Revert "Merge remote-tracking branch 'origin/pr/592'"

This reverts commit 3504875922, reversing
changes made to 5c3a1aecbe.

crates/aether-contracts/src/lib.rs

@@ -16,6 +16,4 @@ pub use plan::{
     TRANSPORT_HTTP_MODE_HTTP1_ONLY, TRANSPORT_POOL_SCOPE_KEY,
 };
 pub use result::{ExecutionResult, ExecutionTelemetry, ResponseBody};
-pub use usage::{
-    ExecutionStreamTerminalSummary, StandardizedUsage, USAGE_SERVER_NOW_UNIX_MS_HEADER,
-};
+pub use usage::{ExecutionStreamTerminalSummary, StandardizedUsage};

crates/aether-contracts/src/usage.rs

@@ -2,8 +2,6 @@ use std::collections::BTreeMap;
 
 use serde::{Deserialize, Serialize};
 
-pub const USAGE_SERVER_NOW_UNIX_MS_HEADER: &str = "x-aether-server-now-unix-ms";
-
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
 pub struct StandardizedUsage {
     pub input_tokens: i64,