Publish harness and TUI open-source

initial sync from the monorepo

crates/common/xai-circuit-breaker/src/state.rs

@@ -0,0 +1,68 @@
+//! Breaker state types: state enum, outcome enum, and the `BreakerOpen`
+//! error returned by [`crate::CircuitBreaker::check`] when the breaker is
+//! refusing traffic.
+
+use std::time::Duration;
+
+/// Tri-state circuit-breaker status.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u8)]
+pub enum BreakerState {
+    Closed = 0,
+    Open = 1,
+    HalfOpen = 2,
+}
+
+impl BreakerState {
+    pub(crate) fn from_u8(v: u8) -> Self {
+        match v {
+            0 => Self::Closed,
+            1 => Self::Open,
+            2 => Self::HalfOpen,
+            invalid => {
+                debug_assert!(false, "invalid BreakerState: {invalid}");
+                Self::Closed
+            }
+        }
+    }
+}
+
+/// Outcome of a wire request fed back to the breaker via
+/// [`crate::CircuitBreaker::record`].
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Outcome {
+    Success,
+    Failure,
+}
+
+/// Returned by [`crate::CircuitBreaker::check`] when the breaker is open
+/// or has already exhausted its half-open probe slots.
+#[derive(Debug)]
+pub struct BreakerOpen {
+    pub retry_after: Duration,
+}
+
+impl std::fmt::Display for BreakerOpen {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "circuit breaker open; retry after {:.1}s",
+            self.retry_after.as_secs_f64()
+        )
+    }
+}
+
+impl std::error::Error for BreakerOpen {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn breaker_open_display() {
+        let err = BreakerOpen {
+            retry_after: Duration::from_millis(5300),
+        };
+        assert_eq!(err.to_string(), "circuit breaker open; retry after 5.3s");
+    }
+}