settled-reach/server/src/cause_chain.rs

// Cause chain tracking system
// Production component for information provenance (D-030)
// Tracks monologue triggers, journal entries, debug causality

use bevy_ecs::prelude::*;
use serde::{Deserialize, Serialize};

#[derive(Component, Debug, Clone, Serialize, Deserialize)]
pub struct CauseChain {
    pub causes: Vec<Cause>,
}

impl CauseChain {
    pub fn new() -> Self {
        Self { causes: Vec::new() }
    }
    pub fn with_cause(mut self, cause: Cause) -> Self {
        self.causes.push(cause);
        self
    }
    pub fn push(&mut self, cause: Cause) {
        self.causes.push(cause);
    }
    pub fn latest(&self) -> Option<&Cause> {
        self.causes.last()
    }
}

impl Default for CauseChain {
    fn default() -> Self {
        Self::new()
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Cause {
    pub tick: u64,
    pub kind: CauseKind,
    pub description: String,
}

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub enum CauseKind {
    Observed,
    Heard,
    Informed,
    Inferred,
    Background,
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn chain_preserves_order() {
        let chain = CauseChain::new()
            .with_cause(Cause {
                tick: 1,
                kind: CauseKind::Observed,
                description: "Saw NPC".into(),
            })
            .with_cause(Cause {
                tick: 5,
                kind: CauseKind::Inferred,
                description: "NPC still inside".into(),
            });
        assert_eq!(chain.causes.len(), 2);
        assert_eq!(chain.latest().unwrap().tick, 5);
        assert_eq!(chain.latest().unwrap().kind, CauseKind::Inferred);
    }
}