Publish harness and TUI open-source

initial sync from the monorepo

crates/codegen/xai-file-utils/src/circuit_breaker_observer.rs

@@ -0,0 +1,86 @@
+//! Tracing-based observer for the storage circuit breaker.
+
+use std::sync::Arc;
+use xai_circuit_breaker::{BreakerState, Observer, Outcome};
+
+/// `Observer` impl that emits `tracing` events matching the legacy
+/// in-tree `circuit_breaker.rs` so existing analytics queries
+/// (`target=circuit_breaker AND breaker=storage_breaker`) keep firing.
+///
+/// Event routing keys on the **new** state — keying on `(old, new)`
+/// tuples invites arm-ordering bugs (an early `(Open, _)` arm would
+/// catch `Open -> HalfOpen` and mis-label it "closed").
+///
+/// | new state | level | message                  |
+/// |-----------|-------|--------------------------|
+/// | `Open`    | warn  | "circuit breaker opened" |
+/// | `HalfOpen`| debug | "circuit breaker half-open" |
+/// | `Closed`  | info  | "circuit breaker closed" |
+///
+/// `on_outcome` emits a `tracing::trace!` per `Outcome::Failure` so
+/// downstream failure-rate dashboards have a per-401 signal.
+/// Successes are dropped (steady state would otherwise dominate log volume).
+pub(crate) struct TracingObserver {
+    name: &'static str,
+}
+
+impl TracingObserver {
+    pub(crate) fn new(name: &'static str) -> Arc<Self> {
+        Arc::new(Self { name })
+    }
+}
+
+impl Observer for TracingObserver {
+    fn on_state_change(&self, old: BreakerState, new: BreakerState, reason: &str) {
+        match new {
+            BreakerState::Open => tracing::warn!(
+                target: "circuit_breaker",
+                breaker = self.name,
+                ?old,
+                ?new,
+                reason,
+                "circuit breaker opened"
+            ),
+            BreakerState::HalfOpen => tracing::debug!(
+                target: "circuit_breaker",
+                breaker = self.name,
+                ?old,
+                ?new,
+                reason,
+                "circuit breaker half-open"
+            ),
+            BreakerState::Closed => tracing::info!(
+                target: "circuit_breaker",
+                breaker = self.name,
+                ?old,
+                ?new,
+                reason,
+                "circuit breaker closed"
+            ),
+        }
+    }
+
+    fn on_probe_admission(&self, allowed: bool) {
+        tracing::debug!(
+            target: "circuit_breaker",
+            breaker = self.name,
+            allowed,
+            "circuit breaker probe admission"
+        );
+    }
+
+    fn on_outcome(&self, outcome: Outcome, state: BreakerState) {
+        if let Outcome::Failure = outcome {
+            tracing::trace!(
+                target: "circuit_breaker",
+                breaker = self.name,
+                ?state,
+                "circuit breaker outcome failure"
+            );
+        }
+    }
+}
+
+#[cfg(test)]
+#[path = "circuit_breaker_observer_tests.rs"]
+mod tests;