alert when claude usage runs ahead of the clock, per account

hive-agent/src/claude_usage_watch.rs

@@ -27,6 +27,8 @@ const USAGE_URL: &str = "https://api.anthropic.com/api/oauth/usage";
 const OAUTH_BETA: &str = "oauth-2025-04-20";
 /// The credentials file `claude` itself reads its OAuth session from.
 const CREDENTIALS_FILE: &str = ".credentials.json";
+/// claude's config file, beside the credentials directory.
+const CONFIG_FILE: &str = ".claude.json";
 
 /// No `Debug`/`Display`, so the token cannot end up in a log line by
 /// accident.
@@ -64,6 +66,33 @@ struct Window {
     resets_at: Option<u64>,
 }
 
+/// The opaque id of the claude login from the claude config file
+/// (`oauthAccount.accountUuid`). Only that one field is deserialised: the
+/// same object holds the email address, which must never reach a metric.
+fn account_from(bytes: &[u8]) -> Option<String> {
+    #[derive(Deserialize)]
+    struct Config {
+        #[serde(rename = "oauthAccount")]
+        account: Option<Account>,
+    }
+    #[derive(Deserialize)]
+    struct Account {
+        #[serde(rename = "accountUuid")]
+        uuid: Option<String>,
+    }
+    let config = serde_json::from_slice::<Config>(bytes).ok()?;
+    config.account?.uuid.filter(|u| !u.is_empty())
+}
+
+/// `claude.json` sits next to the `.claude` directory. Read on every tick so
+/// a re-login is followed.
+async fn read_account(claude_dir: &Path) -> Option<String> {
+    let bytes = tokio::fs::read(claude_dir.with_file_name(CONFIG_FILE))
+        .await
+        .ok()?;
+    account_from(&bytes)
+}
+
 /// Background loop. Detached task — runs for the harness's lifetime; every
 /// failure is logged and retried on the next tick, never fatal.
 pub async fn run() {
@@ -81,7 +110,8 @@ pub async fn run() {
             return;
         }
     };
-    let creds = crate::paths::claude_dir().join(CREDENTIALS_FILE);
+    let claude_dir = crate::paths::claude_dir();
+    let creds = claude_dir.join(CREDENTIALS_FILE);
     let mut skip_logged = false;
     // Separate streak from `skip_logged`: a token can be usable while the
     // response still carries no recognisable window (endpoint change,
@@ -115,8 +145,14 @@ pub async fn run() {
                         "claude usage watch: usage response had no recognisable windows"
                     );
                 }
+                let account = read_account(&claude_dir).await;
                 for w in windows {
-                    crate::otel_turn_metrics::record_claude_usage(&w.name, w.percent, w.resets_at);
+                    crate::otel_turn_metrics::record_claude_usage(
+                        account.as_deref(),
+                        &w.name,
+                        w.percent,
+                        w.resets_at,
+                    );
                 }
             }
             Err(e) => tracing::warn!("claude usage watch: {e}"),
@@ -250,6 +286,28 @@ mod tests {
         );
     }
 
+    const CONFIG: &str = r#"{
+        "oauthAccount": { "accountUuid": "0a1b-uuid", "emailAddress": "someone@example.com" },
+        "projects": {}
+    }"#;
+
+    #[test]
+    fn account_is_the_uuid_and_never_the_email() {
+        let id = account_from(CONFIG.as_bytes()).expect("account");
+        assert_eq!(id, "0a1b-uuid");
+        assert!(!id.contains('@'));
+    }
+
+    #[test]
+    fn missing_account_is_none() {
+        assert_eq!(account_from(b"{}"), None);
+        assert_eq!(
+            account_from(br#"{"oauthAccount":{"accountUuid":""}}"#),
+            None
+        );
+        assert_eq!(account_from(b"not json"), None);
+    }
+
     #[test]
     fn non_object_body_yields_nothing() {
         assert!(windows(&Value::Null).is_empty());