diff --git a/Cargo.lock b/Cargo.lock
index 46dda94..51ba97a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -335,6 +335,7 @@ name = "common"
 version = "0.1.0"
 dependencies = [
  "iced",
+ "toml",
 ]
 
 [[package]]
@@ -354,8 +355,8 @@ dependencies = [
  "common",
  "iced",
  "iced_layershell",
- "module-clock",
- "service-datatime",
+ "modules",
+ "services",
  "tokio",
 ]
 
@@ -1718,7 +1719,16 @@ version = "0.1.0"
 dependencies = [
  "common",
  "iced",
- "service-datatime",
+ "thiserror 2.0.20",
+ "toml",
+]
+
+[[package]]
+name = "modules"
+version = "0.1.0"
+dependencies = [
+ "common",
+ "module-clock",
 ]
 
 [[package]]
@@ -2519,7 +2529,16 @@ dependencies = [
 ]
 
 [[package]]
-name = "service-datatime"
+name = "serde_spanned"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6662b5879511e06e8999a8a235d848113e942c9124f211511b16466ee2995f26"
+dependencies = [
+ "serde_core",
+]
+
+[[package]]
+name = "service-datetime"
 version = "0.1.0"
 dependencies = [
  "chrono",
@@ -2528,6 +2547,15 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "services"
+version = "0.1.0"
+dependencies = [
+ "common",
+ "iced",
+ "service-datetime",
+]
+
 [[package]]
 name = "shlex"
 version = "2.0.1"
@@ -2929,6 +2957,21 @@ dependencies = [
  "syn 3.0.5",
 ]
 
+[[package]]
+name = "toml"
+version = "1.1.5+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "12c0ba9680044b4ce98d391a62094047eada0d64860b80166c39f4a6b5640785"
+dependencies = [
+ "indexmap",
+ "serde_core",
+ "serde_spanned",
+ "toml_datetime",
+ "toml_parser",
+ "toml_writer",
+ "winnow",
+]
+
 [[package]]
 name = "toml_datetime"
 version = "1.1.1+spec-1.1.0"
@@ -2959,6 +3002,12 @@ dependencies = [
  "winnow",
 ]
 
+[[package]]
+name = "toml_writer"
+version = "1.1.2+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d56353a2a665ad0f41a421187180aab746c8c325620617ad883a99a1cbe66d2"
+
 [[package]]
 name = "tracing"
 version = "0.1.44"
diff --git a/Cargo.toml b/Cargo.toml
index 19474cc..fcd7f52 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,5 +1,5 @@
 [workspace]
-members = ["crates/core", "crates/modules/clock", "crates/services/datatime", "crates/common"]
+members = ["crates/core", "crates/common", "crates/modules", "crates/modules/clock", "crates/services", "crates/services/datetime"]
 resolver = "2"
 
 [workspace.package]
@@ -11,6 +11,9 @@ iced = { version = "0.14", default-features = false, features = ["wgpu", "waylan
 iced_layershell = { version = "0.19", default-features = false }
 tokio = { version = "1", features = ["rt-multi-thread", "macros", "sync", "time"] }
 chrono = "0.4"
+toml = "1.1"
+serde = { version = "1", features = ["derive"] }
+thiserror = "2"
 
 # Optimize all dependencies even in dev builds; workspace members keep dev
 # defaults (opt-level 0) and release settings under --release.
diff --git a/crates/common/Cargo.toml b/crates/common/Cargo.toml
index 23458be..69d140c 100644
--- a/crates/common/Cargo.toml
+++ b/crates/common/Cargo.toml
@@ -9,3 +9,4 @@ path = "src/lib.rs"
 
 [dependencies]
 iced = { workspace = true }
+toml = { workspace = true }
diff --git a/crates/common/src/lib.rs b/crates/common/src/lib.rs
index c86caad..d3d1db9 100644
--- a/crates/common/src/lib.rs
+++ b/crates/common/src/lib.rs
@@ -1,15 +1,16 @@
 //! Barbar's protocol crate: the types that cross crate boundaries.
 //!
-//! Nothing here may reference app-level types (`Message`, `Cmd`, `Msg`,
+//! Nothing here may reference app-level types (`Message`, `Msg`,
 //! layer-shell effects). `common` is the hub every other crate depends on,
 //! so it must stay acyclic and pure.
 
 use std::any::Any;
+use std::error::Error;
 use std::fmt;
 use std::sync::Arc;
 
 use iced::window;
-use iced::{Element, Task};
+use iced::{Element, Rectangle, Task};
 
 // ---------------------------------------------------------------------------
 // Service model
@@ -95,12 +96,16 @@ impl fmt::Debug for ModuleMsg {
     }
 }
 
-/// What a module asks the app to do. Modules never name app types; the app
-/// maps these into its own effects (`Cmd`).
+/// What a module asks the app to do — the single effect vocabulary shared by
+/// modules and app, so mapping module output into a `Message` is a plain
+/// `.map(Message::Effect)` with no mirror enum.
 #[derive(Debug, Clone)]
 pub enum ModuleEffect {
     /// Toggle a popup for the given module id (element id anchors it).
     RequestPopup(String, String),
+    /// A widget-tree pass reported a module's laid-out bounds; anchor the
+    /// popup there. App-internal, but one effect type keeps routing trivial.
+    BoundsFound(String, Rectangle),
     /// Request removal of the popup surface.
     ClosePopup(window::Id),
 }
@@ -124,4 +129,11 @@ pub trait BarModule: Send {
     fn popup_size(&self) -> Option<(u32, u32)> {
         None
     }
+
+    /// Digest config from `module.{module-id}`. Error is boxed because this
+    /// runs through `dyn BarModule`; each impl keeps its own concrete error
+    /// internally and may surface it pre-box via its constructor instead.
+    fn config(&mut self, _config: toml::Table) -> Result<(), Box<dyn Error>> {
+        Ok(())
+    }
 }
diff --git a/crates/core/Cargo.toml b/crates/core/Cargo.toml
index 9cdf4a5..b771611 100644
--- a/crates/core/Cargo.toml
+++ b/crates/core/Cargo.toml
@@ -12,7 +12,6 @@ iced = { workspace = true }
 iced_layershell = { workspace = true }
 tokio = { workspace = true }
 chrono = { workspace = true }
-# Modules
-module_clock = { package = "module-clock", path = "../modules/clock" }
-# Services
-service_datatime = { package = "service-datatime", path = "../services/datatime" }
+# Modules + services
+modules = { path = "../modules" }
+services = { path = "../services" }
diff --git a/crates/core/src/main.rs b/crates/core/src/main.rs
index 0fb71cc..04f5e76 100644
--- a/crates/core/src/main.rs
+++ b/crates/core/src/main.rs
@@ -7,7 +7,7 @@
 use std::collections::BTreeMap;
 
 use iced::widget::{column, container, text};
-use iced::{window, Alignment, Element, Length, Rectangle, Subscription, Task, Theme};
+use iced::{window, Alignment, Element, Length, Subscription, Task, Theme};
 use iced_layershell::daemon;
 use iced_layershell::reexport::Anchor;
 use iced_layershell::settings::{LayerShellSettings, Settings, StartMode};
@@ -38,8 +38,9 @@ struct Bar {
 
 impl Bar {
     fn new() -> Self {
-        let mut modules: BTreeMap<&'static str, Box<dyn BarModule>> = BTreeMap::new();
-        modules.insert("clock", Box::new(module_clock::Clock::new()));
+        // Registry owns construction: adding a module never edits this file.
+        let modules: BTreeMap<&'static str, Box<dyn BarModule>> =
+            modules::all().into_iter().map(|m| (m.id(), m)).collect();
         let routes = modules
             .iter()
             .map(|(id, module)| (*id, module.services()))
@@ -68,24 +69,15 @@ pub(crate) enum Msg {
     WindowClosed(window::Id),
 }
 
-/// App-level effects (popups, window ops), emitted via `Task<Message>`.
-#[derive(Debug, Clone)]
-pub(crate) enum Cmd {
-    /// Toggle a module's popup: close if open for it, else open it.
-    RequestPopup(String, String),
-    /// Widget-tree pass reported a module's laid-out bounds; anchor popup.
-    BoundsFound(String, Rectangle),
-    /// Request removal of the popup surface.
-    ClosePopup(window::Id),
-}
-
 /// iced needs one `Message` type. `to_layer_message` must sit here: it
 /// injects the layer-shell effect variants + their `TryInto` impl.
 #[to_layer_message(multi)]
 #[derive(Debug, Clone)]
 pub(crate) enum Message {
     Event(Msg),
-    Effect(Cmd),
+    /// Effects. `common::ModuleEffect` is the one effect vocabulary, so
+    /// mapping module output is a plain `.map(Message::Effect)`.
+    Effect(ModuleEffect),
 }
 
 // ---------------------------------------------------------------------------
@@ -96,24 +88,22 @@ fn namespace() -> String {
     String::from("barbar")
 }
 
-/// Maps a module-requested effect into an app message. Modules never name
-/// app types; this is the only place the two meet.
-fn module_effect_to_message(effect: ModuleEffect) -> Message {
-    match effect {
-        ModuleEffect::RequestPopup(module_id, element_id) => {
-            Message::Effect(Cmd::RequestPopup(module_id, element_id))
-        }
-        ModuleEffect::ClosePopup(id) => Message::Effect(Cmd::ClosePopup(id)),
-    }
-}
-
-/// One arm per service kind: turns a route key into its subscription.
-/// Adding a service touches only this match (plus the leaf crate).
-fn service_subscription(service: &ModuleService) -> Subscription<Message> {
-    match service {
-        ModuleService::Clock(_) => service_datatime::ClockTicker::run()
-            .map(|event| Message::Event(Msg::Subscription(event))),
-    }
+/// Route subscriptions + window-close events (popup really destroyed).
+/// Each module's wants go through the services registry, so adding a
+/// service never edits this file.
+fn gather_subscriptions(bar: &Bar) -> Subscription<Message> {
+    let route_sub = Subscription::batch(
+        bar.routes
+            .values()
+            .flat_map(|wants| wants.iter())
+            .map(|service| {
+                services::subscription(service)
+                    .map(|event| Message::Event(Msg::Subscription(event)))
+            })
+            .collect::<Vec<_>>(),
+    );
+    let close_events = window::close_events().map(|id| Message::Event(Msg::WindowClosed(id)));
+    Subscription::batch(vec![route_sub, close_events])
 }
 
 fn main() -> Result<(), iced_layershell::Error> {
@@ -138,18 +128,6 @@ fn main() -> Result<(), iced_layershell::Error> {
         .run()
 }
 
-/// Route subscriptions + window-close events (popup really destroyed).
-fn gather_subscriptions(bar: &Bar) -> Subscription<Message> {
-    let route_sub = Subscription::batch(
-        bar.routes
-            .values()
-            .flat_map(|x| x.iter().map(service_subscription))
-            .collect::<Vec<_>>(),
-    );
-    let close_events = window::close_events().map(|id| Message::Event(Msg::WindowClosed(id)));
-    Subscription::batch(vec![route_sub, close_events])
-}
-
 // ---------------------------------------------------------------------------
 // Update
 // ---------------------------------------------------------------------------
@@ -157,7 +135,7 @@ fn gather_subscriptions(bar: &Bar) -> Subscription<Message> {
 fn update(bar: &mut Bar, msg: Message) -> Task<Message> {
     match msg {
         Message::Event(event) => handle_event(bar, event),
-        Message::Effect(cmd) => handle_effect(bar, cmd),
+        Message::Effect(effect) => handle_effect(bar, effect),
         // Layer-shell variants injected by `to_layer_message`.
         _ => Task::none(),
     }
@@ -167,8 +145,8 @@ fn update(bar: &mut Bar, msg: Message) -> Task<Message> {
 fn handle_event(bar: &mut Bar, event: Msg) -> Task<Message> {
     match event {
         Msg::Module(m) => match bar.modules.get_mut(m.id) {
-            // Modules return protocol tasks; map effects into `Cmd`s.
-            Some(module) => module.update(m).map(module_effect_to_message),
+            // Modules return protocol tasks; wrap effects into messages.
+            Some(module) => module.update(m).map(Message::Effect),
             None => Task::none(),
         },
 
@@ -190,7 +168,7 @@ fn handle_event(bar: &mut Bar, event: Msg) -> Task<Message> {
                             id: module.id(),
                             payload: payload.clone(),
                         })
-                        .map(module_effect_to_message)
+                        .map(Message::Effect)
                 })
                 .fold(Task::none(), |acc, t| acc.chain(t))
         }
@@ -208,9 +186,9 @@ fn handle_event(bar: &mut Bar, event: Msg) -> Task<Message> {
 }
 
 /// Runs an effect; may set up bar state for it (e.g. which popup is open).
-fn handle_effect(bar: &mut Bar, cmd: Cmd) -> Task<Message> {
-    match cmd {
-        Cmd::RequestPopup(module_id, element_id) => {
+fn handle_effect(bar: &mut Bar, effect: ModuleEffect) -> Task<Message> {
+    match effect {
+        ModuleEffect::RequestPopup(module_id, element_id) => {
             // Toggle: close if already open for this module, else open.
             if bar.active_popup.as_deref() == Some(module_id.as_str()) {
                 popup::close_popup(bar)
@@ -219,9 +197,9 @@ fn handle_effect(bar: &mut Bar, cmd: Cmd) -> Task<Message> {
             }
         }
 
-        Cmd::BoundsFound(module_id, bounds) => popup::open_popup(bar, module_id, bounds),
+        ModuleEffect::BoundsFound(module_id, bounds) => popup::open_popup(bar, module_id, bounds),
 
-        Cmd::ClosePopup(id) => {
+        ModuleEffect::ClosePopup(id) => {
             // Request removal only; keep popup state so the popup content
             // renders until `WindowClosed` confirms it's gone.
             Task::done(Message::RemoveWindow(id))
diff --git a/crates/core/src/popup.rs b/crates/core/src/popup.rs
index a1d9374..d192d0b 100644
--- a/crates/core/src/popup.rs
+++ b/crates/core/src/popup.rs
@@ -10,7 +10,9 @@ use iced::{Alignment, Element, Length, Rectangle, Task};
 use iced_layershell::actions::IcedNewPopupSettings;
 use iced_layershell::reexport::{PopupAnchor, PopupGravity};
 
-use crate::{Bar, Cmd, Message, Msg};
+use common::ModuleEffect;
+
+use crate::{Bar, Message, Msg};
 
 /// Default (small menu) popup size.
 const POPUP_W: u32 = 150;
@@ -52,7 +54,7 @@ pub fn open_popup(bar: &mut Bar, module_id: String, bounds: Rectangle) -> Task<M
 /// `Msg::WindowClosed`, so popup content keeps rendering until then.
 pub fn close_popup(bar: &mut Bar) -> Task<Message> {
     if let Some(id) = bar.popup_id {
-        return Task::done(Message::Effect(Cmd::ClosePopup(id)));
+        return Task::done(Message::Effect(ModuleEffect::ClosePopup(id)));
     }
     Task::none()
 }
@@ -93,7 +95,7 @@ pub fn capture_bounds(module_id: String, element_id: String) -> Task<Message> {
         target,
         found: None,
     })
-    .map(move |bounds| Message::Effect(Cmd::BoundsFound(module_id.clone(), bounds)))
+    .map(move |bounds| Message::Effect(ModuleEffect::BoundsFound(module_id.clone(), bounds)))
 }
 
 /// Popup widget tree on its own LayerShell surface; the active module
@@ -117,7 +119,8 @@ pub fn view(bar: &Bar) -> Element<'_, Message> {
             .width(Length::Fill)
             .align_x(Alignment::Center),
         content,
-        mouse_area(text("close").size(12)).on_press(Message::Effect(Cmd::ClosePopup(popup_id))),
+        mouse_area(text("close").size(12))
+            .on_press(Message::Effect(ModuleEffect::ClosePopup(popup_id))),
     ]
     .spacing(1)
     .into()
diff --git a/crates/modules/Cargo.toml b/crates/modules/Cargo.toml
new file mode 100644
index 0000000..dffa7c1
--- /dev/null
+++ b/crates/modules/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "modules"
+version.workspace = true
+edition.workspace = true
+
+[lib]
+name = "modules"
+path = "src/lib.rs"
+
+[dependencies]
+common = { path = "../common" }
+module_clock = { package = "module-clock", path = "clock" }
diff --git a/crates/modules/clock/Cargo.toml b/crates/modules/clock/Cargo.toml
index d4efd6d..3afb47e 100644
--- a/crates/modules/clock/Cargo.toml
+++ b/crates/modules/clock/Cargo.toml
@@ -9,5 +9,6 @@ path = "src/lib.rs"
 
 [dependencies]
 common = { path = "../../common" }
-service_datatime = { package = "service-datatime", path = "../../services/datatime" }
 iced = { workspace = true }
+thiserror = { workspace = true }
+toml = { workspace = true }
diff --git a/crates/modules/clock/src/lib.rs b/crates/modules/clock/src/lib.rs
index 962f458..f783933 100644
--- a/crates/modules/clock/src/lib.rs
+++ b/crates/modules/clock/src/lib.rs
@@ -11,6 +11,14 @@ use common::{BarModule, ClockKind, ClockPayload, ModuleEffect, ModuleMsg, Servic
 const POPUP_W: u32 = 360;
 const POPUP_H: u32 = 160;
 
+/// Errors digesting the `module.clock` config table.
+#[derive(Debug, thiserror::Error)]
+pub enum ClockError {
+    /// Config value was present but not a bool.
+    #[error("module.clock.{0} must be a bool")]
+    NotBool(&'static str),
+}
+
 /// A module-local message for the clock.
 #[derive(Clone)]
 pub enum ClockMsg {
@@ -100,4 +108,12 @@ impl BarModule for Clock {
     fn popup_size(&self) -> Option<(u32, u32)> {
         Some((POPUP_W, POPUP_H))
     }
+    fn config(&mut self, config: toml::Table) -> Result<(), Box<dyn std::error::Error>> {
+        if let toml::Value::Boolean(e) = config["format"] {
+            if e {
+                self.show_seconds = true;
+            };
+        }
+        Ok(())
+    }
 }
diff --git a/crates/modules/src/lib.rs b/crates/modules/src/lib.rs
new file mode 100644
index 0000000..26d93f6
--- /dev/null
+++ b/crates/modules/src/lib.rs
@@ -0,0 +1,10 @@
+//! Bar module registry: constructs every enabled module. Adding a module is
+//! a new crate under `crates/modules/` plus one entry in `all()` — core
+//! never changes.
+
+use common::BarModule;
+
+/// One instance of every enabled module, ready to insert by `id()`.
+pub fn all() -> Vec<Box<dyn BarModule>> {
+    vec![Box::new(module_clock::Clock::new())]
+}
diff --git a/crates/services/Cargo.toml b/crates/services/Cargo.toml
new file mode 100644
index 0000000..5ab13d6
--- /dev/null
+++ b/crates/services/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "services"
+version.workspace = true
+edition.workspace = true
+
+[lib]
+name = "services"
+path = "src/lib.rs"
+
+[dependencies]
+common = { path = "../common" }
+service_datetime = { package = "service-datetime", path = "datetime" }
+iced = { workspace = true }
diff --git a/crates/services/datatime/Cargo.toml b/crates/services/datetime/Cargo.toml
similarity index 81%
rename from crates/services/datatime/Cargo.toml
rename to crates/services/datetime/Cargo.toml
index 476c2dc..0aedec3 100644
--- a/crates/services/datatime/Cargo.toml
+++ b/crates/services/datetime/Cargo.toml
@@ -1,10 +1,10 @@
 [package]
-name = "service-datatime"
+name = "service-datetime"
 version.workspace = true
 edition.workspace = true
 
 [lib]
-name = "service_datatime"
+name = "service_datetime"
 path = "src/lib.rs"
 
 [dependencies]
diff --git a/crates/services/datatime/src/lib.rs b/crates/services/datetime/src/lib.rs
similarity index 100%
rename from crates/services/datatime/src/lib.rs
rename to crates/services/datetime/src/lib.rs
diff --git a/crates/services/src/lib.rs b/crates/services/src/lib.rs
new file mode 100644
index 0000000..2ad0e16
--- /dev/null
+++ b/crates/services/src/lib.rs
@@ -0,0 +1,14 @@
+//! Service registry: turns a route key into the subscription that backs it.
+//! Adding a service is a new crate under `crates/services/` plus one arm in
+//! `subscription` — core never changes.
+
+use iced::Subscription;
+
+use common::{Service, ServicePayloadKind};
+
+/// The subscription backing a route key.
+pub fn subscription(service: &Service) -> Subscription<ServicePayloadKind> {
+    match service {
+        Service::Clock(_) => service_datetime::ClockTicker::run(),
+    }
+}