updated documentation to have mermaid diagrams; updated AGENTS.md to note that all future diagrams should be mermaid diagrams first with text-based diagrams as fallback where not applicable

resources/ai/research/data-streaming/03-rust-integration.md

@@ -196,6 +196,18 @@ Notes:
 
 ## Building buffers efficiently (Rust specifics)
 
+Build order is **back-to-front** (children before parents):
+
+```mermaid
+flowchart TB
+    A["create_string / create_vector<br/>children first"]
+    B["create nested child tables"]
+    C["create parent table<br/>ObjectBatch::create(&args)"]
+    D["builder.finish(root, Some(&#34;DESI&#34;))"]
+    E["Bytes::copy_from_slice(fbb.finished_data())<br/>→ HTTP / WebSocket response"]
+    A --> B --> C --> D --> E
+```
+
 - `FlatBufferBuilder::with_capacity(n)` pre-allocates; `reset()` reuses the
   buffer across messages. In a loop streaming batches, create one builder, reuse
   it — avoid repeated reallocation.