Struct ScenarioSpec 

pub struct ScenarioSpec {
    pub file: Arc<str>,
    pub name: Arc<str>,
    pub line: usize,
    pub file_root: Option<PathBuf>,
    pub prepare: PrepareFn,
    pub exclusive: bool,
}

Everything a scenario needs at dispatch time. Built by the CLI edge from owned/Arced data so scenario threads are 'static (abandonable).

Fields

file: Arc<str>

Feature file path.

name: Arc<str>

Scenario name (post-expansion).

line: usize

1-based header line.

file_root: Option<PathBuf>

Root for file bodies referenced by the scenario’s entries (the feature file’s directory — hurl context_dir confinement, TECH-SPEC §13).

prepare: PrepareFn

Lower + emit against the live World snapshot (pure; runs in-thread).

exclusive: bool

Run this scenario with the pool to itself (ADR-0007 scheduling).

Not “one of these at a time” but “nothing else at all”: the motivating case is a scenario asserting absolute positions (items[0]) against a database no concurrent scenario may write to. A per-group concurrency limit — the other half of the shape cargo-nextest settled on — bounds members against each other and leaves the rest of the pool running, which is the weaker guarantee and not the one that was missing.