shell theme: add glass-workbench as a second compiled-in theme

Phase 5 of the shell theme system (THEME_SYSTEM_PLAN.md §11): a second
builtin, demo 02's flush edge-to-edge bar with pill workspaces, a plain
date+time clock, and cpu/ram chips instead of the media widget.

- bread-theme/assets/shell/glass-workbench/: theme.toml + CSS template,
  faithful to bos-ui-demos/02-glass-workbench.html. Accent maps to the
  `green` palette token (flat, not a gradient) rather than a hex literal,
  so pywal theming still works.
- builtin.rs: generalized from a single hardcoded liquid-motion constant
  pair to a small BuiltinTheme registry (builtin::ALL / builtin::find),
  so mod.rs's discovery/list()/resolve_builtin no longer special-case one
  id. liquid-motion stays the pinned fallback in resolve_builtin().
- manifest.rs: KNOWN_MODULES gains "cpu"/"ram".
- types.rs: new Tokens::bar_border() ("full" default vs "bottom") so a
  flush bar can ask for a single hairline instead of an island's full
  border.
- Tests: builtin loads, appears in list() alongside liquid-motion, and its
  window spec is the flush/edge shape (36px, zero margin, radius 0).

cargo test -p bread-theme --lib: 63 passing (59 prior + 4 new).

bread-theme/assets/shell/glass-workbench/glass-workbench.css

@@ -0,0 +1,86 @@
+/* CSS template for the glass-workbench builtin (bread-theme/src/shell/
+ * builtin.rs). Same scope and substitution rules as liquid-motion.css: only
+ * the window/workspace/clock chrome the manifest's own concepts model, `{name}`
+ * tokens substituted, `@name` palette references passed through untouched.
+ *
+ * Source: bos-ui-demos/02-glass-workbench.html's <style> block. No
+ * per-digit flip (this theme has no `.clock-digit` markup at all — plain
+ * style is a date label + one time label) and no gradient trail (pill style
+ * never makes `.workspace-trail` visible — see breadbar's
+ * `WorkspaceTrail::place`/`stretch`, which this theme's slot config simply
+ * never calls).
+ */
+
+window.breadbar {
+  background-color: alpha(@bg, {bg_alpha});
+  color: @on-bg;
+  border-radius: {radius_bar}px;
+  border: none;
+  border-bottom: 1px solid alpha(@on-bg, 0.07);
+}
+window.breadbar > centerbox { padding: 0 {pad}px; }
+window.breadbar button { min-height: 0; min-width: 0; }
+
+/* Pill workspaces: solid accent fill when active, dimmed when empty — no
+ * trail overlay is ever shown (place()/stretch() are never called for this
+ * style), so `.workspace-trail` itself needs no rule here.
+ */
+.workspace-btn {
+  background: transparent;
+  opacity: 1;
+  color: alpha(@on-bg, 0.4);
+  border-radius: {radius_sm}px;
+  border: none;
+  outline: none;
+  box-shadow: none;
+  min-width: 22px;
+  min-height: {chip_height}px;
+  margin: 0;
+  padding: 0 6px;
+  font-size: 12px;
+  font-weight: 600;
+  transition: background-color 0.22s {spring_settle}, color 0.22s {spring_settle},
+    opacity 0.22s {spring_settle};
+}
+.workspace-btn:hover { background: alpha(@on-bg, 0.08); }
+.workspace-btn.occupied { color: alpha(@on-bg, 0.8); }
+.workspace-btn:not(.occupied):not(.active) { opacity: 0.35; }
+.workspace-btn.active {
+  background: @{accent_from};
+  color: @on-accent;
+  opacity: 1;
+}
+.workspace-btn.active:hover { background: @{accent_from}; }
+
+.clock-plain { padding: 0 4px; }
+.clock-plain-time {
+  font-size: {font_size_base}px;
+  font-weight: 600;
+  letter-spacing: 0.04em;
+}
+.date-label {
+  font-size: 12px;
+  opacity: 0.48;
+  font-weight: 400;
+  letter-spacing: 0.04em;
+}
+
+window.breadbar-osd {
+  background-color: alpha(@bg, 0.72);
+  color: @on-bg;
+  border-radius: {radius_pill}px;
+  border: 1px solid alpha(@on-bg, 0.10);
+}
+
+window.breadbar-panel {
+  background-color: alpha(@bg, 0.86);
+  color: @on-bg;
+  border-radius: {radius_card}px;
+  border: 1px solid alpha(@on-bg, 0.12);
+}
+
+window.breadbar-dismiss {
+  background-color: alpha(#000000, 0.02);
+}
+
+.bread-widget-slot { margin-right: {pad}px; }

bread-theme/assets/shell/glass-workbench/theme.toml

@@ -0,0 +1,169 @@
+# The second compiled-in builtin (bread-theme/src/shell/builtin.rs), demo 02
+# in THEME_SYSTEM_PLAN.md — "Glass Workbench": a flush edge-to-edge bar with
+# plain pill workspaces, a plain date+time clock, and cpu/ram chips instead
+# of the media widget liquid-motion carries. Values are taken from
+# bos-ui-demos/02-glass-workbench.html's <style> block; where the demo is
+# silent on a number (bar-adjacent chip sizing, satellite offsets) this file
+# scales liquid-motion's own numbers down by the same 36/44 bar-height ratio
+# rather than inventing something unrelated to either source.
+#
+# Unlike liquid-motion, this builtin has no "as the code exists today" tether
+# — it is new, so demo fidelity is the only source of truth. See Phase 5's
+# task notes for the two exceptions: font (IBM Plex Sans is not installed on
+# the dev machine, so this renders in fallback until the user installs
+# ttf-ibm-plex) and colour (the demo's #7a9a88 sage is a *flat* accent, so it
+# maps to the palette's `green` token for both accent_from and accent_to —
+# never a literal hex value, or pywal theming breaks).
+
+name = "Glass Workbench"
+id   = "glass-workbench"
+
+[tokens]
+font_family    = "IBM Plex Sans"
+font_fallback  = "Inter, Noto Sans, sans-serif"
+font_size_base = 13
+radius_bar     = 0
+radius_card    = 10
+radius_sm      = 6
+radius_pill    = 999
+pad            = 12
+bg_alpha       = 0.72
+# The demo defines exactly one easing curve (`--spring: cubic-bezier(.22,
+# 1.2, .36, 1)`), not liquid-motion's overshoot/settle pair — there's no
+# digit-flip or trail-stretch here to want a bounce for. Both `spring` and
+# `spring_settle` point at the demo's one curve rather than inventing a
+# second value the demo never specifies.
+spring         = "cubic-bezier(0.22, 1.2, 0.36, 1)"
+spring_settle  = "cubic-bezier(0.22, 1.2, 0.36, 1)"
+# Palette token NAMES, not hex — #7a9a88 is this palette's `green`. Equal
+# from/to because the demo's accent is flat, not a gradient.
+accent_from    = "green"
+accent_to      = "green"
+# Demo: `.ws button { height: 20px }`. Liquid-motion's chip_height (32) is
+# tied to its 44px island; 20px is the demo's own number for this bar's
+# workspace pills, and is reused for the bar's other small chips (cpu/ram/
+# wifi/battery/control) so they all sit at the same height on the thinner
+# 36px flush bar.
+chip_height    = 20
+# No demo number for bar-icon size; scaled from liquid-motion's 24px by the
+# same 36/44 bar-height ratio liquid-motion itself uses for its 44px bar.
+icon_px        = 18
+# Flush edge-to-edge bar: a full border would draw a stray line along the
+# top/side screen edges a floating island doesn't have to worry about. See
+# Tokens::bar_border's doc comment.
+bar_border     = "bottom"
+
+[bar.window]
+anchors   = ["top", "left", "right"]
+width     = "fill"
+height    = 36
+margin    = { top = 0, left = 0, right = 0 }
+exclusive = "auto"
+keyboard  = "none"
+layer     = "top"
+
+[bar.slots]
+# No media module — demo 02 has no media widget at all (plan §1 table).
+# breadbar must tolerate the omission: `media_widget` is still built and
+# registered under the "media" module name (main.rs), it just never appears
+# in any of this theme's slot lists, so it's never appended anywhere.
+left   = ["workspaces"]
+centre = ["clock"]
+right  = ["cpu", "ram", "wifi", "battery", "control"]
+drawer = []
+
+[modules.workspaces]
+style      = "pill"
+show_empty = true
+
+[modules.clock]
+style     = "plain"
+format    = "%H:%M"
+show_date = true
+
+[launcher]
+mode     = "overlay"
+width    = 560
+top      = "64px"
+radius   = 12
+icon_px  = 32
+row_anim = "stagger"
+rule     = "hairline"
+footer   = "count_results"
+# Declared-but-not-consumed, exactly like liquid-motion's own launcher block:
+# breadbox's Phase 4b-i wiring only reads mode/width/top/radius/icon_px.
+# row_anim/rule/footer are this theme's demo-derived aspirations breadbox
+# does not implement yet; sections/modes describe today's actual (trivial,
+# apps-only) behaviour but are equally unread by any code path.
+sections = false
+modes    = ["apps"]
+
+# Same four satellite namespaces as liquid-motion, keyed identically so the
+# two manifests validate against the same [compositor.*] keyspace. Offsets
+# are liquid-motion's own numbers re-derived from this bar's actual edge
+# instead of the island's: liquid-motion's bar bottom edge sits at
+# margin.top(12) + height(44) = 56px, and its breadbar-notif/-panel top
+# offset (64) is that plus an 8px gap, while breadbar-dismiss (56) sits
+# flush against it with no gap. This bar's edge is margin.top(0) +
+# height(36) = 36px, so the same two relationships give 44 (36 + 8) and 36.
+[surfaces."breadbar-notif"]
+anchor = "top_right"
+offset = [16, 44]
+width  = 320
+layer  = "overlay"
+
+[surfaces."breadbar-osd"]
+# Independent of bar height (an OSD pill near the bottom of the screen) —
+# unchanged from liquid-motion.
+anchor = "bottom_centre"
+offset = 80
+width  = 180
+layer  = "overlay"
+
+[surfaces."breadbar-panel"]
+anchor = "top_right"
+offset = [16, 44]
+width  = "auto"
+layer  = "overlay"
+
+[surfaces."breadbar-dismiss"]
+anchor = "fill"
+offset = 36
+width  = "fill"
+layer  = "overlay"
+
+# Appearance-only, never placement/workspace/focus (plan §12 Layer B
+# boundary) — identical to liquid-motion's rules. Blur *strength* is global
+# (plan §9 known limit), so this theme cannot independently match the demo's
+# per-surface blur radii (20px bar / 16px launcher / 22px popovers / 6px
+# window borders); only on/off, ignore_alpha and slide direction are
+# per-namespace knobs this system actually has.
+[compositor."breadbar"]
+blur         = true
+ignore_alpha = 0.2
+blur_popups  = true
+animation    = "slide top"
+
+[compositor."breadbar-osd"]
+blur         = true
+ignore_alpha = 0.2
+animation    = "slide bottom"
+
+[compositor."breadbar-notif"]
+blur         = true
+ignore_alpha = 0.2
+animation    = "slide right"
+
+[compositor."breadbar-panel"]
+blur         = true
+ignore_alpha = 0.2
+animation    = "slide right"
+
+[compositor."breadbar-dismiss"]
+no_anim = true
+
+[compositor."breadbox"]
+blur         = true
+ignore_alpha = 0.2
+
+# No `css = "..."` overlay — compiled-in builtin, same as liquid-motion.

bread-theme/src/shell/builtin.rs

@@ -1,23 +1,77 @@
-//! The one compiled-in theme (plan §11 phase 1: "**One** built-in manifest
+//! The compiled-in themes (plan §11 phase 1/5: "**One** built-in manifest
-//! (`liquid-motion`) describing the bar as it exists today"). Both files are
+//! (`liquid-motion`) describing the bar as it exists today", extended in
-//! plain data, not Rust — `theme.toml` is the manifest text a user override
+//! Phase 5 with `glass-workbench`, demo 02). Every file here is plain data,
-//! would otherwise supply, and `liquid-motion.css` is the CSS template
+//! not Rust — each `theme.toml` is the manifest text a user override would
-//! `ShellTheme::css` substitutes tokens into (see that method's doc comment
+//! otherwise supply, and each `<id>.css` is the CSS template `ShellTheme::css`
-//! for why this template is a representative subset of `breadbar::theme::
+//! substitutes tokens into (see that method's doc comment for why this
-//! load_css`'s full stylesheet rather than a byte-for-byte copy of it).
+//! template is a representative subset of `breadbar::theme::load_css`'s
+//! full stylesheet rather than a byte-for-byte copy of it).
 //!
-//! Both are read with `include_str!` so a broken build can't ship without
+//! All are read with `include_str!` so a broken build can't ship without
-//! them, and so [`super::builtin`] never touches the filesystem — it must
+//! them, and so [`super`] never touches the filesystem for a builtin — it
-//! work identically whether or not `$XDG_CONFIG_HOME` exists at all.
+//! must work identically whether or not `$XDG_CONFIG_HOME` exists at all.
 
 pub const LIQUID_MOTION_ID: &str = "liquid-motion";
 
-pub const LIQUID_MOTION_TOML: &str = include_str!(concat!(
+const LIQUID_MOTION_TOML: &str = include_str!(concat!(
     env!("CARGO_MANIFEST_DIR"),
     "/assets/shell/liquid-motion/theme.toml"
 ));
 
-pub const LIQUID_MOTION_CSS: &str = include_str!(concat!(
+const LIQUID_MOTION_CSS: &str = include_str!(concat!(
     env!("CARGO_MANIFEST_DIR"),
     "/assets/shell/liquid-motion/liquid-motion.css"
 ));
+
+pub const GLASS_WORKBENCH_ID: &str = "glass-workbench";
+
+const GLASS_WORKBENCH_TOML: &str = include_str!(concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    "/assets/shell/glass-workbench/theme.toml"
+));
+
+const GLASS_WORKBENCH_CSS: &str = include_str!(concat!(
+    env!("CARGO_MANIFEST_DIR"),
+    "/assets/shell/glass-workbench/glass-workbench.css"
+));
+
+/// One compiled-in theme's identity plus its two `include_str!`ed assets.
+/// `id`/`name` are also duplicated inside `toml`'s own `id =`/`name =`
+/// fields — kept here too so [`all`]/[`find`] can list/look up a builtin
+/// without parsing TOML first (`super::list`'s builtin fallback entry, and
+/// `super::find_source`'s existence check, both run before any manifest
+/// parsing happens).
+pub struct BuiltinTheme {
+    pub id: &'static str,
+    pub name: &'static str,
+    pub toml: &'static str,
+    pub css: &'static str,
+}
+
+/// Every compiled-in theme, in the order [`super::list`] should present
+/// them. Adding a third builtin is one entry here plus its two asset files
+/// — nothing else in `mod.rs` names a specific builtin id except the always-
+/// -safe fallback ([`LIQUID_MOTION_ID`], deliberately still hardcoded at
+/// its one call site in `super::resolve_builtin` — see that function's doc
+/// comment for why that one reference must NOT become "whichever builtin is
+/// listed first").
+pub const ALL: &[BuiltinTheme] = &[
+    BuiltinTheme {
+        id: LIQUID_MOTION_ID,
+        name: "Liquid Motion",
+        toml: LIQUID_MOTION_TOML,
+        css: LIQUID_MOTION_CSS,
+    },
+    BuiltinTheme {
+        id: GLASS_WORKBENCH_ID,
+        name: "Glass Workbench",
+        toml: GLASS_WORKBENCH_TOML,
+        css: GLASS_WORKBENCH_CSS,
+    },
+];
+
+/// Looks up a compiled-in theme by id — `None` means "not a builtin",
+/// exactly like a miss in the user/system theme directories.
+pub fn find(id: &str) -> Option<&'static BuiltinTheme> {
+    ALL.iter().find(|t| t.id == id)
+}

bread-theme/src/shell/manifest.rs

@@ -29,6 +29,11 @@ const KNOWN_MODULES: &[&str] = &[
     "control",
     "launcher_entry",
     "launcher_results",
+    // `02-glass-workbench` (plan §11 phase 5): plain right-side stat chips,
+    // reusing the same `AppInput::StatsUpdate` data the control panel's
+    // sys-grid already receives — see breadbar's `bar::slots` module docs.
+    "cpu",
+    "ram",
 ];
 
 pub(super) fn validate_module_name(theme_id: &str, slot: &str, module: &str) -> anyhow::Result<()> {

bread-theme/src/shell/mod.rs

@@ -175,7 +175,10 @@ fn system_theme_path(id: &str) -> PathBuf {
 enum Source {
     User(PathBuf),
     System(PathBuf),
-    Builtin,
+    /// Carries the id rather than being a bare unit variant now that there's
+    /// more than one compiled-in theme — [`read_source`]/[`css_template_for`]
+    /// need to know *which* builtin's assets to hand back.
+    Builtin(String),
 }
 
 fn find_source(id: &str) -> Option<Source> {
@@ -187,8 +190,8 @@ fn find_source(id: &str) -> Option<Source> {
     if system.is_file() {
         return Some(Source::System(system));
     }
-    if id == builtin::LIQUID_MOTION_ID {
+    if builtin::find(id).is_some() {
-        return Some(Source::Builtin);
+        return Some(Source::Builtin(id.to_string()));
     }
     None
 }
@@ -202,16 +205,19 @@ fn read_source(src: &Source) -> anyhow::Result<(String, Option<PathBuf>)> {
                 std::fs::read_to_string(p).with_context(|| format!("reading {}", p.display()))?;
             Ok((text, p.parent().map(|d| d.to_path_buf())))
         }
-        Source::Builtin => Ok((builtin::LIQUID_MOTION_TOML.to_string(), None)),
+        Source::Builtin(id) => {
+            let toml = builtin::find(id)
+                .map(|t| t.toml.to_string())
+                .unwrap_or_default();
+            Ok((toml, None))
+        }
     }
 }
 
 fn css_template_for(id: &str) -> String {
-    if id == builtin::LIQUID_MOTION_ID {
+    builtin::find(id)
-        builtin::LIQUID_MOTION_CSS.to_string()
+        .map(|t| t.css.to_string())
-    } else {
+        .unwrap_or_default()
-        String::new()
-    }
 }
 
 /// The fallible primitive: look up `id` through discovery, apply one level
@@ -278,24 +284,26 @@ fn resolve_theme(id: &str, extends_depth: u8) -> anyhow::Result<ShellTheme> {
 }
 
 /// Bypasses discovery entirely and resolves straight from the compiled-in
-/// `LIQUID_MOTION_TOML`/`LIQUID_MOTION_CSS` constants — used as [`load`]'s
+/// `liquid-motion` assets — used as [`load`]'s fallback specifically
-/// fallback specifically *because* it cannot be affected by a broken user
+/// *because* it cannot be affected by a broken user override file at the
-/// override file at the same id (unlike calling `load_named("liquid-motion")`
+/// same id (unlike calling `load_named("liquid-motion")` again, which would
-/// again, which would hit that same broken file first via discovery and
+/// hit that same broken file first via discovery and fail identically).
-/// fail identically).
+/// Deliberately always `liquid-motion`, not "whichever theme was active" or
+/// "the first entry in `builtin::ALL`" — this is the one theme every other
+/// fallback path in this module bottoms out at, so its identity has to stay
+/// pinned regardless of how many more builtins `glass-workbench` grows
+/// siblings.
 fn resolve_builtin() -> ShellTheme {
-    let value: toml::Value = toml::from_str(builtin::LIQUID_MOTION_TOML)
+    let asset = builtin::find(builtin::LIQUID_MOTION_ID)
-        .expect("compiled-in builtin theme.toml must parse");
+        .expect("liquid-motion must always be present in builtin::ALL");
+    let value: toml::Value =
+        toml::from_str(asset.toml).expect("compiled-in builtin theme.toml must parse");
     let raw: RawManifest = value
         .try_into()
         .expect("compiled-in builtin theme.toml must satisfy the manifest schema");
     manifest::validate_slots(&raw, builtin::LIQUID_MOTION_ID)
         .expect("compiled-in builtin theme.toml must use only known module names");
-    raw.resolve(
+    raw.resolve(builtin::LIQUID_MOTION_ID, asset.css.to_string(), None)
-        builtin::LIQUID_MOTION_ID,
-        builtin::LIQUID_MOTION_CSS.to_string(),
-        None,
-    )
         .expect("compiled-in builtin theme.toml must resolve")
 }
 
@@ -390,13 +398,15 @@ pub fn list() -> Vec<ThemeSummary> {
         &mut out,
         &mut seen,
     );
-    if seen.insert(builtin::LIQUID_MOTION_ID.to_string()) {
+    for b in builtin::ALL {
+        if seen.insert(b.id.to_string()) {
             out.push(ThemeSummary {
-            id: builtin::LIQUID_MOTION_ID.to_string(),
+                id: b.id.to_string(),
-            name: "Liquid Motion".to_string(),
+                name: b.name.to_string(),
                 source: ThemeSource::Builtin,
             });
         }
+    }
     out
 }
 
@@ -618,6 +628,99 @@ mod tests {
         }
     }
 
+    // ---- glass-workbench builtin (plan §11 phase 5) -----------------------
+
+    #[test]
+    fn glass_workbench_loads_and_appears_in_list() {
+        let theme = load_named(builtin::GLASS_WORKBENCH_ID)
+            .expect("glass-workbench builtin should resolve");
+        assert_eq!(theme.id(), "glass-workbench");
+        assert_eq!(theme.name(), "Glass Workbench");
+
+        let summaries = list();
+        assert!(
+            summaries
+                .iter()
+                .any(|s| s.id == "glass-workbench" && s.source == ThemeSource::Builtin),
+            "glass-workbench missing from list(): {summaries:?}"
+        );
+        // Both builtins must be listed side by side — Phase 5 must not have
+        // dropped liquid-motion in the process of adding a second theme.
+        assert!(summaries
+            .iter()
+            .any(|s| s.id == "liquid-motion" && s.source == ThemeSource::Builtin));
+    }
+
+    #[test]
+    fn glass_workbench_window_is_flush_edge_to_edge_not_a_floating_island() {
+        let theme =
+            load_named(builtin::GLASS_WORKBENCH_ID).expect("glass-workbench should resolve");
+        let w = theme.window();
+        assert_eq!(w.anchors, vec!["top", "left", "right"]);
+        assert!(matches!(w.width, Width::Fill));
+        assert_eq!(w.height, 36);
+        assert_eq!(
+            w.margin,
+            Margin {
+                top: 0,
+                left: 0,
+                right: 0,
+                bottom: 0
+            },
+            "flush bar must have no margin on any edge"
+        );
+        assert_eq!(
+            theme.tokens().radius_bar(),
+            0,
+            "flush edge-to-edge bar must have square corners"
+        );
+        assert_eq!(
+            theme.tokens().bar_border(),
+            "bottom",
+            "flush bar draws only a bottom hairline, not liquid-motion's full border"
+        );
+    }
+
+    #[test]
+    fn glass_workbench_modules_are_pill_and_plain_with_no_media_slot() {
+        let theme =
+            load_named(builtin::GLASS_WORKBENCH_ID).expect("glass-workbench should resolve");
+        assert!(matches!(
+            theme.modules().workspaces.style,
+            WorkspaceStyle::Pill
+        ));
+        assert!(matches!(theme.modules().clock.style, ClockStyle::Plain));
+        assert!(theme.modules().clock.show_date);
+        assert_eq!(theme.slots().centre, vec!["clock"]);
+        assert!(
+            !theme.slots().centre.contains(&"media".to_string()),
+            "demo 02 has no media widget"
+        );
+        assert_eq!(
+            theme.slots().right,
+            vec!["cpu", "ram", "wifi", "battery", "control"]
+        );
+    }
+
+    #[test]
+    fn glass_workbench_accent_is_flat_and_a_palette_token_not_hex() {
+        let theme =
+            load_named(builtin::GLASS_WORKBENCH_ID).expect("glass-workbench should resolve");
+        let t = theme.tokens();
+        assert_eq!(t.accent_from(), "green");
+        assert_eq!(t.accent_to(), "green");
+        let css = theme.css(&crate::Palette::default());
+        assert!(
+            css.contains("@green"),
+            "accent_from/accent_to must resolve to the @green palette token, not a hex literal:\n{css}"
+        );
+        assert!(
+            !css.contains("#7a9a88"),
+            "the demo's sage hex must never leak into the manifest — pywal theming depends on \
+             this staying a palette token name:\n{css}"
+        );
+    }
+
     // ---- extends merge ------------------------------------------------
 
     #[test]

bread-theme/src/shell/types.rs

@@ -348,6 +348,16 @@ impl Tokens {
     pub fn icon_px(&self) -> i64 {
         self.int_or("icon_px", 24)
     }
+    /// Not in the plan §4 schema. `"full"` (default, liquid-motion's island)
+    /// draws a border on all four edges; `"bottom"` (glass-workbench's flush
+    /// edge-to-edge bar, plan §1) draws only the bottom hairline the demo's
+    /// `.bar { border-bottom: 1px solid #ffffff12 }` calls for — a floating
+    /// island's full border would otherwise render as a stray top/side line
+    /// flush against the screen edge. See [`Tokens`] doc; consumed by
+    /// `breadbar::theme::load_css`, not by [`crate::shell::ShellTheme::css`].
+    pub fn bar_border(&self) -> String {
+        self.str_or("bar_border", "full")
+    }
 
     /// Replace every `{name}` occurrence in `template` with that token's
     /// [`TokenValue::as_css`] form. Longest names are substituted first