Enum UiSignal 

pub enum UiSignal {
    LogLine {
        step: Option<StepId>,
        icon: Icon,
        text: String,
    },
    Progress {
        step: StepId,
        phase: String,
        fraction: Option<f32>,
    },
    CeremonyOverview {
        description: Option<String>,
        materials: Vec<MaterialOverview>,
        step_count: usize,
    },
    SystemInfo(Box<SystemInfo>),
    Environment(Environment),
}

Transient UI-only signal. Never written to the transcript.

Signals are operator-assistance, not evidence. A frontend may drop any variant without affecting correctness or the transcript (this is exactly why headless and console ignore most of them). To persist information, emit a StepFact from an action; nothing here is ever promoted into the transcript. See docs/development/runtime-and-frontend.md for the full fact-vs-signal model.

The enum is intentionally not #[non_exhaustive]: it is a workspace-internal protocol type, and forcing every frontend to match each variant exhaustively (no wildcard arms) is the wanted compile-time check that a new signal is consciously handled or ignored everywhere. Public-API enums still get #[non_exhaustive].

Variants fall into three sub-families:

• narration: ephemeral lines and progress (LogLine, Progress).
• one-shot structured: a single snapshot emitted at ceremony start (CeremonyOverview, SystemInfo).
• re-emittable structured: state the runtime may resend during the run; the frontend replaces its view on each (Environment).

Variants

LogLine

Human-readable narration line for the live UI.

Fields

step: Option<StepId>

Step the line belongs to (if any).

icon: Icon

Visual cue.

text: String

Line text.

Progress

Progress signal for spinners and progress bars.

Fields

step: StepId

Step the progress belongs to.

phase: String

Short phase label (e.g. signing, verifying).

fraction: Option<f32>

Optional completion fraction in [0.0, 1.0].

CeremonyOverview

Descriptive metadata for the pre-ceremony overview screen. Emitted once, right after StepFact::CeremonyStarted. Deliberately kept out of the transcript: the YAML is the source of truth for these fields, and embedding them in the persisted record would bloat every transcript with data that the verifier could pull from the ceremony source instead.

Fields

description: Option<String>

Optional ceremony description.

materials: Vec<MaterialOverview>

Declared materials, in declaration order.

step_count: usize

Total number of steps in the execution plan.

SystemInfo(Box<SystemInfo>)

Static build and host identity for the System tab. Emitted once, right after CeremonyOverview. UI-only: machine identity that belongs in the transcript is recorded by the machine_info action, not fed in through this channel.

Boxed: SystemInfo is much larger than the other variants, and keeping the enum (and ExecEvent) small avoids bloating every channel message.

Environment(Environment)

Live device inventory for the System tab. Emitted once today, but shaped to be re-emitted: the frontend replaces its environment view on each, so a future live observer is purely additive. UI-only, never persisted.

Trait Implementations

impl Clone for UiSignal

fn clone(&self) -> UiSignal

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for UiSignal

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.