phase 5

spikes/wasm-phase3/README.md

@@ -0,0 +1,63 @@
+# spikes/wasm-phase3 — dynamic loader + workspace scaffold
+
+Phase 3 combines the Phase 0 dynamic PIC-module loader with the Phase 2 UCEB1
+request-context membrane. It is still a spike, not the production wasm worker,
+but it validates the load-bearing pieces together:
+
+1. build a core WASM reactor that owns memory, allocator, `Request`, `DValue`,
+   UCEB1, and output buffering;
+2. build a separate PIC side module with `dylink.0` from a generated-shape UCE
+   page C++ file;
+3. parse `dylink.0`, allocate `__memory_base`/`__table_base`, resolve
+   `env.*`, `GOT.mem.*`, and `GOT.func.*` imports against the core/workspace;
+4. instantiate the unit, run relocations/constructors, set its Request pointer,
+   call `__uce_render`, and read rendered output from core-owned memory.
+
+The fixture intentionally exercises the loader branches that are easiest to
+accidentally leave dark: non-zero `table_size` / `__table_base`, `GOT.func`
+resolution (`phase3_core_print`), and deferred self-resolution of unit-owned
+`GOT.mem` entries. The loader output prints those resolutions before the final
+pass marker. Its generated-shape expressions call `html_escape(...)` so the
+side-module import surface includes the first ordinary UCE helper dependency
+rather than only `types.h`/`DValue`.
+
+Run on `k-uce`:
+
+```bash
+bash spikes/wasm-phase3/build_modules.sh
+bash spikes/wasm-phase3/build_loader.sh
+/tmp/uce/wasm-phase3/loader
+```
+
+Expected final line:
+
+```text
+PHASE3 EXIT CRITERION: PASS
+```
+
+Files:
+
+- `core.cpp` — core/workspace scaffold and UCEB1 membrane decode.
+- `page.uce` — source page for the generated-shape fixture.
+- `generated/page.uce.cpp` — checked-in UCE-preprocessor-shaped side-module
+  fixture: `uce_lib.h` include, `__uce_set_current_request`, `__uce_render`,
+  literal markup lowered to `print(R"(...)")`, expression prints wrapped in
+  `html_escape(...)`, callback/lambda/table exercises, and self-GOT data.
+- `loader.cpp` — dynamic linker/runner adapted from Phase 0.
+- `hostcalls.syms` — explicit core hostcall allowlist.
+
+Still deferred to production Phase 3/4 work:
+
+- running the actual UCE preprocessor inside this build script rather than using
+  a checked-in generated-shape fixture;
+- lazy component/path dispatch for a full site tree;
+- uce-starter end-to-end under a wasm FastCGI worker;
+- productionizing the side-module allocator gate as a real `#ifdef` in
+  `types.h` instead of this spike's copied-header text patch;
+- parser hardening beyond the spike's basic magic/version/bounds/alignment
+  checks, including fuzzing malformed wasm/dylink sections before accepting
+  cache or third-party units;
+- import-policy hardening beyond this spike's fail-fast resolver;
+- workspace birth/drop integration with the real server lifecycle, including
+  retaining unaligned allocation pointers needed to unload units or drop a
+  workspace cleanly.

spikes/wasm-phase3/build_loader.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+# Phase 3: build the dynamic-loader/membrane runner against Wasmtime's wasm-c-api.
+set -e
+cd "$(dirname "$0")"
+
+OUT=/tmp/uce/wasm-phase3
+mkdir -p "$OUT"
+
+c++ -std=c++17 -O2 loader.cpp \
+	-I/opt/wasmtime/include \
+	-L/opt/wasmtime/lib \
+	-Wl,-rpath,/opt/wasmtime/lib \
+	-lwasmtime \
+	-o "$OUT/loader"
+
+echo "built: $OUT/loader"

spikes/wasm-phase3/build_modules.sh

@@ -0,0 +1,70 @@
+#!/bin/bash
+# Phase 3: build a core reactor plus one generated-shape PIC side module.
+# Runs on k-uce; artifacts go under /tmp/uce/wasm-phase3.
+set -e
+cd "$(dirname "$0")"
+
+SDK=/opt/wasi-sdk
+ROOT=$(cd ../.. && pwd)
+OUT=/tmp/uce/wasm-phase3
+SHIM="$OUT/shim"
+mkdir -p "$OUT" "$SHIM"
+
+cat > "$SHIM/uce_lib.h" <<'EOF'
+#pragma once
+#include "types.h"
+String html_escape(String s);
+EOF
+cp "$ROOT/src/lib/types.h" "$SHIM/types.h"
+python3 - <<'PY'
+from pathlib import Path
+p = Path('/tmp/uce/wasm-phase3/shim/types.h')
+s = p.read_text()
+start = s.index('void * operator new(decltype(sizeof(0)) n) noexcept(false)')
+end = s.index('void operator delete(void * p) throw()')
+end = s.index('\n}', end) + 3
+replacement = '''// WASM side-module shim: allocator is owned by the core module.\nvoid * operator new(decltype(sizeof(0)) n) noexcept(false);\nvoid operator delete(void * p) throw();\nvoid operator delete(void * p, decltype(sizeof(0)) n) noexcept;\n'''
+p.write_text(s[:start] + replacement + s[end:])
+PY
+cat > "$SHIM/signal.h" <<'EOF'
+#pragma once
+typedef int sig_atomic_t;
+typedef void (*sighandler_t)(int);
+#define SIGTERM 15
+int raise(int);
+sighandler_t signal(int, sighandler_t);
+EOF
+
+"$SDK/bin/clang++" --target=wasm32-wasip1 -mexec-model=reactor \
+	-O1 -fno-exceptions \
+	-I../.. -I../../src/lib \
+	core.cpp -o "$OUT/core.wasm" \
+	-Wl,--export-all \
+	-Wl,--import-table \
+	-Wl,--export=__stack_pointer \
+	-Wl,--export=__heap_base \
+	-Wl,--allow-undefined-file=hostcalls.syms \
+	-Wl,--undefined=_ZTVN10__cxxabiv117__class_type_infoE
+
+"$SDK/bin/clang++" --target=wasm32-wasip1 -fPIC -fvisibility=default \
+	-fvisibility-inlines-hidden \
+	-O1 -fno-exceptions \
+	-I"$SHIM" -I"$ROOT/src/lib" \
+	-c generated/page.uce.cpp -o "$OUT/page.o"
+
+"$SDK/bin/clang++" --target=wasm32-wasip1 -fPIC -fvisibility=default \
+	-fvisibility-inlines-hidden \
+	-O1 -fno-exceptions \
+	-I"$SHIM" -I"$ROOT/src/lib" \
+	-c generated/helper.cpp -o "$OUT/helper.o"
+
+"$SDK/bin/wasm-ld" -shared --experimental-pic \
+	--unresolved-symbols=import-dynamic \
+	"$OUT/page.o" "$OUT/helper.o" -o "$OUT/page.wasm" \
+	--export=__uce_set_current_request \
+	--export=__uce_render
+
+echo "--- phase3 core.wasm ---"
+ls -la "$OUT/core.wasm"
+echo "--- phase3 page.wasm ---"
+ls -la "$OUT/page.wasm"

spikes/wasm-phase3/core.cpp

@@ -0,0 +1,188 @@
+// WASM-PROPOSAL Phase 3 — dynamic-loader core scaffold.
+//
+// This core owns the UCE heap, Request, DValue/UCEB1, and output buffer. The
+// Phase 3 loader dynamically links a PIC side module generated in the same
+// shape as UCE preprocessor output, sets its Request* context, and invokes its
+// __uce_render entry.
+
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+
+#include "../../src/lib/types.h"
+#include "../../src/lib/dvalue.cpp"
+
+extern "C" {
+size_t uce_host_ctx_read(char* buf, size_t cap);
+void uce_host_log(int level, const char* buf, size_t len);
+}
+
+extern "C" void phase3_core_print(const char* data, size_t len)
+{
+	if(context && context->ob)
+		context->ob->write(data, len);
+}
+
+extern "C" void phase3_core_invoke_callback(void (*cb)(int), int value)
+{
+	cb(value);
+}
+
+extern "C" void phase3_core_invoke_function(std::function<int(int)>* f, int value)
+{
+	String out = "<p>fn=" + std::to_string((*f)(value)) + "</p>\n";
+	phase3_core_print(out.data(), out.size());
+}
+
+extern "C" intptr_t core_table_index_of_phase3_core_print()
+{
+	return(reinterpret_cast<intptr_t>(phase3_core_print));
+}
+
+static Request g_request;
+static ByteStream g_ob;
+static String g_output;
+
+SharedUnit::~SharedUnit() {}
+
+String html_escape(String s)
+{
+	String result;
+	for(char c : s)
+	{
+		switch(c)
+		{
+			case '&': result += "&amp;"; break;
+			case '<': result += "&lt;"; break;
+			case '>': result += "&gt;"; break;
+			case '"': result += "&quot;"; break;
+			case '\'': result += "&#39;"; break;
+			default: result.push_back(c); break;
+		}
+	}
+	return(result);
+}
+
+String nibble(String div, String& haystack)
+{
+	auto pos = haystack.find(div);
+	if(pos == String::npos)
+	{
+		auto result = haystack;
+		haystack.clear();
+		return(result);
+	}
+	auto result = haystack.substr(0, pos);
+	haystack.erase(0, pos + div.length());
+	return(result);
+}
+
+void Request::ob_start()
+{
+	ob_stack.push_back(new ByteStream());
+	ob = ob_stack.back();
+}
+
+void Request::set_status(s32 code, String reason)
+{
+	if(reason == "")
+		reason = code == 200 ? "OK" : "Status";
+	response_code = "HTTP/1.1 " + std::to_string(code) + " " + reason;
+}
+
+Request::~Request()
+{
+	for(auto* stream : ob_stack)
+		delete stream;
+	ob_stack.clear();
+}
+
+static void phase3_clear_ob_stack()
+{
+	for(auto* stream : g_request.ob_stack)
+		delete stream;
+	g_request.ob_stack.clear();
+}
+
+static void phase3_apply_context(DValue& root)
+{
+	g_request.call = root;
+	g_request.params.clear();
+	DValue* params = root.key("params");
+	if(params)
+	{
+		params->each([&](const DValue& item, String key) {
+			g_request.params[key] = item.to_string();
+		});
+	}
+}
+
+extern "C" {
+
+void* uce_alloc(size_t len)
+{
+	return(malloc(len));
+}
+
+void uce_free(void* ptr)
+{
+	free(ptr);
+}
+
+int uce_phase3_prepare()
+{
+	context = &g_request;
+	phase3_clear_ob_stack();
+	g_ob.str("");
+	g_ob.clear();
+	g_request.ob = &g_ob;
+	g_request.out = "";
+	g_output = "";
+
+	size_t ctx_required = uce_host_ctx_read(0, 0);
+	if(ctx_required == 0)
+		return(10);
+	char* ctx_buf = (char*)malloc(ctx_required);
+	if(ctx_buf == 0)
+		return(11);
+	size_t ctx_len = uce_host_ctx_read(ctx_buf, ctx_required);
+	if(ctx_len != ctx_required)
+	{
+		free(ctx_buf);
+		return(12);
+	}
+
+	DValue decoded;
+	String error;
+	bool ok = ucb_decode(String(ctx_buf, ctx_len), decoded, &error);
+	free(ctx_buf);
+	if(!ok)
+	{
+		uce_host_log(3, error.data(), error.size());
+		return(20);
+	}
+	phase3_apply_context(decoded);
+	return(0);
+}
+
+Request* uce_phase3_request()
+{
+	return(&g_request);
+}
+
+void uce_phase3_finish()
+{
+	g_output = g_ob.str();
+}
+
+const char* uce_phase3_output_data()
+{
+	return(g_output.data());
+}
+
+size_t uce_phase3_output_size()
+{
+	return(g_output.size());
+}
+
+}

spikes/wasm-phase3/generated/helper.cpp

@@ -0,0 +1,6 @@
+extern int phase3_unit_state;
+
+extern "C" int phase3_helper_state_plus(int value)
+{
+	return(phase3_unit_state + value);
+}

spikes/wasm-phase3/generated/page.uce.cpp

@@ -0,0 +1,72 @@
+#include "uce_lib.h"
+#include <functional>
+#include <map>
+#include <tuple>
+
+extern "C" void phase3_core_print(const char* data, size_t len);
+extern "C" void phase3_core_invoke_callback(void (*cb)(int), int value);
+extern "C" void phase3_core_invoke_function(std::function<int(int)>* f, int value);
+extern "C" int phase3_helper_state_plus(int value);
+
+int phase3_unit_state = 40;
+int phase3_weak_data __attribute__((weak)) = 0;
+
+static void phase3_unit_callback(int value)
+{
+	String out = "<p>callback=" + std::to_string(value + phase3_unit_state) + "</p>\n";
+	print(out);
+}
+
+#ifndef UCE_SET_CURRENT_REQUEST_DEFINED
+#define UCE_SET_CURRENT_REQUEST_DEFINED
+
+/*load_declarations*/
+
+extern "C" void __uce_set_current_request(Request* _request)
+{
+	context = _request;
+	/*load_units*/
+}
+
+#endif
+#line 4 "spikes/wasm-phase3/page.uce"
+extern "C" void __uce_render(Request& context)
+{
+	print(R"(<section class="phase3">
+		<h1>PHASE3 PAGE OK</h1>
+		<p>host=)");
+	print(html_escape(context.params["HTTP_HOST"]));
+	print(R"(</p>
+		<p>route=)");
+	print(html_escape(context.call["route"].to_string()));
+	print(R"(</p>
+		<p>answer=)");
+	print(html_escape(context.call["nested"]["answer"].to_string()));
+	print(R"(</p>
+)");
+	context.call["nested"].each([&](const DValue& value, String key) {
+		print(R"(		<p>each=)");
+		print(html_escape(key + ":" + value.to_string()));
+		print(R"(</p>
+)");
+	});
+	print(R"(		<p>self-got=)");
+	phase3_weak_data = 7;
+	print(std::to_string(phase3_helper_state_plus(2) + phase3_weak_data - 7));
+	print(R"(</p>
+)");
+	std::map<String, String> phase3_map;
+	phase3_map.emplace(std::piecewise_construct, std::forward_as_tuple("piece"), std::forward_as_tuple("wise"));
+	print(R"(		<p>map=)");
+	print(html_escape(phase3_map["piece"]));
+	print(R"(</p>
+)");
+	phase3_core_invoke_callback(phase3_unit_callback, 2);
+	void (*volatile print_ptr)(const char*, size_t) = phase3_core_print;
+	print_ptr("<p>got-func-ok</p>\n", 19);
+	auto* fn = new std::function<int(int)>([](int value) { return(value * 3); });
+	phase3_core_invoke_function(fn, 14);
+	delete fn;
+	print(R"(	</section>
+)");
+}

spikes/wasm-phase3/hostcalls.syms

@@ -0,0 +1,2 @@
+uce_host_ctx_read
+uce_host_log

spikes/wasm-phase3/loader.cpp

@@ -0,0 +1,554 @@
+// WASM-PROPOSAL Phase 3 — dynamic loader + membrane scaffold.
+//
+// Embeds a wasm runtime through the standard wasm-c-api and links a core
+// workspace module with a generated-shape PIC UCE side module:
+//
+//   1. instantiate core.wasm (owns memory/table/allocator/Request/DValue)
+//   2. parse page.wasm's dylink.0 → data size/align, table slots needed
+//   3. allocate __memory_base by calling core malloc, and __table_base by
+//      appending to the shared funcref table
+//   4. build the unit's import vector: env.memory / env.__indirect_function_table /
+//      env.__stack_pointer from core; env.* functions from core exports;
+//      GOT.mem.* and GOT.func.* through the same rules as Phase 0
+//   5. instantiate unit, patch deferred GOT entries, run relocations/ctors
+//   6. prepare a UCEB1 request context in core, set the unit's Request*, call
+//      __uce_render, then read output back out of core-owned linear memory
+//
+// Everything here is deliberately validation-grade: fail loudly, never guess.
+
+#include <wasm.h>
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <vector>
+#include <map>
+
+#define FAIL(...) do { fprintf(stderr, "FAIL: " __VA_ARGS__); fprintf(stderr, "\n"); exit(1); } while(0)
+#define CHECK(cond, ...) do { if(!(cond)) FAIL(__VA_ARGS__); } while(0)
+
+static std::vector<uint8_t> read_file(const char* fn)
+{
+	FILE* f = fopen(fn, "rb");
+	CHECK(f, "cannot open %s", fn);
+	fseek(f, 0, SEEK_END);
+	long n = ftell(f);
+	fseek(f, 0, SEEK_SET);
+	std::vector<uint8_t> buf(n);
+	CHECK(fread(buf.data(), 1, n, f) == (size_t)n, "short read on %s", fn);
+	fclose(f);
+	return buf;
+}
+
+// ---- minimal dylink.0 parser -------------------------------------------
+
+struct DylinkInfo
+{
+	uint32_t mem_size = 0;
+	uint32_t mem_align = 0;   // power of 2
+	uint32_t table_size = 0;
+	uint32_t table_align = 0;
+	bool found = false;
+};
+
+static uint64_t read_uleb(const uint8_t* buf, size_t& pos, size_t end)
+{
+	uint64_t result = 0;
+	int shift = 0;
+	while(true)
+	{
+		CHECK(pos < end, "truncated uleb in wasm custom section");
+		CHECK(shift < 64, "oversized uleb in wasm custom section");
+		uint8_t b = buf[pos++];
+		result |= (uint64_t)(b & 0x7f) << shift;
+		if(!(b & 0x80))
+			return result;
+		shift += 7;
+	}
+}
+
+static DylinkInfo parse_dylink(const std::vector<uint8_t>& wasm)
+{
+	DylinkInfo info;
+	CHECK(wasm.size() >= 8 && !memcmp(wasm.data(), "\0asm", 4), "not a wasm module");
+	CHECK(wasm[4] == 1 && wasm[5] == 0 && wasm[6] == 0 && wasm[7] == 0, "unsupported wasm binary version");
+	size_t pos = 8;
+	while(pos < wasm.size())
+	{
+		uint8_t sec_id = wasm[pos++];
+		uint64_t size = read_uleb(wasm.data(), pos, wasm.size());
+		CHECK(size <= wasm.size() - pos, "wasm section exceeds file size");
+		size_t end = pos + size;
+		if(sec_id == 0)
+		{
+			uint64_t name_len = read_uleb(wasm.data(), pos, end);
+			CHECK(name_len <= end - pos, "custom section name exceeds section size");
+			std::string name((const char*)wasm.data() + pos, name_len);
+			pos += name_len;
+			if(name == "dylink.0")
+			{
+				while(pos < end)
+				{
+					uint8_t sub = wasm[pos++];
+					uint64_t sub_len = read_uleb(wasm.data(), pos, end);
+					CHECK(sub_len <= end - pos, "dylink subsection exceeds section size");
+					size_t sub_end = pos + sub_len;
+					if(sub == 1) // WASM_DYLINK_MEM_INFO
+					{
+						info.mem_size = read_uleb(wasm.data(), pos, sub_end);
+						info.mem_align = read_uleb(wasm.data(), pos, sub_end);
+						info.table_size = read_uleb(wasm.data(), pos, sub_end);
+						info.table_align = read_uleb(wasm.data(), pos, sub_end);
+						CHECK(!info.found, "duplicate dylink.0 mem_info subsection");
+						CHECK(info.mem_align < 31 && info.table_align < 31, "unsupported dylink alignment");
+						info.found = true;
+					}
+					pos = sub_end;
+				}
+			}
+		}
+		pos = end;
+	}
+	return info;
+}
+
+// ---- tiny UCEB1 request-context encoder ---------------------------------
+
+static void append_varuint(std::string& out, uint64_t value)
+{
+	while(value >= 0x80)
+	{
+		out.push_back((char)((value & 0x7f) | 0x80));
+		value >>= 7;
+	}
+	out.push_back((char)value);
+}
+
+struct Node
+{
+	std::string scalar;
+	std::vector<std::pair<std::string, Node>> children;
+};
+
+static Node scalar(const char* value)
+{
+	Node n;
+	n.scalar = value;
+	return n;
+}
+
+static void encode_node(std::string& out, const Node& node)
+{
+	out.push_back(0);
+	append_varuint(out, node.scalar.size());
+	out.append(node.scalar);
+	append_varuint(out, node.children.size());
+	for(const auto& child : node.children)
+	{
+		append_varuint(out, child.first.size());
+		out.append(child.first);
+		encode_node(out, child.second);
+	}
+}
+
+static std::string make_context()
+{
+	Node params;
+	params.children.push_back({"HTTP_HOST", scalar("phase3.example.test")});
+	params.children.push_back({"SCRIPT_URL", scalar("/spikes/wasm-phase3/page.uce")});
+	Node nested;
+	nested.children.push_back({"answer", scalar("42")});
+	Node root;
+	root.children.push_back({"params", params});
+	root.children.push_back({"route", scalar("/spikes/wasm-phase3/page.uce")});
+	root.children.push_back({"nested", nested});
+	std::string out = "UCEB";
+	out.push_back((char)1);
+	encode_node(out, root);
+	return out;
+}
+
+// ---- host imports --------------------------------------------------------
+
+static wasm_memory_t* g_memory = nullptr;
+static std::string g_context;
+
+static void set_i32_result(wasm_val_t* result, int32_t value)
+{
+	result->kind = WASM_I32;
+	result->of.i32 = value;
+}
+
+static wasm_trap_t* host_ctx_read(void* env, const wasm_val_vec_t* args, wasm_val_vec_t* results)
+{
+	(void)env;
+	uint32_t ptr = args->data[0].of.i32;
+	uint32_t cap = args->data[1].of.i32;
+	if(ptr == 0 || cap == 0 || cap < g_context.size())
+	{
+		set_i32_result(&results->data[0], (int32_t)g_context.size());
+		return nullptr;
+	}
+	CHECK(g_memory, "host ctx_read called before memory export was captured");
+	uint8_t* mem = (uint8_t*)wasm_memory_data(g_memory);
+	size_t mem_size = wasm_memory_data_size(g_memory);
+	CHECK((size_t)ptr + g_context.size() <= mem_size, "ctx_read buffer outside memory");
+	memcpy(mem + ptr, g_context.data(), g_context.size());
+	set_i32_result(&results->data[0], (int32_t)g_context.size());
+	return nullptr;
+}
+
+static wasm_trap_t* host_log(void* env, const wasm_val_vec_t* args, wasm_val_vec_t* results)
+{
+	(void)env; (void)results;
+	int level = args->data[0].of.i32;
+	uint32_t ptr = args->data[1].of.i32;
+	uint32_t len = args->data[2].of.i32;
+	uint8_t* mem = (uint8_t*)wasm_memory_data(g_memory);
+	size_t mem_size = wasm_memory_data_size(g_memory);
+	if((size_t)ptr + len <= mem_size)
+		fprintf(stderr, "[guest log %d] %.*s\n", level, (int)len, (const char*)mem + ptr);
+	return nullptr;
+}
+
+// ---- named trap stubs for unsatisfied (WASI) imports --------------------
+
+static wasm_store_t* g_store_for_stubs = nullptr;
+
+static wasm_trap_t* stub_callback(void* env, const wasm_val_vec_t* args, wasm_val_vec_t* results)
+{
+	(void)args; (void)results;
+	fprintf(stderr, "[stub called: %s]\n", (const char*)env);
+	char msg[256];
+	snprintf(msg, sizeof(msg), "unimplemented host import called: %s", (const char*)env);
+	wasm_message_t message;
+	wasm_byte_vec_new(&message, strlen(msg) + 1, msg);
+	wasm_trap_t* trap = wasm_trap_new(g_store_for_stubs, &message);
+	wasm_byte_vec_delete(&message);
+	return trap;
+}
+
+// ---- instance wrapper: name → extern map --------------------------------
+
+struct Instance
+{
+	wasm_module_t* module = nullptr;
+	wasm_instance_t* instance = nullptr;
+	wasm_extern_vec_t exports = WASM_EMPTY_VEC;
+	std::map<std::string, wasm_extern_t*> by_name;
+
+	void index_exports()
+	{
+		wasm_exporttype_vec_t types = WASM_EMPTY_VEC;
+		wasm_module_exports(module, &types);
+		wasm_instance_exports(instance, &exports);
+		CHECK(types.size == exports.size, "export type/extern count mismatch");
+		for(size_t i = 0; i < types.size; i++)
+		{
+			const wasm_name_t* nm = wasm_exporttype_name(types.data[i]);
+			std::string key(nm->data, nm->size);
+			// some wasm-c-api impls include the trailing NUL in name size
+			while(!key.empty() && key.back() == '\0')
+				key.pop_back();
+			by_name[key] = exports.data[i];
+		}
+		wasm_exporttype_vec_delete(&types);
+	}
+
+	wasm_func_t* func(const char* name)
+	{
+		auto it = by_name.find(name);
+		return it == by_name.end() ? nullptr : wasm_extern_as_func(it->second);
+	}
+	wasm_global_t* global(const char* name)
+	{
+		auto it = by_name.find(name);
+		return it == by_name.end() ? nullptr : wasm_extern_as_global(it->second);
+	}
+};
+
+static wasm_store_t* g_store = nullptr;
+
+static void report_trap(wasm_trap_t* trap, const char* what)
+{
+	if(!trap)
+		return;
+	wasm_message_t msg;
+	wasm_trap_message(trap, &msg);
+	FAIL("trap during %s: %.*s", what, (int)msg.size, msg.data);
+}
+
+static int32_t call_i32(Instance& inst, const char* name, std::vector<int32_t> argv = {})
+{
+	wasm_func_t* f = inst.func(name);
+	CHECK(f, "missing export func %s", name);
+	wasm_val_t args_buf[4];
+	CHECK(argv.size() <= 4, "call_i32 argv overflow for %s", name);
+	for(size_t i = 0; i < argv.size(); i++)
+		args_buf[i] = WASM_I32_VAL(argv[i]);
+	wasm_val_t results_buf[1] = { WASM_INIT_VAL };
+	wasm_val_vec_t args = { argv.size(), args_buf };
+	wasm_val_vec_t results = { 1, results_buf };
+	size_t result_arity = wasm_func_result_arity(f);
+	wasm_val_vec_t no_results = WASM_EMPTY_VEC;
+	wasm_trap_t* trap = wasm_func_call(f, &args, result_arity ? &results : &no_results);
+	report_trap(trap, name);
+	return result_arity ? results_buf[0].of.i32 : 0;
+}
+
+static wasm_global_t* make_i32_global(int32_t value, wasm_mutability_t mut)
+{
+	wasm_globaltype_t* gt = wasm_globaltype_new(wasm_valtype_new(WASM_I32), mut);
+	wasm_val_t val = WASM_I32_VAL(value);
+	wasm_global_t* g = wasm_global_new(g_store, gt, &val);
+	CHECK(g, "wasm_global_new failed (host-created globals unsupported?)");
+	wasm_globaltype_delete(gt);
+	return g;
+}
+
+int main(int argc, char** argv)
+{
+	const char* core_path = argc > 1 ? argv[1] : "/tmp/uce/wasm-phase3/core.wasm";
+	const char* unit_path = argc > 2 ? argv[2] : "/tmp/uce/wasm-phase3/page.wasm";
+	g_context = make_context();
+
+	wasm_engine_t* engine = wasm_engine_new();
+	CHECK(engine, "engine");
+	g_store = wasm_store_new(engine);
+	CHECK(g_store, "store");
+	g_store_for_stubs = g_store;
+
+	// ---- 1. core module ---------------------------------------------------
+	std::vector<uint8_t> core_bytes = read_file(core_path);
+	wasm_byte_vec_t core_bv;
+	wasm_byte_vec_new(&core_bv, core_bytes.size(), (const char*)core_bytes.data());
+	Instance core;
+	core.module = wasm_module_new(g_store, &core_bv);
+	wasm_byte_vec_delete(&core_bv);
+	CHECK(core.module, "core module load failed");
+
+	// the shared funcref table is host-created (core links with --import-table)
+	// because WAMR cannot grow a table from the host: size it up front as
+	// core's declared minimum (= its own elem needs) plus headroom for unit
+	// module table regions. __table_base allocation bumps from the minimum.
+	wasm_table_t* table = nullptr;
+	uint32_t table_next_free = 0;
+	const uint32_t TABLE_HEADROOM = 2048;
+
+	wasm_importtype_vec_t core_imports = WASM_EMPTY_VEC;
+	wasm_module_imports(core.module, &core_imports);
+	std::vector<wasm_extern_t*> core_import_externs(core_imports.size);
+	for(size_t i = 0; i < core_imports.size; i++)
+	{
+		const wasm_name_t* mod = wasm_importtype_module(core_imports.data[i]);
+		const wasm_name_t* nm = wasm_importtype_name(core_imports.data[i]);
+		const wasm_externtype_t* et = wasm_importtype_type(core_imports.data[i]);
+		std::string name(nm->data, nm->size);
+		if(wasm_externtype_kind(et) == WASM_EXTERN_TABLE)
+		{
+			CHECK(name.rfind("__indirect_function_table", 0) == 0,
+				"unexpected core table import %s", name.c_str());
+			const wasm_tabletype_t* tt = wasm_externtype_as_tabletype_const(et);
+			uint32_t core_min = wasm_tabletype_limits(tt)->min;
+			wasm_limits_t limits = { core_min + TABLE_HEADROOM, core_min + TABLE_HEADROOM };
+			wasm_tabletype_t* host_tt = wasm_tabletype_new(wasm_valtype_new(WASM_FUNCREF), &limits);
+			table = wasm_table_new(g_store, host_tt, nullptr);
+			CHECK(table, "wasm_table_new failed (host-created tables unsupported?)");
+			wasm_tabletype_delete(host_tt);
+			table_next_free = core_min;
+			printf("host table created: size=%u, core region=[0,%u)\n", core_min + TABLE_HEADROOM, core_min);
+			core_import_externs[i] = wasm_table_as_extern(table);
+			continue;
+		}
+		CHECK(wasm_externtype_kind(et) == WASM_EXTERN_FUNC,
+			"core has unexpected non-func import %.*s.%s",
+			(int)mod->size, mod->data, name.c_str());
+		const wasm_functype_t* ft = wasm_externtype_as_functype_const(et);
+		wasm_func_t* import_func = nullptr;
+		std::string mod_name(mod->data, mod->size);
+		while(!mod_name.empty() && mod_name.back() == '\0') mod_name.pop_back();
+		while(!name.empty() && name.back() == '\0') name.pop_back();
+		if(mod_name == "env" && name == "uce_host_ctx_read")
+			import_func = wasm_func_new_with_env(g_store, ft, host_ctx_read, nullptr, nullptr);
+		else if(mod_name == "env" && name == "uce_host_log")
+			import_func = wasm_func_new_with_env(g_store, ft, host_log, nullptr, nullptr);
+		else
+		{
+			// named trap stub; leaks the name string, fine for a spike
+			char* label = strdup((mod_name + "." + name).c_str());
+			import_func = wasm_func_new_with_env(g_store, ft, stub_callback, label, nullptr);
+		}
+		CHECK(import_func, "stub func creation failed for %s", name.c_str());
+		core_import_externs[i] = wasm_func_as_extern(import_func);
+	}
+	CHECK(table, "core does not import __indirect_function_table — rebuild with --import-table");
+	wasm_extern_vec_t core_iv = { core_import_externs.size(), core_import_externs.data() };
+	wasm_trap_t* trap = nullptr;
+	core.instance = wasm_instance_new(g_store, core.module, &core_iv, &trap);
+	report_trap(trap, "core instantiation");
+	CHECK(core.instance, "core instantiation failed");
+	core.index_exports();
+	printf("core instantiated: %zu exports\n", core.by_name.size());
+
+	// reactor init (runs ctors). Wasmtime does not auto-run _initialize;
+	// WAMR does — and calling it twice trips wasi-libc's double-init guard
+	// (__builtin_trap → "unreachable"), which cost us a debugging round.
+	if(core.func("_initialize"))
+		call_i32(core, "_initialize");
+
+	wasm_memory_t* memory = wasm_extern_as_memory(core.by_name.count("memory") ? core.by_name["memory"] : nullptr);
+	CHECK(memory, "core does not export memory");
+	g_memory = memory;
+
+	// ---- 2./3. dylink + base allocation ------------------------------------
+	std::vector<uint8_t> unit_bytes = read_file(unit_path);
+	DylinkInfo dl = parse_dylink(unit_bytes);
+	CHECK(dl.found, "unit has no dylink.0 mem_info");
+	printf("dylink.0: memsize=%u memalign=2^%u tablesize=%u\n", dl.mem_size, dl.mem_align, dl.table_size);
+
+	uint32_t align = 1u << dl.mem_align;
+	uint32_t raw = (uint32_t)call_i32(core, "malloc", { (int32_t)(dl.mem_size + align) });
+	CHECK(raw, "core malloc returned 0");
+	uint32_t memory_base = (raw + (align - 1)) & ~(align - 1);
+
+	uint32_t table_base = table_next_free;
+	table_next_free += dl.table_size;
+	CHECK(table_next_free <= wasm_table_size(table), "table headroom exhausted");
+	printf("bases: __memory_base=%u __table_base=%u (table size %u)\n",
+		memory_base, table_base, wasm_table_size(table));
+
+	// ---- 4. unit import resolution -----------------------------------------
+	wasm_byte_vec_t unit_bv;
+	wasm_byte_vec_new(&unit_bv, unit_bytes.size(), (const char*)unit_bytes.data());
+	Instance unit;
+	unit.module = wasm_module_new(g_store, &unit_bv);
+	wasm_byte_vec_delete(&unit_bv);
+	CHECK(unit.module, "unit module load failed");
+
+	wasm_importtype_vec_t unit_imports = WASM_EMPTY_VEC;
+	wasm_module_imports(unit.module, &unit_imports);
+	std::vector<wasm_extern_t*> unit_import_externs(unit_imports.size);
+	// GOT.mem entries that must be self-resolved from the unit's own exports
+	// after instantiation (weak data the core does not define)
+	std::vector<std::pair<std::string, wasm_global_t*>> deferred_got;
+
+	for(size_t i = 0; i < unit_imports.size; i++)
+	{
+		const wasm_name_t* mod_n = wasm_importtype_module(unit_imports.data[i]);
+		const wasm_name_t* nm_n = wasm_importtype_name(unit_imports.data[i]);
+		std::string mod(mod_n->data, mod_n->size);
+		std::string nm(nm_n->data, nm_n->size);
+		const wasm_externtype_t* et = wasm_importtype_type(unit_imports.data[i]);
+		wasm_externkind_t kind = wasm_externtype_kind(et);
+		wasm_extern_t* resolved = nullptr;
+
+		if(mod == "env" && nm == "memory")
+			resolved = wasm_memory_as_extern(memory);
+		else if(mod == "env" && nm == "__indirect_function_table")
+			resolved = wasm_table_as_extern(table);
+		else if(mod == "env" && nm == "__stack_pointer")
+		{
+			CHECK(core.global("__stack_pointer"), "core does not export __stack_pointer");
+			resolved = core.by_name["__stack_pointer"];
+		}
+		else if(mod == "env" && nm == "__memory_base")
+			resolved = wasm_global_as_extern(make_i32_global((int32_t)memory_base, WASM_CONST));
+		else if(mod == "env" && nm == "__table_base")
+			resolved = wasm_global_as_extern(make_i32_global((int32_t)table_base, WASM_CONST));
+		else if(mod == "env" && kind == WASM_EXTERN_FUNC)
+		{
+			auto it = core.by_name.find(nm);
+			CHECK(it != core.by_name.end(), "unresolved unit func import env.%s", nm.c_str());
+			resolved = it->second;
+		}
+		else if(mod == "GOT.mem")
+		{
+			wasm_global_t* src = core.global(nm.c_str());
+			if(src)
+			{
+				wasm_val_t v;
+				wasm_global_get(src, &v);
+				resolved = wasm_global_as_extern(make_i32_global(v.of.i32, WASM_VAR));
+			}
+			else
+			{
+				// provisional 0; patched from the unit's own export post-instantiation
+				wasm_global_t* g = make_i32_global(0, WASM_VAR);
+				deferred_got.push_back({ nm, g });
+				resolved = wasm_global_as_extern(g);
+			}
+		}
+		else if(mod == "GOT.func")
+		{
+			// resolved guest-side: the core exports a helper returning
+			// (intptr_t)&func, which on wasm is the function's table index —
+			// no host-side funcref injection needed (WAMR forbids it anyway)
+			std::string helper = "core_table_index_of_" + nm;
+			CHECK(core.func(helper.c_str()), "no GOT.func resolver %s in core", helper.c_str());
+			int32_t slot = call_i32(core, helper.c_str());
+			CHECK(slot > 0, "GOT.func resolver %s returned %d", helper.c_str(), slot);
+			printf("resolved GOT.func.%s = table[%d]\n", nm.c_str(), slot);
+			resolved = wasm_global_as_extern(make_i32_global(slot, WASM_VAR));
+		}
+		CHECK(resolved, "unhandled unit import %s.%s (kind %d)", mod.c_str(), nm.c_str(), (int)kind);
+		unit_import_externs[i] = resolved;
+	}
+
+	// ---- 5. instantiate unit, patch GOT, run init ---------------------------
+	wasm_extern_vec_t unit_iv = { unit_import_externs.size(), unit_import_externs.data() };
+	trap = nullptr;
+	unit.instance = wasm_instance_new(g_store, unit.module, &unit_iv, &trap);
+	report_trap(trap, "unit instantiation");
+	CHECK(unit.instance, "unit instantiation failed");
+	unit.index_exports();
+	printf("unit instantiated: %zu exports\n", unit.by_name.size());
+
+	for(auto& [nm, got] : deferred_got)
+	{
+		wasm_global_t* own = unit.global(nm.c_str());
+		CHECK(own, "GOT.mem.%s defined neither by core nor by unit", nm.c_str());
+		wasm_val_t v;
+		wasm_global_get(own, &v);
+		// dylink ABI: a PIC module's exported data symbols are offsets relative
+		// to its __memory_base; the linker must add the base when resolving
+		wasm_val_t nv = WASM_I32_VAL((int32_t)(memory_base + (uint32_t)v.of.i32));
+		wasm_global_set(got, &nv);
+		printf("self-resolved GOT.mem.%s = %u (offset %d)\n", nm.c_str(), memory_base + (uint32_t)v.of.i32, v.of.i32);
+	}
+
+	if(unit.func("__wasm_apply_data_relocs"))
+		call_i32(unit, "__wasm_apply_data_relocs");
+	if(unit.func("__wasm_call_ctors"))
+		call_i32(unit, "__wasm_call_ctors");
+
+	// ---- 6. membrane prepare, render and read back ---------------------------
+	int32_t rc = call_i32(core, "uce_phase3_prepare");
+	CHECK(rc == 0, "uce_phase3_prepare returned %d", rc);
+	int32_t request_ptr = call_i32(core, "uce_phase3_request");
+	CHECK(request_ptr != 0, "core returned null Request*");
+	call_i32(unit, "__uce_set_current_request", { request_ptr });
+	call_i32(unit, "__uce_render", { request_ptr });
+	call_i32(core, "uce_phase3_finish");
+
+	int32_t out_ptr = call_i32(core, "uce_phase3_output_data");
+	int32_t out_len = call_i32(core, "uce_phase3_output_size");
+	byte_t* mem = wasm_memory_data(memory); // may have moved if memory grew
+
+	printf("---- phase3 unit output (%d bytes) ----\n%.*s\n--------------------------------------\n",
+		out_len, out_len, mem + out_ptr);
+
+	bool ok = out_len > 0 &&
+		memmem(mem + out_ptr, out_len, "PHASE3 PAGE OK", 14) &&
+		memmem(mem + out_ptr, out_len, "host=phase3.example.test", 24) &&
+		memmem(mem + out_ptr, out_len, "answer=42", 9) &&
+		memmem(mem + out_ptr, out_len, "each=answer:42", 14) &&
+		memmem(mem + out_ptr, out_len, "self-got=42", 11) &&
+		memmem(mem + out_ptr, out_len, "map=wise", 8) &&
+		memmem(mem + out_ptr, out_len, "callback=42", 11) &&
+		memmem(mem + out_ptr, out_len, "got-func-ok", 11) &&
+		memmem(mem + out_ptr, out_len, "fn=42", 5);
+
+	printf(ok ? "PHASE3 EXIT CRITERION: PASS\n" : "PHASE3 EXIT CRITERION: FAIL (see output above)\n");
+	return ok ? 0 : 1;
+}

spikes/wasm-phase3/page.uce

@@ -0,0 +1,12 @@
+// Phase 3 generated-unit fixture source. The checked-in generated/page.uce.cpp
+// is the UCE-preprocessor-shaped output used by the wasm side-module build.
+
+RENDER(Request& context)
+{
+	<><section class="phase3">
+		<h1>PHASE3 PAGE OK</h1>
+		<p>host=<?= context.params["HTTP_HOST"] ?></p>
+		<p>route=<?= context.call["route"].to_string() ?></p>
+		<p>answer=<?= context.call["nested"]["answer"].to_string() ?></p>
+	</section>
+}