scope nested component props without deep copies

docs/wasm-runtime-architecture.md

@@ -401,6 +401,11 @@ header free-functions are `inline`. The wasm backend exposes only declarations
   share one source, compile, artifact, and module-cache identity. The compiler
   independently enforces the same canonical identity, and persisted failures
   are reused only when their recorded source path matches the current request.
+  `scripts/test_nested_component_props.sh` passes a large prop tree through an
+  outer component, invokes 300 nested components, and verifies both inner and
+  caller props are restored. Its warm-request ceiling guards the request-scope
+  invariant that entering a nested component swaps the active prop trees in
+  constant time instead of deep-copying the outer tree for every child.
 
 - **Log timeliness**: the base process line-buffers stdout before forking
   workers, the proactive compiler, and the WebSocket broker. This keeps each

scripts/run_cli_tests.sh

@@ -68,6 +68,7 @@ if [[ "$action" == "run" ]]; then
 	done
 	scripts/test_dependency_invalidation.sh
 	scripts/test_cold_component_deadline.sh
+	scripts/test_nested_component_props.sh
 	scripts/test_password_hashing.sh
 	scripts/test_log_timeliness.sh
 fi

scripts/test_nested_component_props.sh

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+test_name="nested-component-props-test-$$"
+site_directory="${UCE_TEST_SITE_DIRECTORY:-site}"
+if [[ -z "${UCE_TEST_SITE_DIRECTORY:-}" && -r /etc/uce/settings.cfg ]]; then
+	configured_site_directory=$(awk -F= '/^[[:space:]]*SITE_DIRECTORY[[:space:]]*=/ {gsub(/^[[:space:]]+|[[:space:]]+$/, "", $2); print $2; exit}' /etc/uce/settings.cfg)
+	if [[ -n "${configured_site_directory:-}" ]]; then
+		site_directory="$configured_site_directory"
+	fi
+fi
+source_dir="$site_directory/$test_name"
+threshold_ms="${UCE_NESTED_COMPONENT_PROPS_MAX_MS:-1500}"
+
+cleanup() {
+	rm -rf "$source_dir"
+}
+trap cleanup EXIT
+mkdir -p "$source_dir"
+
+printf '%s\n' \
+	'CLI(Request& context) {' \
+	'  context.props["sentinel"] = "caller";' \
+	'  String payload; for(u64 i = 0; i < 4096; ++i) payload += "x";' \
+	'  DValue props; for(u64 i = 0; i < 300; ++i) { DValue item; item = payload; props["items"].push(item); }' \
+	'  String output = component("outer", props, context);' \
+	'  if(context.props["sentinel"].to_string() != "caller") { print("caller props not restored"); return; }' \
+	'  print(output);' \
+	'}' >"$source_dir/parent.uce"
+
+printf '%s\n' \
+	'COMPONENT(Request& context) {' \
+	'  if(context.props["items"]._map.size() != 300) { print("outer props missing"); return; }' \
+	'  for(u64 i = 0; i < 300; ++i) {' \
+	'    DValue props; props["index"] = std::to_string(i); component("leaf", props, context);' \
+	'    if(context.props["items"]._map.size() != 300) { print("outer props not restored"); return; }' \
+	'  }' \
+	'  print("nested-component-props-ok");' \
+	'}' >"$source_dir/outer.uce"
+
+printf '%s\n' \
+	'COMPONENT(Request& context) {' \
+	'  if(context.props["index"].to_string() == "") print("leaf props missing");' \
+	'}' >"$source_dir/leaf.uce"
+
+warm_output=$(scripts/uce-cli "/$test_name/parent.uce")
+if [[ "$warm_output" != "nested-component-props-ok" ]]; then
+	echo "nested component props warmup failed: $warm_output" >&2
+	exit 1
+fi
+
+start_ns=$(date +%s%N)
+output=$(scripts/uce-cli "/$test_name/parent.uce")
+elapsed_ms=$(( ($(date +%s%N) - start_ns) / 1000000 ))
+if [[ "$output" != "nested-component-props-ok" ]]; then
+	echo "nested component props failed: $output" >&2
+	exit 1
+fi
+if (( elapsed_ms > threshold_ms )); then
+	echo "nested component props took ${elapsed_ms}ms (limit ${threshold_ms}ms)" >&2
+	exit 1
+fi
+
+echo "nested component props passed in ${elapsed_ms}ms"

src/lib/dvalue.h

@@ -12,11 +12,11 @@ struct DValue {
 	char type = 'S';
 
 	String 	_String;
-	f64 	_float;
+	f64 	_float = 0;
 	s64 	_array_index = 0;
-	bool	_bool;
+	bool	_bool = false;
 	bool	_list_mode = false;
-	void*	_ptr;
+	void*	_ptr = 0;
 	std::map<String, DValue> _map;
 
 	// Read accessors are const and never create or modify nodes. The to_*

src/wasm/core.cpp

@@ -494,20 +494,32 @@ struct RequestPropsScope
 	Request* context = 0;
 	DValue previous_props;
 
-	RequestPropsScope(Request* context, const DValue& props)
+	static void swap_value(DValue& left, DValue& right)
+	{
+		std::swap(left.type, right.type);
+		left._String.swap(right._String);
+		std::swap(left._float, right._float);
+		std::swap(left._array_index, right._array_index);
+		std::swap(left._bool, right._bool);
+		std::swap(left._list_mode, right._list_mode);
+		std::swap(left._ptr, right._ptr);
+		left._map.swap(right._map);
+	}
+
+	RequestPropsScope(Request* context, DValue& props)
 	{
 		this->context = context;
 		if(this->context)
 		{
-			previous_props = this->context->props;
+			swap_value(previous_props, this->context->props);
-			this->context->props = props;
+			swap_value(this->context->props, props);
 		}
 	}
 
 	~RequestPropsScope()
 	{
 		if(context)
-			context->props = previous_props;
+			swap_value(context->props, previous_props);
 	}
 };
 
@@ -600,7 +612,8 @@ DValue* unit_call(String file_name, String function_name, DValue* call_param)
 			print("Error: unit_call() function '", function_name, "' not found");
 			return(0);
 		}
-		RequestPropsScope props_scope(context, (call_param ? *call_param : DValue()));
+		DValue props = call_param ? *call_param : DValue();
+		RequestPropsScope props_scope(context, props);
 		if((handler == "render" || handler.rfind("render:", 0) == 0 || handler == "component" || handler.rfind("component:", 0) == 0) && resolved != "")
 			wasm_run_once(resolved, *context);
 		String previous_unit = context->resources.current_unit_file;
@@ -634,7 +647,7 @@ DValue* unit_call(String file_name, String function_name, DValue* call_param)
 	return(0);
 }
 
-void component_render(String name, DValue props, Request& request)
+static void component_render_with_props(String name, DValue& props, Request& request)
 {
 	String file_name, render_name;
 	component_parse_target(trim(name), file_name, render_name);
@@ -658,14 +671,15 @@ void component_render(String name, DValue props, Request& request)
 	request.resources.current_unit_file = previous_unit;
 }
 
-void component_render(String name) { DValue props; component_render(name, props, *context); }
+void component_render(String name, DValue props, Request& request) { component_render_with_props(name, props, request); }
-void component_render(String name, Request& request) { DValue props; component_render(name, props, request); }
+void component_render(String name) { DValue props; component_render_with_props(name, props, *context); }
-void component_render(String name, DValue props) { component_render(name, props, *context); }
+void component_render(String name, Request& request) { DValue props; component_render_with_props(name, props, request); }
+void component_render(String name, DValue props) { component_render_with_props(name, props, *context); }
 
 String component(String name, DValue props, Request& request)
 {
 	ob_start();
-	component_render(name, props, request);
+	component_render_with_props(name, props, request);
 	return(ob_get_close());
 }