diff --git a/.gitignore b/.gitignore
index 0753ab7..9dbd8bb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,5 @@ resources/ai/sessions
 infra/Pulumi.*.yaml.backup
 infra/desi-explorer-infra
 api/target/
+.env
+.env.*
diff --git a/gui/Makefile b/gui/Makefile
index 84951f2..00df428 100644
--- a/gui/Makefile
+++ b/gui/Makefile
@@ -46,7 +46,7 @@ build-web: ## WebAssembly build -> build/web (needs emscripten)
 
 test: ## Run Odin unit tests
 	@mkdir -p lib/local
-	$(ODIN) test src $(ODIN_FLAGS)
+	$(ODIN) test test $(ODIN_FLAGS)
 
 clean: ## Remove build artifacts
 	rm -rf $(BIN) build
diff --git a/gui/lib/local/dotenv/dotenv.odin b/gui/lib/local/dotenv/dotenv.odin
new file mode 100644
index 0000000..8084b6d
--- /dev/null
+++ b/gui/lib/local/dotenv/dotenv.odin
@@ -0,0 +1,95 @@
+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/src/config.odin b/gui/src/config.odin
new file mode 100644
index 0000000..f019d99
--- /dev/null
+++ b/gui/src/config.odin
@@ -0,0 +1,29 @@
+package main
+
+import "lib:dotenv"
+
+Config :: struct {
+	api_url: string,
+}
+
+get_config :: proc() -> (^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 err := validate_config(c); err != nil {
+		return nil, err
+	}
+
+	return c, nil
+}
+
+validate_config :: proc(c: ^Config) -> ^Error {
+	err := new(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/src/error.odin b/gui/src/error.odin
new file mode 100644
index 0000000..daeb84f
--- /dev/null
+++ b/gui/src/error.odin
@@ -0,0 +1,20 @@
+package main
+
+import "core:fmt"
+import "core:strings"
+ErrorType :: enum {
+	Config,
+	API,
+}
+
+Error :: struct {
+	type:    ErrorType,
+	message: string,
+}
+
+format_error :: proc(err: ^Error) -> string {
+	sb := strings.builder_make(context.temp_allocator)
+
+	return fmt.sbprintf(&sb, "[%s] => %s", err.type, err.message)
+}
+
diff --git a/gui/src/main.odin b/gui/src/main.odin
index 67285fb..315b1cb 100644
--- a/gui/src/main.odin
+++ b/gui/src/main.odin
@@ -24,6 +24,13 @@ universe: [dynamic]Galaxy
 rng: rand.Default_Random_State
 
 main :: proc() {
+
+	c: ^Config
+
+	if c, err := get_config(); err != nil {
+		panic(format_error(err))
+	}
+
 	rng = rand.create(0xDE51_0000)
 	context.random_generator = rand.default_random_generator(&rng)
 
@@ -103,11 +110,5 @@ draw :: proc() {
 	}
 
 	rl.DrawFPS(10, 10)
-	rl.DrawText(
-		"DESI Explorer — drag to rotate, scroll to zoom",
-		10,
-		34,
-		18,
-		rl.RAYWHITE,
-	)
+	rl.DrawText("DESI Explorer — drag to rotate, scroll to zoom", 10, 34, 18, rl.RAYWHITE)
 }
diff --git a/gui/test/dotenv_test.odin b/gui/test/dotenv_test.odin
new file mode 100644
index 0000000..d7ba8f6
--- /dev/null
+++ b/gui/test/dotenv_test.odin
@@ -0,0 +1,87 @@
+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