diff --git a/gui/Makefile b/gui/Makefile
index 00df428..94dca55 100644
--- a/gui/Makefile
+++ b/gui/Makefile
@@ -46,7 +46,14 @@ build-web: ## WebAssembly build -> build/web (needs emscripten)
 
 test: ## Run Odin unit tests
 	@mkdir -p lib/local
-	$(ODIN) test test $(ODIN_FLAGS)
+	@if ls test/*.odin >/dev/null 2>&1; then \
+		echo "== gui/test =="; \
+		$(ODIN) test test $(ODIN_FLAGS); \
+	fi
+	@for dir in $$(find lib/local -name '*_test.odin' -exec dirname {} \; | sort -u); do \
+		echo "== $$dir =="; \
+		$(ODIN) test "$$dir" $(ODIN_FLAGS); \
+	done
 
 clean: ## Remove build artifacts
 	rm -rf $(BIN) build
diff --git a/gui/lib/local/dotenv/dotenv.odin b/gui/lib/local/dotenv/dotenv.odin
deleted file mode 100644
index 8084b6d..0000000
--- a/gui/lib/local/dotenv/dotenv.odin
+++ /dev/null
@@ -1,95 +0,0 @@
-package dotenv
-
-import "core:os"
-import "core:strconv"
-import "core:strings"
-
-// parse parses dotenv-format source (KEY=VALUE lines) into a map allocated
-// with allocator. Blank lines, lines starting with '#', and lines without a
-// '=' are skipped. Keys and values are trimmed; values may be wrapped in
-// double quotes. Precedence with the real process environment is handled by
-// the get_* accessors (real env vars win over the file).
-parse :: proc(src: string, allocator := context.allocator) -> map[string]string {
-	result := make(map[string]string, allocator)
-
-	it := src
-	for line in strings.split_lines_iterator(&it) {
-		tr := strings.trim_space(line)
-		if len(tr) == 0 || strings.has_prefix(tr, "#") {
-			continue
-		}
-
-		eq := strings.index_byte(tr, '=')
-		if eq < 0 {
-			continue
-		}
-
-		key := strings.trim_space(tr[:eq])
-		if key == "" {
-			continue
-		}
-
-		value := strings.trim_space(tr[eq + 1:])
-		if len(value) >= 2 && value[0] == '"' && value[len(value) - 1] == '"' {
-			value = value[1:len(value) - 1]
-		}
-
-		// clone so the map outlives the source buffer (e.g. a freed file read)
-		result[strings.clone(key, allocator)] = strings.clone(value, allocator)
-	}
-
-	return result
-}
-
-// parse_file reads a dotenv file from disk and parses it. It returns
-// (nil, false) when the file cannot be read (e.g. it does not exist).
-parse_file :: proc(filename: string, allocator := context.allocator) -> (map[string]string, bool) {
-	data, err := os.read_entire_file(filename, allocator)
-	if err != nil {
-		return nil, false
-	}
-	defer delete(data)
-
-	return parse(string(data), allocator), true
-}
-
-// destroy frees the cloned keys/values and the map itself. Use it to release
-// a map returned by parse/parse_file (plain delete does not free the strings).
-destroy :: proc(env: map[string]string) {
-	for key, value in env {
-		delete(key)
-		delete(value)
-	}
-	delete(env)
-}
-
-// get_string returns the value for key from the real process environment if
-// set, otherwise from the parsed dotenv map (or "" if neither has it).
-get_string :: proc(env: map[string]string, key: string) -> string {
-	if value, found := os.lookup_env(key, context.temp_allocator); found {
-		return value
-	}
-	return env[key]
-}
-
-// get_bool resolves key and parses it as a boolean (true/false, 1/0,
-// yes/no, on/off). Missing or unparsable values yield default.
-get_bool :: proc(env: map[string]string, key: string, default := false) -> bool {
-	if v := get_string(env, key); v != "" {
-		if parsed, ok := strconv.parse_bool(v); ok {
-			return parsed
-		}
-	}
-	return default
-}
-
-// get_int resolves key and parses it as an integer. Missing or unparsable
-// values yield default.
-get_int :: proc(env: map[string]string, key: string, default := 0) -> int {
-	if v := get_string(env, key); v != "" {
-		if parsed, ok := strconv.parse_int(v); ok {
-			return parsed
-		}
-	}
-	return default
-}
\ No newline at end of file
diff --git a/gui/lib/local/dotenv/src/dotenv.odin b/gui/lib/local/dotenv/src/dotenv.odin
new file mode 100644
index 0000000..ebfccb8
--- /dev/null
+++ b/gui/lib/local/dotenv/src/dotenv.odin
@@ -0,0 +1,165 @@
+package dotenv
+
+import "base:runtime"
+import "core:os"
+import "core:reflect"
+import "core:strconv"
+import "core:strings"
+
+// parse parses dotenv-format source (KEY=VALUE lines) into a map allocated
+// with allocator. Blank lines, lines starting with '#', and lines without a
+// '=' are skipped. Keys and values are trimmed; values may be wrapped in
+// double quotes. Real process environment variables take precedence over the
+// file. The returned map owns its keys/values; release it with destroy.
+@(private)
+parse :: proc(
+	src: string,
+	allocator := context.allocator,
+) -> map[string]string {
+	result := make(map[string]string, allocator)
+
+	it := src
+	for line in strings.split_lines_iterator(&it) {
+		tr := strings.trim_space(line)
+		if len(tr) == 0 || strings.has_prefix(tr, "#") {
+			continue
+		}
+
+		eq := strings.index_byte(tr, '=')
+		if eq < 0 {
+			continue
+		}
+
+		key := strings.trim_space(tr[:eq])
+		if key == "" {
+			continue
+		}
+
+		value := strings.trim_space(tr[eq + 1:])
+		if len(value) >= 2 && value[0] == '"' && value[len(value) - 1] == '"' {
+			value = value[1:len(value) - 1]
+		}
+
+		// real process env vars win over the file
+		if override, found := os.lookup_env(key, context.temp_allocator); found {
+			value = override
+		}
+
+		// clone so the map outlives the source buffer (e.g. a freed file read)
+		result[strings.clone(key, allocator)] = strings.clone(value, allocator)
+	}
+
+	return result
+}
+
+// parse_file reads a dotenv file from disk and parses it into a map. It
+// returns (nil, false) when the file cannot be read (e.g. it does not exist).
+parse_file :: proc(
+	filename: string,
+	allocator := context.allocator,
+) -> (
+	map[string]string,
+	bool,
+) {
+	data, err := os.read_entire_file(filename, allocator)
+	if err != nil {
+		return nil, false
+	}
+	defer delete(data)
+
+	return parse(string(data), allocator), true
+}
+
+// destroy frees the cloned keys/values and the map itself. Use it to release
+// a map returned by parse/parse_file (plain delete does not free the strings).
+destroy :: proc(env: map[string]string) {
+	for key, value in env {
+		delete(key)
+		delete(value)
+	}
+	delete(env)
+}
+
+// decode populates dest's fields from env, matching each field by name
+// (case-insensitively, so API_URL maps onto api_url). Values are converted
+// to the field's type: string is cloned as-is into allocator, integers are
+// parsed with strconv.parse_int (decimal/hex/negative), booleans with
+// strconv.parse_bool, and floats with strconv.parse_f64. Keys missing from
+// env leave the field at its zero value. It returns false if a present value
+// cannot be converted to the field's type.
+decode :: proc(
+	env: map[string]string,
+	dest: ^$T,
+	allocator := context.allocator,
+) -> bool {
+	ti := reflect.type_info_base(type_info_of(T))
+	fields, ok := ti.variant.(runtime.Type_Info_Struct)
+	if !ok {
+		return false
+	}
+
+	name: string
+	value: string
+	field_ptr := rawptr(dest)
+	for _, i in fields.names[:fields.field_count] {
+		name = fields.names[i]
+		value = ""
+		found := false
+		for key, v in env {
+			if key == name || strings.equal_fold(key, name) {
+				value, found = v, true
+				break
+			}
+		}
+		if !found {
+			continue
+		}
+
+		field_ptr = rawptr(uintptr(dest) + fields.offsets[i])
+		field_ti := reflect.type_info_base(fields.types[i])
+		#partial switch variant in field_ti.variant {
+		case runtime.Type_Info_String:
+			(^string)(field_ptr)^ = strings.clone(value, allocator)
+		case runtime.Type_Info_Integer:
+			parsed, err := strconv.parse_int(value)
+			if !err {
+				return false
+			}
+			switch field_ti.size {
+			case 1:
+				(^i8)(field_ptr)^ = cast(i8)parsed
+			case 2:
+				(^i16)(field_ptr)^ = cast(i16)parsed
+			case 4:
+				(^i32)(field_ptr)^ = cast(i32)parsed
+			case 8:
+				(^i64)(field_ptr)^ = cast(i64)parsed
+			case:
+				return false
+			}
+		case runtime.Type_Info_Boolean:
+			parsed, err := strconv.parse_bool(value)
+			if !err {
+				return false
+			}
+			(^bool)(field_ptr)^ = parsed
+		case runtime.Type_Info_Float:
+			parsed, err := strconv.parse_f64(value)
+			if !err {
+				return false
+			}
+			switch field_ti.size {
+			case 4:
+				(^f32)(field_ptr)^ = cast(f32)parsed
+			case 8:
+				(^f64)(field_ptr)^ = parsed
+			case:
+				return false
+			}
+		case:
+			// unsupported field type (slices, pointers, ...) is left untouched
+		}
+	}
+
+	return true
+}
diff --git a/gui/lib/local/dotenv/test/dotenv_test.odin b/gui/lib/local/dotenv/test/dotenv_test.odin
new file mode 100644
index 0000000..e0f17fa
--- /dev/null
+++ b/gui/lib/local/dotenv/test/dotenv_test.odin
@@ -0,0 +1,201 @@
+package dotenv_tests
+
+import "core:os"
+import "core:strings"
+import "core:testing"
+import dotenv "lib:dotenv/src"
+
+Test_Config :: struct {
+	api_url: string,
+	debug:   bool,
+	port:    int,
+	ratio:   f64,
+}
+
+// load_env writes src to a unique temp file and parses it via parse_file.
+// The returned map owns its strings; callers must destroy it.
+load_env :: proc(t: ^testing.T, src: string) -> map[string]string {
+	dir, err := os.make_directory_temp("", "dotenv_test_*", context.allocator)
+	testing.expect(t, err == nil, "expected temp dir to be created")
+	defer os.remove_all(dir)
+	defer delete(dir)
+
+	path := strings.concatenate({dir, "/.env"})
+	defer delete(path)
+
+	testing.expect(
+		t,
+		os.write_entire_file(path, src) == nil,
+		"expected file write to succeed",
+	)
+
+	env, ok := dotenv.parse_file(path)
+	testing.expect(t, ok, "expected parse_file to succeed")
+	return env
+}
+
+@(test)
+test_parse_basic :: proc(t: ^testing.T) {
+	env := load_env(t, "API_URL=http://127.0.0.1:8080\nDEBUG=true\nPORT=8080\n")
+	defer dotenv.destroy(env)
+
+	testing.expect(t, env["API_URL"] == "http://127.0.0.1:8080")
+	testing.expect(t, env["DEBUG"] == "true")
+	testing.expect(t, env["PORT"] == "8080")
+}
+
+@(test)
+test_parse_ignores_comments_and_blank_lines :: proc(t: ^testing.T) {
+	env := load_env(t, "# leading comment\n\n   \nFOO=bar  \nBAZ =  qux  \n")
+	defer dotenv.destroy(env)
+
+	testing.expect(t, env["FOO"] == "bar", "value should be trimmed")
+	testing.expect(
+		t,
+		env["BAZ"] == "qux",
+		"key and value should be trimmed around '='",
+	)
+	testing.expect(
+		t,
+		"API_URL" not_in env,
+		"comment-only lines should not be parsed",
+	)
+}
+
+@(test)
+test_parse_quoted_values :: proc(t: ^testing.T) {
+	env := load_env(t, "GREETING=\"hello world\"\nEMPTY=\"\"\n")
+	defer dotenv.destroy(env)
+
+	testing.expect(
+		t,
+		env["GREETING"] == "hello world",
+		"quoted value with inner space",
+	)
+	testing.expect(t, env["EMPTY"] == "", "double-quoted empty value")
+}
+
+@(test)
+test_parse_skips_lines_without_equals :: proc(t: ^testing.T) {
+	env := load_env(t, "not-an-assignment\nOK=yep\n")
+	defer dotenv.destroy(env)
+
+	testing.expect(t, env["OK"] == "yep")
+	testing.expect(
+		t,
+		"not-an-assignment" not_in env,
+		"line without '=' should be skipped",
+	)
+}
+
+@(test)
+test_parse_missing_file :: proc(t: ^testing.T) {
+	env, ok := dotenv.parse_file("/nonexistent/dotenv_test_does_not_exist.env")
+	testing.expect(t, !ok, "missing file should report failure")
+	testing.expect(t, env == nil, "missing file should return nil map")
+}
+
+@(test)
+test_real_env_overrides_file :: proc(t: ^testing.T) {
+	testing.expect(t, os.set_env("DESI_EXPLORER_TEST_FOO", "from_env") == nil)
+	defer os.unset_env("DESI_EXPLORER_TEST_FOO")
+
+	env := load_env(t, "DESI_EXPLORER_TEST_FOO=from_file\n")
+	defer dotenv.destroy(env)
+
+	testing.expect(
+		t,
+		env["DESI_EXPLORER_TEST_FOO"] == "from_env",
+		"real env var should win over file",
+	)
+}
+
+@(test)
+test_decode_maps_fields_case_insensitively :: proc(t: ^testing.T) {
+	env := load_env(
+		t,
+		"API_URL=http://127.0.0.1:8080\nDEBUG=true\nPORT=8080\nRATIO=0.5\n",
+	)
+	defer dotenv.destroy(env)
+
+	cfg := Test_Config{}
+	testing.expect(t, dotenv.decode(env, &cfg))
+	defer delete(cfg.api_url)
+
+	testing.expect(
+		t,
+		cfg.api_url == "http://127.0.0.1:8080",
+		"API_URL maps onto api_url",
+	)
+	testing.expect(t, cfg.debug == true, "DEBUG=true should decode to true")
+	testing.expect(t, cfg.port == 8080, "PORT=8080 should decode to int 8080")
+	testing.expect(t, cfg.ratio == 0.5, "RATIO=0.5 should decode to f64 0.5")
+}
+
+@(test)
+test_decode_matches_exact_and_lowercase_keys :: proc(t: ^testing.T) {
+	env := load_env(t, "api_url=http://exact\nPort=9090\n")
+	defer dotenv.destroy(env)
+
+	cfg := Test_Config{}
+	testing.expect(t, dotenv.decode(env, &cfg))
+	defer delete(cfg.api_url)
+
+	testing.expect(
+		t,
+		cfg.api_url == "http://exact",
+		"exact-case key should match",
+	)
+	testing.expect(t, cfg.port == 9090, "mixed-case key should match field")
+}
+
+@(test)
+test_decode_missing_keys_leave_zero_values :: proc(t: ^testing.T) {
+	env := load_env(t, "UNRELATED=value\n")
+	defer dotenv.destroy(env)
+
+	cfg := Test_Config{}
+	testing.expect(t, dotenv.decode(env, &cfg))
+
+	testing.expect(t, cfg.api_url == "")
+	testing.expect(t, !cfg.debug)
+	testing.expect(t, cfg.port == 0)
+	testing.expect(t, cfg.ratio == 0)
+}
+
+@(test)
+test_decode_unparsable_int_fails :: proc(t: ^testing.T) {
+	env := load_env(t, "PORT=oops\n")
+	defer dotenv.destroy(env)
+
+	cfg := Test_Config{}
+	testing.expect(
+		t,
+		!dotenv.decode(env, &cfg),
+		"unparsable int should make decode fail",
+	)
+}
+
+@(test)
+test_decode_unparsable_bool_fails :: proc(t: ^testing.T) {
+	env := load_env(t, "DEBUG=maybe\nAPI_URL=http://127.0.0.1:8080\n")
+	defer dotenv.destroy(env)
+
+	cfg := Test_Config{}
+	testing.expect(
+		t,
+		!dotenv.decode(env, &cfg),
+		"unparsable bool should make decode fail",
+	)
+	defer delete(cfg.api_url)
+}
+
+@(test)
+test_decode_hex_and_negative_ints :: proc(t: ^testing.T) {
+	env := load_env(t, "PORT=0x1F\n")
+	defer dotenv.destroy(env)
+
+	cfg := Test_Config{}
+	testing.expect(t, dotenv.decode(env, &cfg))
+	testing.expect(t, cfg.port == 31, "hex int should decode")
+}
diff --git a/gui/src/config.odin b/gui/src/config.odin
index f019d99..b5caa65 100644
--- a/gui/src/config.odin
+++ b/gui/src/config.odin
@@ -1,18 +1,26 @@
 package main
 
-import "lib:dotenv"
+import "core:os"
+import dotenv "lib:dotenv/src"
 
 Config :: struct {
 	api_url: string,
 }
 
-get_config :: proc() -> (^Config, ^Error) {
+get_config :: proc(env_file: ^string = nil) -> (^Config, ^Error) {
 	env, _ := dotenv.parse_file(".env", context.temp_allocator)
 	defer dotenv.destroy(env)
 
 	c := new(Config)
 
-	c.api_url = dotenv.get_string(env, "API_URL")
+	if env == nil {
+		c.api_url = os.get_env("API_URL", context.temp_allocator)
+	} else if !dotenv.decode(env, c) {
+		err := new(Error)
+		err.type = .Config
+		err.message = "failed to decode .env into Config"
+		return nil, err
+	}
 
 	if err := validate_config(c); err != nil {
 		return nil, err
@@ -26,4 +34,4 @@ validate_config :: proc(c: ^Config) -> ^Error {
 	if c.api_url == "" do err.type = .Config; err.message = "'API_URL' is required"
 
 	return err
-}
\ No newline at end of file
+}
diff --git a/gui/test/dotenv_test.odin b/gui/test/dotenv_test.odin
deleted file mode 100644
index d7ba8f6..0000000
--- a/gui/test/dotenv_test.odin
+++ /dev/null
@@ -1,87 +0,0 @@
-package dotenv_tests
-
-import "core:os"
-import "core:testing"
-import "lib:dotenv"
-
-@(test)
-test_parse_basic :: proc(t: ^testing.T) {
-	env := dotenv.parse("API_URL=http://127.0.0.1:8080\nDEBUG=true\nPORT=8080\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, env["API_URL"] == "http://127.0.0.1:8080")
-	testing.expect(t, env["DEBUG"] == "true")
-	testing.expect(t, env["PORT"] == "8080")
-}
-
-@(test)
-test_parse_ignores_comments_and_blank_lines :: proc(t: ^testing.T) {
-	env := dotenv.parse("# leading comment\n\n   \nFOO=bar  \nBAZ =  qux  \n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, env["FOO"] == "bar", "value should be trimmed")
-	testing.expect(t, env["BAZ"] == "qux", "key and value should be trimmed around '='")
-	testing.expect(t, "API_URL" not_in env, "comment-only lines should not be parsed")
-}
-
-@(test)
-test_parse_quoted_values :: proc(t: ^testing.T) {
-	env := dotenv.parse("GREETING=\"hello world\"\nEMPTY=\"\"\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, env["GREETING"] == "hello world", "quoted value with inner space")
-	testing.expect(t, env["EMPTY"] == "", "double-quoted empty value")
-}
-
-@(test)
-test_parse_skips_lines_without_equals :: proc(t: ^testing.T) {
-	env := dotenv.parse("not-an-assignment\nOK=yep\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, env["OK"] == "yep")
-	testing.expect(t, "not-an-assignment" not_in env, "line without '=' should be skipped")
-}
-
-@(test)
-test_get_string_falls_back_to_file :: proc(t: ^testing.T) {
-	env := dotenv.parse("FOO=from_file\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, dotenv.get_string(env, "FOO") == "from_file", "missing env var should use file value")
-	testing.expect(t, dotenv.get_string(env, "MISSING") == "", "absent everywhere should be empty")
-}
-
-@(test)
-test_get_string_prefers_real_env :: proc(t: ^testing.T) {
-	env := dotenv.parse("FOO=from_file\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, os.set_env("FOO", "from_env") == nil)
-	defer os.unset_env("FOO")
-
-	testing.expect(t, dotenv.get_string(env, "FOO") == "from_env", "real env var should win over file")
-}
-
-@(test)
-test_get_bool :: proc(t: ^testing.T) {
-	env := dotenv.parse("A=true\nB=0\nC=FALSE\nD=garbage\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, dotenv.get_bool(env, "A", false), "\"true\" should parse to true")
-	testing.expect(t, !dotenv.get_bool(env, "B", true), "\"0\" should parse to false")
-	testing.expect(t, !dotenv.get_bool(env, "C", true), "\"FALSE\" should parse to false")
-	testing.expect(t, dotenv.get_bool(env, "D", true), "unparsable value should fall back to default")
-	testing.expect(t, dotenv.get_bool(env, "MISSING", true), "missing key should fall back to default")
-}
-
-@(test)
-test_get_int :: proc(t: ^testing.T) {
-	env := dotenv.parse("PORT=8080\nNEG=-42\nHEX=0x1F\nGARBAGE=abc\n")
-	defer dotenv.destroy(env)
-
-	testing.expect(t, dotenv.get_int(env, "PORT", -1) == 8080, "decimal int")
-	testing.expect(t, dotenv.get_int(env, "NEG", 0) == -42, "negative int")
-	testing.expect(t, dotenv.get_int(env, "HEX", 0) == 31, "hex int")
-	testing.expect(t, dotenv.get_int(env, "GARBAGE", 7) == 7, "unparsable value should fall back to default")
-	testing.expect(t, dotenv.get_int(env, "MISSING", 7) == 7, "missing key should fall back to default")
-}
\ No newline at end of file