diff --git a/.gitignore b/.gitignore
index b3395e4..a8f4b3b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ build-wasm/
 compile_commands.json
 /.emscripten-cache
 /.cache/clangd/index
+/build-asan
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5115aac..36851fd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,11 +5,19 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 option(REGOLITH_BUILD_TESTS "Build tests" ON)
 option(REGOLITH_BUILD_SDL3 "Build the SDL3 backend" ON)
+option(REGOLITH_SANITIZE "Build with ASan and UBSan" OFF)
+if(REGOLITH_SANITIZE AND NOT MSVC AND NOT EMSCRIPTEN)
+  add_compile_options(-fsanitize=address,undefined -fno-omit-frame-pointer)
+  add_link_options(-fsanitize=address,undefined)
+endif()
 
 add_subdirectory(third_party)
 
 add_library(regolith
   src/context.c
+  src/nodes.c
+  src/props.c
+  src/types.c
   src/layout_clay.c
   src/text_stb.c
   src/lua_module.c
diff --git a/include/regolith.h b/include/regolith.h
index 643b916..e8c4e77 100644
--- a/include/regolith.h
+++ b/include/regolith.h
@@ -39,7 +39,10 @@ enum {
   RG_ERR_GENERIC = -1,
   RG_ERR_NO_MEMORY = -2,
   RG_ERR_STATE = -3,
-  RG_ERR_LUA = -4
+  RG_ERR_LUA = -4,
+  RG_ERR_HANDLE = -5,
+  RG_ERR_TYPE = -6,
+  RG_ERR_PROP = -7
 };
 
 enum { RG_LOG_TRACE = 0, RG_LOG_DEBUG, RG_LOG_INFO, RG_LOG_WARN, RG_LOG_ERROR };
@@ -72,6 +75,96 @@ RG_API rg_context *rg_create(const rg_config *config);
 RG_API void rg_destroy(rg_context *ctx);
 RG_API const char *rg_last_error(const rg_context *ctx);
 
+typedef uint64_t rg_node;
+#define RG_NODE_NONE ((rg_node)0)
+
+enum {
+  RG_NODE_ROOT = 0,
+  RG_NODE_BOX,
+  RG_NODE_HBOX,
+  RG_NODE_VBOX,
+  RG_NODE_PANEL,
+  RG_NODE_LABEL,
+  RG_NODE_BUTTON,
+  RG_NODE_TYPE_COUNT
+};
+
+enum {
+  RG_VAL_NONE = 0,
+  RG_VAL_BOOL,
+  RG_VAL_INT,
+  RG_VAL_FLOAT,
+  RG_VAL_ENUM,
+  RG_VAL_COLOR,
+  RG_VAL_SIZE,
+  RG_VAL_VEC4,
+  RG_VAL_STRING
+};
+
+enum { RG_SIZE_FIT = 0, RG_SIZE_GROW, RG_SIZE_FIXED, RG_SIZE_PERCENT };
+enum { RG_DIR_ROW = 0, RG_DIR_COLUMN };
+enum { RG_ALIGN_START = 0, RG_ALIGN_CENTER, RG_ALIGN_END };
+
+enum {
+  RG_PROP_DIRECTION = 0,
+  RG_PROP_WIDTH,
+  RG_PROP_HEIGHT,
+  RG_PROP_PADDING,
+  RG_PROP_GAP,
+  RG_PROP_ALIGN_X,
+  RG_PROP_ALIGN_Y,
+  RG_PROP_BACKGROUND,
+  RG_PROP_BORDER_COLOR,
+  RG_PROP_BORDER_WIDTH,
+  RG_PROP_CORNER_RADIUS,
+  RG_PROP_OPACITY,
+  RG_PROP_VISIBLE,
+  RG_PROP_TEXT,
+  RG_PROP_FONT,
+  RG_PROP_FONT_SIZE,
+  RG_PROP_COLOR,
+  RG_PROP_COUNT
+};
+
+typedef struct rg_value {
+  int32_t type;
+  int32_t i;
+  float f[4];
+  const char *s;
+} rg_value;
+
+RG_API int32_t rg_type_find(const char *name);
+RG_API const char *rg_type_name(int32_t type);
+
+RG_API rg_node rg_root(const rg_context *ctx);
+RG_API rg_node rg_node_create(rg_context *ctx, int32_t type);
+RG_API void rg_node_destroy(rg_context *ctx, rg_node node);
+RG_API int rg_node_valid(const rg_context *ctx, rg_node node);
+RG_API int32_t rg_node_type(const rg_context *ctx, rg_node node);
+RG_API int rg_node_append(rg_context *ctx, rg_node parent, rg_node child);
+RG_API int rg_node_insert_before(rg_context *ctx, rg_node parent, rg_node child,
+                                 rg_node ref);
+RG_API int rg_node_detach(rg_context *ctx, rg_node node);
+RG_API rg_node rg_node_parent(const rg_context *ctx, rg_node node);
+RG_API rg_node rg_node_first_child(const rg_context *ctx, rg_node node);
+RG_API rg_node rg_node_next_sibling(const rg_context *ctx, rg_node node);
+
+RG_API int32_t rg_prop_find(const char *name);
+RG_API const char *rg_prop_name(int32_t prop);
+RG_API int32_t rg_prop_type(int32_t prop);
+
+RG_API int rg_set(rg_context *ctx, rg_node node, int32_t prop,
+                  const rg_value *value);
+RG_API int rg_get(rg_context *ctx, rg_node node, int32_t prop, rg_value *out);
+RG_API int rg_unset(rg_context *ctx, rg_node node, int32_t prop);
+
+RG_API int rg_set_int(rg_context *ctx, rg_node node, int32_t prop, int32_t v);
+RG_API int rg_set_float(rg_context *ctx, rg_node node, int32_t prop, float v);
+RG_API int rg_set_string(rg_context *ctx, rg_node node, int32_t prop,
+                         const char *v);
+RG_API int rg_set_color(rg_context *ctx, rg_node node, int32_t prop, float r,
+                        float g, float b, float a);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/scripts/build.sh b/scripts/build.sh
new file mode 100755
index 0000000..005af99
--- /dev/null
+++ b/scripts/build.sh
@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+usage() {
+    cat <<EOF
+usage: scripts/build.sh <command>
+
+commands:
+  debug     configure, build, and test into build/
+  release   configure, build, and test into build-release/
+  asan      configure, build, and test with ASan and UBSan into build-asan/
+  wasm      configure, build, and test with Emscripten into build-wasm/
+  all       debug, asan, then wasm
+  clean     remove all build directories
+EOF
+}
+
+build() {
+    local dir=$1 launcher=$2
+    shift 2
+    $launcher cmake -S . -B "$dir" -G Ninja "$@"
+    cmake --build "$dir"
+    ctest --test-dir "$dir" --output-on-failure
+}
+
+link_compile_commands() {
+    ln -sf build/compile_commands.json compile_commands.json
+}
+
+case "${1:-}" in
+    debug)
+        build build "" -DCMAKE_BUILD_TYPE=Debug
+        link_compile_commands
+        ;;
+    release)
+        build build-release "" -DCMAKE_BUILD_TYPE=Release
+        ;;
+    asan)
+        build build-asan "" -DCMAKE_BUILD_TYPE=Debug -DREGOLITH_SANITIZE=ON
+        ;;
+    wasm)
+        build build-wasm emcmake -DCMAKE_BUILD_TYPE=Debug
+        ;;
+    all)
+        "$0" debug
+        "$0" asan
+        "$0" wasm
+        ;;
+    clean)
+        rm -rf build build-release build-asan build-wasm compile_commands.json
+        ;;
+    *)
+        usage
+        exit 1
+        ;;
+esac
diff --git a/src/context.c b/src/context.c
index 20939cb..31b43d2 100644
--- a/src/context.c
+++ b/src/context.c
@@ -1,4 +1,5 @@
 #include "internal.h"
+#include "regolith.h"
 
 #include <stdarg.h>
 #include <stdio.h>
@@ -102,6 +103,11 @@ rg_context *rg_create(const rg_config *config) {
   ctx->viewport_h = cfg.viewport_h;
   ctx->display_scale = cfg.display_scale;
 
+  if(rg__nodes_init(ctx) != RG_OK) {
+    rg_destroy(ctx);
+    return NULL;
+  }
+
   rg__log(ctx, RG_LOG_DEBUG, "clay minimum memory: %zu bytes",
           rg__clay_min_memory());
   rg__log(ctx, RG_LOG_INFO, "context created (%dx%d @ %.2fx)",
@@ -116,7 +122,31 @@ void rg_destroy(rg_context *ctx) {
   if (!ctx)
     return;
   rg__lua_close(ctx);
+  rg__nodes_free(ctx);
   rg__log(ctx, RG_LOG_INFO, "context destroyed");
   a = ctx->alloc;
   a.free(ctx, sizeof *ctx, a.user);
 }
+
+void *rg__alloc(rg_context *ctx, size_t size) {
+  return ctx->alloc.alloc(size, ctx->alloc.user);
+}
+
+void *rg__zalloc(rg_context *ctx, size_t size) {
+  void *p = rg__alloc(ctx, size);
+  if (p)
+    memset(p, 0, size);
+  return p;
+}
+
+void *rg__realloc(rg_context *ctx, void *ptr, size_t old_size,
+                  size_t new_size) {
+  if (!ptr)
+    return rg__alloc(ctx, new_size);
+  return ctx->alloc.realloc(ptr, old_size, new_size, ctx->alloc.user);
+}
+
+void rg__free(rg_context *ctx, void *ptr, size_t size) {
+  if (ptr)
+    ctx->alloc.free(ptr, size, ctx->alloc.user);
+}
diff --git a/src/internal.h b/src/internal.h
index 6306570..5b0c1c0 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -1,33 +1,99 @@
 #ifndef RG_INTERNAL_H
 #define RG_INTERNAL_H
 
-
 #include "regolith.h"
 
 #if defined(__GNUC__)
-  #define RG_PRINTF(f, a) __attribute__((format(printf, f, a)))
+#define RG_PRINTF(f, a) __attribute__((format(printf, f, a)))
 #else
-  #define RG_PRINTF(f, a)
+#define RG_PRINTF(f, a)
 #endif
 
+#define RG_NIL 0xFFFFFFFFu
+
+enum { RG_PF_INHERIT = 1, RG_PF_LAYOUT = 2, RG_PF_ANIMATE = 4 };
+enum { RG_TF_FOCUSABLE = 1, RG_TF_TEXT = 2 };
+
+#define RG_V_BOOL(v) {RG_VAL_BOOL, (v), {0, 0, 0, 0}, NULL}
+#define RG_V_ENUM(v) {RG_VAL_ENUM, (v), {0, 0, 0, 0}, NULL}
+#define RG_V_FLOAT(v) {RG_VAL_FLOAT, 0, {(v), 0, 0, 0}, NULL}
+#define RG_V_COLOR(r, g, b, a) {RG_VAL_COLOR, 0, {(r), (g), (b), (a)}, NULL}
+#define RG_V_VEC4(a, b, c, d) {RG_VAL_VEC4, 0, {(a), (b), (c), (d)}, NULL}
+#define RG_V_SIZE(mode, v) {RG_VAL_SIZE, (mode), {(v), 0, 0, 0}, NULL}
+#define RG_V_STRING(s) {RG_VAL_STRING, 0, {0, 0, 0, 0}, (s)}
+
+typedef struct rg_override {
+  int32_t prop;
+  rg_value value;
+} rg_override;
+
+typedef struct rg_prop_info {
+  const char *name;
+  int32_t type;
+  uint32_t flags;
+  rg_value def;
+} rg_prop_info;
+
+typedef struct rg_type_info {
+  const char *name;
+  uint32_t flags;
+  const rg_override *defaults;
+  int32_t default_count;
+} rg_type_info;
+
+typedef struct rg_node_data {
+  uint32_t index;
+  uint32_t generation;
+  uint32_t alive;
+  uint32_t parent, first_child, last_child, prev, next;
+  uint32_t next_free;
+  int32_t type;
+  rg_override *ov;
+  uint32_t ov_count, ov_cap;
+} rg_node_data;
+
 struct lua_State;
 
 struct rg_context {
   rg_allocator alloc;
   rg_log_fn log;
-  void* log_user;
+  void *log_user;
   int32_t log_level;
   int32_t viewport_w;
   int32_t viewport_h;
   float display_scale;
   char last_error[256];
-  struct lua_State* L;
+  struct lua_State *L;
+
+  rg_node_data **chunks;
+  uint32_t chunk_count;
+  uint32_t chunk_cap;
+  uint32_t slot_count;
+  uint32_t free_head;
+  uint32_t node_count;
+  rg_node root;
 };
 
-void rg__log(rg_context* ctx, int32_t level, const char* fmt, ...) RG_PRINTF(3, 4);
-int rg__fail(rg_context* ctx, int code, const char* fmt, ...) RG_PRINTF(3, 4);
+void rg__log(rg_context *ctx, int32_t level, const char *fmt, ...)
+    RG_PRINTF(3, 4);
+int rg__fail(rg_context *ctx, int code, const char *fmt, ...) RG_PRINTF(3, 4);
+
+void *rg__alloc(rg_context *ctx, size_t size);
+void *rg__zalloc(rg_context *ctx, size_t size);
+void *rg__realloc(rg_context *ctx, void *ptr, size_t old_size, size_t new_size);
+void rg__free(rg_context *ctx, void *ptr, size_t size);
+
+int rg__nodes_init(rg_context *ctx);
+void rg__nodes_free(rg_context *ctx);
+rg_node rg__node_create(rg_context *ctx, int32_t type);
+rg_node_data *rg__node_resolve(const rg_context *ctx, rg_node node);
+
+const rg_prop_info *rg__prop_info(int32_t prop);
+const rg_type_info *rg__type_info(int32_t type);
+const rg_value *rg__default_value(int32_t type, int32_t prop);
+void rg__overrides_free(rg_context *ctx, rg_node_data *n);
 
 size_t rg__clay_min_memory(void);
-void rg__lua_close(rg_context* ctx);
+void rg__lua_close(rg_context *ctx);
 
 #endif
diff --git a/src/nodes.c b/src/nodes.c
new file mode 100644
index 0000000..6b43795
--- /dev/null
+++ b/src/nodes.c
@@ -0,0 +1,276 @@
+#include "internal.h"
+
+#define CHUNK_SHIFT 8
+#define CHUNK_SIZE (1u << CHUNK_SHIFT)
+#define CHUNK_MASK (CHUNK_SIZE - 1u)
+
+static rg_node_data *slot_at(const rg_context *ctx, uint32_t idx) {
+  return &ctx->chunks[idx >> CHUNK_SHIFT][idx & CHUNK_MASK];
+}
+
+static rg_node make_handle(const rg_node_data *n) {
+  return ((rg_node)n->generation << 32) | (rg_node)n->index;
+}
+
+static rg_node handle_of(const rg_context *ctx, uint32_t idx) {
+  return idx == RG_NIL ? RG_NODE_NONE : make_handle(slot_at(ctx, idx));
+}
+
+rg_node_data *rg__node_resolve(const rg_context *ctx, rg_node h) {
+  uint32_t idx = (uint32_t)(h & 0xFFFFFFFFu);
+  uint32_t gen = (uint32_t)(h >> 32);
+  rg_node_data *n;
+
+  if (h == RG_NODE_NONE || idx >= ctx->slot_count)
+    return NULL;
+  n = slot_at(ctx, idx);
+  if (!n->alive || n->generation != gen)
+    return NULL;
+  return n;
+}
+
+static int grow_chunks(rg_context *ctx) {
+  rg_node_data *chunk;
+
+  if (ctx->chunk_count == ctx->chunk_cap) {
+    uint32_t cap = ctx->chunk_cap ? ctx->chunk_cap * 2 : 4;
+    rg_node_data **arr = rg__realloc(
+        ctx, ctx->chunks, ctx->chunk_cap * sizeof *arr, cap * sizeof *arr);
+    if (!arr)
+      return RG_ERR_NO_MEMORY;
+    ctx->chunks = arr;
+    ctx->chunk_cap = cap;
+  }
+  chunk = rg__zalloc(ctx, CHUNK_SIZE * sizeof *chunk);
+  if (!chunk)
+    return RG_ERR_NO_MEMORY;
+  ctx->chunks[ctx->chunk_count++] = chunk;
+  return RG_OK;
+}
+
+static rg_node_data *slot_alloc(rg_context *ctx) {
+  rg_node_data *n;
+  uint32_t idx;
+
+  if (ctx->free_head != RG_NIL) {
+    idx = ctx->free_head;
+    n = slot_at(ctx, idx);
+    ctx->free_head = n->next_free;
+  } else {
+    idx = ctx->slot_count;
+    if ((idx >> CHUNK_SHIFT) == ctx->chunk_count && grow_chunks(ctx) != RG_OK)
+      return NULL;
+    n = slot_at(ctx, idx);
+    ctx->slot_count++;
+  }
+
+  n->index = idx;
+  if (n->generation == 0)
+    n->generation = 1;
+  n->alive = 1;
+  n->parent = n->first_child = n->last_child = RG_NIL;
+  n->prev = n->next = n->next_free = RG_NIL;
+  n->ov = NULL;
+  n->ov_count = n->ov_cap = 0;
+  ctx->node_count++;
+  return n;
+}
+
+static void release_slot(rg_context *ctx, rg_node_data *n) {
+  rg__log(ctx, RG_LOG_TRACE, "node destroyed: %s (slot %u)",
+          rg_type_name(n->type), (unsigned)n->index);
+  rg__overrides_free(ctx, n);
+  n->alive = 0;
+  if (++n->generation == 0)
+    n->generation = 1;
+  n->next_free = ctx->free_head;
+  ctx->free_head = n->index;
+  ctx->node_count--;
+}
+
+static void unlink_node(rg_context *ctx, rg_node_data *n) {
+  rg_node_data *p;
+
+  if (n->parent == RG_NIL)
+    return;
+  p = slot_at(ctx, n->parent);
+  if (n->prev != RG_NIL)
+    slot_at(ctx, n->prev)->next = n->next;
+  else
+    p->first_child = n->next;
+  if (n->next != RG_NIL)
+    slot_at(ctx, n->next)->prev = n->prev;
+  else
+    p->last_child = n->prev;
+  n->parent = n->prev = n->next = RG_NIL;
+}
+
+static void destroy_subtree(rg_context *ctx, rg_node_data *top) {
+  uint32_t top_idx = top->index;
+  uint32_t cur = top_idx;
+
+  for (;;) {
+    rg_node_data *n = slot_at(ctx, cur);
+    uint32_t parent;
+
+    if (n->first_child != RG_NIL) {
+      cur = n->first_child;
+      continue;
+    }
+    parent = n->parent;
+    unlink_node(ctx, n);
+    release_slot(ctx, n);
+    if (cur == top_idx)
+      break;
+    cur = parent;
+  }
+}
+
+static int is_self_or_ancestor(const rg_context *ctx, const rg_node_data *anc,
+                               const rg_node_data *n) {
+  while (n) {
+    if (n == anc)
+      return 1;
+    n = n->parent == RG_NIL ? NULL : slot_at(ctx, n->parent);
+  }
+  return 0;
+}
+
+rg_node rg__node_create(rg_context *ctx, int32_t type) {
+  rg_node_data *n = slot_alloc(ctx);
+
+  if (!n) {
+    rg__fail(ctx, RG_ERR_NO_MEMORY, "node allocation failed");
+    return RG_NODE_NONE;
+  }
+  n->type = type;
+  rg__log(ctx, RG_LOG_TRACE, "node created: %s (slot %u)", rg_type_name(type),
+          (unsigned)n->index);
+  return make_handle(n);
+}
+
+int rg__nodes_init(rg_context *ctx) {
+  ctx->free_head = RG_NIL;
+  ctx->root = rg__node_create(ctx, RG_NODE_ROOT);
+  return ctx->root == RG_NODE_NONE ? RG_ERR_NO_MEMORY : RG_OK;
+}
+
+void rg__nodes_free(rg_context *ctx) {
+  uint32_t i;
+
+  for (i = 0; i < ctx->slot_count; i++) {
+    rg_node_data *n = slot_at(ctx, i);
+    if (n->alive)
+      rg__overrides_free(ctx, n);
+  }
+  for (i = 0; i < ctx->chunk_count; i++)
+    rg__free(ctx, ctx->chunks[i], CHUNK_SIZE * sizeof(rg_node_data));
+  rg__free(ctx, ctx->chunks, ctx->chunk_cap * sizeof *ctx->chunks);
+  ctx->chunks = NULL;
+  ctx->chunk_count = ctx->chunk_cap = ctx->slot_count = ctx->node_count = 0;
+  ctx->root = RG_NODE_NONE;
+}
+
+rg_node rg_root(const rg_context *ctx) { return ctx->root; }
+
+rg_node rg_node_create(rg_context *ctx, int32_t type) {
+  if (type <= RG_NODE_ROOT || type >= RG_NODE_TYPE_COUNT) {
+    rg__fail(ctx, RG_ERR_TYPE, "cannot create node of type %d", (int)type);
+    return RG_NODE_NONE;
+  }
+  return rg__node_create(ctx, type);
+}
+
+void rg_node_destroy(rg_context *ctx, rg_node node) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+
+  if (!n) {
+    rg__log(ctx, RG_LOG_WARN, "destroy of a stale or invalid handle ignored");
+    return;
+  }
+  if (node == ctx->root) {
+    rg__log(ctx, RG_LOG_WARN, "the root node cannot be destroyed");
+    return;
+  }
+  unlink_node(ctx, n);
+  destroy_subtree(ctx, n);
+}
+
+int rg_node_valid(const rg_context *ctx, rg_node node) {
+  return rg__node_resolve(ctx, node) != NULL;
+}
+
+int32_t rg_node_type(const rg_context *ctx, rg_node node) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  return n ? n->type : -1;
+}
+
+int rg_node_insert_before(rg_context *ctx, rg_node parent, rg_node child,
+                          rg_node ref) {
+  rg_node_data *p = rg__node_resolve(ctx, parent);
+  rg_node_data *c = rg__node_resolve(ctx, child);
+  rg_node_data *r = NULL;
+
+  if (!p || !c)
+    return rg__fail(ctx, RG_ERR_HANDLE, "stale or invalid handle");
+  if (child == ctx->root)
+    return rg__fail(ctx, RG_ERR_STATE, "the root cannot be a child");
+  if (ref != RG_NODE_NONE) {
+    r = rg__node_resolve(ctx, ref);
+    if (!r)
+      return rg__fail(ctx, RG_ERR_HANDLE, "stale or invalid reference handle");
+    if (r == c || r->parent != p->index)
+      return rg__fail(ctx, RG_ERR_STATE,
+                      "reference is not a child of the parent");
+  }
+  if (is_self_or_ancestor(ctx, c, p))
+    return rg__fail(ctx, RG_ERR_STATE, "insert would create a cycle");
+
+  unlink_node(ctx, c);
+  c->parent = p->index;
+  if (r) {
+    c->next = r->index;
+    c->prev = r->prev;
+    if (r->prev != RG_NIL)
+      slot_at(ctx, r->prev)->next = c->index;
+    else
+      p->first_child = c->index;
+    r->prev = c->index;
+  } else {
+    c->prev = p->last_child;
+    if (p->last_child != RG_NIL)
+      slot_at(ctx, p->last_child)->next = c->index;
+    else
+      p->first_child = c->index;
+    p->last_child = c->index;
+  }
+  return RG_OK;
+}
+
+int rg_node_append(rg_context *ctx, rg_node parent, rg_node child) {
+  return rg_node_insert_before(ctx, parent, child, RG_NODE_NONE);
+}
+
+int rg_node_detach(rg_context *ctx, rg_node node) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+
+  if (!n)
+    return rg__fail(ctx, RG_ERR_HANDLE, "stale or invalid handle");
+  unlink_node(ctx, n);
+  return RG_OK;
+}
+
+rg_node rg_node_parent(const rg_context *ctx, rg_node node) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  return n ? handle_of(ctx, n->parent) : RG_NODE_NONE;
+}
+
+rg_node rg_node_first_child(const rg_context *ctx, rg_node node) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  return n ? handle_of(ctx, n->first_child) : RG_NODE_NONE;
+}
+
+rg_node rg_node_next_sibling(const rg_context *ctx, rg_node node) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  return n ? handle_of(ctx, n->next) : RG_NODE_NONE;
+}
diff --git a/src/props.c b/src/props.c
new file mode 100644
index 0000000..3c4eede
--- /dev/null
+++ b/src/props.c
@@ -0,0 +1,251 @@
+#include "internal.h"
+
+#include <string.h>
+
+static const rg_prop_info prop_table[RG_PROP_COUNT] = {
+    [RG_PROP_DIRECTION] = {"direction", RG_VAL_ENUM, RG_PF_LAYOUT,
+                           RG_V_ENUM(RG_DIR_ROW)},
+    [RG_PROP_WIDTH] = {"width", RG_VAL_SIZE, RG_PF_LAYOUT | RG_PF_ANIMATE,
+                       RG_V_SIZE(RG_SIZE_FIT, 0)},
+    [RG_PROP_HEIGHT] = {"height", RG_VAL_SIZE, RG_PF_LAYOUT | RG_PF_ANIMATE,
+                        RG_V_SIZE(RG_SIZE_FIT, 0)},
+    [RG_PROP_PADDING] = {"padding", RG_VAL_VEC4, RG_PF_LAYOUT | RG_PF_ANIMATE,
+                         RG_V_VEC4(0, 0, 0, 0)},
+    [RG_PROP_GAP] = {"gap", RG_VAL_FLOAT, RG_PF_LAYOUT | RG_PF_ANIMATE,
+                     RG_V_FLOAT(0)},
+    [RG_PROP_ALIGN_X] = {"align_x", RG_VAL_ENUM, RG_PF_LAYOUT,
+                         RG_V_ENUM(RG_ALIGN_START)},
+    [RG_PROP_ALIGN_Y] = {"align_y", RG_VAL_ENUM, RG_PF_LAYOUT,
+                         RG_V_ENUM(RG_ALIGN_START)},
+    [RG_PROP_BACKGROUND] = {"background", RG_VAL_COLOR, RG_PF_ANIMATE,
+                            RG_V_COLOR(0, 0, 0, 0)},
+    [RG_PROP_BORDER_COLOR] = {"border_color", RG_VAL_COLOR, RG_PF_ANIMATE,
+                              RG_V_COLOR(0, 0, 0, 0)},
+    [RG_PROP_BORDER_WIDTH] = {"border_width", RG_VAL_VEC4,
+                              RG_PF_LAYOUT | RG_PF_ANIMATE,
+                              RG_V_VEC4(0, 0, 0, 0)},
+    [RG_PROP_CORNER_RADIUS] = {"corner_radius", RG_VAL_VEC4, RG_PF_ANIMATE,
+                               RG_V_VEC4(0, 0, 0, 0)},
+    [RG_PROP_OPACITY] = {"opacity", RG_VAL_FLOAT, RG_PF_ANIMATE, RG_V_FLOAT(1)},
+    [RG_PROP_VISIBLE] = {"visible", RG_VAL_BOOL, RG_PF_LAYOUT, RG_V_BOOL(1)},
+    [RG_PROP_TEXT] = {"text", RG_VAL_STRING, RG_PF_LAYOUT, RG_V_STRING("")},
+    [RG_PROP_FONT] = {"font", RG_VAL_STRING, RG_PF_LAYOUT | RG_PF_INHERIT,
+                      RG_V_STRING("")},
+    [RG_PROP_FONT_SIZE] = {"font_size", RG_VAL_FLOAT,
+                           RG_PF_LAYOUT | RG_PF_INHERIT, RG_V_FLOAT(16)},
+    [RG_PROP_COLOR] = {"color", RG_VAL_COLOR, RG_PF_INHERIT | RG_PF_ANIMATE,
+                       RG_V_COLOR(1, 1, 1, 1)},
+};
+
+static const char *val_type_name(int32_t t) {
+  static const char *names[] = {"none",  "bool", "int",  "float", "enum",
+                                "color", "size", "vec4", "string"};
+  return t >= 0 && t <= RG_VAL_STRING ? names[t] : "invalid";
+}
+
+static void value_init(rg_value *v, int32_t type) {
+  memset(v, 0, sizeof *v);
+  v->type = type;
+}
+
+const rg_prop_info *rg__prop_info(int32_t prop) {
+  if (prop < 0 || prop >= RG_PROP_COUNT)
+    return NULL;
+  return &prop_table[prop];
+}
+
+int32_t rg_prop_find(const char *name) {
+  int32_t i;
+
+  if (!name)
+    return -1;
+  for (i = 0; i < RG_PROP_COUNT; i++)
+    if (strcmp(prop_table[i].name, name) == 0)
+      return i;
+  return -1;
+}
+
+const char *rg_prop_name(int32_t prop) {
+  const rg_prop_info *info = rg__prop_info(prop);
+  return info ? info->name : NULL;
+}
+
+int32_t rg_prop_type(int32_t prop) {
+  const rg_prop_info *info = rg__prop_info(prop);
+  return info ? info->type : RG_VAL_NONE;
+}
+
+const rg_value *rg__default_value(int32_t type, int32_t prop) {
+  const rg_type_info *t = rg__type_info(type);
+  int32_t i;
+
+  if (t)
+    for (i = 0; i < t->default_count; i++)
+      if (t->defaults[i].prop == prop)
+        return &t->defaults[i].value;
+  return &prop_table[prop].def;
+}
+
+static char *dup_string(rg_context *ctx, const char *s) {
+  size_t len = strlen(s) + 1;
+  char *p = rg__alloc(ctx, len);
+
+  if (p)
+    memcpy(p, s, len);
+  return p;
+}
+
+static void drop_value(rg_context *ctx, rg_value *v) {
+  if (v->type == RG_VAL_STRING && v->s) {
+    rg__free(ctx, (void *)v->s, strlen(v->s) + 1);
+    v->s = NULL;
+  }
+}
+
+void rg__overrides_free(rg_context *ctx, rg_node_data *n) {
+  uint32_t i;
+
+  for (i = 0; i < n->ov_count; i++)
+    drop_value(ctx, &n->ov[i].value);
+  rg__free(ctx, n->ov, n->ov_cap * sizeof *n->ov);
+  n->ov = NULL;
+  n->ov_count = n->ov_cap = 0;
+}
+
+static rg_override *find_override(const rg_node_data *n, int32_t prop) {
+  uint32_t i;
+
+  for (i = 0; i < n->ov_count; i++)
+    if (n->ov[i].prop == prop)
+      return &n->ov[i];
+  return NULL;
+}
+
+int rg_set(rg_context *ctx, rg_node node, int32_t prop, const rg_value *value) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  const rg_prop_info *info = rg__prop_info(prop);
+  rg_override *o;
+  rg_value v;
+
+  if (!n)
+    return rg__fail(ctx, RG_ERR_HANDLE, "set: stale or invalid handle");
+  if (!info)
+    return rg__fail(ctx, RG_ERR_PROP, "set: unknown property %d", (int)prop);
+  if (!value || value->type != info->type)
+    return rg__fail(ctx, RG_ERR_TYPE, "set: property '%s' expects %s",
+                    info->name, val_type_name(info->type));
+  if (value->type == RG_VAL_STRING && !value->s)
+    return rg__fail(ctx, RG_ERR_TYPE, "set: property '%s' got a null string",
+                    info->name);
+  if (value->type == RG_VAL_SIZE &&
+      (value->i < RG_SIZE_FIT || value->i > RG_SIZE_PERCENT))
+    return rg__fail(ctx, RG_ERR_TYPE,
+                    "set: property '%s' got an invalid size mode", info->name);
+
+  v = *value;
+  if (v.type == RG_VAL_STRING) {
+    v.s = dup_string(ctx, value->s);
+    if (!v.s)
+      return rg__fail(ctx, RG_ERR_NO_MEMORY, "set: string allocation failed");
+  }
+
+  o = find_override(n, prop);
+  if (o) {
+    drop_value(ctx, &o->value);
+    o->value = v;
+  } else {
+    if (n->ov_count == n->ov_cap) {
+      uint32_t cap = n->ov_cap ? n->ov_cap * 2 : 4;
+      rg_override *arr =
+          rg__realloc(ctx, n->ov, n->ov_cap * sizeof *arr, cap * sizeof *arr);
+      if (!arr) {
+        drop_value(ctx, &v);
+        return rg__fail(ctx, RG_ERR_NO_MEMORY,
+                        "set: override allocation failed");
+      }
+      n->ov = arr;
+      n->ov_cap = cap;
+    }
+    n->ov[n->ov_count].prop = prop;
+    n->ov[n->ov_count].value = v;
+    n->ov_count++;
+  }
+  rg__log(ctx, RG_LOG_TRACE, "set %s on %s", info->name, rg_type_name(n->type));
+  return RG_OK;
+}
+
+int rg_get(rg_context *ctx, rg_node node, int32_t prop, rg_value *out) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  const rg_override *o;
+
+  if (!n)
+    return rg__fail(ctx, RG_ERR_HANDLE, "get: stale or invalid handle");
+  if (!rg__prop_info(prop))
+    return rg__fail(ctx, RG_ERR_PROP, "get: unknown property %d", (int)prop);
+  if (!out)
+    return rg__fail(ctx, RG_ERR_STATE, "get: null output");
+
+  o = find_override(n, prop);
+  *out = o ? o->value : *rg__default_value(n->type, prop);
+  return RG_OK;
+}
+
+int rg_unset(rg_context *ctx, rg_node node, int32_t prop) {
+  rg_node_data *n = rg__node_resolve(ctx, node);
+  rg_override *o;
+
+  if (!n)
+    return rg__fail(ctx, RG_ERR_HANDLE, "unset: stale or invalid handle");
+  if (!rg__prop_info(prop))
+    return rg__fail(ctx, RG_ERR_PROP, "unset: unknown property %d", (int)prop);
+
+  o = find_override(n, prop);
+  if (o) {
+    drop_value(ctx, &o->value);
+    *o = n->ov[--n->ov_count];
+  }
+  return RG_OK;
+}
+
+int rg_set_int(rg_context *ctx, rg_node node, int32_t prop, int32_t v) {
+  const rg_prop_info *info = rg__prop_info(prop);
+  rg_value val;
+
+  if (!info)
+    return rg__fail(ctx, RG_ERR_PROP, "set: unknown property %d", (int)prop);
+  if (info->type != RG_VAL_BOOL && info->type != RG_VAL_INT &&
+      info->type != RG_VAL_ENUM)
+    return rg__fail(ctx, RG_ERR_TYPE,
+                    "set: property '%s' is not an integer type", info->name);
+  value_init(&val, info->type);
+  val.i = v;
+  return rg_set(ctx, node, prop, &val);
+}
+
+int rg_set_float(rg_context *ctx, rg_node node, int32_t prop, float v) {
+  rg_value val;
+
+  value_init(&val, RG_VAL_FLOAT);
+  val.f[0] = v;
+  return rg_set(ctx, node, prop, &val);
+}
+
+int rg_set_string(rg_context *ctx, rg_node node, int32_t prop, const char *v) {
+  rg_value val;
+
+  value_init(&val, RG_VAL_STRING);
+  val.s = v;
+  return rg_set(ctx, node, prop, &val);
+}
+
+int rg_set_color(rg_context *ctx, rg_node node, int32_t prop, float r, float g,
+                 float b, float a) {
+  rg_value val;
+
+  value_init(&val, RG_VAL_COLOR);
+  val.f[0] = r;
+  val.f[1] = g;
+  val.f[2] = b;
+  val.f[3] = a;
+  return rg_set(ctx, node, prop, &val);
+}
diff --git a/src/types.c b/src/types.c
new file mode 100644
index 0000000..d4e4ce2
--- /dev/null
+++ b/src/types.c
@@ -0,0 +1,62 @@
+#include "internal.h"
+
+#include <string.h>
+
+#define COUNT(a) ((int32_t)(sizeof(a) / sizeof((a)[0])))
+
+static const rg_override root_defaults[] = {
+    {RG_PROP_WIDTH, RG_V_SIZE(RG_SIZE_GROW, 0)},
+    {RG_PROP_HEIGHT, RG_V_SIZE(RG_SIZE_GROW, 0)},
+};
+
+static const rg_override hbox_defaults[] = {
+    {RG_PROP_DIRECTION, RG_V_ENUM(RG_DIR_ROW)},
+};
+
+static const rg_override vbox_defaults[] = {
+    {RG_PROP_DIRECTION, RG_V_ENUM(RG_DIR_COLUMN)},
+};
+
+static const rg_override panel_defaults[] = {
+    {RG_PROP_PADDING, RG_V_VEC4(8, 8, 8, 8)},
+    {RG_PROP_BACKGROUND, RG_V_COLOR(0.15f, 0.15f, 0.18f, 1.0f)},
+};
+
+static const rg_override button_defaults[] = {
+    {RG_PROP_PADDING, RG_V_VEC4(8, 16, 8, 16)},
+    {RG_PROP_BACKGROUND, RG_V_COLOR(0.25f, 0.25f, 0.30f, 1.0f)},
+    {RG_PROP_CORNER_RADIUS, RG_V_VEC4(4, 4, 4, 4)},
+};
+
+static const rg_type_info type_table[RG_NODE_TYPE_COUNT] = {
+    [RG_NODE_ROOT] = {"Root", 0, root_defaults, COUNT(root_defaults)},
+    [RG_NODE_BOX] = {"Box", 0, NULL, 0},
+    [RG_NODE_HBOX] = {"HBox", 0, hbox_defaults, COUNT(hbox_defaults)},
+    [RG_NODE_VBOX] = {"VBox", 0, vbox_defaults, COUNT(vbox_defaults)},
+    [RG_NODE_PANEL] = {"Panel", 0, panel_defaults, COUNT(panel_defaults)},
+    [RG_NODE_LABEL] = {"Label", RG_TF_TEXT, NULL, 0},
+    [RG_NODE_BUTTON] = {"Button", RG_TF_TEXT | RG_TF_FOCUSABLE, button_defaults,
+                        COUNT(button_defaults)},
+};
+
+const rg_type_info *rg__type_info(int32_t type) {
+  if (type < 0 || type >= RG_NODE_TYPE_COUNT)
+    return NULL;
+  return &type_table[type];
+}
+
+int32_t rg_type_find(const char *name) {
+  int32_t i;
+
+  if (!name)
+    return -1;
+  for (i = 0; i < RG_NODE_TYPE_COUNT; i++)
+    if (strcmp(type_table[i].name, name) == 0)
+      return i;
+  return -1;
+}
+
+const char *rg_type_name(int32_t type) {
+  const rg_type_info *t = rg__type_info(type);
+  return t ? t->name : "invalid";
+}
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 9e9ee46..d316db0 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -7,3 +7,7 @@ if(TARGET SDL3::SDL3)
   target_link_libraries(smoke_sdl3 PRIVATE SDL3::SDL3)
   add_test(NAME smoke_sdl3 COMMAND smoke_sdl3)
 endif()
+
+add_executable(test_nodes nodes.c)
+target_link_libraries(test_nodes PRIVATE regolith)
+add_test(NAME nodes COMMAND test_nodes)
diff --git a/tests/nodes.c b/tests/nodes.c
new file mode 100644
index 0000000..fa3b367
--- /dev/null
+++ b/tests/nodes.c
@@ -0,0 +1,191 @@
+#include "testing.h"
+
+#include <string.h>
+
+static int child_count(rg_context *ctx, rg_node parent) {
+  int n = 0;
+  rg_node c;
+
+  for (c = rg_node_first_child(ctx, parent); c != RG_NODE_NONE;
+       c = rg_node_next_sibling(ctx, c))
+    n++;
+  return n;
+}
+
+static void test_tree(rg_context *ctx) {
+  rg_node root = rg_root(ctx);
+  rg_node a = rg_node_create(ctx, RG_NODE_VBOX);
+  rg_node b = rg_node_create(ctx, RG_NODE_LABEL);
+  rg_node c = rg_node_create(ctx, RG_NODE_BUTTON);
+  rg_node d = rg_node_create(ctx, RG_NODE_LABEL);
+
+  CHECK(rg_node_valid(ctx, root));
+  CHECK(rg_node_type(ctx, root) == RG_NODE_ROOT);
+  CHECK(rg_node_create(ctx, RG_NODE_ROOT) == RG_NODE_NONE);
+
+  CHECK(rg_node_append(ctx, root, a) == RG_OK);
+  CHECK(rg_node_append(ctx, a, b) == RG_OK);
+  CHECK(rg_node_append(ctx, a, c) == RG_OK);
+  CHECK(rg_node_insert_before(ctx, a, d, c) == RG_OK);
+
+  CHECK(child_count(ctx, a) == 3);
+  CHECK(rg_node_first_child(ctx, a) == b);
+  CHECK(rg_node_next_sibling(ctx, b) == d);
+  CHECK(rg_node_next_sibling(ctx, d) == c);
+  CHECK(rg_node_next_sibling(ctx, c) == RG_NODE_NONE);
+  CHECK(rg_node_parent(ctx, d) == a);
+
+  CHECK(rg_node_append(ctx, a, b) == RG_OK);
+  CHECK(rg_node_next_sibling(ctx, c) == b);
+  CHECK(child_count(ctx, a) == 3);
+
+  CHECK(rg_node_append(ctx, b, a) == RG_ERR_STATE);
+  CHECK(rg_node_append(ctx, a, a) == RG_ERR_STATE);
+  CHECK(rg_node_append(ctx, a, root) == RG_ERR_STATE);
+  CHECK(rg_node_insert_before(ctx, root, b, c) == RG_ERR_STATE);
+
+  CHECK(rg_node_detach(ctx, d) == RG_OK);
+  CHECK(rg_node_parent(ctx, d) == RG_NODE_NONE);
+  CHECK(child_count(ctx, a) == 2);
+
+  rg_node_destroy(ctx, a);
+  rg_node_destroy(ctx, d);
+}
+
+static void test_handles(rg_context *ctx) {
+  rg_node root = rg_root(ctx);
+  rg_node a = rg_node_create(ctx, RG_NODE_PANEL);
+  rg_node b = rg_node_create(ctx, RG_NODE_LABEL);
+  rg_node c = rg_node_create(ctx, RG_NODE_LABEL);
+  rg_node fresh;
+
+  CHECK(rg_node_append(ctx, root, a) == RG_OK);
+  CHECK(rg_node_append(ctx, a, b) == RG_OK);
+  CHECK(rg_node_append(ctx, b, c) == RG_OK);
+
+  rg_node_destroy(ctx, a);
+  CHECK(!rg_node_valid(ctx, a));
+  CHECK(!rg_node_valid(ctx, b));
+  CHECK(!rg_node_valid(ctx, c));
+  CHECK(rg_set_float(ctx, b, RG_PROP_GAP, 1.0f) == RG_ERR_HANDLE);
+  CHECK(child_count(ctx, root) == 0);
+
+  fresh = rg_node_create(ctx, RG_NODE_BOX);
+  CHECK(fresh != a && fresh != b && fresh != c);
+  CHECK(!rg_node_valid(ctx, a));
+  CHECK(rg_node_valid(ctx, fresh));
+
+  rg_node_destroy(ctx, root);
+  CHECK(rg_node_valid(ctx, root));
+  rg_node_destroy(ctx, fresh);
+}
+
+static void test_props(rg_context *ctx) {
+  rg_node hbox = rg_node_create(ctx, RG_NODE_HBOX);
+  rg_node vbox = rg_node_create(ctx, RG_NODE_VBOX);
+  rg_node btn = rg_node_create(ctx, RG_NODE_BUTTON);
+  rg_node lbl = rg_node_create(ctx, RG_NODE_LABEL);
+  rg_value v;
+  char buf[16];
+  int i;
+
+  for (i = 0; i < RG_PROP_COUNT; i++) {
+    CHECK(rg_prop_name(i) != NULL);
+    CHECK(rg_prop_find(rg_prop_name(i)) == i);
+    CHECK(rg_prop_type(i) != RG_VAL_NONE);
+  }
+  CHECK(rg_prop_find("no_such_prop") == -1);
+  CHECK(rg_type_find("Button") == RG_NODE_BUTTON);
+  CHECK(rg_type_find("Nope") == -1);
+
+  CHECK(rg_get(ctx, hbox, RG_PROP_DIRECTION, &v) == RG_OK && v.i == RG_DIR_ROW);
+  CHECK(rg_get(ctx, vbox, RG_PROP_DIRECTION, &v) == RG_OK &&
+        v.i == RG_DIR_COLUMN);
+  CHECK(rg_get(ctx, btn, RG_PROP_PADDING, &v) == RG_OK);
+  CHECK(v.f[0] == 8.0f && v.f[1] == 16.0f && v.f[2] == 8.0f && v.f[3] == 16.0f);
+  CHECK(rg_get(ctx, lbl, RG_PROP_OPACITY, &v) == RG_OK && v.f[0] == 1.0f);
+  CHECK(rg_get(ctx, lbl, RG_PROP_TEXT, &v) == RG_OK && strcmp(v.s, "") == 0);
+
+  CHECK(rg_set_int(ctx, vbox, RG_PROP_DIRECTION, RG_DIR_ROW) == RG_OK);
+  CHECK(rg_get(ctx, vbox, RG_PROP_DIRECTION, &v) == RG_OK && v.i == RG_DIR_ROW);
+  CHECK(rg_unset(ctx, vbox, RG_PROP_DIRECTION) == RG_OK);
+  CHECK(rg_get(ctx, vbox, RG_PROP_DIRECTION, &v) == RG_OK &&
+        v.i == RG_DIR_COLUMN);
+  CHECK(rg_unset(ctx, vbox, RG_PROP_DIRECTION) == RG_OK);
+
+  CHECK(rg_set_color(ctx, btn, RG_PROP_BACKGROUND, 1, 0, 0, 1) == RG_OK);
+  CHECK(rg_get(ctx, btn, RG_PROP_BACKGROUND, &v) == RG_OK && v.f[0] == 1.0f &&
+        v.f[1] == 0.0f);
+
+  CHECK(rg_set_float(ctx, btn, RG_PROP_BACKGROUND, 1.0f) == RG_ERR_TYPE);
+  CHECK(rg_set_int(ctx, btn, RG_PROP_GAP, 1) == RG_ERR_TYPE);
+  CHECK(rg_set(ctx, btn, RG_PROP_GAP, NULL) == RG_ERR_TYPE);
+  CHECK(rg_set_string(ctx, btn, RG_PROP_TEXT, NULL) == RG_ERR_TYPE);
+  CHECK(rg_set_float(ctx, btn, 9999, 1.0f) == RG_ERR_PROP);
+  CHECK(rg_get(ctx, btn, -1, &v) == RG_ERR_PROP);
+
+  memset(&v, 0, sizeof v);
+  v.type = RG_VAL_SIZE;
+  v.i = 99;
+  CHECK(rg_set(ctx, btn, RG_PROP_WIDTH, &v) == RG_ERR_TYPE);
+  v.i = RG_SIZE_FIXED;
+  v.f[0] = 200.0f;
+  CHECK(rg_set(ctx, btn, RG_PROP_WIDTH, &v) == RG_OK);
+
+  strcpy(buf, "Start");
+  CHECK(rg_set_string(ctx, lbl, RG_PROP_TEXT, buf) == RG_OK);
+  strcpy(buf, "Other");
+  CHECK(rg_get(ctx, lbl, RG_PROP_TEXT, &v) == RG_OK &&
+        strcmp(v.s, "Start") == 0);
+
+  CHECK(rg_set_string(ctx, lbl, RG_PROP_TEXT, v.s) == RG_OK);
+  CHECK(rg_get(ctx, lbl, RG_PROP_TEXT, &v) == RG_OK &&
+        strcmp(v.s, "Start") == 0);
+
+  CHECK(rg_set_string(ctx, lbl, RG_PROP_TEXT,
+                      "A much longer replacement string") == RG_OK);
+  CHECK(rg_get(ctx, lbl, RG_PROP_TEXT, &v) == RG_OK &&
+        strcmp(v.s, "A much longer replacement string") == 0);
+
+  for (i = 0; i < RG_PROP_COUNT; i++) {
+    rg_value tmp;
+    memset(&tmp, 0, sizeof tmp);
+    tmp.type = rg_prop_type(i);
+    tmp.s = tmp.type == RG_VAL_STRING ? "x" : NULL;
+    if (tmp.type == RG_VAL_SIZE)
+      tmp.i = RG_SIZE_FIT;
+    CHECK(rg_set(ctx, btn, i, &tmp) == RG_OK);
+  }
+
+  rg_node_destroy(ctx, hbox);
+  rg_node_destroy(ctx, vbox);
+  rg_node_destroy(ctx, btn);
+  rg_node_destroy(ctx, lbl);
+}
+
+int main(void) {
+  testing_alloc ta = {0, 0};
+  rg_config cfg;
+  rg_context *ctx;
+
+  rg_config_init(&cfg);
+  testing_use_counting_allocator(&cfg, &ta);
+  cfg.log_level = RG_LOG_WARN;
+
+  ctx = rg_create(&cfg);
+  CHECK(ctx != NULL);
+  if (!ctx)
+    return 1;
+
+  test_tree(ctx);
+  test_handles(ctx);
+  test_props(ctx);
+
+  rg_destroy(ctx);
+  CHECK(ta.live == 0);
+  if (ta.live != 0)
+    printf("leak: %zu bytes still live\n", ta.live);
+
+  printf("nodes: %s, peak %zu bytes\n", g_failures ? "FAILED" : "ok", ta.peak);
+  return g_failures ? 1 : 0;
+}
diff --git a/tests/testing.h b/tests/testing.h
new file mode 100644
index 0000000..a4799b2
--- /dev/null
+++ b/tests/testing.h
@@ -0,0 +1,58 @@
+
+#ifndef RG_TESTING_H
+#define RG_TESTING_H
+
+#include "regolith.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static int g_failures;
+
+#define CHECK(cond)                                                            \
+  do {                                                                         \
+    if (!(cond)) {                                                             \
+      printf("FAIL %s:%d: %s\n", __FILE__, __LINE__, #cond);                   \
+      g_failures++;                                                            \
+    }                                                                          \
+  } while (0)
+
+typedef struct testing_alloc {
+  size_t live;
+  size_t peak;
+} testing_alloc;
+
+static void ta_track(testing_alloc *t, size_t add, size_t sub) {
+  t->live = t->live + add - sub;
+  if (t->live > t->peak)
+    t->peak = t->live;
+}
+
+static void *ta_alloc(size_t size, void *user) {
+  void *p = malloc(size);
+  if (p)
+    ta_track(user, size, 0);
+  return p;
+}
+
+static void *ta_realloc(void *ptr, size_t old_size, size_t new_size,
+                        void *user) {
+  void *p = realloc(ptr, new_size);
+  if (p)
+    ta_track(user, new_size, old_size);
+  return p;
+}
+
+static void ta_free(void *ptr, size_t size, void *user) {
+  ta_track(user, 0, size);
+  free(ptr);
+}
+
+static void testing_use_counting_allocator(rg_config *cfg, testing_alloc *t) {
+  cfg->allocator.alloc = ta_alloc;
+  cfg->allocator.realloc = ta_realloc;
+  cfg->allocator.free = ta_free;
+  cfg->allocator.user = t;
+}
+
+#endif