diff --git a/source/app.cpp b/source/app.cpp
index 84a3f56..edc539d 100644
--- a/source/app.cpp
+++ b/source/app.cpp
@@ -1,61 +1,103 @@
+module;
+
+#include <SDL2/SDL.h>
+
 export module app;
 
 import core;
+import core.files;
 import core.image;
 import core.lalgebra;
 
+import oar;
+
 export namespace app {
-	struct path {
-		static constexpr core::usize max = 0xff;
+	struct directory : public core::fs {
+		using core::fs::access_result;
 
-		static constexpr char seperator = '/';
+		struct rules {
+			bool can_read;
 
-		core::u8 buffer[max + 1];
+			bool can_write;
+		};
 
-		static constexpr path empty() {
-			path empty_path = {0};
+		directory() : path_buffer{0} {}
 
-			empty_path.buffer[max] = max;
+		access_result read_file(core::path const & file_path,
+			core::callable<void(core::readable const &)> const & then) {
 
-			return empty_path;
+			if (this->prefix_length == 0) return access_result::not_found;
+
+			if (!this->access_rules.can_read) return access_result::access_denied;
+
+			::SDL_RWops * rw_ops = this->open_rw(file_path, {.can_read = true});
+
+			if (rw_ops == nullptr) return access_result::not_found;
+
+			then([rw_ops](core::slice<uint8_t> const & buffer) -> size_t {
+				return ::SDL_RWread(rw_ops, buffer.pointer, sizeof(uint8_t), buffer.length);
+			});
+
+			::SDL_RWclose(rw_ops);
+
+			return access_result::ok;
 		}
 
-		core::slice<char const> as_slice() const {
-			return {reinterpret_cast<char const *>(this->buffer),  this->size()};
-		}
+		void target(core::slice<char const> const & directory_path, rules const & access_rules) {
+			this->access_rules = access_rules;
+			this->prefix_length = core::min(directory_path.length, path_max - 1);
 
-		constexpr core::usize size() const {
-			return max - this->buffer[max];
-		}
+			{
+				core::slice const path_buffer_slice{this->path_buffer};
 
-		core::i16 compare(path const & that) {
-			return 0;
-		}
+				core::copy(path_buffer_slice.sliced(0, this->prefix_length),
+					directory_path.sliced(0, this->prefix_length).as_bytes());
 
-		bool equals(path const & that) const {
-			return core::equals(this->as_slice().as_bytes(), that.as_slice().as_bytes());
-		}
-
-		constexpr path joined(core::slice<char const> const & text) const {
-			if (text.length > this->buffer[max]) return empty();
-
-			path joined_path = *this;
-
-			for (char const c : text) {
-				joined_path.buffer[joined_path.size()] = c;
-				joined_path.buffer[max] -= 1;
+				core::zero(path_buffer_slice.sliced(this->prefix_length, path_max - this->prefix_length));
 			}
-
-			return joined_path;
 		}
 
-		core::u64 hash() {
-			return 0;
-		}
-	};
+		access_result write_file(core::path const & file_path,
+			core::callable<void(core::writable const &)> const & then) {
 
-	struct file_store {
-		virtual void read_file(app::path const & file_path, core::callable<void(core::readable const &)> const & then) = 0;
+			if (this->prefix_length == 0) return access_result::not_found;
+
+			if (!this->access_rules.can_write) return access_result::access_denied;
+
+			::SDL_RWops * rw_ops = this->open_rw(file_path, {.can_write = true});
+
+			if (rw_ops == nullptr) return access_result::not_found;
+
+			then([rw_ops](core::slice<uint8_t const> const & buffer) -> size_t {
+				return ::SDL_RWwrite(rw_ops, buffer.pointer, sizeof(uint8_t), buffer.length);
+			});
+
+			::SDL_RWclose(rw_ops);
+
+			return access_result::ok;
+		}
+
+		private:
+		static constexpr core::usize path_max = 4096;
+
+		rules access_rules;
+
+		core::usize prefix_length;
+
+		core::u8 path_buffer[path_max];
+
+		::SDL_RWops * open_rw(core::path const & file_path, rules const & file_rules) {
+			core::u8 * const path_begin = this->path_buffer + this->prefix_length;
+
+			core::slice const path_remaining =
+				{path_begin, path_begin + (path_max - this->prefix_length) - 1};
+
+			if (path_remaining.length < file_path.byte_size()) return nullptr;
+
+			core::copy(path_remaining, core::slice{file_path.begin(), file_path.end()}.as_bytes());
+
+			return ::SDL_RWFromFile(reinterpret_cast<char const *>(this->path_buffer), "r");
+		}
 	};
 
 	enum class log_level {
@@ -65,18 +107,103 @@ export namespace app {
 	};
 
 	struct system {
-		virtual bool poll() = 0;
+		system(core::path const & title) : res_archive{}  {
+			constexpr directory::rules read_only_rules = {.can_read = true};
 
-		virtual file_store & bundle() = 0;
+			{
+				char * const path = ::SDL_GetBasePath();
 
-		virtual void log(log_level level, core::slice<char const> const & message) = 0;
+				if (path == nullptr) {
+					this->cwd_directory.target("./", read_only_rules);
+				} else {
+					core::usize path_length = 0;
 
-		virtual core::allocator & thread_safe_allocator() = 0;
+					while (path[path_length] != 0) path_length += 1;
+
+					if (path_length == 0) {
+						this->cwd_directory.target("./", read_only_rules);
+					} else {
+						this->cwd_directory.target({path, path_length}, read_only_rules);
+					}
+				}
+
+				::SDL_free(path);
+			}
+
+			{
+				char * const path = ::SDL_GetPrefPath("ona", title.begin());
+
+				if (path != nullptr) {
+					core::usize path_length = 0;
+
+					while (path[path_length] != 0) path_length += 1;
+
+					if (path_length != 0) this->cwd_directory.target({path, path_length}, {
+						.can_read = true,
+					});
+				}
+
+				::SDL_free(path);
+			}
+		}
+
+		core::fs & cwd_fs() {
+			return this->cwd_directory;
+		}
+
+		bool poll() {
+			while (::SDL_PollEvent(&this->sdl_event) != 0) {
+				switch (this->sdl_event.type) {
+					case SDL_QUIT: return false;
+				}
+			}
+
+			return true;
+		}
+
+		core::fs & res_fs() {
+			return this->res_archive;
+		}
+
+		void log(app::log_level level, core::slice<char const> const & message) {
+			core::i32 const length = static_cast<core::i32>(
+				core::min(message.length, static_cast<size_t>(core::i32_max)));
+
+			::SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION,
+				SDL_LOG_PRIORITY_INFO, "%.*s", length, message.pointer);
+		}
+
+		core::allocator & thread_safe_allocator() {
+			return this->allocator;
+		}
+
+		core::fs & user_fs() {
+			return this->user_directory;
+		}
+
+		private:
+		::SDL_Event sdl_event;
+
+		struct : public core::allocator {
+			core::u8 * reallocate(core::u8 * maybe_allocation, core::usize requested_size) override {
+				return reinterpret_cast<core::u8 *>(::SDL_malloc(requested_size));
+			}
+
+			void deallocate(void * allocation) override {
+				::SDL_free(allocation);
+			}
+		} allocator;
+
+		oar::archive res_archive;
+
+		directory cwd_directory;
+
+		directory user_directory;
 	};
 
 	struct graphics {
-		enum class show_error {
-			none,
+		enum class [[nodiscard]] show_result {
+			ok,
 			out_of_memory,
 		};
 
@@ -84,12 +211,72 @@ export namespace app {
 			core::color background_color;
 		};
 
-		virtual void render(canvas & source_canvas) = 0;
+		graphics(core::path const & title) {
+			this->retitle(title);
+		}
 
-		virtual void present() = 0;
+		void render(canvas & source_canvas) {
+			if (this->sdl_renderer != nullptr) {
+				SDL_SetRenderDrawColor(this->sdl_renderer, source_canvas.background_color.to_r8(),
+					source_canvas.background_color.to_g8(), source_canvas.background_color.to_b8(),
+						source_canvas.background_color.to_a8());
 
-		virtual show_error show(core::u16 physical_width, core::u16 physical_height) = 0;
+				SDL_RenderClear(this->sdl_renderer);
+			}
+		}
 
-		virtual void retitle(core::slice<const char> const & updated_title) = 0;
+		void retitle(core::path const & title) {
+			this->title = title;
+
+			if (this->sdl_window != nullptr)
+				::SDL_SetWindowTitle(this->sdl_window, this->title.begin());
+		}
+
+		show_result show(core::u16 physical_width, core::u16 physical_height) {
+			if (this->sdl_window == nullptr) {
+				constexpr int sdl_windowpos = SDL_WINDOWPOS_UNDEFINED;
+				constexpr core::u32 sdl_windowflags = 0;
+
+				this->sdl_window = ::SDL_CreateWindow(this->title.begin(), sdl_windowpos,
+					sdl_windowpos, static_cast<int>(physical_width), static_cast<int>(physical_height),
+						sdl_windowflags);
+
+				if (this->sdl_window == nullptr) return show_result::out_of_memory;
+			} else {
+				::SDL_ShowWindow(this->sdl_window);
+			}
+
+			if (this->sdl_renderer == nullptr) {
+				constexpr core::u32 sdl_rendererflags = 0;
+
+				this->sdl_renderer = ::SDL_CreateRenderer(this->sdl_window, -1, sdl_rendererflags);
+
+				if (this->sdl_renderer == nullptr) return show_result::out_of_memory;
+			}
+
+			return show_result::ok;
+		}
+
+		void present() {
+			if (this->sdl_renderer != nullptr) {
+				::SDL_RenderPresent(this->sdl_renderer);
+			}
+		}
+
+		private:
+		core::path title;
+
+		::SDL_Window * sdl_window = nullptr;
+
+		::SDL_Renderer * sdl_renderer = nullptr;
 	};
+
+	using graphical_runnable = core::callable<int(system &, graphics &)>;
+
+	int display(core::path const & title, graphical_runnable const & run) {
+		system app_system{title};
+		graphics app_graphics{title};
+
+		return run(app_system, app_graphics);
+	}
 }
diff --git a/source/app/sdl.cpp b/source/app/sdl.cpp
deleted file mode 100644
index c332c6b..0000000
--- a/source/app/sdl.cpp
+++ /dev/null
@@ -1,167 +0,0 @@
-module;
-
-#include <SDL2/SDL.h>
-
-export module app.sdl;
-
-import app;
-
-import core;
-import core.image;
-import core.sequence;
-import core.lalgebra;
-
-struct bundled_file_store : public app::file_store {
-	void read_file(app::path const & file_path, core::callable<void(core::readable const &)> const & then) override {
-		constexpr core::slice<char const> path_prefix = "./";
-		constexpr core::usize path_max = 512;
-
-		if ((file_path.size() + path_prefix.length) > path_max) core::unreachable();
-
-		core::stack<char, path_max> path_buffer{&core::null_allocator()};
-
-		if (path_buffer.append("./") != core::append_result::ok) core::unreachable();
-
-		// File path is guaranteed to be null-terminated.
-		if (path_buffer.append(file_path.as_slice()) != core::append_result::ok)
-			core::unreachable();
-
-		SDL_RWops * rw_ops = ::SDL_RWFromFile(path_buffer.begin(), "r");
-
-		if (rw_ops == nullptr) return;
-
-		then([rw_ops](core::slice<uint8_t> const & buffer) -> size_t {
-			return ::SDL_RWread(rw_ops, buffer.pointer, sizeof(uint8_t), buffer.length);
-		});
-
-		::SDL_RWclose(rw_ops);
-	}
-};
-
-struct sdl_allocator : public core::allocator {
-	core::u8 * reallocate(core::u8 * maybe_allocation, core::usize requested_size) override {
-		return reinterpret_cast<core::u8 *>(::SDL_malloc(requested_size));
-	}
-
-	void deallocate(void * allocation) override {
-		::SDL_free(allocation);
-	}
-};
-
-struct sdl_system : public app::system {
-	private:
-	::SDL_Event sdl_event;
-
-	sdl_allocator allocator;
-
-	bundled_file_store bundled_store;
-
-	public:
-	sdl_system() :
-		sdl_event{0},
-		allocator{} {}
-
-	bool poll() override {
-		while (::SDL_PollEvent(&this->sdl_event) != 0) {
-			switch (this->sdl_event.type) {
-				case SDL_QUIT: return false;
-			}
-		}
-
-		return true;
-	}
-
-	app::file_store & bundle() override {
-		return this->bundled_store;
-	}
-
-	void log(app::log_level level, core::slice<char const> const & message) override {
-		core::i32 const length = static_cast<core::i32>(
-			core::min(message.length, static_cast<size_t>(core::i32_max)));
-
-		::SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION,
-			SDL_LOG_PRIORITY_INFO, "%.*s", length, message.pointer);
-	}
-
-	core::allocator & thread_safe_allocator() override {
-		return this->allocator;
-	}
-};
-
-struct sdl_graphics : public app::graphics {
-	static constexpr core::usize title_maximum = 128;
-
-	core::u32 title_length;
-
-	char title_buffer[title_maximum];
-
-	::SDL_Window * sdl_window = nullptr;
-
-	::SDL_Renderer * sdl_renderer = nullptr;
-
-	sdl_graphics(core::slice<char const> const & title) {
-		this->retitle(title);
-	}
-
-	void render(canvas & source_canvas) override {
-		if (this->sdl_renderer != nullptr) {
-			SDL_SetRenderDrawColor(this->sdl_renderer, source_canvas.background_color.to_r8(),
-				source_canvas.background_color.to_g8(), source_canvas.background_color.to_b8(),
-					source_canvas.background_color.to_a8());
-
-			SDL_RenderClear(this->sdl_renderer);
-		}
-	}
-
-	void retitle(core::slice<char const> const & title) override {
-		this->title_length = core::min(title.length, title_maximum - 1);
-
-		for (core::usize i = 0; i < this->title_length; i += 1) title_buffer[i] = title[i];
-
-		for (core::usize i = this->title_length; i < title_maximum; i += 1) title_buffer[i] = 0;
-
-		if (this->sdl_window != nullptr) ::SDL_SetWindowTitle(this->sdl_window, title_buffer);
-	}
-
-	app::graphics::show_error show(core::u16 physical_width, core::u16 physical_height) override {
-		if (this->sdl_window == nullptr) {
-			constexpr int sdl_windowpos = SDL_WINDOWPOS_UNDEFINED;
-			constexpr core::u32 sdl_windowflags = 0;
-
-			this->sdl_window = ::SDL_CreateWindow(title_buffer, sdl_windowpos, sdl_windowpos,
-				static_cast<int>(physical_width), static_cast<int>(physical_height),
-					sdl_windowflags);
-
-			if (this->sdl_window == nullptr) return show_error::out_of_memory;
-		} else {
-			::SDL_ShowWindow(this->sdl_window);
-		}
-
-		if (this->sdl_renderer == nullptr) {
-			constexpr core::u32 sdl_rendererflags = 0;
-
-			this->sdl_renderer = ::SDL_CreateRenderer(this->sdl_window, -1, sdl_rendererflags);
-
-			if (this->sdl_renderer == nullptr) return show_error::out_of_memory;
-		}
-
-		return show_error::none;
-	}
-
-	void present() override {
-		if (this->sdl_renderer != nullptr) {
-			::SDL_RenderPresent(this->sdl_renderer);
-		}
-	}
-};
-
-export namespace app {
-	int display(core::slice<char const> const & title,
-		core::callable<int(app::system &, app::graphics &)> const & run) {
-
-		sdl_system system;
-		sdl_graphics graphics(title);
-
-		return run(system, graphics);
-	}
-}
diff --git a/source/runtime.cpp b/source/runtime.cpp
index a933521..bed15e1 100644
--- a/source/runtime.cpp
+++ b/source/runtime.cpp
@@ -1,9 +1,9 @@
 export module runtime;
 
 import app;
-import app.sdl;
 
 import core;
+import core.files;
 import core.lalgebra;
 import core.sequence;
 
@@ -12,13 +12,14 @@ import kym.environment;
 
 extern "C" int main(int argc, char const * const * argv) {
 	return app::display("Ona Runtime", [](app::system & system, app::graphics & graphics) -> int {
-		constexpr app::path config_path = app::path::empty().joined("config.kym");
-		bool is_config_loaded = false;
+		constexpr core::path config_path{"config.kym"};
+		bool is_config_loaded{false};
 
-		system.bundle().read_file(config_path, [&](core::readable const & file) {
-			kym::vm vm{&system.thread_safe_allocator(), [&system](core::slice<char const> const & error_message) {
-				system.log(app::log_level::error, error_message);
-			}};
+		if ((system.res_fs().read_file(config_path, [&](core::readable const & file) {
+			kym::vm vm{&system.thread_safe_allocator(),
+				[&system](core::slice<char const> const & error_message) {
+					system.log(app::log_level::error, error_message);
+				}};
 
 			if (!vm.init({
 				.datastack_size = 64,
@@ -30,24 +31,25 @@ extern "C" int main(int argc, char const * const * argv) {
 			}
 
 			core::stack<core::u8> script_source{&system.thread_safe_allocator()};
-			core::u8 stream_buffer[1024] = {};
+			core::u8 stream_buffer[1024]{0};
 
 			if (!core::stream(core::sequence_writer{&script_source}, file, stream_buffer).is_ok())
 				return;
 
 			vm.with_object(vm.compile(core::slice{script_source.begin(), script_source.end()}.as_chars()), [&](kym::bound_object & script) {
 				vm.with_object(script.call({}), [&](kym::bound_object & config) {
-					core::u16 const width = config.get_field("width").as_u16().value_or(0);
+					core::u16 const width{config.get_field("width").as_u16().value_or(0)};
 
 					if (width == 0) return system.log(app::log_level::error,
 						"failed to decode `width` property of config");
 
-					core::u16 const height = config.get_field("height").as_u16().value_or(0);
+					core::u16 const height{config.get_field("height").as_u16().value_or(0)};
 
 					if (height == 0) return system.log(app::log_level::error,
 						"failed to decode `height` property of config");
 
-					graphics.show(width, height);
+					if (graphics.show(width, height) != app::graphics::show_result::ok)
+						return system.log(app::log_level::error, "failed to initialize window");
 
 					vm.with_object(config.get_field("title"), [&](kym::bound_object & title) {
 						core::stack<core::u8, 128> title_buffer{&system.thread_safe_allocator()};
@@ -63,13 +65,7 @@ extern "C" int main(int argc, char const * const * argv) {
 					});
 				});
 			});
-		});
-
-		if (!is_config_loaded) {
-			system.log(app::log_level::error, "failed to load config");
-
-			return core::u8_max;
-		}
+		}) != core::fs::access_result::ok) || (!is_config_loaded)) return core::u8_max;
 
 		// app::canvas canvas_2d();