refactor ai serving modules and crates

apps/aether-gateway/src/ai_serving/finalize/internal/stream_rewrite.rs

@@ -0,0 +1,35 @@
+use serde_json::Value;
+
+use crate::ai_serving::{
+    maybe_build_ai_surface_stream_rewriter, AiSurfaceFinalizeError, AiSurfaceStreamRewriter,
+};
+use crate::GatewayError;
+
+pub(crate) struct LocalStreamRewriter<'a> {
+    inner: AiSurfaceStreamRewriter<'a>,
+}
+
+pub(crate) fn maybe_build_local_stream_rewriter<'a>(
+    report_context: Option<&'a Value>,
+) -> Option<LocalStreamRewriter<'a>> {
+    maybe_build_ai_surface_stream_rewriter(report_context)
+        .map(|inner| LocalStreamRewriter { inner })
+}
+
+impl LocalStreamRewriter<'_> {
+    pub(crate) fn push_chunk(&mut self, chunk: &[u8]) -> Result<Vec<u8>, GatewayError> {
+        self.inner.push_chunk(chunk).map_err(map_surface_error)
+    }
+
+    pub(crate) fn finish(&mut self) -> Result<Vec<u8>, GatewayError> {
+        self.inner.finish().map_err(map_surface_error)
+    }
+}
+
+fn map_surface_error(error: AiSurfaceFinalizeError) -> GatewayError {
+    error.into()
+}
+
+#[cfg(test)]
+#[path = "../tests_stream.rs"]
+mod tests;