feat(home): add floating chevron scroll buttons to card sections

Extract <chip-scroll> custom element into its own file and wrap
Recent Brews and Open Bags horizontal scrollers with desktop-only
chevron navigation that half-overlaps the card edges.

CLAUDE.md

@@ -362,6 +362,32 @@ Clicking the element opens the camera/file picker, reads the file as a data URL,
 
 Place `<button>` children with `value` and `data-display` attributes. The component handles search filtering, hidden input, and selected-value display internally.
 
+**`<chip-scroll>`** (`static/js/components/chip-scroll.js`):
+
+Wraps a horizontal scroll container with floating left/right chevron buttons on desktop. Buttons auto-show/hide based on scroll position and are hidden on mobile (`max-width: 767px`). Uses `ResizeObserver` and `MutationObserver` to update when content changes (including Datastar morphs).
+
+Required child structure:
+
+| Selector | Purpose |
+|----------|---------|
+| `[data-chip-scroll]` | The scrollable container |
+| `[data-scroll-left]` | Left chevron button |
+| `[data-scroll-right]` | Right chevron button |
+
+Scroll distance and button sizing are set in the template `onclick` handler, not the component — use `scrollBy({left: ±200})` for chips, `±220` for cards. For chips use `p-1` + `h-4 w-4` icons at `left-0`/`right-0`. For cards use `p-1.5` + `h-5 w-5` icons at `-left-4`/`-right-4` (half-overlapping the card edges).
+
+**`<world-map>`** (`static/js/components/world-map.js`):
+
+Renders an inline SVG choropleth world map colored by country counts.
+
+| Attribute | Purpose |
+|-----------|---------|
+| `data-countries` | Comma-separated `ISO:count` pairs (e.g. `ET:5,CO:3`) |
+| `data-max` | Maximum count value (for color scaling) |
+| `data-selected` | ISO code of the currently selected country (optional) |
+
+Uses `requestAnimationFrame` to defer rendering until after Datastar morphing completes.
+
 ### FlexiblePayload
 
 Handlers accept both JSON and form data via `FlexiblePayload<T>`. When form fields don't map 1:1 to the domain `New*` struct (e.g., a roaster name needing resolution to an ID), use a `*Submission` newtype that handles the conversion.

src/application/routes/app/mod.rs

@@ -34,6 +34,7 @@ pub(super) fn router() -> axum::Router<AppState> {
             "/components/searchable-select.js",
             get(searchable_select_js),
         )
+        .route("/components/chip-scroll.js", get(chip_scroll_js))
         .route("/components/world-map.js", get(world_map_js))
         .route("/favicon-light.svg", get(favicon_light))
         .route("/favicon-dark.svg", get(favicon_dark))
@@ -83,6 +84,16 @@ async fn searchable_select_js() -> impl IntoResponse {
     )
 }
 
+async fn chip_scroll_js() -> impl IntoResponse {
+    (
+        [
+            ("content-type", "application/javascript; charset=utf-8"),
+            ("cache-control", "public, max-age=604800"),
+        ],
+        include_str!("../../../../static/js/components/chip-scroll.js"),
+    )
+}
+
 async fn world_map_js() -> impl IntoResponse {
     (
         [

static/js/components/chip-scroll.js

@@ -0,0 +1,30 @@
+customElements.define("chip-scroll", class extends HTMLElement {
+  connectedCallback() { this._setup(); }
+
+  _setup() {
+    if (this._observer) this._observer.disconnect();
+
+    const scroller = this.querySelector("[data-chip-scroll]");
+    const btnL = this.querySelector("[data-scroll-left]");
+    const btnR = this.querySelector("[data-scroll-right]");
+    if (!scroller || !btnL || !btnR) return;
+
+    const update = () => {
+      if (window.matchMedia("(max-width: 767px)").matches) {
+        btnL.style.display = "none";
+        btnR.style.display = "none";
+        return;
+      }
+      btnL.style.display = scroller.scrollLeft > 0 ? "flex" : "none";
+      btnR.style.display = scroller.scrollLeft + scroller.clientWidth < scroller.scrollWidth - 1 ? "flex" : "none";
+    };
+
+    scroller.addEventListener("scroll", update, { passive: true });
+    new ResizeObserver(update).observe(scroller);
+
+    this._observer = new MutationObserver(update);
+    this._observer.observe(scroller, { childList: true });
+
+    update();
+  }
+});

static/js/components/world-map.js

@@ -94,34 +94,3 @@ customElements.define("world-map", class extends HTMLElement {
     });
   }
 });
-
-customElements.define("chip-scroll", class extends HTMLElement {
-  connectedCallback() { this._setup(); }
-
-  _setup() {
-    if (this._observer) this._observer.disconnect();
-
-    const scroller = this.querySelector("[data-chip-scroll]");
-    const btnL = this.querySelector("[data-scroll-left]");
-    const btnR = this.querySelector("[data-scroll-right]");
-    if (!scroller || !btnL || !btnR) return;
-
-    const update = () => {
-      if (window.matchMedia("(max-width: 767px)").matches) {
-        btnL.style.display = "none";
-        btnR.style.display = "none";
-        return;
-      }
-      btnL.style.display = scroller.scrollLeft > 0 ? "flex" : "none";
-      btnR.style.display = scroller.scrollLeft + scroller.clientWidth < scroller.scrollWidth - 1 ? "flex" : "none";
-    };
-
-    scroller.addEventListener("scroll", update, { passive: true });
-    new ResizeObserver(update).observe(scroller);
-
-    this._observer = new MutationObserver(update);
-    this._observer.observe(scroller, { childList: true });
-
-    update();
-  }
-});

templates/base.html

@@ -27,6 +27,7 @@
     ></script>
     <script defer src="/components/photo-capture.js"></script>
     <script defer src="/components/searchable-select.js"></script>
+    <script defer src="/components/chip-scroll.js"></script>
     <script defer src="/components/world-map.js"></script>
     {% block head %}{% endblock %}
     <script>

templates/pages/home.html

@@ -108,9 +108,23 @@ is_authenticated %}
     >
   </div>
   {% if !recent_brews.is_empty() %}
-  <div class="flex gap-4 overflow-x-auto scroll-smooth snap-x snap-mandatory scrollbar-hide">
+  <chip-scroll class="relative block">
+    <button type="button" aria-label="Scroll left"
+      class="hidden absolute -left-4 top-1/2 z-10 -translate-y-1/2 items-center justify-center rounded-full border bg-surface p-1.5 text-text-muted shadow-sm transition hover:text-text"
+      data-scroll-left
+      onclick="this.closest('chip-scroll').querySelector('[data-chip-scroll]').scrollBy({left: -220, behavior: 'smooth'})">
+      {{ icons::chevron_left("h-5 w-5") }}
+    </button>
+    <div class="flex gap-4 overflow-x-auto scroll-smooth snap-x snap-mandatory scrollbar-hide" data-chip-scroll>
       {% for brew in recent_brews %} {{ brew_card::card(brew, is_authenticated) }} {% endfor %}
     </div>
+    <button type="button" aria-label="Scroll right"
+      class="hidden absolute -right-4 top-1/2 z-10 -translate-y-1/2 items-center justify-center rounded-full border bg-surface p-1.5 text-text-muted shadow-sm transition hover:text-text"
+      data-scroll-right
+      onclick="this.closest('chip-scroll').querySelector('[data-chip-scroll]').scrollBy({left: 220, behavior: 'smooth'})">
+      {{ icons::chevron_right("h-5 w-5") }}
+    </button>
+  </chip-scroll>
   {% else %}
   <div class="relative">
     <div class="flex gap-4 overflow-hidden blur-[2px] select-none pointer-events-none" aria-hidden="true">
@@ -146,12 +160,27 @@ is_authenticated %}
     >
   </div>
   {% if !open_bags.is_empty() %}
+  <chip-scroll class="relative block">
+    <button type="button" aria-label="Scroll left"
+      class="hidden absolute -left-4 top-1/2 z-10 -translate-y-1/2 items-center justify-center rounded-full border bg-surface p-1.5 text-text-muted shadow-sm transition hover:text-text"
+      data-scroll-left
+      onclick="this.closest('chip-scroll').querySelector('[data-chip-scroll]').scrollBy({left: -220, behavior: 'smooth'})">
+      {{ icons::chevron_left("h-5 w-5") }}
+    </button>
     <div
       id="open-bags-grid"
       class="flex gap-4 overflow-x-auto scroll-smooth snap-x snap-mandatory scrollbar-hide"
+      data-chip-scroll
     >
       {% for bag in open_bags %} {{ bag_card::card(bag, is_authenticated) }} {% endfor %}
     </div>
+    <button type="button" aria-label="Scroll right"
+      class="hidden absolute -right-4 top-1/2 z-10 -translate-y-1/2 items-center justify-center rounded-full border bg-surface p-1.5 text-text-muted shadow-sm transition hover:text-text"
+      data-scroll-right
+      onclick="this.closest('chip-scroll').querySelector('[data-chip-scroll]').scrollBy({left: 220, behavior: 'smooth'})">
+      {{ icons::chevron_right("h-5 w-5") }}
+    </button>
+  </chip-scroll>
   {% else %}
   <div class="relative">
     <div class="flex gap-4 overflow-hidden blur-[2px] select-none pointer-events-none" aria-hidden="true">