Will change this commit message to mean something later

Documentation.md

@@ -11,6 +11,7 @@
 - [Debugging tips](#debugging-tips)
 - [Dictionary: Lua API](#dictionary-lua-api)
   - [Workflows](#workflows-since-v12)
+  - [Widgets](#widgets-since-v13)
   - [Bluetooth](#bluetooth)
 - [Dictionary: Built-in modules](#dictionary-built-in-modules)
 - [Dictionary: Event reference](#dictionary-event-reference)
@@ -286,6 +287,105 @@ Returns the current status for `name`, or `nil` if no workflow with that name ha
 #### `bread.workflow.list() -> table`
 Returns an array of every workflow's current status, in the same shape as `bread.workflow.status`.
 
+### Widgets *(Since: v1.3)*
+
+Declarative, live-updating widgets rendered by sibling `bread*` apps (breadbar) in their own bar/popover free space. A widget is a small tree of typed nodes — `box`, `label`, `icon`, `progress` — not raw markup: this keeps rendering generic across every consuming app and keeps a node's appearance confined to a bounded, typed `style` vocabulary the renderer already knows about (see `style` below), with no style/CSS injection surface from Lua.
+
+Widgets are registered per-module and are re-registered fresh on every hot reload (the whole registry is cleared right before the Lua VM resets, same as `bread.module`'s per-reload re-execution) — call `bread.widget.register` at module top level or in `on_load`, not somewhere that only runs once ever.
+
+#### `bread.widget.register(spec) -> ok, err`
+Registers (or replaces, if `spec.id` already exists for this module) a widget. `spec`:
+
+| Key | Type | Description |
+|-----|------|-------------|
+| `id` | string | Local id, unique within your module. Stored/addressed elsewhere as `"<module>.<id>"`. |
+| `placement` | string | One of `tray`, `left_of_clock`, `right_of_clock`, `right_of_workspaces`, `left_of_stats` — which fixed slot in the consuming app's layout this widget renders into. |
+| `order` | number | Optional, default `0`. Sort priority within a placement; lower sorts first. |
+| `visible` | bool | Optional, default `true`. |
+| `tooltip` | string | Optional. |
+| `root` | node | The render tree (see Node types below). |
+
+Returns `true` on success, or `false, err` if `root` fails validation (tree too deep, too many nodes, or an invalid `class`), `root` contains a `style` field with a value outside its enum (a deserialization error, reported the same way), or `bread.widget.register` was called outside a module.
+
+##### Node types
+
+Every node accepts an optional `style` (a bounded, typed vocabulary — see below; this is the primary way to control a node's appearance), an optional `class` (a small freeform escape hatch, see [Style vs. class](#style-vs-class) below), and an optional `on_click` (any Lua value, passed through opaquely — see Click events below).
+
+| `type` | Fields |
+|--------|--------|
+| `box` | `orientation` (`"horizontal"` \| `"vertical"`, default horizontal), `spacing`, `children` (array of nodes) |
+| `label` | `text` |
+| `icon` | `name` (bundled icon) or `path` (arbitrary SVG file) — exactly one; `size` |
+| `progress` | `value` (0.0–1.0) |
+
+A tree is capped at depth 4 (root counts as depth 1) and 50 total nodes — comfortably enough for a status readout, not enough to build a full custom UI.
+
+```lua
+bread.widget.register({
+    id = "weather",
+    placement = "left_of_stats",
+    tooltip = "Sydney: Partly cloudy",
+    root = {
+        type = "box",
+        children = {
+            { type = "icon", name = "cloud" },
+            { type = "label", text = "22°C", style = { color = "dim" }, on_click = "refresh" },
+        },
+    },
+})
+```
+
+##### `style` *(Since: v1.4)*
+
+`style` is a bounded, typed vocabulary for a node's appearance — every field is a small closed enum, not a string, so a typo is a `bread.widget.register` validation failure at registration time, not a silently-ignored CSS class. There is deliberately **no raw CSS/style-string field** anywhere in this API: a module can only ever pick from the fixed set below, never inject arbitrary style.
+
+| Field | Type | Values |
+|-------|------|--------|
+| `color` | string | `fg`, `dim` (muted foreground), `accent`, `red`, `green`, `yellow`, `blue`, `pink`, `teal` |
+| `weight` | string | `normal`, `bold` |
+| `size` | string | `xs`, `sm`, `md`, `lg`, `xl` — text size in px (10/12/14/16/20); `sm`/`md` match the bread design system's own secondary/base font sizes |
+| `align` | string | `start`, `center`, `end` |
+| `background` | string | `none`, `surface`, `card` (surface + rounded corners + padding) |
+| `radius` | string | `none`, `sm`, `md`, `full` (pill) |
+| `padding` | string | `none`, `xs`, `sm`, `md` |
+
+Every field is optional and independent — set only what you need. Colors, font sizes, radii, and padding all reuse the exact same palette, font, and spacing scale every other `bread*` GUI (breadbar, bos-settings, breadpad, ...) is themed from, so a widget recolors with the rest of the desktop when pywal's palette changes instead of drifting out of sync.
+
+```lua
+{ type = "label", text = "LOW BATTERY", style = { color = "yellow", weight = "bold" } }
+```
+
+##### Style vs. `class`
+
+`class` still exists as an escape hatch for a CSS class the *consuming app's own stylesheet* happens to define (restricted to `^[a-zA-Z][a-zA-Z0-9_-]{0,63}$`) — useful if you're targeting a specific app you know the internals of, but undiscoverable and app-specific otherwise. As of this writing, breadbar's stylesheet only gives real meaning to `dim` this way (fades a node to 60% opacity) — everything else a module needs (color, weight, size, alignment, background, radius, padding) should go through `style` instead, which every renderer is expected to understand identically.
+
+#### `bread.widget.update(id, patch) -> ok, err`
+Patches an already-registered widget (local `id`, not the fully-qualified form). Any of `root`, `tooltip`, `visible`, `order` may be given; omitted fields are left as-is. `root`, when given, replaces the whole tree — there is no node-level patching. Returns `false, "no such widget"` if `id` isn't registered.
+
+```lua
+bread.widget.update("weather", {
+    root = { type = "box", children = { { type = "label", text = "23°C" } } },
+})
+```
+
+#### `bread.widget.remove(id) -> bool`
+Removes a widget registered by the calling module. Returns whether anything was removed.
+
+#### `bread.widget.list() -> table`
+Returns an array of every widget the calling module currently has registered.
+
+##### Click events
+
+A clicked node's `on_click` value doesn't travel back through `breadd` directly — the rendering app (breadbar) emits `bread.bar.widget_clicked` with `{ widget_id, action }` (`action` being whatever you put in `on_click`), because a rendering app may only publish inside its own `bread.<app_id>.*` namespace (see [Namespaces](#namespaces)). React to it like any other event, filtering on `widget_id`:
+
+```lua
+bread.on("bread.bar.widget_clicked", function(e)
+    if e.data.widget_id == "weather.weather" then
+        -- e.data.action == "refresh"
+    end
+end)
+```
+
 ### State
 
 #### `bread.state.get(path)`
@@ -816,6 +916,17 @@ Both USB/udev devices and Bluetooth devices emit `bread.device.connected` / `bre
 | `bread.notify.sent` | `{ title, message, urgency }` |
 | `bread.state.changed.<path>` | emitted by state watches |
 
+#### Widgets *(Since: v1.3)*
+
+Emitted by `breadd` itself on every `bread.widget.*` mutation — see [Widgets](#widgets-since-v13). `data` is the full `WidgetSpec` for `registered`/`updated`; just `{ id }` for `removed`.
+
+| Event | Data |
+|-------|------|
+| `bread.widget.registered` | `{ id, module, placement, order, visible, tooltip, root, updated_at }` |
+| `bread.widget.updated` | same shape as `registered` |
+| `bread.widget.removed` | `{ id }` |
+| `bread.widget.cleared` | `{}` — fired once at the end of every module reload (`bread reload`), whether or not the widget set actually changed. The registry itself is wiped and re-populated as modules re-run; this is a "go re-fetch" signal for consumers that only react to `bread.widget.*` events, so a module that stops registering widgets (e.g. gets disabled) is noticed even though nothing else fires. |
+
 #### Terminal (shell precmd/preexec hooks)
 
 Requires `bread hooks install shell` and sourcing the generated script from your shell rc — see the CLI reference. Fires via the `bread-emit` helper, not the daemon reaching out.
@@ -885,6 +996,8 @@ Rides the same shell-hook transport as Terminal events (`bread hooks install she
 
 *Since: v1.1 — the `AdapterSource::App` variant and the known-apps registry (`bread_shared::apps::KNOWN_APPS`). No sibling app emits through this path yet as of this writing except the breadclip pilot (see its own `EVENTS.md` once that lands); the daemon-side plumbing and the convention itself are what v1.1 adds.*
 
+*Since: v1.3 — breadbar is now an active `bread-client` consumer under the `bar` app id (already present in `KNOWN_APPS`): it emits `bread.bar.widget_clicked` for widget clicks (see [Widgets](#widgets-since-v13)) and reads `bread.widget.*` to render the [Dictionary: Runtime state schema](#dictionary-runtime-state-schema)'s `widgets` field.*
+
 Two dotted-name segments are reserved, permanent parts of the schema — not one-off conventions:
 
 - **`bread.<app>.*`** — inbound events published *by* a sibling `bread*` application about its own state (e.g. `bread.clip.copied`). An app may only publish within its own segment; the daemon enforces this at the IPC boundary (a socket client claiming a `source` of an app id it doesn't own is rejected the same way spoofing `power`/`hyprland` is rejected today).
@@ -969,11 +1082,30 @@ This is the checklist for adding a new sibling `bread*` application to the fabri
       "updated_at": 1710000001500,
       "error": null
     }
+  ],
+  "widgets": [
+    {
+      "id": "weather.weather",
+      "module": "weather",
+      "placement": "left_of_stats",
+      "order": 0,
+      "visible": true,
+      "tooltip": "Sydney: Partly cloudy",
+      "root": {
+        "type": "box",
+        "orientation": "horizontal",
+        "children": [
+          { "type": "icon", "name": "cloud" },
+          { "type": "label", "text": "22°C" }
+        ]
+      },
+      "updated_at": 1710000001500
+    }
   ]
 }
 ```
 
-`modules[].status` values: `loaded`, `load_error`, `not_found`, `degraded`, `disabled`. `workflows[].state` values: `running`, `done`, `failed`, `timed_out` *(Since: v1.2 — see [Workflows](#workflows-since-v12))*.
+`modules[].status` values: `loaded`, `load_error`, `not_found`, `degraded`, `disabled`. `workflows[].state` values: `running`, `done`, `failed`, `timed_out` *(Since: v1.2 — see [Workflows](#workflows-since-v12))*. `widgets[].placement` values: `tray`, `left_of_clock`, `right_of_clock`, `right_of_workspaces`, `left_of_stats` *(Since: v1.3 — see [Widgets](#widgets-since-v13))*.
 
 ---
 
@@ -1009,5 +1141,6 @@ Available methods:
 | `events.replay` | `since_ms` | Replay buffered events from the last N ms |
 | `emit` | `event`, `data`, optional `source`, `kind` | Inject an event. Without `source`, builds a `BreadEvent` directly tagged `System` (legacy path). With `source` set to `terminal`/`git`/`remote`, or a registered sibling-app id (see [Namespaces](#namespaces)), builds a real `RawEvent` (requires `kind` too) that goes through the normalizer like any adapter. Any other `source` value is rejected — this is the anti-spoofing boundary that stops a socket client from forging e.g. `power`/`hyprland` events. |
 | `workflows.list` | — | List running/completed workflow instances and their step/status *(Since: v1.2)* |
+| `widgets.list` | — | List all registered widgets across every module *(Since: v1.3)* |
 
 The `health` response's `api_version` field lets a client — the CLI, a Lua module via `bread.exec`, or a `bread-client`-linked sibling app — assert compatibility with this document's versioned schema at connect time (see [API Stability & Versioning](#api-stability--versioning)).

Examples.md

@@ -238,6 +238,78 @@ Check on a running (or finished) workflow via the IPC method directly (there's n
 echo '{"id":"1","method":"workflows.list","params":{}}' | nc -U -q0 "$XDG_RUNTIME_DIR/bread/breadd.sock"
 ```
 
+## Example 5: A live widget in breadbar
+
+The examples above all react to something; they don't put anything on
+screen. `bread.widget` *(Since: v1.3)* does — a module declares a small node
+tree and breadbar (or any sibling app that renders `bread.widget.*`) shows
+it in one of five fixed layout slots, live-updated from Lua.
+
+Full source: `examples/modules/cpu-temp-widget.lua`.
+
+```lua
+-- ~/.config/bread/modules/cpu-temp-widget.lua
+local M = bread.module({ name = "cpu-temp-widget", version = "1.0.0" })
+
+local TEMP_PATH = "/sys/class/hwmon/hwmon6/temp1_input"
+local HOT_THRESHOLD_C = 80
+
+local function read_temp_c()
+    local raw = bread.fs.read(TEMP_PATH)
+    return raw and (tonumber(raw) / 1000) or nil
+end
+
+local function widget_root(temp_c)
+    local text = temp_c and string.format("%.0f°C", temp_c) or "—"
+    local hot = temp_c ~= nil and temp_c >= HOT_THRESHOLD_C
+    return {
+        type = "box",
+        children = {
+            {
+                type = "label",
+                text = text,
+                style = hot and { color = "red", weight = "bold" } or { color = "dim" },
+            },
+            {
+                type = "progress",
+                value = temp_c and math.min(temp_c / 100, 1.0) or 0,
+                style = hot and { color = "red" } or nil,
+            },
+        },
+    }
+end
+
+function M.on_load()
+    bread.widget.register({
+        id = "cpu-temp",
+        placement = "left_of_stats",
+        tooltip = "CPU package temperature (Tctl)",
+        root = widget_root(read_temp_c()),
+    })
+
+    bread.every(5000, function()
+        bread.widget.update("cpu-temp", { root = widget_root(read_temp_c()) })
+    end)
+end
+
+return M
+```
+
+Walking through what each piece buys you:
+
+- **`root` is a small typed tree, not markup.** `box`/`label`/`icon`/`progress` map directly onto GTK primitives, so any renderer can draw it without interpreting a DSL — see [Widgets](Documentation.md#widgets-since-v13) for the full node reference and the size/depth caps.
+- **`bread.widget.update(id, { root = ... })` replaces the whole tree.** There's no node-level patching — for something this small, rebuilding the tree on every tick (here, every 5s) is simpler than diffing, and it's cheap enough that it doesn't matter.
+- **`style` is a bounded, typed vocabulary, not a style string.** `color = "red"` here maps to one fixed CSS class the rendering app defines, resolved from the real pywal-derived palette — see [Widgets §style](Documentation.md#style-since-v14) for the full field list. There's also a freeform `class` escape hatch, but a module can't inject arbitrary CSS through either path.
+- **Clicks come back as events, not callbacks.** A node's `on_click` value isn't invoked directly — the rendering app emits `bread.bar.widget_clicked` with `{ widget_id, action }`, and your module reacts with a normal `bread.on` handler. See `examples/modules/bluetooth-toggle-widget.lua` for a widget that uses this to drive a real action (`bread.bluetooth.power`) instead of just displaying something — or `examples/modules/focus-mode-widget.lua` for one that drives `bread.profile.activate` and stays in sync when the profile changes from somewhere else entirely (the CLI, another module), not just from its own click.
+- **Placement is one of five fixed slots** (`tray`, `left_of_clock`, `right_of_clock`, `right_of_workspaces`, `left_of_stats`) — see `examples/modules/active-window-widget.lua` for `right_of_workspaces` driven by `bread.state.watch` instead of a timer.
+- **A widget doesn't have to read hardware.** `examples/modules/workflow-status-widget.lua` polls `bread.workflow.list()` instead — the same engine from Example 4 — and sets `visible = false` to disappear entirely when there's nothing to report, rather than showing a stale or empty readout.
+
+Check what's currently registered over IPC (there's no dedicated `bread` subcommand for this yet — see `widgets.list` in the [IPC protocol dictionary](Documentation.md#dictionary-ipc-protocol)):
+
+```bash
+echo '{"id":"1","method":"widgets.list","params":{}}' | nc -U -q0 "$XDG_RUNTIME_DIR/bread/breadd.sock"
+```
+
 ## Tips for porting your own scripts
 
 - Start by logging the event payload: `bread.log(event.data.raw)`

bread-shared/src/lib.rs

@@ -10,6 +10,7 @@ use serde::{Deserialize, Serialize};
 
 pub mod apps;
 pub mod glob;
+pub mod widget;
 
 /// Identifies which adapter produced an event.
 ///

bread-shared/src/widget.rs

@@ -0,0 +1,580 @@
+//! Wire types for Lua-declared bar widgets.
+//!
+//! A module running in breadd's Lua runtime can register a small declarative
+//! node tree (see [`WidgetNode`]) that gets rendered generically by a
+//! sibling `bread*` app (breadbar) in its bar or hamburger-popover free
+//! space. These types are the shared contract between `breadd` (which
+//! stores/validates/emits them from `bread.widget.*`) and any renderer.
+
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+/// Maximum nesting depth of a widget's node tree (the root counts as depth 1).
+pub const MAX_NODE_DEPTH: usize = 4;
+/// Maximum total number of nodes (root + all descendants) in a widget's tree.
+pub const MAX_NODE_COUNT: usize = 50;
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum Orientation {
+    Horizontal,
+    Vertical,
+}
+
+/// One node in a widget's declarative render tree.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case", tag = "type")]
+pub enum WidgetNode {
+    Box {
+        #[serde(default = "default_orientation")]
+        orientation: Orientation,
+        #[serde(default)]
+        spacing: Option<i32>,
+        #[serde(default)]
+        class: Option<String>,
+        #[serde(default)]
+        style: Option<WidgetStyle>,
+        #[serde(default)]
+        on_click: Option<Value>,
+        #[serde(default)]
+        children: Vec<WidgetNode>,
+    },
+    Label {
+        text: String,
+        #[serde(default)]
+        class: Option<String>,
+        #[serde(default)]
+        style: Option<WidgetStyle>,
+        #[serde(default)]
+        on_click: Option<Value>,
+    },
+    Icon {
+        #[serde(default)]
+        name: Option<String>,
+        #[serde(default)]
+        path: Option<String>,
+        #[serde(default)]
+        size: Option<i32>,
+        #[serde(default)]
+        class: Option<String>,
+        #[serde(default)]
+        style: Option<WidgetStyle>,
+        #[serde(default)]
+        on_click: Option<Value>,
+    },
+    Progress {
+        value: f64,
+        #[serde(default)]
+        class: Option<String>,
+        #[serde(default)]
+        style: Option<WidgetStyle>,
+        #[serde(default)]
+        on_click: Option<Value>,
+    },
+}
+
+fn default_orientation() -> Orientation {
+    Orientation::Horizontal
+}
+
+/// A bounded, typed vocabulary for a node's appearance — the alternative to
+/// letting Lua hand the renderer a raw CSS/style string. Every field is a
+/// small closed enum, so an invalid value is simply a deserialization error,
+/// the same as any other malformed field; there is no free-text surface here
+/// for a module to smuggle style-string injection through.
+///
+/// Fields left `None` mean "renderer default" (see `render.rs`'s `build_node`
+/// for what that default looks like), not "no style" — a node with no
+/// `style` at all is fully equivalent to one whose every field is `None`.
+#[derive(Debug, Clone, Copy, Default, Serialize, Deserialize)]
+pub struct WidgetStyle {
+    pub color: Option<SemanticColor>,
+    pub weight: Option<FontWeight>,
+    pub size: Option<TextSize>,
+    pub align: Option<Align>,
+    pub background: Option<Background>,
+    pub radius: Option<Radius>,
+    pub padding: Option<Padding>,
+}
+
+/// Foreground/text colors, one per name `bread-theme`'s shared stylesheet
+/// defines via `@define-color` (see that crate's `color_pairs()`). Deliberately
+/// excludes `bg`/`surface`/`overlay`, which only make sense as backgrounds.
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum SemanticColor {
+    /// Foreground / body text color.
+    Fg,
+    /// Muted foreground — the existing `.dim` look, formalized.
+    Dim,
+    Accent,
+    Red,
+    Green,
+    Yellow,
+    Blue,
+    Pink,
+    Teal,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum FontWeight {
+    Normal,
+    Bold,
+}
+
+/// Text size scale (10/12/14/16/20px) — `sm`/`md` match `bread-theme::tokens`'
+/// existing `FONT_SIZE_SECONDARY`/`FONT_SIZE_BASE` rather than inventing a
+/// second set of magic numbers; `xs`/`lg`/`xl` fill out the rest of the scale
+/// (the spacing scale's 4/8/12/16/20px is for padding/radius, not text —
+/// applying it directly to `font-size` renders illegibly at the small end).
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum TextSize {
+    Xs,
+    Sm,
+    Md,
+    Lg,
+    Xl,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum Align {
+    Start,
+    Center,
+    End,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum Background {
+    None,
+    Surface,
+    Card,
+}
+
+/// Reuses `bread-theme::tokens`' radius scale: `sm` = tertiary (4px, small
+/// interactive elements), `md` = primary (8px), `full` = pill (999px).
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum Radius {
+    None,
+    Sm,
+    Md,
+    Full,
+}
+
+/// Reuses `bread-theme::tokens`' spacing scale (4/8/12px).
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum Padding {
+    None,
+    Xs,
+    Sm,
+    Md,
+}
+
+/// Where a widget renders in breadbar. Each variant names a fixed slot in
+/// breadbar's existing `CenterBox` layout (workspaces | clock | stats), plus
+/// the hamburger control-panel popover's tray section.
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Eq, PartialEq, Hash)]
+#[serde(rename_all = "snake_case")]
+pub enum WidgetPlacement {
+    /// Tucked inside the hamburger control-panel popover, alongside the
+    /// existing SNI tray icons.
+    Tray,
+    /// In the center section, immediately left of the clock label.
+    LeftOfClock,
+    /// In the center section, immediately right of the clock label.
+    RightOfClock,
+    /// In the start section, immediately right of the workspace buttons.
+    RightOfWorkspaces,
+    /// In the end section, immediately left of the CPU/RAM/power/battery group.
+    LeftOfStats,
+}
+
+/// A full widget declaration, as stored in `RuntimeState.widgets` and
+/// returned by the `widgets.list` IPC method.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WidgetSpec {
+    /// Fully-qualified id: `"<module>.<local_id>"`. Unique across all widgets.
+    pub id: String,
+    /// Name of the module that registered this widget.
+    pub module: String,
+    pub placement: WidgetPlacement,
+    /// Sort priority within a placement; lower sorts first.
+    #[serde(default)]
+    pub order: i32,
+    #[serde(default = "default_visible")]
+    pub visible: bool,
+    #[serde(default)]
+    pub tooltip: Option<String>,
+    pub root: WidgetNode,
+    /// Unix epoch milliseconds of the last register/update.
+    pub updated_at: u64,
+}
+
+fn default_visible() -> bool {
+    true
+}
+
+/// Why a [`WidgetNode`] tree failed validation.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum WidgetValidationError {
+    TooDeep { max: usize },
+    TooManyNodes { max: usize },
+    InvalidClass { class: String },
+}
+
+impl std::fmt::Display for WidgetValidationError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::TooDeep { max } => write!(f, "widget node tree exceeds max depth of {max}"),
+            Self::TooManyNodes { max } => {
+                write!(f, "widget node tree exceeds max node count of {max}")
+            }
+            Self::InvalidClass { class } => write!(
+                f,
+                "invalid css class '{class}': must match ^[a-zA-Z][a-zA-Z0-9_-]{{0,63}}$"
+            ),
+        }
+    }
+}
+
+impl std::error::Error for WidgetValidationError {}
+
+/// A CSS class is restricted to a conservative identifier shape so widget
+/// styling can only opt into classes predefined in breadbar's stylesheet —
+/// there is no raw style/CSS injection surface from Lua.
+fn is_valid_class(class: &str) -> bool {
+    let mut chars = class.chars();
+    let Some(first) = chars.next() else {
+        return false;
+    };
+    if !first.is_ascii_alphabetic() {
+        return false;
+    }
+    class.len() <= 64
+        && chars.all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
+}
+
+impl WidgetNode {
+    /// The node's CSS class hook, if any — a renderer should apply this via
+    /// its GTK equivalent of `add_css_class` rather than injecting raw style.
+    pub fn class(&self) -> Option<&str> {
+        match self {
+            Self::Box { class, .. }
+            | Self::Label { class, .. }
+            | Self::Icon { class, .. }
+            | Self::Progress { class, .. } => class.as_deref(),
+        }
+    }
+
+    /// The node's typed style vocabulary, if any — a renderer maps each
+    /// `Some` field to a predefined CSS class (see `render.rs`'s
+    /// `apply_style`), never to raw injected CSS.
+    pub fn style(&self) -> Option<&WidgetStyle> {
+        match self {
+            Self::Box { style, .. }
+            | Self::Label { style, .. }
+            | Self::Icon { style, .. }
+            | Self::Progress { style, .. } => style.as_ref(),
+        }
+    }
+
+    /// The node's opaque click payload, if any — a renderer attaches a click
+    /// handler that reports this value back verbatim (see the Lua API's
+    /// "Click events" contract in `Documentation.md`), it never interprets it.
+    pub fn on_click(&self) -> Option<&Value> {
+        match self {
+            Self::Box { on_click, .. }
+            | Self::Label { on_click, .. }
+            | Self::Icon { on_click, .. }
+            | Self::Progress { on_click, .. } => on_click.as_ref(),
+        }
+    }
+
+    fn children(&self) -> &[WidgetNode] {
+        match self {
+            Self::Box { children, .. } => children,
+            _ => &[],
+        }
+    }
+
+    /// Validate depth, total node count, and every `class` field. Call this
+    /// on any tree received from Lua before storing or broadcasting it.
+    pub fn validate(&self) -> Result<(), WidgetValidationError> {
+        let mut total = 0usize;
+        self.validate_inner(1, &mut total)
+    }
+
+    fn validate_inner(
+        &self,
+        depth: usize,
+        total: &mut usize,
+    ) -> Result<(), WidgetValidationError> {
+        if depth > MAX_NODE_DEPTH {
+            return Err(WidgetValidationError::TooDeep { max: MAX_NODE_DEPTH });
+        }
+        *total += 1;
+        if *total > MAX_NODE_COUNT {
+            return Err(WidgetValidationError::TooManyNodes { max: MAX_NODE_COUNT });
+        }
+        if let Some(class) = self.class() {
+            if !is_valid_class(class) {
+                return Err(WidgetValidationError::InvalidClass {
+                    class: class.to_string(),
+                });
+            }
+        }
+        for child in self.children() {
+            child.validate_inner(depth + 1, total)?;
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    fn label(class: Option<&str>) -> WidgetNode {
+        WidgetNode::Label {
+            text: "x".to_string(),
+            class: class.map(str::to_string),
+            style: None,
+            on_click: None,
+        }
+    }
+
+    fn box_of(children: Vec<WidgetNode>) -> WidgetNode {
+        WidgetNode::Box {
+            orientation: Orientation::Horizontal,
+            spacing: None,
+            class: None,
+            style: None,
+            on_click: None,
+            children,
+        }
+    }
+
+    #[test]
+    fn simple_label_is_valid() {
+        assert!(label(Some("dim")).validate().is_ok());
+    }
+
+    #[test]
+    fn rejects_invalid_class_characters() {
+        assert_eq!(
+            label(Some("dim; color: red")).validate(),
+            Err(WidgetValidationError::InvalidClass {
+                class: "dim; color: red".to_string()
+            })
+        );
+    }
+
+    #[test]
+    fn rejects_class_starting_with_digit() {
+        assert!(label(Some("1dim")).validate().is_err());
+    }
+
+    #[test]
+    fn rejects_empty_class() {
+        assert!(label(Some("")).validate().is_err());
+    }
+
+    #[test]
+    fn accepts_class_with_underscore_and_hyphen() {
+        assert!(label(Some("my_class-2")).validate().is_ok());
+    }
+
+    #[test]
+    fn rejects_tree_deeper_than_max() {
+        // depth 1 (root box) -> 2 -> 3 -> 4 -> 5 (label), exceeds MAX_NODE_DEPTH=4
+        let tree = box_of(vec![box_of(vec![box_of(vec![box_of(vec![label(None)])])])]);
+        assert_eq!(
+            tree.validate(),
+            Err(WidgetValidationError::TooDeep { max: MAX_NODE_DEPTH })
+        );
+    }
+
+    #[test]
+    fn accepts_tree_at_max_depth() {
+        // depth 1 -> 2 -> 3 -> 4 (label), exactly MAX_NODE_DEPTH
+        let tree = box_of(vec![box_of(vec![box_of(vec![label(None)])])]);
+        assert!(tree.validate().is_ok());
+    }
+
+    #[test]
+    fn rejects_too_many_nodes() {
+        let children: Vec<WidgetNode> = (0..MAX_NODE_COUNT).map(|_| label(None)).collect();
+        let tree = box_of(children);
+        assert_eq!(
+            tree.validate(),
+            Err(WidgetValidationError::TooManyNodes { max: MAX_NODE_COUNT })
+        );
+    }
+
+    #[test]
+    fn accepts_node_count_at_max() {
+        let children: Vec<WidgetNode> = (0..MAX_NODE_COUNT - 1).map(|_| label(None)).collect();
+        let tree = box_of(children);
+        assert!(tree.validate().is_ok());
+    }
+
+    #[test]
+    fn widget_spec_round_trips_through_json() {
+        let spec = WidgetSpec {
+            id: "weather.temp".to_string(),
+            module: "weather".to_string(),
+            placement: WidgetPlacement::LeftOfStats,
+            order: 10,
+            visible: true,
+            tooltip: Some("Sydney".to_string()),
+            root: box_of(vec![
+                WidgetNode::Icon {
+                    name: Some("cloud".to_string()),
+                    path: None,
+                    size: Some(16),
+                    class: None,
+                    style: None,
+                    on_click: None,
+                },
+                label(Some("dim")),
+                WidgetNode::Progress {
+                    value: 0.5,
+                    class: None,
+                    style: Some(WidgetStyle {
+                        color: Some(SemanticColor::Accent),
+                        ..Default::default()
+                    }),
+                    on_click: Some(json!({ "action": "refresh" })),
+                },
+            ]),
+            updated_at: 1_700_000_000_000,
+        };
+        let raw = serde_json::to_string(&spec).unwrap();
+        let decoded: WidgetSpec = serde_json::from_str(&raw).unwrap();
+        assert_eq!(decoded.id, spec.id);
+        assert_eq!(decoded.placement, spec.placement);
+    }
+
+    #[test]
+    fn placement_serializes_as_snake_case() {
+        assert_eq!(
+            serde_json::to_string(&WidgetPlacement::Tray).unwrap(),
+            "\"tray\""
+        );
+        assert_eq!(
+            serde_json::to_string(&WidgetPlacement::LeftOfClock).unwrap(),
+            "\"left_of_clock\""
+        );
+        assert_eq!(
+            serde_json::to_string(&WidgetPlacement::RightOfClock).unwrap(),
+            "\"right_of_clock\""
+        );
+        assert_eq!(
+            serde_json::to_string(&WidgetPlacement::RightOfWorkspaces).unwrap(),
+            "\"right_of_workspaces\""
+        );
+        assert_eq!(
+            serde_json::to_string(&WidgetPlacement::LeftOfStats).unwrap(),
+            "\"left_of_stats\""
+        );
+    }
+
+    #[test]
+    fn node_serializes_with_type_tag() {
+        let value = serde_json::to_value(label(Some("dim"))).unwrap();
+        assert_eq!(value["type"], "label");
+        assert_eq!(value["text"], "x");
+        assert_eq!(value["class"], "dim");
+    }
+
+    #[test]
+    fn node_without_style_omits_it_when_serialized_and_back() {
+        let node = label(None);
+        assert!(node.style().is_none());
+        let raw = serde_json::to_string(&node).unwrap();
+        let decoded: WidgetNode = serde_json::from_str(&raw).unwrap();
+        assert!(decoded.style().is_none());
+    }
+
+    #[test]
+    fn style_field_is_optional_when_absent_from_json() {
+        let raw = json!({ "type": "label", "text": "x" });
+        let node: WidgetNode = serde_json::from_value(raw).unwrap();
+        assert!(node.style().is_none());
+    }
+
+    #[test]
+    fn style_round_trips_through_json() {
+        let node = WidgetNode::Label {
+            text: "x".to_string(),
+            class: None,
+            style: Some(WidgetStyle {
+                color: Some(SemanticColor::Red),
+                weight: Some(FontWeight::Bold),
+                size: Some(TextSize::Lg),
+                align: Some(Align::Center),
+                background: Some(Background::Card),
+                radius: Some(Radius::Sm),
+                padding: Some(Padding::Xs),
+            }),
+            on_click: None,
+        };
+        let raw = serde_json::to_string(&node).unwrap();
+        let decoded: WidgetNode = serde_json::from_str(&raw).unwrap();
+        let style = decoded.style().expect("style should round-trip");
+        assert_eq!(style.color, Some(SemanticColor::Red));
+        assert_eq!(style.weight, Some(FontWeight::Bold));
+        assert_eq!(style.size, Some(TextSize::Lg));
+        assert_eq!(style.align, Some(Align::Center));
+        assert_eq!(style.background, Some(Background::Card));
+        assert_eq!(style.radius, Some(Radius::Sm));
+        assert_eq!(style.padding, Some(Padding::Xs));
+    }
+
+    #[test]
+    fn style_enums_serialize_as_snake_case() {
+        assert_eq!(serde_json::to_string(&SemanticColor::Dim).unwrap(), "\"dim\"");
+        assert_eq!(serde_json::to_string(&Background::None).unwrap(), "\"none\"");
+        assert_eq!(serde_json::to_string(&Radius::Full).unwrap(), "\"full\"");
+        assert_eq!(serde_json::to_string(&Padding::Xs).unwrap(), "\"xs\"");
+        assert_eq!(serde_json::to_string(&Align::End).unwrap(), "\"end\"");
+        assert_eq!(serde_json::to_string(&FontWeight::Bold).unwrap(), "\"bold\"");
+    }
+
+    #[test]
+    fn invalid_style_color_fails_to_deserialize() {
+        let raw = json!({ "type": "label", "text": "x", "style": { "color": "bg" } });
+        assert!(serde_json::from_value::<WidgetNode>(raw).is_err());
+    }
+
+    #[test]
+    fn style_with_all_fields_none_is_equivalent_to_default() {
+        assert_eq!(
+            serde_json::to_value(WidgetStyle::default()).unwrap(),
+            json!({
+                "color": null, "weight": null, "size": null,
+                "align": null, "background": null, "radius": null, "padding": null
+            })
+        );
+    }
+
+    #[test]
+    fn style_does_not_affect_validation() {
+        let node = WidgetNode::Label {
+            text: "x".to_string(),
+            class: None,
+            style: Some(WidgetStyle {
+                color: Some(SemanticColor::Accent),
+                ..Default::default()
+            }),
+            on_click: None,
+        };
+        assert!(node.validate().is_ok());
+    }
+}

breadd/src/core/state_engine.rs

@@ -38,6 +38,7 @@ pub enum StateCommand {
     },
     ClearSubscriptions,
     ClearModules,
+    ClearWidgets,
     SetModuleStatus {
         name: String,
         status: ModuleLoadState,
@@ -117,6 +118,10 @@ impl StateHandle {
         let _ = self.command_tx.send(StateCommand::ClearModules);
     }
 
+    pub fn clear_widgets(&self) {
+        let _ = self.command_tx.send(StateCommand::ClearWidgets);
+    }
+
     pub fn set_module_status(
         &self,
         name: String,
@@ -290,6 +295,9 @@ async fn handle_command(
         StateCommand::ClearModules => {
             state.write().await.modules.clear();
         }
+        StateCommand::ClearWidgets => {
+            state.write().await.widgets.clear();
+        }
         StateCommand::SetModuleStatus {
             name,
             status,

breadd/src/core/types.rs

@@ -1,5 +1,6 @@
 use std::collections::{BTreeMap, HashMap};
 
+use bread_shared::widget::WidgetSpec;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
@@ -15,6 +16,10 @@ pub struct RuntimeState {
     pub profile: ProfileState,
     pub modules: Vec<ModuleStatus>,
     pub workflows: Vec<WorkflowStatus>,
+    /// Widgets registered via `bread.widget.register` from any Lua module,
+    /// keyed implicitly by `WidgetSpec.id` (fully-qualified `<module>.<local_id>`).
+    /// Surfaced via the `widgets.list` IPC method for breadbar to render.
+    pub widgets: Vec<WidgetSpec>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]

breadd/src/ipc/mod.rs

@@ -27,7 +27,7 @@ use crate::lua::RuntimeHandle;
 /// something new-but-additive (a binding, an event, an IPC param); bump the
 /// major version only for a breaking change, which should not happen inside
 /// this daemon's v1 lifetime per that section's stated policy.
-const API_VERSION: &str = "1.2.0";
+const API_VERSION: &str = "1.4.0";
 
 #[derive(Clone)]
 pub struct Server {
@@ -222,6 +222,10 @@ impl Server {
                 let full = self.state_handle.state_dump().await;
                 Ok(full.get("workflows").cloned().unwrap_or_else(|| json!([])))
             }
+            "widgets.list" => {
+                let full = self.state_handle.state_dump().await;
+                Ok(full.get("widgets").cloned().unwrap_or_else(|| json!([])))
+            }
             "modules.reload" => {
                 let started = Instant::now();
                 if let Err(err) = self.lua_runtime.reload().await {

breadd/src/lua/mod.rs

@@ -8,9 +8,10 @@ use std::sync::{Arc, Mutex};
 use std::time::Duration;
 
 use anyhow::{anyhow, Result};
+use bread_shared::widget::{WidgetNode, WidgetPlacement, WidgetSpec};
 use bread_shared::{AdapterSource, BreadEvent};
 use mlua::{Error as LuaError, Function, Lua, LuaSerdeExt, RegistryKey, Table, Value};
-use serde::Serialize;
+use serde::{Deserialize, Serialize};
 use serde_json::Value as JsonValue;
 use tokio::sync::{mpsc, oneshot, watch, RwLock};
 use tokio::task;
@@ -181,6 +182,11 @@ struct TimerEntry {
     callback: RegistryKey,
     repeating: bool,
     cancel_tx: watch::Sender<bool>,
+    /// The module active when `bread.after`/`bread.every` registered this
+    /// timer, so `handle_timer` can restore module context for the callback
+    /// (needed by module-scoped APIs like `bread.widget.*`) — same
+    /// `current_module` capture used for `bread.on`'s `HandlerEntry.module`.
+    module: Option<String>,
 }
 
 #[derive(Clone)]
@@ -253,6 +259,7 @@ impl LuaEngine {
         self.cancel_all_timers();
         self.state_handle.clear_subscriptions();
         self.state_handle.clear_modules();
+        self.state_handle.clear_widgets();
         self.lua = Lua::new();
         self.handlers
             .lock()
@@ -280,6 +287,21 @@ impl LuaEngine {
         self.load_profiles()?;
         self.load_init_and_modules()?;
         self.run_on_reload();
+
+        // clear_widgets() above is silent (no event) since it's just a state
+        // wipe ahead of modules re-registering. That's a problem when a
+        // module goes from "registered some widgets" to "disabled and
+        // skipped" across this reload: nothing re-registers, so no
+        // bread.widget.registered fires, and a renderer that only refetches
+        // on bread.widget.* events (see breadbar's widgets::client) never
+        // learns the registry emptied out. One definitive signal per reload,
+        // regardless of whether anything actually changed, closes that gap.
+        let _ = self.emit_tx.send(BreadEvent::new(
+            "bread.widget.cleared",
+            AdapterSource::System,
+            serde_json::json!({}),
+        ));
+
         info!("lua runtime reloaded");
         Ok(())
     }
@@ -618,12 +640,17 @@ impl LuaEngine {
         let timers = self.timers.clone();
         let next_timer_id = self.next_timer_id.clone();
         let lua_tx = self.lua_tx.clone();
+        let current_module = self.current_module.clone();
         let after_fn =
             self.lua
                 .create_function(move |lua, (delay_ms, callback): (u64, Function)| {
                     let id = TimerId(next_timer_id.fetch_add(1, Ordering::Relaxed));
                     let key = lua.create_registry_value(callback)?;
                     let (cancel_tx, mut cancel_rx) = watch::channel(false);
+                    let module = current_module
+                        .lock()
+                        .map_err(|_| LuaError::external("module context lock poisoned"))?
+                        .clone();
                     timers
                         .lock()
                         .map_err(|_| LuaError::external("timer lock poisoned"))?
@@ -633,6 +660,7 @@ impl LuaEngine {
                                 callback: key,
                                 repeating: false,
                                 cancel_tx,
+                                module,
                             },
                         );
                     let lua_tx = lua_tx.clone();
@@ -653,12 +681,17 @@ impl LuaEngine {
         let timers = self.timers.clone();
         let next_timer_id = self.next_timer_id.clone();
         let lua_tx = self.lua_tx.clone();
+        let current_module = self.current_module.clone();
         let every_fn =
             self.lua
                 .create_function(move |lua, (interval_ms, callback): (u64, Function)| {
                     let id = TimerId(next_timer_id.fetch_add(1, Ordering::Relaxed));
                     let key = lua.create_registry_value(callback)?;
                     let (cancel_tx, mut cancel_rx) = watch::channel(false);
+                    let module = current_module
+                        .lock()
+                        .map_err(|_| LuaError::external("module context lock poisoned"))?
+                        .clone();
                     timers
                         .lock()
                         .map_err(|_| LuaError::external("timer lock poisoned"))?
@@ -668,6 +701,7 @@ impl LuaEngine {
                                 callback: key,
                                 repeating: true,
                                 cancel_tx,
+                                module,
                             },
                         );
                     let lua_tx = lua_tx.clone();
@@ -737,7 +771,7 @@ impl LuaEngine {
                 .map_err(|e| LuaError::external(e.to_string()))?;
             let json: JsonValue =
                 serde_json::from_str(&resp).map_err(|e| LuaError::external(e.to_string()))?;
-            lua.to_value(&json)
+            json_to_lua(lua, &json)
                 .map_err(|e| LuaError::external(e.to_string()))
         })?;
         hyprland_tbl.set("active_window", active_window_fn)?;
@@ -747,7 +781,7 @@ impl LuaEngine {
                 hyprland_request("j/monitors").map_err(|e| LuaError::external(e.to_string()))?;
             let json: JsonValue =
                 serde_json::from_str(&resp).map_err(|e| LuaError::external(e.to_string()))?;
-            lua.to_value(&json)
+            json_to_lua(lua, &json)
                 .map_err(|e| LuaError::external(e.to_string()))
         })?;
         hyprland_tbl.set("monitors", monitors_fn)?;
@@ -757,7 +791,7 @@ impl LuaEngine {
                 hyprland_request("j/workspaces").map_err(|e| LuaError::external(e.to_string()))?;
             let json: JsonValue =
                 serde_json::from_str(&resp).map_err(|e| LuaError::external(e.to_string()))?;
-            lua.to_value(&json)
+            json_to_lua(lua, &json)
                 .map_err(|e| LuaError::external(e.to_string()))
         })?;
         hyprland_tbl.set("workspaces", workspaces_fn)?;
@@ -767,7 +801,7 @@ impl LuaEngine {
                 hyprland_request("j/clients").map_err(|e| LuaError::external(e.to_string()))?;
             let json: JsonValue =
                 serde_json::from_str(&resp).map_err(|e| LuaError::external(e.to_string()))?;
-            lua.to_value(&json)
+            json_to_lua(lua, &json)
                 .map_err(|e| LuaError::external(e.to_string()))
         })?;
         hyprland_tbl.set("clients", clients_fn)?;
@@ -840,9 +874,7 @@ impl LuaEngine {
             let state_arc_get = state_arc.clone();
             let get_fn = lua.create_function(move |lua, key: String| {
                 if let Some(value) = module_store_get(&state_arc_get, &module_name, &key) {
-                    return lua
+                    return json_to_lua(lua, &value).map_err(|e| LuaError::external(e.to_string()));
-                        .to_value(&value)
-                        .map_err(|e| LuaError::external(e.to_string()));
                 }
                 Ok(Value::Nil)
             })?;
@@ -875,6 +907,122 @@ impl LuaEngine {
         })?;
         bread.set("module", module_fn)?;
 
+        // bread.widget — declarative, live-updating widgets rendered by
+        // sibling bread* apps (breadbar) in their bar/popover free space.
+        // Follows the same Rust-backed-registry pattern as bread.workflow
+        // (see install_workflow_helpers / workflow_register below):
+        // mutate RuntimeState.widgets via the try_write spin-lock, then
+        // emit a bread.widget.* event so subscribers (and, indirectly,
+        // breadbar's events.subscribe stream) observe the change.
+        let widget_tbl = self.lua.create_table()?;
+
+        let state_arc = self.state_handle.state_arc();
+        let current_module = self.current_module.clone();
+        let emit_tx = self.emit_tx.clone();
+        let widget_register_fn = self.lua.create_function(
+            move |lua, spec_table: Table| -> mlua::Result<(bool, Option<String>)> {
+                let module = current_module
+                    .lock()
+                    .map_err(|_| LuaError::external("module context lock poisoned"))?
+                    .clone()
+                    .ok_or_else(|| {
+                        LuaError::external("bread.widget.register must be called from within a module")
+                    })?;
+                let args: WidgetRegisterArgs = match lua.from_value(Value::Table(spec_table)) {
+                    Ok(a) => a,
+                    Err(e) => return Ok((false, Some(e.to_string()))),
+                };
+                Ok(match widget_register(&state_arc, &module, args) {
+                    Ok(spec) => {
+                        let data = serde_json::to_value(&spec).unwrap_or_default();
+                        let _ = emit_tx.send(BreadEvent::new(
+                            "bread.widget.registered",
+                            AdapterSource::System,
+                            data,
+                        ));
+                        (true, None)
+                    }
+                    Err(e) => (false, Some(e.to_string())),
+                })
+            },
+        )?;
+        widget_tbl.set("register", widget_register_fn)?;
+
+        let state_arc = self.state_handle.state_arc();
+        let current_module = self.current_module.clone();
+        let emit_tx = self.emit_tx.clone();
+        let widget_update_fn = self.lua.create_function(
+            move |lua, (local_id, patch): (String, Table)| -> mlua::Result<(bool, Option<String>)> {
+                let module = current_module
+                    .lock()
+                    .map_err(|_| LuaError::external("module context lock poisoned"))?
+                    .clone()
+                    .ok_or_else(|| {
+                        LuaError::external("bread.widget.update must be called from within a module")
+                    })?;
+                let args: WidgetUpdateArgs = match lua.from_value(Value::Table(patch)) {
+                    Ok(a) => a,
+                    Err(e) => return Ok((false, Some(e.to_string()))),
+                };
+                Ok(match widget_update(&state_arc, &module, &local_id, args) {
+                    Ok(Some(spec)) => {
+                        let data = serde_json::to_value(&spec).unwrap_or_default();
+                        let _ = emit_tx.send(BreadEvent::new(
+                            "bread.widget.updated",
+                            AdapterSource::System,
+                            data,
+                        ));
+                        (true, None)
+                    }
+                    Ok(None) => (false, Some("no such widget".to_string())),
+                    Err(e) => (false, Some(e.to_string())),
+                })
+            },
+        )?;
+        widget_tbl.set("update", widget_update_fn)?;
+
+        let state_arc = self.state_handle.state_arc();
+        let current_module = self.current_module.clone();
+        let emit_tx = self.emit_tx.clone();
+        let widget_remove_fn = self.lua.create_function(move |_lua, local_id: String| {
+            let module = current_module
+                .lock()
+                .map_err(|_| LuaError::external("module context lock poisoned"))?
+                .clone()
+                .ok_or_else(|| {
+                    LuaError::external("bread.widget.remove must be called from within a module")
+                })?;
+            let full_id = format!("{module}.{local_id}");
+            let removed = widget_remove(&state_arc, &module, &local_id);
+            if removed {
+                let _ = emit_tx.send(BreadEvent::new(
+                    "bread.widget.removed",
+                    AdapterSource::System,
+                    serde_json::json!({ "id": full_id }),
+                ));
+            }
+            Ok(removed)
+        })?;
+        widget_tbl.set("remove", widget_remove_fn)?;
+
+        let state_arc = self.state_handle.state_arc();
+        let current_module = self.current_module.clone();
+        let widget_list_fn = self.lua.create_function(move |lua, ()| {
+            let module = current_module
+                .lock()
+                .map_err(|_| LuaError::external("module context lock poisoned"))?
+                .clone()
+                .ok_or_else(|| {
+                    LuaError::external("bread.widget.list must be called from within a module")
+                })?;
+            let json = widget_list_json(&state_arc, &module);
+            json_to_lua(lua, &json)
+                .map_err(|e| LuaError::external(e.to_string()))
+        })?;
+        widget_tbl.set("list", widget_list_fn)?;
+
+        bread.set("widget", widget_tbl)?;
+
         // bread.machine — hostname/tags; reads an optional, externally-managed
         // ~/.config/bread/sync.toml if present (bread does not create it)
         let machine_tbl = self.lua.create_table()?;
@@ -1122,10 +1270,22 @@ impl LuaEngine {
             .into_iter()
             .filter(|p| !is_lib_path(&self.module_path, p))
         {
+            let name = module_name_from_path(&self.module_path, &path);
+            // bos-settings' module picker writes filenames (e.g.
+            // "widget.lua") into `disable`, not the bare module name a file
+            // registers under via bread.module({name=...}) — match either
+            // form so both conventions work rather than requiring the UI
+            // and the daemon to agree on one exact string.
+            let filename = path.file_name().and_then(|f| f.to_str()).unwrap_or("");
+            if disabled.contains(&name) || disabled.contains(filename) {
+                self.state_handle
+                    .set_module_status(name, ModuleLoadState::Disabled, None, false);
+                continue;
+            }
+
             match self.scan_module_decl(&path) {
                 Ok(decl) => decls.push(decl),
                 Err(err) => {
-                    let name = module_name_from_path(&self.module_path, &path);
                     self.state_handle.set_module_status(
                         name,
                         ModuleLoadState::LoadError,
@@ -1192,8 +1352,7 @@ impl LuaEngine {
             return Err(anyhow!("module did not call bread.module"));
         }
 
-        self.run_on_load(&decl.name);
+        self.run_on_load(&decl.name)
-        Ok(())
     }
 
     fn load_lua_file(&self, path: &Path, module_name: &str, builtin: bool) -> Result<()> {
@@ -1257,26 +1416,28 @@ impl LuaEngine {
         }
 
         if let Some(filter) = filter {
-            let event_value = self.lua.to_value(&event)?;
+            let event_value = json_to_lua(&self.lua, &event)?;
             let allowed = filter.call::<_, bool>(event_value).unwrap_or(false);
             if !allowed {
                 return Ok(());
             }
         }
 
+        self.set_current_module(module.clone());
         let result = match kind {
             HandlerKind::Event => {
-                let event_value = self.lua.to_value(&event)?;
+                let event_value = json_to_lua(&self.lua, &event)?;
                 callback.call::<_, ()>(event_value)
             }
             HandlerKind::StateWatch => {
                 let new_val = event.data.get("new").cloned().unwrap_or(JsonValue::Null);
                 let old_val = event.data.get("old").cloned().unwrap_or(JsonValue::Null);
-                let new_lua = self.lua.to_value(&new_val)?;
+                let new_lua = json_to_lua(&self.lua, &new_val)?;
-                let old_lua = self.lua.to_value(&old_val)?;
+                let old_lua = json_to_lua(&self.lua, &old_val)?;
                 callback.call::<_, ()>((new_lua, old_lua))
             }
         };
+        self.set_current_module(None);
 
         if let Err(err) = result {
             error!(subscription = id.0, error = %err, "lua callback failed");
@@ -1286,15 +1447,18 @@ impl LuaEngine {
     }
 
     fn handle_timer(&self, id: TimerId) -> Result<()> {
-        let (callback, repeating) = {
+        let (callback, repeating, module) = {
             let timers = self.timers.lock().unwrap_or_else(|e| e.into_inner());
             let Some(entry) = timers.get(&id) else {
                 return Ok(());
             };
             let callback: Function = self.lua.registry_value(&entry.callback)?;
-            (callback, entry.repeating)
+            (callback, entry.repeating, entry.module.clone())
         };
-        if let Err(err) = callback.call::<_, ()>(()) {
+        self.set_current_module(module);
+        let result = callback.call::<_, ()>(());
+        self.set_current_module(None);
+        if let Err(err) = result {
             error!(timer = id.0, error = %err, "lua timer callback failed");
         }
 
@@ -1312,19 +1476,24 @@ impl LuaEngine {
         }
     }
 
-    fn run_on_load(&self, name: &str) {
+    fn run_on_load(&self, name: &str) -> Result<()> {
         if let Some(hook) = self.get_module_hook(name, "on_load") {
-            if let Err(err) = hook.call::<_, ()>(()) {
+            self.set_current_module(Some(name.to_string()));
+            let result = hook.call::<_, ()>(());
+            self.set_current_module(None);
+            if let Err(err) = result {
                 error!(module = %name, error = %err, "module on_load failed");
-                let builtin = self.module_is_builtin(name);
+                // Propagate rather than setting LoadError here directly: the
-                self.state_handle.set_module_status(
+                // caller (load_module, via load_init_and_modules) is the
-                    name.to_string(),
+                // single place that decides Loaded vs LoadError for a
-                    ModuleLoadState::LoadError,
+                // module, so this failure isn't immediately clobbered back
-                    Some(err.to_string()),
+                // to Loaded by that outer Ok(()) branch — which is exactly
-                    builtin,
+                // what used to happen when this function swallowed the
-                );
+                // error and always returned successfully.
+                return Err(anyhow!(err.to_string()));
             }
         }
+        Ok(())
     }
 
     fn run_on_reload(&self) {
@@ -1335,7 +1504,10 @@ impl LuaEngine {
             .clone();
         for name in order {
             if let Some(hook) = self.get_module_hook(&name, "on_reload") {
-                if let Err(err) = hook.call::<_, ()>(()) {
+                self.set_current_module(Some(name.clone()));
+                let result = hook.call::<_, ()>(());
+                self.set_current_module(None);
+                if let Err(err) = result {
                     error!(module = %name, error = %err, "module on_reload failed");
                     let builtin = self.module_is_builtin(&name);
                     self.state_handle.set_module_status(
@@ -1357,7 +1529,10 @@ impl LuaEngine {
             .clone();
         for name in order.into_iter().rev() {
             if let Some(hook) = self.get_module_hook(&name, "on_unload") {
-                if let Err(err) = hook.call::<_, ()>(()) {
+                self.set_current_module(Some(name.clone()));
+                let result = hook.call::<_, ()>(());
+                self.set_current_module(None);
+                if let Err(err) = result {
                     error!(module = %name, error = %err, "module on_unload failed");
                     let builtin = self.module_is_builtin(&name);
                     self.state_handle.set_module_status(
@@ -1741,9 +1916,7 @@ impl LuaEngine {
         let state_arc = self.state_handle.state_arc();
         let status_fn = self.lua.create_function(move |lua, name: String| {
             match workflow_status_json(&state_arc, &name) {
-                Some(json) => lua
+                Some(json) => json_to_lua(lua, &json).map_err(|e| LuaError::external(e.to_string())),
-                    .to_value(&json)
-                    .map_err(|e| LuaError::external(e.to_string())),
                 None => Ok(Value::Nil),
             }
         })?;
@@ -1752,7 +1925,7 @@ impl LuaEngine {
         let state_arc = self.state_handle.state_arc();
         let list_fn = self.lua.create_function(move |lua, ()| {
             let json = workflow_list_json(&state_arc);
-            lua.to_value(&json)
+            json_to_lua(lua, &json)
                 .map_err(|e| LuaError::external(e.to_string()))
         })?;
         bread.set("__workflow_list", list_fn)?;
@@ -2037,6 +2210,133 @@ fn workflow_list_json(state_arc: &Arc<RwLock<RuntimeState>>) -> JsonValue {
     serde_json::to_value(&guard.workflows).unwrap_or_else(|_| JsonValue::Array(vec![]))
 }
 
+/// Table shape accepted by `bread.widget.register`. Parsed directly from the
+/// Lua table via mlua's serde bridge, so `root`'s nested `children` tables
+/// deserialize straight into a `WidgetNode` tree without a manual walker.
+#[derive(Debug, Deserialize)]
+struct WidgetRegisterArgs {
+    id: String,
+    placement: WidgetPlacement,
+    #[serde(default)]
+    order: i32,
+    #[serde(default = "default_widget_visible")]
+    visible: bool,
+    #[serde(default)]
+    tooltip: Option<String>,
+    root: WidgetNode,
+}
+
+/// Table shape accepted by `bread.widget.update` — every field optional, so
+/// a caller can patch just what changed (typically just `root` on a timer).
+#[derive(Debug, Default, Deserialize)]
+struct WidgetUpdateArgs {
+    #[serde(default)]
+    root: Option<WidgetNode>,
+    #[serde(default)]
+    tooltip: Option<String>,
+    #[serde(default)]
+    visible: Option<bool>,
+    #[serde(default)]
+    order: Option<i32>,
+}
+
+fn default_widget_visible() -> bool {
+    true
+}
+
+fn widget_register(
+    state_arc: &Arc<RwLock<RuntimeState>>,
+    module: &str,
+    args: WidgetRegisterArgs,
+) -> std::result::Result<WidgetSpec, bread_shared::widget::WidgetValidationError> {
+    args.root.validate()?;
+    let spec = WidgetSpec {
+        id: format!("{module}.{}", args.id),
+        module: module.to_string(),
+        placement: args.placement,
+        order: args.order,
+        visible: args.visible,
+        tooltip: args.tooltip,
+        root: args.root,
+        updated_at: now_unix_ms(),
+    };
+    let mut guard = loop {
+        if let Ok(g) = state_arc.try_write() {
+            break g;
+        }
+        std::hint::spin_loop();
+        std::thread::yield_now();
+    };
+    if let Some(existing) = guard.widgets.iter_mut().find(|w| w.id == spec.id) {
+        *existing = spec.clone();
+    } else {
+        guard.widgets.push(spec.clone());
+    }
+    Ok(spec)
+}
+
+fn widget_update(
+    state_arc: &Arc<RwLock<RuntimeState>>,
+    module: &str,
+    local_id: &str,
+    args: WidgetUpdateArgs,
+) -> std::result::Result<Option<WidgetSpec>, bread_shared::widget::WidgetValidationError> {
+    if let Some(root) = &args.root {
+        root.validate()?;
+    }
+    let full_id = format!("{module}.{local_id}");
+    let mut guard = loop {
+        if let Ok(g) = state_arc.try_write() {
+            break g;
+        }
+        std::hint::spin_loop();
+        std::thread::yield_now();
+    };
+    let Some(entry) = guard.widgets.iter_mut().find(|w| w.id == full_id) else {
+        return Ok(None);
+    };
+    if let Some(root) = args.root {
+        entry.root = root;
+    }
+    if let Some(tooltip) = args.tooltip {
+        entry.tooltip = Some(tooltip);
+    }
+    if let Some(visible) = args.visible {
+        entry.visible = visible;
+    }
+    if let Some(order) = args.order {
+        entry.order = order;
+    }
+    entry.updated_at = now_unix_ms();
+    Ok(Some(entry.clone()))
+}
+
+fn widget_remove(state_arc: &Arc<RwLock<RuntimeState>>, module: &str, local_id: &str) -> bool {
+    let full_id = format!("{module}.{local_id}");
+    let mut guard = loop {
+        if let Ok(g) = state_arc.try_write() {
+            break g;
+        }
+        std::hint::spin_loop();
+        std::thread::yield_now();
+    };
+    let before = guard.widgets.len();
+    guard.widgets.retain(|w| w.id != full_id);
+    before != guard.widgets.len()
+}
+
+fn widget_list_json(state_arc: &Arc<RwLock<RuntimeState>>, module: &str) -> JsonValue {
+    let guard = loop {
+        if let Ok(g) = state_arc.try_read() {
+            break g;
+        }
+        std::hint::spin_loop();
+        std::thread::yield_now();
+    };
+    let mine: Vec<&WidgetSpec> = guard.widgets.iter().filter(|w| w.module == module).collect();
+    serde_json::to_value(&mine).unwrap_or_else(|_| JsonValue::Array(vec![]))
+}
+
 fn order_module_decls(decls: Vec<ModuleDecl>) -> (Vec<ModuleDecl>, Vec<(String, String)>) {
     let mut errors = Vec::new();
     let mut map: HashMap<String, ModuleDecl> = HashMap::new();
@@ -2129,6 +2429,27 @@ fn is_lib_path(module_root: &Path, path: &Path) -> bool {
         .unwrap_or(false)
 }
 
+/// `lua.to_value()`'s default `Options` map JSON null / Rust `Option::None`
+/// to a distinct `lua.null()` sentinel rather than real Lua `nil`, to
+/// preserve JSON round-trip fidelity — but bread never round-trips a Lua
+/// value back into JSON through mlua, so that distinction buys nothing here
+/// and only sets a trap for the ordinary Lua idiom `if not value then ...`,
+/// which silently doesn't catch the sentinel (found via a module crashing
+/// on `#value` when `active_window` was null: `not <sentinel>` is `false`,
+/// same as any other non-nil value). Every JSON/state value handed to Lua
+/// goes through this instead of a bare `to_value` call.
+fn json_to_lua<'lua, T>(lua: &'lua Lua, value: &T) -> mlua::Result<Value<'lua>>
+where
+    T: Serialize + ?Sized,
+{
+    lua.to_value_with(
+        value,
+        mlua::SerializeOptions::new()
+            .serialize_none_to_null(false)
+            .serialize_unit_to_null(false),
+    )
+}
+
 fn state_value_to_lua<'lua>(
     lua: &'lua Lua,
     state_arc: &Arc<RwLock<RuntimeState>>,
@@ -2147,9 +2468,7 @@ fn state_value_to_lua<'lua>(
     let mut value =
         serde_json::to_value(&*snapshot).map_err(|e| LuaError::external(e.to_string()))?;
     if path.is_empty() {
-        return lua
+        return json_to_lua(lua, &value).map_err(|e| LuaError::external(e.to_string()));
-            .to_value(&value)
-            .map_err(|e| LuaError::external(e.to_string()));
     }
     for part in path.split('.') {
         value = value
@@ -2157,8 +2476,7 @@ fn state_value_to_lua<'lua>(
             .cloned()
             .ok_or_else(|| LuaError::external("state path not found"))?;
     }
-    lua.to_value(&value)
+    json_to_lua(lua, &value).map_err(|e| LuaError::external(e.to_string()))
-        .map_err(|e| LuaError::external(e.to_string()))
 }
 
 fn module_store_get(

examples/modules/README.md

@@ -21,6 +21,11 @@ bread reload
 | `low-battery-warning.lua` | Critical notification once when the battery runs low; resets on AC. | none |
 | `pause-media-on-headphone-unplug.lua` | Runs `playerctl pause` when a headphone/earbud device disconnects. | none (needs `playerctl`) |
 | `dock-monitors.lua` | Applies a multi-monitor layout when an external display connects, reverts when removed. | edit output names/resolutions |
+| `active-window-widget.lua` | Shows the focused window next to the workspace pills in breadbar, via `bread.widget` + `bread.state.watch`. | none |
+| `cpu-temp-widget.lua` | Live CPU temperature readout in breadbar's stats area, via `bread.widget` + `bread.fs.read` on a timer. | edit `TEMP_PATH` for your hwmon layout |
+| `bluetooth-toggle-widget.lua` | One-click Bluetooth power toggle in breadbar's tray, via `bread.widget` + a click handler. | none |
+| `focus-mode-widget.lua` | Click-to-toggle "Focus" profile that mutes audio; a widget as an action launcher, not just a readout, and stays in sync with profile changes triggered elsewhere. | none (needs `wpctl`) |
+| `workflow-status-widget.lua` | Surfaces `bread.workflow.list()` in breadbar's tray — shows whichever workflow (e.g. `dock-workflow.lua`, below) is currently running or failed, hidden otherwise. | none |
 
 Each module is the standard skeleton — `bread.module{...}`, an `on_load` that
 registers subscriptions, `return M` — so they double as references for writing

examples/modules/active-window-widget.lua

@@ -0,0 +1,46 @@
+-- active-window-widget — shows the focused app right next to the
+-- workspace pills, live-updated via bread.state.watch (no polling, no
+-- bread.on needed).
+--
+-- Demonstrates: WidgetPlacement "right_of_workspaces", a state-watch-driven
+-- widget (as opposed to a timer or event handler), and calling
+-- bread.widget.update from inside the watch callback. breadbar's own bar
+-- doesn't show the focused window anywhere today — this adds that for free.
+--
+-- Drop-in: copy into ~/.config/bread/modules/. Zero configuration.
+
+local M = bread.module({ name = "active-window-widget", version = "1.0.0" })
+
+local function label_for(window)
+    -- A JSON null (no window focused) doesn't necessarily arrive as Lua nil
+    -- through bread.state.* — mlua's serde bridge can hand back a distinct
+    -- null sentinel instead, which `not window` won't catch. Guard on the
+    -- type directly so any non-string value (nil, the sentinel, ...) falls
+    -- through to the placeholder rather than crashing on #window below.
+    if type(window) ~= "string" or window == "" then
+        return "—"
+    end
+    if #window > 24 then
+        return window:sub(1, 24) .. "…"
+    end
+    return window
+end
+
+local function widget_root(window)
+    return { type = "label", text = label_for(window), style = { color = "dim" } }
+end
+
+function M.on_load()
+    bread.widget.register({
+        id = "active-window",
+        placement = "right_of_workspaces",
+        tooltip = "Currently focused window",
+        root = widget_root(bread.state.active_window()),
+    })
+
+    bread.state.watch("active_window", function(new_val)
+        bread.widget.update("active-window", { root = widget_root(new_val) })
+    end)
+end
+
+return M

examples/modules/bluetooth-toggle-widget.lua

@@ -0,0 +1,66 @@
+-- bluetooth-toggle-widget — a real one-click Bluetooth power toggle in the
+-- hamburger popover's tray section, showing power state and connected
+-- device count. breadbar's native bar only shows a passive BT icon; this
+-- adds an actual control surface for it.
+--
+-- Demonstrates: WidgetPlacement "tray", a bread.every-polled read of
+-- bread.bluetooth.devices()/.powered(), and bread.bar.widget_clicked
+-- driving a real action (bread.bluetooth.power) rather than just display.
+--
+-- Drop-in: copy into ~/.config/bread/modules/. Zero configuration.
+
+local M = bread.module({ name = "bluetooth-toggle-widget", version = "1.0.0" })
+
+local function widget_root()
+    local powered = bread.bluetooth.powered()
+    local devices = bread.bluetooth.devices() or {}
+    local connected = 0
+    for _, d in ipairs(devices) do
+        if d.connected then
+            connected = connected + 1
+        end
+    end
+
+    local text, style
+    if powered == nil then
+        text, style = "BT n/a", { color = "dim" }
+    elseif not powered then
+        text, style = "BT off", { color = "dim" }
+    elseif connected > 0 then
+        text, style = "BT (" .. connected .. ")", { color = "accent", weight = "bold" }
+    else
+        text, style = "BT on", { color = "fg" }
+    end
+
+    return {
+        type = "label",
+        text = text,
+        style = style,
+        on_click = "toggle",
+    }
+end
+
+function M.on_load()
+    bread.widget.register({
+        id = "toggle",
+        placement = "tray",
+        tooltip = "Click to toggle Bluetooth power",
+        root = widget_root(),
+    })
+
+    bread.every(5000, function()
+        bread.widget.update("toggle", { root = widget_root() })
+    end)
+
+    bread.on("bread.bar.widget_clicked", function(e)
+        if e.data.widget_id == "bluetooth-toggle-widget.toggle" and e.data.action == "toggle" then
+            bread.bluetooth.power(not bread.bluetooth.powered())
+            -- Give BlueZ a moment to apply before refreshing the label.
+            bread.after(500, function()
+                bread.widget.update("toggle", { root = widget_root() })
+            end)
+        end
+    end)
+end
+
+return M

examples/modules/cpu-temp-widget.lua

@@ -0,0 +1,64 @@
+-- cpu-temp-widget — live CPU package temperature, read straight from the
+-- k10temp hwmon sysfs node via bread.fs.read.
+--
+-- Demonstrates: WidgetPlacement "left_of_stats", a bread.every-polled
+-- widget reading real hardware state (the same category of readout
+-- breadbar's native CPU%/RAM stats already do in Rust — this shows it's
+-- just as easy from a drop-in Lua module), and the typed `style` vocabulary
+-- (color + weight) swapping based on a threshold so the widget visually
+-- flags when something's hot — no CSS, no guessing which class names the
+-- rendering app happens to define.
+--
+-- Drop-in: copy into ~/.config/bread/modules/. TEMP_PATH is specific to
+-- this machine (AMD, k10temp) — find yours with:
+--   grep -l k10temp /sys/class/hwmon/hwmon*/name
+-- and adjust below; a missing/unreadable path just shows "—" rather than
+-- erroring, since bread.fs.read returns nil (not an error) for that case.
+
+local M = bread.module({ name = "cpu-temp-widget", version = "1.0.0" })
+
+local TEMP_PATH = "/sys/class/hwmon/hwmon6/temp1_input"
+local HOT_THRESHOLD_C = 80
+
+local function read_temp_c()
+    local raw = bread.fs.read(TEMP_PATH)
+    if not raw then
+        return nil
+    end
+    return tonumber(raw) / 1000
+end
+
+local function widget_root(temp_c)
+    local text = temp_c and string.format("%.0f°C", temp_c) or "—"
+    local hot = temp_c ~= nil and temp_c >= HOT_THRESHOLD_C
+    return {
+        type = "box",
+        children = {
+            {
+                type = "label",
+                text = text,
+                style = hot and { color = "red", weight = "bold" } or { color = "dim" },
+            },
+            {
+                type = "progress",
+                value = temp_c and math.min(temp_c / 100, 1.0) or 0,
+                style = hot and { color = "red" } or nil,
+            },
+        },
+    }
+end
+
+function M.on_load()
+    bread.widget.register({
+        id = "cpu-temp",
+        placement = "left_of_stats",
+        tooltip = "CPU package temperature (Tctl)",
+        root = widget_root(read_temp_c()),
+    })
+
+    bread.every(5000, function()
+        bread.widget.update("cpu-temp", { root = widget_root(read_temp_c()) })
+    end)
+end
+
+return M

examples/modules/focus-mode-widget.lua

@@ -0,0 +1,66 @@
+-- focus-mode-widget — a widget that does something, not just shows
+-- something: click to toggle a "focus" bread profile, which mutes audio
+-- output as an observable effect. Stays in sync if the profile changes
+-- from elsewhere too — the CLI (`bread profile-activate default`), another
+-- module, another widget — not just from its own click, by reacting to
+-- bread.profile.activated rather than tracking its own local state.
+--
+-- Demonstrates: a widget as an action launcher wired to bread's actual
+-- profile primitive (bread.profile.activate), not just a passive readout;
+-- staying in sync with state that can change from other sources; combining
+-- bread.exec with a profile switch for a real, checkable effect.
+--
+-- Drop-in: copy into ~/.config/bread/modules/. Needs `wpctl` (pipewire —
+-- already a dependency of breadbar's own volume slider, so if the bar's
+-- volume control works, this will too).
+
+local M = bread.module({ name = "focus-mode-widget", version = "1.0.0" })
+
+local FOCUS_PROFILE = "focus"
+local DEFAULT_PROFILE = "default"
+
+local function is_focused()
+    return bread.state.profile().active == FOCUS_PROFILE
+end
+
+local function widget_root()
+    return {
+        type = "label",
+        text = "Focus",
+        style = is_focused() and { color = "accent", weight = "bold" } or { color = "dim" },
+        on_click = "toggle",
+    }
+end
+
+function M.on_load()
+    bread.widget.register({
+        id = "toggle",
+        placement = "left_of_clock",
+        tooltip = "Click to toggle Focus mode (mutes audio, activates the 'focus' profile)",
+        root = widget_root(),
+    })
+
+    -- Not just self.click -> self.update: any profile change, from any
+    -- source, is reflected here. Try `bread profile-activate default` from
+    -- a terminal while this is in "focus" state to see it flip on its own.
+    bread.on("bread.profile.activated", function()
+        bread.widget.update("toggle", { root = widget_root() })
+    end)
+
+    bread.on("bread.bar.widget_clicked", function(e)
+        if e.data.widget_id ~= "focus-mode-widget.toggle" or e.data.action ~= "toggle" then
+            return
+        end
+        if is_focused() then
+            bread.profile.activate(DEFAULT_PROFILE)
+            bread.exec("wpctl set-mute @DEFAULT_AUDIO_SINK@ 0")
+            bread.notify("Focus mode off", { title = "bread" })
+        else
+            bread.profile.activate(FOCUS_PROFILE)
+            bread.exec("wpctl set-mute @DEFAULT_AUDIO_SINK@ 1")
+            bread.notify("Focus mode on — audio muted", { title = "bread" })
+        end
+    end)
+end
+
+return M

examples/modules/workflow-status-widget.lua

@@ -0,0 +1,83 @@
+-- workflow-status-widget — surfaces bread's workflow engine (bread.workflow,
+-- see Examples.md's "Example 4" and dock-workflow.lua in this directory) in
+-- the bar, which had zero visibility anywhere in the UI before this. Shows
+-- whichever non-done workflow was most recently updated, with its current
+-- step if it's set one via bread.workflow.step(); hides entirely when
+-- nothing is running/failed/timed_out, so it stays out of the way until
+-- there's actually something to look at.
+--
+-- Demonstrates: WidgetPlacement "tray", polling an existing bread subsystem
+-- (bread.workflow.list()) instead of raw hardware or a single module's own
+-- state, and a widget that disappears (visible = false) rather than
+-- showing a stale or empty readout.
+--
+-- Drop-in: copy into ~/.config/bread/modules/. Zero configuration — it
+-- reflects whatever workflow any other loaded module starts, including
+-- dock-workflow.lua in this same directory.
+
+local M = bread.module({ name = "workflow-status-widget", version = "1.0.0" })
+
+local function most_relevant()
+    local workflows = bread.workflow.list()
+    local best = nil
+    for _, w in ipairs(workflows) do
+        if w.state ~= "done" and (not best or w.updated_at > best.updated_at) then
+            best = w
+        end
+    end
+    return best
+end
+
+local function widget_update()
+    local w = most_relevant()
+    if not w then
+        -- bread.widget.update leaves an omitted field unchanged, not
+        -- cleared — a Lua table can't distinguish "tooltip = nil" from
+        -- "no tooltip key at all", so an explicit "" is what actually wipes
+        -- the previous tooltip instead of leaving it stale under a hidden
+        -- widget (harmless in practice since GTK won't show a tooltip on
+        -- an invisible widget, but `bread state widgets` would otherwise
+        -- report it forever).
+        return { visible = false, tooltip = "", root = { type = "label", text = "" } }
+    end
+
+    local color = "dim"
+    if w.state == "failed" or w.state == "timed_out" then
+        color = "red"
+    elseif w.state == "running" then
+        color = "accent"
+    end
+
+    local text = w.name
+    if w.step then
+        text = text .. ": " .. w.step
+    end
+
+    return {
+        visible = true,
+        tooltip = "Workflow " .. w.name .. " — " .. w.state,
+        root = { type = "label", text = text, style = { color = color } },
+    }
+end
+
+function M.on_load()
+    local u = widget_update()
+    bread.widget.register({
+        id = "status",
+        placement = "tray",
+        visible = u.visible,
+        tooltip = u.tooltip,
+        root = u.root,
+    })
+
+    bread.every(3000, function()
+        local next_u = widget_update()
+        bread.widget.update("status", {
+            visible = next_u.visible,
+            tooltip = next_u.tooltip,
+            root = next_u.root,
+        })
+    end)
+end
+
+return M