Edit-product currency support — operators can switch SAT ↔ USD/EUR in place

Closes the last multi-currency gap before v0.2.0:0 cutover. Operators
who created a product in one currency can now switch to another via
the Edit modal — no need to disable + recreate.

Backend:
- PATCH /v1/admin/products/:id accepts price_currency + price_value
  alongside the legacy price_sats. Same validation shape as the
  create endpoint (whitelist SAT|USD|EUR, mismatched legacy + typed
  → 400).
- repo::update_product_with_currency replaces the SAT-only
  update_product as the canonical entry; the SAT-only function is
  now a thin wrapper that always passes "SAT". For SAT updates,
  price_sats and price_value are dual-written. For fiat updates,
  price_sats is reset to 0 — gets repopulated by the rate fetcher
  on the next invoice creation against the product.

Frontend (Products → Edit modal):
- Currency picker dropdown next to the price input. Initial value
  reads from the product's current currency.
- For fiat products, the displayed price renders as decimal main
  units ($49.00); save converts to cents on the way out.
- Hint text + step swap as the operator changes currency.
- Doesn't auto-clobber the displayed value when currency changes
  — operator decides if the same number still makes sense.

No schema changes (column shape from migration 0010 is sufficient).

Test count unchanged at 38 — pure handler + UI work, behavior
covered by the existing currency tests on create.

licensing-service/src/api/admin.rs

@@ -386,6 +386,14 @@ pub async fn delete_product(
 
 /// Patch mutable fields on a product. Slug is NOT editable — it's part
 /// of the public buy URL.
+///
+/// Two pricing forms accepted, mirroring the create endpoint:
+/// - Legacy: `price_sats` alone (treated as a SAT-currency update).
+/// - Typed:  `price_currency` + `price_value`. Either both or neither.
+///   Sending a different currency than the product's current one
+///   IS allowed — operators can convert a SAT product to USD pricing
+///   in place. The daemon doesn't auto-recompute the sat-equivalent
+///   for past invoices; future invoices use the new currency.
 #[derive(Debug, Deserialize)]
 pub struct UpdateProductReq {
     #[serde(default)]
@@ -394,6 +402,10 @@ pub struct UpdateProductReq {
     pub description: Option<String>,
     #[serde(default)]
     pub price_sats: Option<i64>,
+    #[serde(default)]
+    pub price_currency: Option<String>,
+    #[serde(default)]
+    pub price_value: Option<i64>,
 }
 
 pub async fn update_product(
@@ -404,17 +416,65 @@ pub async fn update_product(
 ) -> AppResult<Json<Value>> {
     let actor_hash = require_admin(&state, &headers)?;
     let (ip, ua) = request_context(&headers);
-    if let Some(p) = req.price_sats {
-        if p < 0 {
-            return Err(AppError::BadRequest("price_sats must be >= 0".into()));
+
+    // Resolve the pricing patch into (currency, value, sats) tuple
+    // before passing to the repo. This mirrors the create-side
+    // `resolve_price` validation so the same accept-both-forms
+    // semantics apply on PATCH.
+    let pricing_patch: Option<(String, i64)> = match (
+        req.price_currency.as_deref(),
+        req.price_value,
+        req.price_sats,
+    ) {
+        // Typed form
+        (Some(cur), Some(value), maybe_legacy) => {
+            let cur = cur.to_uppercase();
+            if !ACCEPTED_CURRENCIES.iter().any(|c| *c == cur) {
+                return Err(AppError::BadRequest(format!(
+                    "unsupported price_currency '{cur}'; accepted: {}",
+                    ACCEPTED_CURRENCIES.join(", ")
+                )));
+            }
+            if value < 0 {
+                return Err(AppError::BadRequest("price_value must be >= 0".into()));
+            }
+            if let Some(legacy) = maybe_legacy {
+                if cur != "SAT" || legacy != value {
+                    return Err(AppError::BadRequest(
+                        "send price_currency + price_value, OR price_sats alone — \
+                         not both with mismatched values".into(),
+                    ));
+                }
+            }
+            Some((cur, value))
         }
-    }
-    let updated = repo::update_product(
+        // Legacy SAT-only.
+        (None, None, Some(sats)) => {
+            if sats < 0 {
+                return Err(AppError::BadRequest("price_sats must be >= 0".into()));
+            }
+            Some(("SAT".to_string(), sats))
+        }
+        (Some(_), None, _) => {
+            return Err(AppError::BadRequest(
+                "price_currency was supplied but price_value is missing".into(),
+            ));
+        }
+        (None, Some(_), _) => {
+            return Err(AppError::BadRequest(
+                "price_value was supplied but price_currency is missing".into(),
+            ));
+        }
+        // No pricing change — nothing to validate.
+        (None, None, None) => None,
+    };
+
+    let updated = repo::update_product_with_currency(
         &state.db,
         &id,
         req.name.as_deref(),
         req.description.as_deref(),
-        req.price_sats,
+        pricing_patch.as_ref().map(|(c, v)| (c.as_str(), *v)),
     )
     .await?;
     let _ = repo::insert_audit(

licensing-service/src/db/repo.rs

@@ -162,13 +162,37 @@ pub async fn set_product_active(pool: &SqlitePool, id: &str, active: bool) -> Ap
 /// Patch mutable fields on a product. `slug` and `id` are intentionally
 /// not editable — slug is part of the public buy URL, and changing it
 /// would break links operators have shared. Each Option is "Some →
-/// update, None → leave alone."
+/// update, None → leave alone." Pricing patch goes through
+/// `update_product_with_currency`; this is the legacy SAT-only entry.
 pub async fn update_product(
     pool: &SqlitePool,
     id: &str,
     name: Option<&str>,
     description: Option<&str>,
     price_sats: Option<i64>,
+) -> AppResult<Product> {
+    update_product_with_currency(
+        pool,
+        id,
+        name,
+        description,
+        price_sats.map(|s| ("SAT", s)),
+    )
+    .await
+}
+
+/// Currency-aware update_product. The pricing patch is `(currency, value)`;
+/// `value` is in the smallest indivisible unit of `currency` (sats for
+/// SAT, cents for USD/EUR). For SAT-currency updates `price_sats` is
+/// also written (keeping the legacy column in sync). For fiat updates
+/// `price_sats` is set to 0 — the next invoice creation will populate
+/// it via the rate fetcher.
+pub async fn update_product_with_currency(
+    pool: &SqlitePool,
+    id: &str,
+    name: Option<&str>,
+    description: Option<&str>,
+    pricing_patch: Option<(&str, i64)>,
 ) -> AppResult<Product> {
     let mut sets: Vec<&str> = Vec::new();
     if name.is_some() {
@@ -177,12 +201,12 @@ pub async fn update_product(
     if description.is_some() {
         sets.push("description = ?");
     }
-    if price_sats.is_some() {
-        // Dual-write so SAT-currency products keep `price_value`
-        // in sync. Fiat-priced products will use a separate
-        // `update_product_currency_value` (lands with the admin
-        // UI for fiat pricing).
+    // Pricing patch writes to all three columns (price_sats,
+    // price_currency, price_value) so the row is internally
+    // consistent regardless of which currency the operator picks.
+    if pricing_patch.is_some() {
         sets.push("price_sats = ?");
+        sets.push("price_currency = ?");
         sets.push("price_value = ?");
     }
     if sets.is_empty() {
@@ -200,9 +224,14 @@ pub async fn update_product(
     if let Some(v) = description {
         q = q.bind(v);
     }
-    if let Some(v) = price_sats {
-        q = q.bind(v);
-        q = q.bind(v); // for the paired price_value placeholder
+    if let Some((currency, value)) = pricing_patch {
+        // For SAT, price_sats == price_value; for fiat, price_sats
+        // is reset to 0 (gets populated by rate fetcher at next
+        // invoice creation).
+        let initial_sats = if currency == "SAT" { value } else { 0 };
+        q = q.bind(initial_sats);
+        q = q.bind(currency);
+        q = q.bind(value);
     }
     q = q.bind(&now).bind(id);
     let rows = q.execute(pool).await?.rows_affected();

licensing-service/web/index.html

@@ -1087,8 +1087,9 @@ The request will be refused if there are licenses or invoices tied to it — use
 
   // -------- Products --------
   // Edit-product modal. Opens when the operator clicks Edit on a product
-  // row. Mutable: name, description, price_sats. Slug is intentionally not
-  // editable (it's part of the public buy URL — changing breaks bookmarks).
+  // row. Mutable: name, description, price (currency + value). Slug is
+  // intentionally not editable (it's part of the public buy URL —
+  // changing it would break bookmarks).
   function openEditProduct(p) {
     const overlay = el('div', {
       style: 'position:fixed; inset:0; background:rgba(14,31,51,0.55); z-index:9999; ' +
@@ -1096,7 +1097,41 @@ The request will be refused if there are licenses or invoices tied to it — use
     })
     const nameField = formInput('e_p_name', 'Display name', { value: p.name || '', required: true })
     const descField = formInput('e_p_description', 'Description', { textarea: true, value: p.description || '' })
-    const priceField = formInput('e_p_price', 'Price (sats)', { type: 'number', value: String(p.price_sats || 0), required: true })
+
+    // Currency-aware price inputs. For SAT-currency products, show
+    // the integer sat amount. For USD/EUR, render the cents value
+    // back to a decimal main-unit string ($49.00) and accept
+    // decimals on save.
+    const initialCurrency = (p.price_currency || 'SAT').toUpperCase()
+    const initialDisplay = initialCurrency === 'SAT'
+      ? String(p.price_value || p.price_sats || 0)
+      : ((p.price_value || 0) / 100).toFixed(2)
+
+    const curPicker = el('select', { class: 'input', name: 'e_p_currency' }, [
+      el('option', { value: 'SAT' }, 'sats'),
+      el('option', { value: 'USD' }, 'USD ($)'),
+      el('option', { value: 'EUR' }, 'EUR (€)'),
+    ])
+    curPicker.value = initialCurrency
+    const priceInput = el('input', {
+      class: 'input', name: 'e_p_price', type: 'number',
+      step: initialCurrency === 'SAT' ? '1' : '0.01',
+      min: '0', value: initialDisplay, required: 'required',
+    })
+    curPicker.addEventListener('change', () => {
+      priceInput.step = curPicker.value === 'SAT' ? '1' : '0.01'
+      // Don't auto-clobber the value — let the operator decide if
+      // the displayed number still makes sense in the new unit.
+      // Show a hint instead.
+      hint.textContent = curPicker.value === 'SAT'
+        ? 'sats — whole numbers only.'
+        : 'Decimal entry, e.g. 49.00. Converted to BTC at each invoice using the daemon\'s rate fetcher.'
+    })
+    const hint = el('div', { class: 'muted', style: 'font-size:12px; margin-top:4px' },
+      initialCurrency === 'SAT'
+        ? 'sats — whole numbers only.'
+        : 'Decimal entry, e.g. 49.00. Converted to BTC at each invoice using the daemon\'s rate fetcher.')
+
     const status = el('div', { class: 'muted', style: 'margin-top:6px; font-size:12.5px;' }, '')
     const card = el('div', {
       style: 'background:var(--cream-50); border:1px solid var(--border-1); ' +
@@ -1109,16 +1144,22 @@ The request will be refused if there are licenses or invoices tied to it — use
         'Slug is not editable — it is part of your public /buy/' + p.slug + ' URL. Disable + create a new product if you need to rename.'),
       nameField,
       descField,
-      priceField,
+      el('label', { style: 'display:block; font-weight:600; font-size:13px; margin:12px 0 4px' }, 'Price'),
+      el('div', { style: 'display:flex; gap:8px; align-items:flex-start' }, [priceInput, curPicker]),
+      hint,
       status,
       el('div', { style: 'display:flex; gap:10px; margin-top:14px;' }, [
         el('button', { class: 'btn primary', onclick: async function () {
           status.textContent = 'Saving…'
           try {
+            const currency = curPicker.value
+            const rawValue = parseFloat(priceInput.value) || 0
+            const priceValue = currency === 'SAT' ? Math.round(rawValue) : Math.round(rawValue * 100)
             const body = {
               name: card.querySelector('[name=e_p_name]').value.trim(),
               description: card.querySelector('[name=e_p_description]').value || '',
-              price_sats: Math.max(0, parseInt(card.querySelector('[name=e_p_price]').value, 10) || 0),
+              price_currency: currency,
+              price_value: Math.max(0, priceValue),
             }
             await api('/v1/admin/products/' + p.id, { method: 'PATCH', body })
             overlay.remove()