core: type agent timestamps

crates/crank-core/src/agent.rs

@@ -1,5 +1,6 @@
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
+use time::OffsetDateTime;
 
 use crate::ids::{AgentId, OperationId, WorkspaceId};
 
@@ -21,9 +22,12 @@ pub struct Agent {
     pub status: AgentStatus,
     pub current_draft_version: u32,
     pub latest_published_version: Option<u32>,
-    pub created_at: String,
-    pub updated_at: String,
-    pub published_at: Option<String>,
+    #[serde(with = "time::serde::rfc3339")]
+    pub created_at: OffsetDateTime,
+    #[serde(with = "time::serde::rfc3339")]
+    pub updated_at: OffsetDateTime,
+    #[serde(with = "time::serde::rfc3339::option")]
+    pub published_at: Option<OffsetDateTime>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
@@ -33,7 +37,8 @@ pub struct AgentVersion {
     pub status: AgentStatus,
     pub instructions: Value,
     pub tool_selection_policy: Value,
-    pub created_at: String,
+    #[serde(with = "time::serde::rfc3339")]
+    pub created_at: OffsetDateTime,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
@@ -45,3 +50,53 @@ pub struct AgentOperationBinding {
     pub tool_description_override: Option<String>,
     pub enabled: bool,
 }
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+    use time::{OffsetDateTime, format_description::well_known::Rfc3339};
+
+    use super::{Agent, AgentStatus, AgentVersion};
+    use crate::ids::{AgentId, WorkspaceId};
+
+    #[test]
+    fn agent_serializes_timestamps_as_rfc3339() {
+        let agent = Agent {
+            id: AgentId::new("agent_01"),
+            workspace_id: WorkspaceId::new("ws_01"),
+            slug: "triage".to_owned(),
+            display_name: "Triage".to_owned(),
+            description: "Triage agent".to_owned(),
+            status: AgentStatus::Published,
+            current_draft_version: 2,
+            latest_published_version: Some(2),
+            created_at: OffsetDateTime::parse("2026-03-25T12:00:00Z", &Rfc3339).unwrap(),
+            updated_at: OffsetDateTime::parse("2026-03-25T12:05:00Z", &Rfc3339).unwrap(),
+            published_at: Some(OffsetDateTime::parse("2026-03-25T12:10:00Z", &Rfc3339).unwrap()),
+        };
+
+        let value = serde_json::to_value(&agent).unwrap();
+
+        assert_eq!(value["created_at"], json!("2026-03-25T12:00:00Z"));
+        assert_eq!(value["updated_at"], json!("2026-03-25T12:05:00Z"));
+        assert_eq!(value["published_at"], json!("2026-03-25T12:10:00Z"));
+    }
+
+    #[test]
+    fn agent_version_deserializes_created_at_from_rfc3339() {
+        let version: AgentVersion = serde_json::from_value(json!({
+            "agent_id": "agent_01",
+            "version": 1,
+            "status": "draft",
+            "instructions": {"system": "triage"},
+            "tool_selection_policy": {"mode": "allow_list"},
+            "created_at": "2026-03-25T12:00:00Z"
+        }))
+        .unwrap();
+
+        assert_eq!(
+            version.created_at,
+            OffsetDateTime::parse("2026-03-25T12:00:00Z", &Rfc3339).unwrap()
+        );
+    }
+}