Mutating a component with insert(_one) doesn't trigger Mutated query filter

[dallenng]

Expected Behavior

I tried to make a small example and it should print "Tag added" once because the system with Added filter should be called once.
Or maybe I'm wrong and there is another way to add a component to an entity.

Actual Behavior

"Tag added" is never printed meaning the print_added function is never called.

Steps to Reproduce the Problem

1. Write a system inserting a component into an entity with insert_one or insert
2. Write a system using one of the three filter with the previous component
3. This system will not work as intented

Specifications

• Version: 0.1.3 rev=#f7131509b94b3f70eb29be092d4fd82971f547fa
• Platform: Linux (Manjaro)

Example

use bevy::prelude::*;

fn main() {
    App::build()
        .add_default_plugins()
        .add_resource(PrintTimer(Timer::from_seconds(3.0, true)))
        .add_startup_system(setup.system())
        .add_system(add_tag_on_click.system())
        .add_system(print_added.system())
        .add_system(print_timed.system())
        .run();
}

fn setup(mut commands: Commands, mut materials: ResMut<Assets<ColorMaterial>>) {
    commands
        .spawn(UiCameraComponents::default())
        .spawn(ButtonComponents {
            material: materials.add(Color::RED.into()),
            style: Style {
                size: Size::new(Val::Percent(100.0), Val::Percent(100.0)),
                ..Default::default()
            },
            ..Default::default()
        });
}

struct Tag;

fn add_tag_on_click(mut commands: Commands, mut query: Query<(Mutated<Interaction>, Entity)>) {
    for (interaction, entity) in &mut query.iter() {
        if let Interaction::Clicked = *interaction {
            println!("Click on {:?}", entity);
            commands.insert_one(entity, Tag);
            println!("Tag inserted");
        }
    }
}

fn print_added(_: Added<Tag>) {
    println!("Tag added");
}

struct PrintTimer(Timer);

fn print_timed(time: Res<Time>, mut timer: ResMut<PrintTimer>, mut query: Query<&Tag>) {
    timer.0.tick(time.delta_seconds);

    if timer.0.finished {
        for (i, _) in &mut query.iter().iter().enumerate() {
            println!("I'm Tag #{}", i);
        }
    }
}

[dallenng]

I did a bit of digging and the problem is the two systems add_tag_on_click and print_added run on the same stage. So when the component is added, the Added system has probably already been run and on each iteration the trackers are cleared. The solution is to add print_added to POST_UPDATE stage and it works fine, the mistake was in my code.

However, when you insert an already existing component into an entity, it is not flagged as mutated (see World::insert() and Archetype::put_dynamic). I made a showcase of this where the expected behaviour would be to print "Tag added" on the first click and then "Tag mutated" on all other clicks but "Tag mutated" is never printed.

use bevy::prelude::{stage::POST_UPDATE, *};

fn main() {
    App::build()
        .add_default_plugins()
        .add_startup_system(setup.system())
        .add_system(add_tag_on_click.system())
        .add_system_to_stage(POST_UPDATE, print_added.system())
        .add_system_to_stage(POST_UPDATE, print_mutated.system())
        .run();
}

fn setup(mut commands: Commands, mut materials: ResMut<Assets<ColorMaterial>>) {
    commands
        .spawn(UiCameraComponents::default())
        .spawn(ButtonComponents {
            material: materials.add(Color::RED.into()),
            style: Style {
                size: Size::new(Val::Percent(100.0), Val::Percent(100.0)),
                ..Default::default()
            },
            ..Default::default()
        });
}

struct Tag;

fn add_tag_on_click(mut commands: Commands, mut query: Query<(Mutated<Interaction>, Entity)>) {
    for (interaction, entity) in &mut query.iter() {
        if let Interaction::Clicked = *interaction {
            println!("Click on {:?}", entity);
            commands.insert_one(entity, Tag);
            println!("Tag inserted");
        }
    }
}

fn print_added(_: Added<Tag>) {
    println!("Tag added");
}

fn print_mutated(_: Mutated<Tag>) {
    println!("Tag mutated");
}