Reuse loaded component units per request

docs/wasm-runtime-architecture.md

@@ -139,8 +139,12 @@ The request entry unit is already loaded by the host, so its selected handler
 and optional `ONCE` export are placed directly into the workspace table and
 passed to `uce_wasm_invoke_loaded_entry()`. Dynamic component and unit calls
 continue through `wasm_resolve_target()`, where relative-path resolution is
-required. Opt-in verbose response headers split entry invocation into load,
-presence lookup, table linking, and core dispatch time.
+required. Handler cache keys include the calling unit so identically named
+relative targets in different directories cannot alias. Once a unit has passed
+freshness checks and loaded into a request workspace, later handler lookups
+reuse that immutable request-local instance; `component_loaded_reuse_count`
+reports those lookups. Opt-in verbose response headers split entry invocation
+into load, presence lookup, table linking, and core dispatch time.
 
 `wasm_backend_should_handle(request, entry_unit)` checks whether the wasm
 backend is initialized and the requested artifact/handler is currently