eur czk can be disabled from now on

src/controllers/admin_currencies.rs

@@ -82,6 +82,8 @@ async fn update(
     active.rate_e4 = Set(currency::parse_rate(&form.rate)?);
     active.enabled = Set(is_checked(&form.enabled));
     active.update(&ctx.db).await?;
+    // Keep the navbar/settings chrome snapshot in sync with the new rate/state.
+    currency::refresh_snapshot(&ctx.db).await?;
     format::redirect("/admin/currencies")
 }
 

src/initializers/currency_seeder.rs

@@ -10,7 +10,7 @@ use loco_rs::prelude::*;
 use sea_orm::{ActiveModelTrait, ColumnTrait, EntityTrait, PaginatorTrait, QueryFilter, Set};
 
 use crate::models::currencies;
-use crate::shared::currency::SCALE;
+use crate::shared::currency::{self, SCALE};
 
 /// `(code, symbol, default_rate_e4)` — default rate is a placeholder the admin
 /// is expected to update from the live FX rate.
@@ -45,6 +45,8 @@ impl Initializer for CurrencySeeder {
             .await?;
             tracing::info!(currency = code, "seeded display currency");
         }
+        // Prime the process-wide snapshot used by the navbar/settings chrome.
+        currency::refresh_snapshot(&ctx.db).await?;
         Ok(())
     }
 }

src/initializers/view_engine.rs

@@ -54,6 +54,12 @@ impl Initializer for ViewEngineInitializer {
                     crate::shared::csrf::current_token().unwrap_or_default(),
                 ))
             });
+            // `currencies()`: the EUR base plus enabled alternative currencies
+            // (from the process-wide snapshot), used by the global chrome — the
+            // settings-menu switcher and the navbar exchange-rate display.
+            tera.register_function("currencies", |_args: &HashMap<String, serde_json::Value>| {
+                Ok(crate::shared::currency::selectable_json())
+            });
             Ok(())
         })?;
 

src/shared/currency.rs

@@ -7,8 +7,11 @@
 //! [`Currency`] resolved per request converts EUR cents into the chosen currency
 //! for display only — the cart logic, orders and admin stay in EUR.
 
+use std::sync::RwLock;
+
 use axum_extra::extract::cookie::CookieJar;
 use loco_rs::prelude::*;
+use sea_orm::{ColumnTrait, EntityTrait, QueryFilter, QueryOrder};
 
 use crate::models::currencies;
 use crate::shared::money::format_price;
@@ -99,6 +102,65 @@ pub async fn resolve(ctx: &AppContext, jar: &CookieJar) -> Currency {
     }
 }
 
+/// One enabled, buyer-selectable alternative currency in the process-wide
+/// snapshot below.
+#[derive(Clone)]
+struct Selectable {
+    code: String,
+    symbol: String,
+    rate_e4: i64,
+}
+
+/// Process-wide snapshot of the enabled alternative currencies, so the global
+/// chrome (the settings-menu switcher and the navbar rate) can be rendered via a
+/// Tera function without a per-request DB hit. Loaded at boot by
+/// `initializers::currency_seeder` and refreshed by the admin on every edit (see
+/// [`refresh_snapshot`]). EUR (the base) is implicit and never listed here.
+static ENABLED: RwLock<Vec<Selectable>> = RwLock::new(Vec::new());
+
+/// Reload the [`ENABLED`] snapshot from the database. Call at boot and after any
+/// admin change to a currency's rate/enabled state.
+pub async fn refresh_snapshot<C: sea_orm::ConnectionTrait>(db: &C) -> Result<()> {
+    let rows = currencies::Entity::find()
+        .filter(currencies::Column::Enabled.eq(true))
+        .order_by_asc(currencies::Column::Code)
+        .all(db)
+        .await?;
+    let list = rows
+        .into_iter()
+        .map(|m| Selectable {
+            code: m.code,
+            symbol: m.symbol,
+            rate_e4: m.rate_e4,
+        })
+        .collect();
+    *ENABLED.write().unwrap() = list;
+    Ok(())
+}
+
+/// The selectable currencies for templates (the Tera `currencies()` function):
+/// the EUR base plus every enabled alternative, each with a human rate string.
+/// `alts` is empty when the store is effectively EUR-only.
+#[must_use]
+pub fn selectable_json() -> serde_json::Value {
+    let alts: Vec<serde_json::Value> = ENABLED
+        .read()
+        .unwrap()
+        .iter()
+        .map(|s| {
+            serde_json::json!({
+                "code": s.code,
+                "symbol": s.symbol,
+                "rate": format_rate(s.rate_e4),
+            })
+        })
+        .collect();
+    serde_json::json!({
+        "base": { "code": BASE_CODE, "symbol": BASE_SYMBOL },
+        "alts": alts,
+    })
+}
+
 /// Parse an exchange rate typed in major units ("25", "25.3", "25,30",
 /// "25.3045") into `rate_e4` (×10000). Rejects negatives and >4 decimals.
 pub fn parse_rate(value: &str) -> Result<i64> {