What causes "Cannot construct system event" in sxyazi/yazi?

Rename your event kind to something in your own namespace that does not use reserved prefixes (key-, ind-, emit-, relay-) or the reserved names like `theme`.

sxyazi/yazi · error

Cannot construct system event

Error message

Cannot construct system event

What it means

Ember (DDS event) validation (yazi-dds/src/ember/ember.rs:87) forbids external construction of events whose kind collides with Yazi's own namespaces: reserved body kinds like `theme`, any `key-*`, `ind-*`, `emit-*`, or `relay-*` prefix. Attempting to validate/construct such a kind bails because only Yazi itself may emit system events.

Source

Thrown at yazi-dds/src/ember/ember.rs:87

				| "load"
				| "hover"
				| "rename"
				| "bulk-rename"
				| "@yank"
				| "duplicate"
				| "move"
				| "trash"
				| "delete"
				| "download"
				| "input"
				| "mount"
				| "theme"
		) || kind.starts_with("key-")
			|| kind.starts_with("ind-")
			|| kind.starts_with("emit-")
			|| kind.starts_with("relay-")
		{
			bail!("Cannot construct system event");
		}

		let mut it = kind.bytes().peekable();
		if it.peek() == Some(&b'@') {
			it.next(); // Skip `@` as it's a prefix for static messages
		}
		if !it.all(|b| matches!(b, b'0'..=b'9' | b'a'..=b'z' | b'-')) {
			bail!("Kind `{kind}` must be in kebab-case");
		}

		Ok(())
	}
}

impl<'a> Ember<'a> {
	pub fn kind(&self) -> &str {
		match self {
			Self::Hi(_) => "hi",

View on GitHub (pinned to 5f901b886b)

Solutions

Rename your event kind to something in your own namespace that does not use reserved prefixes (key-, ind-, emit-, relay-) or the reserved names like `theme`.
If broadcasting a real system event, use the designated API (`ya emit`) rather than constructing it manually.
Prefix custom events with `@` (static messages) or a unique vendor prefix.

Example fix

// before
Ember::validate("emit-my-event")?;
// after
Ember::validate("my-plugin:my-event")?;

Defensive patterns

Strategy: validation

Validate before calling

const RESERVED: [&str; 1] = ["theme"];
fn kind_allowed(kind: &str) -> bool {
    !RESERVED.contains(&kind)
        && !kind.starts_with("key-")
        && !kind.starts_with("ind-")
        && !kind.starts_with("emit-")
        && !kind.starts_with("relay-")
}

Prevention

Namespace custom plugin events with a unique prefix that avoids key-, ind-, emit-, relay-.
Use `ya emit` for genuine system events instead of manual construction.
Keep a list of reserved kinds in your plugin and assert against it in tests.

When it happens

Trigger: Calling `Ember::validate` (or constructing an Ember) with a kind string that equals a reserved kind (e.g. `theme`, `key-move`, `ind-start`) or begins with `emit-`, `relay-`, `key-`, `ind-`.

Common situations: Third-party plugin or remote client via `ya pub-emit`/DDS trying to emit an event that shadows Yazi's internal event names.

Related errors

AI-assisted analysis of sxyazi/yazi@5f901b886b (2026-09-02). Data as JSON: /api/errors/e4f953f82fe39982. Report an issue: GitHub.