UI, and WESL shader support.

bevy = {version = "0.19", default-features=false, features=["3d", "ui",  "shader_format_wesl"]}

What you did

I am attempting to implement a theming approach for my game so I can more easily compose GUI elements from higher level themed widgets.

Minimal Version

bsn! { 
  TextFont {
    font: font_source ,
  }
}

In Context:

let font_component: Box<dyn Scene> = match self.font_kind.clone() {
  FontKind::Asset(path) => Box::new(bsn! { TextFont {
    font: FontSource::Handle(path)
  }}),
  FontKind::Existing(font_source) => Box::new(bsn! { TextFont {
    font: font_source ,
  }}),
};

pub enum FontKind {
    Asset(String),
    Existing(FontSource),
}

What went wrong

I was expecting for a FontSource to be able to be passed into TextFont.font within a BSN macro.

I get the build errors:

error[E0277]: the trait bound `FontSourceTemplate: From<bevy::bevy_text::FontSource>` is not satisfied
  --> psq/src/gui/theming/text.rs:43:47
   |
43 |               FontKind::Asset(path) => Box::new(bsn! { TextFont {
   |  _______________________________________________^
44 | |                font: FontSource::Handle(path)
45 | |             }}),
   | |______________^ the trait `From<bevy::bevy_text::FontSource>` is not implemented for `FontSourceTemplate`
   |
   = note: required for `bevy::bevy_text::FontSource` to implement `Into<FontSourceTemplate>`
   = note: this error originates in the macro `bsn` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `FontSourceTemplate: From<bevy::bevy_text::FontSource>` is not satisfied
  --> psq/src/gui/theming/text.rs:43:47
   |
43 |               FontKind::Asset(path) => Box::new(bsn! { TextFont {
   |  _______________________________________________^
44 | |                font: FontSource::Handle(path)
45 | |             }}),
   | |______________^ the trait `From<bevy::bevy_text::FontSource>` is not implemented for `FontSourceTemplate`
   |
   = note: required for `bevy::bevy_text::FontSource` to implement `Into<FontSourceTemplate>`
   = note: this error originates in the macro `bsn` (in Nightly builds, run with -Z macro-backtrace for more info)

Additional information

To validate that this was a persisting issue I ran rustup update and cargo update to ensure everything is fully presented. So rust toolchain version rustc 1.98.1 (48a229cea 2026-09-01).

I spent some time digging around the bevy_text crate to determine where the implementation would be missing from, and I couldn't figure it out. I did my best to look into the scene code but proc macros melt my brain so I gave up.

I'd be happy to write the PR to fix this myself if I could get a little guidance on where to begin looking. No love lost if I don't get to though, I just want it fixed