From ec5fbb453dae4cf97bb369e83bf7888e157058e4 Mon Sep 17 00:00:00 2001
From: NotAShelf <raf@notashelf.dev>
Date: Sat, 14 Feb 2026 01:37:09 +0300
Subject: [PATCH] fc-common: add `AlertConfig` and `AlertManager` for error
 tracking

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: Iaf2f52f6e0cf33e3275528ac13cd92046a6a6964
---
 crates/common/src/alerts.rs | 86 +++++++++++++++++++++++++++++++++++++
 crates/common/src/config.rs | 23 +++++++++-
 crates/common/src/lib.rs    |  1 +
 3 files changed, 108 insertions(+), 2 deletions(-)
 create mode 100644 crates/common/src/alerts.rs

diff --git a/crates/common/src/alerts.rs b/crates/common/src/alerts.rs
new file mode 100644
index 0000000..6d55f6c
--- /dev/null
+++ b/crates/common/src/alerts.rs
@@ -0,0 +1,86 @@
+use std::sync::Arc;
+
+use chrono::Utc;
+use sqlx::PgPool;
+use tokio::sync::RwLock;
+use tracing::info;
+use uuid::Uuid;
+
+use crate::{config::AlertConfig, repo::build_metrics};
+
+#[derive(Debug, Clone)]
+pub struct AlertState {
+  pub last_alert_at: chrono::DateTime<Utc>,
+}
+
+impl Default for AlertState {
+  fn default() -> Self {
+    Self {
+      last_alert_at: chrono::DateTime::<Utc>::MIN_UTC,
+    }
+  }
+}
+
+pub struct AlertManager {
+  config: AlertConfig,
+  state:  Arc<RwLock<AlertState>>,
+}
+
+impl std::fmt::Debug for AlertManager {
+  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    f.debug_struct("AlertManager")
+      .field("config", &self.config)
+      .finish()
+  }
+}
+
+impl AlertManager {
+  pub fn new(config: AlertConfig) -> Self {
+    Self {
+      config,
+      state: Arc::new(RwLock::new(AlertState::default())),
+    }
+  }
+
+  pub fn is_enabled(&self) -> bool {
+    self.config.enabled
+  }
+
+  pub async fn check_and_alert(
+    &self,
+    pool: &PgPool,
+    project_id: Option<Uuid>,
+    jobset_id: Option<Uuid>,
+  ) -> Option<f64> {
+    if !self.is_enabled() {
+      return None;
+    }
+
+    let failure_rate = match build_metrics::calculate_failure_rate(
+      pool,
+      project_id,
+      jobset_id,
+      self.config.time_window_minutes,
+    )
+    .await
+    {
+      Ok(rate) => rate,
+      Err(_) => return None,
+    };
+
+    if failure_rate > self.config.error_threshold {
+      let mut state = self.state.write().await;
+      let time_since_last = (Utc::now() - state.last_alert_at).num_minutes();
+
+      if time_since_last >= self.config.time_window_minutes {
+        state.last_alert_at = Utc::now();
+        info!(
+          "Alert: failure rate {:.1}% exceeds threshold {:.1}%",
+          failure_rate, self.config.error_threshold
+        );
+        return Some(failure_rate);
+      }
+    }
+    None
+  }
+}
diff --git a/crates/common/src/config.rs b/crates/common/src/config.rs
index 3b9e52f..ead09ea 100644
--- a/crates/common/src/config.rs
+++ b/crates/common/src/config.rs
@@ -118,6 +118,25 @@ pub struct NotificationsConfig {
   pub gitlab_url:   Option<String>,
   pub gitlab_token: Option<String>,
   pub email:        Option<EmailConfig>,
+  pub alerts:       Option<AlertConfig>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
+pub struct AlertConfig {
+  pub enabled:             bool,
+  pub error_threshold:     f64,
+  pub time_window_minutes: i64,
+}
+
+impl Default for AlertConfig {
+  fn default() -> Self {
+    Self {
+      enabled:             false,
+      error_threshold:     20.0,
+      time_window_minutes: 60,
+    }
+  }
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
@@ -220,8 +239,8 @@ pub struct DeclarativeProject {
 /// Declarative notification configuration.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct DeclarativeNotification {
-  /// Notification type: `github_status`, email, `gitlab_status`, `gitea_status`,
-  /// `run_command`
+  /// Notification type: `github_status`, email, `gitlab_status`,
+  /// `gitea_status`, `run_command`
   pub notification_type: String,
   /// Type-specific configuration (JSON object)
   pub config:            serde_json::Value,
diff --git a/crates/common/src/lib.rs b/crates/common/src/lib.rs
index 0c6b6ea..6303886 100644
--- a/crates/common/src/lib.rs
+++ b/crates/common/src/lib.rs
@@ -1,5 +1,6 @@
 //! Common types and utilities for CI
 
+pub mod alerts;
 pub mod config;
 pub mod database;
 pub mod error;