Refactor HTTP implementation of API methods

sync-server/src/api/mod.rs

@@ -4,5 +4,15 @@ use std::sync::Arc;
 pub(crate) mod add_version;
 pub(crate) mod get_child_version;
 
+/// The content-type for history segments (opaque blobs of bytes)
+pub(crate) const HISTORY_SEGMENT_CONTENT_TYPE: &str =
+    "application/vnd.taskchampion.history-segment";
+
+/// The header names for version ID
+pub(crate) const VERSION_ID_HEADER: &str = "X-Version-Id";
+
+/// The header names for parent version ID
+pub(crate) const PARENT_VERSION_ID_HEADER: &str = "X-Parent-Version-Id";
+
 /// The type containing a reference to the SyncServer object in the Actix state.
 pub(crate) type ServerState = Arc<Box<dyn SyncServer>>;