diff --git a/assets/config.example.json b/assets/config.example.json
index 2ec03be..7b28b9a 100644
--- a/assets/config.example.json
+++ b/assets/config.example.json
@@ -3,6 +3,8 @@
   "input_priority": "normal",
   "advanced_debug": false,
   "auto_insert": false,
+  "close_mic_when_idle": false,
+  "backend": "redux",
   "lock_layout": false,
   "clock_24h": false,
   "date_format": "mdy",
diff --git a/src/config.cpp b/src/config.cpp
index e602165..2b41b47 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -196,12 +196,22 @@ Config load_config(const std::filesystem::path& path) {
         if (key == "font") {
             if (!value.is_string) throw std::runtime_error("Config font must be a path string");
             config.font = value.value;
+        } else if (key == "backend") {
+            if (!value.is_string || value.value.empty() || value.value.size() > 48 ||
+                value.value[0] < 'a' || value.value[0] > 'z' ||
+                !std::all_of(value.value.begin(), value.value.end(), [](unsigned char c) {
+                    return (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '_' || c == '-';
+                })) throw std::runtime_error("Config backend must be a manifest ID");
+            config.backend = value.value;
         } else if (key == "advanced_debug") {
             if (!value.is_bool) throw std::runtime_error("Config advanced_debug must be a boolean");
             config.advanced_debug = value.value == "true";
         } else if (key == "auto_insert") {
             if (!value.is_bool) throw std::runtime_error("Config auto_insert must be a boolean");
             config.auto_insert = value.value == "true";
+        } else if (key == "close_mic_when_idle") {
+            if (!value.is_bool) throw std::runtime_error("Config close_mic_when_idle must be a boolean");
+            config.close_mic_when_idle = value.value == "true";
         } else if (key == "lock_layout") {
             if (!value.is_bool) throw std::runtime_error("Config lock_layout must be a boolean");
             config.lock_layout = value.value == "true";
@@ -323,6 +333,9 @@ bool save_advanced_debug(const std::filesystem::path& path, bool enabled) noexce
 bool save_auto_insert(const std::filesystem::path& path, bool enabled) noexcept {
     return save_bool_option(path, "auto_insert", enabled);
 }
+bool save_close_mic_when_idle(const std::filesystem::path& path, bool enabled) noexcept {
+    return save_bool_option(path, "close_mic_when_idle", enabled);
+}
 bool save_lock_layout(const std::filesystem::path& path, bool enabled) noexcept {
     return save_bool_option(path, "lock_layout", enabled);
 }
@@ -338,6 +351,13 @@ bool save_date_format(const std::filesystem::path& path, DateFormat format) noex
     }
     return false;
 }
+bool save_backend(const std::filesystem::path& path, const std::string& id) noexcept {
+    if (id.empty() || id.size() > 48 || id[0] < 'a' || id[0] > 'z' ||
+        !std::all_of(id.begin(), id.end(), [](unsigned char c) {
+            return (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '_' || c == '-';
+        })) return false;
+    return save_option(path, "backend", id, true);
+}
 std::string resolve_font(const std::string& assets, const std::string& requested) {
     const auto bundled = std::filesystem::path(assets) / "fonts/Inconsolata-Regular.ttf";
     const std::array<std::filesystem::path, 4> candidates{requested, bundled,
diff --git a/src/config.hpp b/src/config.hpp
index f9661da..b1dba9e 100644
--- a/src/config.hpp
+++ b/src/config.hpp
@@ -18,10 +18,12 @@ enum class DateFormat { Off, MonthDayYear, DayMonthYear, Iso };
 struct Config {
     Theme theme;
     std::string font; // absolute TTF/OTF path; empty uses the bundled face
+    std::string backend = "redux"; // selected manifest ID; never triggers a download
     // Requests OpenVR's experimental global action priority; SteamVR must allow it too.
     bool experimental_input_priority = false;
     bool advanced_debug = false; // opt-in full diagnostic logging; never raw audio recording
     bool auto_insert = false; // opt-in; runtime also requires uninterrupted verified Xwayland focus
+    bool close_mic_when_idle = false; // default keeps the device open, discarding idle audio
     bool lock_layout = false; // hide the grab and scale handles when enabled
     bool clock_24h = false;
     DateFormat date_format = DateFormat::MonthDayYear;
@@ -36,9 +38,11 @@ Config load_config(const std::filesystem::path& path);
 // Other user customizations and formatting are retained; creates a minimal config if absent.
 bool save_advanced_debug(const std::filesystem::path& path, bool enabled) noexcept;
 bool save_auto_insert(const std::filesystem::path& path, bool enabled) noexcept;
+bool save_close_mic_when_idle(const std::filesystem::path& path, bool enabled) noexcept;
 bool save_lock_layout(const std::filesystem::path& path, bool enabled) noexcept;
 bool save_clock_24h(const std::filesystem::path& path, bool enabled) noexcept;
 bool save_date_format(const std::filesystem::path& path, DateFormat format) noexcept;
+bool save_backend(const std::filesystem::path& path, const std::string& id) noexcept;
 std::string resolve_font(const std::string& assets, const std::string& requested);
 // No writes or OpenVR access when no custom button mappings are specified.
 // When customized, build a generated manifest and bindings under XDG cache.
diff --git a/tests/config_test.cpp b/tests/config_test.cpp
index 7273181..3a2749e 100644
--- a/tests/config_test.cpp
+++ b/tests/config_test.cpp
@@ -40,9 +40,11 @@ int main(int argc, char** argv) {
     ::setenv("XDG_CONFIG_HOME", dir.c_str(), 1);
     assert(load_config(path).buttons.empty());
     assert((load_config(path).quick_inputs == std::vector<std::string>{"/new", "/questions", "/help"}));
+    assert(load_config(path).backend == "redux");
     assert(!load_config(path).experimental_input_priority);
     assert(!load_config(path).advanced_debug);
     assert(!load_config(path).auto_insert);
+    assert(!load_config(path).close_mic_when_idle);
     assert(!load_config(path).lock_layout);
     assert(!load_config(path).clock_24h);
     assert(load_config(path).date_format == DateFormat::MonthDayYear);
@@ -56,10 +58,14 @@ int main(int argc, char** argv) {
     assert(!example.experimental_input_priority);
     assert(!example.advanced_debug);
     assert(!example.auto_insert);
+    assert(!example.close_mic_when_idle);
     assert(!example.lock_layout);
     assert(!example.clock_24h && example.date_format == DateFormat::MonthDayYear);
     assert(example.wrist.y == .18f && example.wrist.z == .089f);
     std::filesystem::create_directories(path.parent_path());
+    assert(save_backend(path, "fixture_cpu"));
+    assert(load_config(path).backend == "fixture_cpu");
+    assert(!save_backend(path, "../escaped") && !save_backend(path, "UPPER"));
     assert(save_advanced_debug(path, true));
     assert(load_config(path).advanced_debug);
     assert(get(path).find("\"advanced_debug\":true") != std::string::npos);
@@ -69,6 +75,10 @@ int main(int argc, char** argv) {
     assert(load_config(path).auto_insert);
     assert(save_auto_insert(path, false));
     assert(!load_config(path).auto_insert);
+    assert(save_close_mic_when_idle(path, true));
+    assert(load_config(path).close_mic_when_idle);
+    assert(save_close_mic_when_idle(path, false));
+    assert(!load_config(path).close_mic_when_idle);
     assert(save_lock_layout(path, true));
     assert(load_config(path).lock_layout);
     assert(save_lock_layout(path, false));
@@ -95,6 +105,11 @@ int main(int argc, char** argv) {
     assert(!load_config(path).advanced_debug);
     auto before = get(path);
     assert(save_advanced_debug(path, false) && get(path) == before);
+    for (const auto* invalid : {R"({"backend":"../escape"})", R"({"backend":""})",
+                               R"({"backend":2})"}) {
+        put(path, invalid); fails([&] { load_config(path); });
+        assert(!save_backend(path, "redux"));
+    }
     put(path, R"({"advanced_debug":false, "font":"kept"})");
     assert(save_advanced_debug(path, true));
     assert(get(path) == R"({"advanced_debug":true, "font":"kept"})");
@@ -107,6 +122,7 @@ int main(int argc, char** argv) {
     std::filesystem::create_symlink(path, link);
     assert(!save_advanced_debug(link, false));
     assert(!save_auto_insert(link, true));
+    assert(!save_close_mic_when_idle(link, true));
     assert(!save_lock_layout(link, true));
     assert(get(path) == before);
     std::filesystem::remove(link);
@@ -128,6 +144,21 @@ int main(int argc, char** argv) {
     put(path, R"({"date_format":"off","font":"kept"})");
     assert(save_date_format(path, DateFormat::Iso));
     assert(get(path) == R"({"date_format":"iso","font":"kept"})");
+    for (const auto* invalid : {R"({"close_mic_when_idle":"true"})", R"({"close_mic_when_idle":1})",
+                               R"({"close_mic_when_idle":null})", R"({"close_mic_when_idle":[]})"}) {
+        put(path, invalid);
+        fails([&] { load_config(path); });
+        assert(!save_close_mic_when_idle(path, true));
+        assert(get(path) == invalid);
+    }
+    put(path, R"({"close_mic_when_idle":false,"font":"kept"})");
+    assert(save_close_mic_when_idle(path, true));
+    assert(load_config(path).close_mic_when_idle);
+    assert(get(path) == R"({"close_mic_when_idle":true,"font":"kept"})");
+    before = get(path);
+    assert(save_close_mic_when_idle(path, true) && get(path) == before);
+    assert(save_close_mic_when_idle(path, false));
+    assert(get(path) == R"({"close_mic_when_idle":false,"font":"kept"})");
     put(path, R"({"auto_insert":"on"})");
     fails([&] { load_config(path); });
     assert(!save_auto_insert(path, true));