buddy fix

config/assistant_test.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"os"
 	"strings"
 	"testing"
 )
@@ -206,3 +207,55 @@ func TestEachDefaultIsStillOverridable(t *testing.T) {
 		t.Fatalf("a local model was refused: %s", cfg.Why())
 	}
 }
+
+// The container reads its own configuration from a file beside the binary.
+//
+// The Dockerfile copies `.env.production` into the runtime image and sets
+// APP_ENV=production, so `loadEnvFiles` reads it on boot. This asserts the
+// mechanism rather than the Dockerfile — a COPY line is easy to check by eye
+// and easy to believe wrongly, and the failure it produces is a server that
+// starts fine with a variable silently unset.
+func TestTheEnvironmentFileBesideTheBinaryIsRead(t *testing.T) {
+	dir := t.TempDir()
+	t.Chdir(dir)
+
+	if err := os.WriteFile(".env.production",
+		[]byte("ASSISTANT_API_KEY=from-the-file\n"), 0o600); err != nil {
+		t.Fatalf("writing the fixture: %v", err)
+	}
+
+	t.Setenv("APP_ENV", "production")
+	// Registered with t.Setenv first so it is restored on return, then removed:
+	// godotenv does not overwrite a variable that is PRESENT, and an empty
+	// string is present. Setting it to "" would have tested nothing.
+	t.Setenv("ASSISTANT_API_KEY", "placeholder")
+	os.Unsetenv("ASSISTANT_API_KEY")
+
+	loadEnvFiles()
+
+	if os.Getenv("ASSISTANT_API_KEY") != "from-the-file" {
+		t.Fatal("the environment file beside the binary was not read")
+	}
+}
+
+func TestThePlatformStillWinsOverTheFile(t *testing.T) {
+	// godotenv never overwrites a variable already in the environment, so a
+	// value set on the hosting platform overrides the committed file without
+	// the file having to change. Both mechanisms work; neither fights the other.
+	dir := t.TempDir()
+	t.Chdir(dir)
+
+	if err := os.WriteFile(".env.production",
+		[]byte("ASSISTANT_API_KEY=from-the-file\n"), 0o600); err != nil {
+		t.Fatalf("writing the fixture: %v", err)
+	}
+
+	t.Setenv("APP_ENV", "production")
+	t.Setenv("ASSISTANT_API_KEY", "from-the-platform")
+
+	loadEnvFiles()
+
+	if got := os.Getenv("ASSISTANT_API_KEY"); got != "from-the-platform" {
+		t.Fatalf("the file overrode the platform: ASSISTANT_API_KEY=%q", got)
+	}
+}