Reuse core host definitions across requests

docs/wasm-runtime-architecture.md

@@ -218,7 +218,7 @@ Each request gets a fresh **workspace** — a per-request wasm instance tree wit
 the membrane wired in. `wasm_worker_serve(worker, ctx, entry_unit, handler)`
 (`src/wasm/worker.cpp`) is the single entry point for *every* mode:
 
-1. Birth a request-scoped workspace with fresh per-request state. Current production workers instantiate a fresh workspace for each request; any future snapshot/CoW optimization must preserve that request-isolation contract.
+1. Birth a request-scoped workspace with fresh per-request state. Current production workers instantiate a fresh Store, table, core instance, memory, globals, constructors, and request tree for each request. The worker retains only Wasmtime's store-independent host-function definitions and their fixed import order, avoiding reconstruction of 73 identical callback definitions. Every callback resolves the one active request workspace at invocation. Any future snapshot/CoW optimization must preserve that request-isolation contract.
 2. Resolve `entry_unit` + `handler` to an export; components referenced at
    runtime are resolved on demand via the `uce_host_component_resolve` hostcall
    (`component_resolve()` → `__uce_<...>` slot), loading dependency modules
@@ -240,6 +240,15 @@ module cache, adding a visible cold-start request. Request state remains bounded
 by the fresh workspace and the normal per-request database/resource cleanup;
 faulted workers still exit and are replaced by the parent.
 
+The request context remains UCEB2 so application `context.call` semantics do
+not fork into a private transport type. Validated decode trees move into the
+request rather than being deep-copied twice; the historical by-value
+`DValue::operator=(DValue)` symbol remains exported so warmed side-module
+artifacts stay ABI-compatible. `request_perf()` subdivides birth into policy,
+import materialization, core instantiation, export lookup, and initialization,
+and context transfer into bytes, host encode, guest allocation/write,
+guest decode/application, and free.
+
 ### Task callbacks and workspace lifetime
 
 `task()` and `task_repeat()` are fork-backed. The `uce_host_task_spawn` hostcall