config: GP_CHECKOUT_METHODS to pick which checkout methods show

Operators can now choose which payment methods the hosted /pay page
offers: GP_CHECKOUT_METHODS=nostr, =slatepack, or nostr,slatepack
(unset = both, current behavior). Gates the two checkout sections
independently; slatepack still also requires a loaded wallet. The Nostr
ingest service (GP_INGEST) and the /invoice JSON API are unchanged.

README.md

@@ -77,6 +77,7 @@ Everything is environment variables, defaults are safe for local use.
 | `GP_RELAYS` | unset | Comma-separated relay URLs |
 | `GP_NYM` | `on` | Route Nostr traffic over the Nym mixnet (`on` or `off`) |
 | `GP_INGEST` | `on` | Nostr ingest service (`off` = HTTP surface only, for debugging) |
+| `GP_CHECKOUT_METHODS` | `nostr,slatepack` | Which payment methods the hosted `/pay/<token>` page shows: comma list of `nostr` (Goblin Wallet) and `slatepack` (`grin1`). Unset = both. Unknown tokens are ignored; an empty result falls back to both |
 | `GP_MATCH_MODE` | `memo` | Default matching mode: `memo`, `derived`, `amount` |
 | `GP_MNEMONIC` | unset | Grin seed mnemonic (money secret) |
 | `GP_WALLET_PASSWORD` | unset | Password encrypting the wallet seed and the Nostr identity at rest |
@@ -99,6 +100,19 @@ Everything is environment variables, defaults are safe for local use.
 | `GP_QUOTE_TTL` | `900` | Seconds a created fiat invoice locks its Grin quote (its expiry window) |
 | `GP_RATE_STALE_MAX` | `0` | Bounded stale-rate fallback in seconds if a live fetch fails (0 = off) |
 
+### Checkout methods
+
+`GP_CHECKOUT_METHODS` only controls what the hosted `/pay/<token>` page
+advertises to a payer; it does not turn any payment processing on or off. The
+Slatepack (`grin1`) method also needs a loaded wallet to appear, so an enabled
+method that cannot work is simply hidden. Keep this consistent with `GP_INGEST`:
+`GP_INGEST` runs the Nostr ingest service that actually receives and matches
+Goblin Wallet payments, so `GP_INGEST=off` with `GP_CHECKOUT_METHODS=nostr`
+would advertise a Nostr method that nothing is listening for. If you disable
+ingest, drop `nostr` from `GP_CHECKOUT_METHODS`; if you advertise `nostr`, keep
+ingest on. The connector `POST /invoice` JSON response still returns the
+`nprofile` regardless of this setting, which affects only the hosted page.
+
 ### Conversion rates (optional)
 
 A store that prices in fiat (for example cryptodrip.com prices in USD) sends

crates/gp-core/src/config.rs

@@ -136,6 +136,15 @@ pub struct Config {
     /// Run the Nostr ingest service (`GP_INGEST`: `on` or `off`, default on).
     /// When on, the wallet and identity secrets are required at boot.
     pub ingest: bool,
+    /// Show the Nostr (Goblin Wallet, `nprofile`) method on the hosted checkout
+    /// page. Part of `GP_CHECKOUT_METHODS` (comma list of `nostr`/`slatepack`;
+    /// unset = both). This gates only the hosted PAGE display, not the connector
+    /// API or the ingest service.
+    pub checkout_nostr: bool,
+    /// Show the Slatepack (`grin1`) method on the hosted checkout page. Part of
+    /// `GP_CHECKOUT_METHODS`. Still requires a loaded wallet to actually appear:
+    /// an enabled method that cannot work is simply hidden.
+    pub checkout_slatepack: bool,
     /// Global default matching mode (`GP_MATCH_MODE`).
     pub match_mode: MatchMode,
     /// Grin seed mnemonic (`GP_MNEMONIC` or `GP_MNEMONIC_FILE`). Money secret.
@@ -228,6 +237,8 @@ impl Default for Config {
             relays: Vec::new(),
             nym: true,
             ingest: true,
+            checkout_nostr: true,
+            checkout_slatepack: true,
             match_mode: MatchMode::Memo,
             mnemonic: None,
             wallet_password: None,
@@ -322,6 +333,9 @@ impl Config {
             other => return Err(format!("GP_INGEST must be `on` or `off` (got `{other}`)")),
         };
 
+        let (checkout_nostr, checkout_slatepack) =
+            parse_checkout_methods(get("GP_CHECKOUT_METHODS"));
+
         let match_mode = match get("GP_MATCH_MODE").as_deref().unwrap_or("memo") {
             "memo" => MatchMode::Memo,
             "derived" => MatchMode::Derived,
@@ -394,6 +408,8 @@ impl Config {
             relays,
             nym,
             ingest,
+            checkout_nostr,
+            checkout_slatepack,
             match_mode,
             mnemonic,
             wallet_password,
@@ -425,6 +441,18 @@ impl Config {
         self.qr_logo.as_deref()
     }
 
+    /// The enabled checkout methods as a stable comma list, for the startup log.
+    fn checkout_methods_str(&self) -> String {
+        let mut methods = Vec::new();
+        if self.checkout_nostr {
+            methods.push("nostr");
+        }
+        if self.checkout_slatepack {
+            methods.push("slatepack");
+        }
+        methods.join(",")
+    }
+
     /// Fail-fast consistency checks.
     fn validate(&self) -> Result<(), String> {
         if self.bind.is_empty() {
@@ -479,7 +507,8 @@ impl Config {
         let set = |o: bool| if o { "set" } else { "unset" };
         format!(
             "bind={} tls={} db={} data_dir={} node={} chain={:?} relay_mode={:?} \
-             relays={:?} nym={} ingest={} match_mode={:?} mnemonic={} wallet_password={} \
+             relays={:?} nym={} ingest={} checkout_methods={} match_mode={:?} mnemonic={} \
+             wallet_password={} \
              nsec={} ncryptsec={} public_url={} api_token={} admin_token={} webhook_url={} \
              webhook_secret={} qr_logo={} merchant_npub={} notify_merchant_dm={} \
              notify_payer_receipt={} endpub_rotate_interval={} endpub_overlap_epochs={} \
@@ -498,6 +527,7 @@ impl Config {
             self.relays,
             if self.nym { "on" } else { "off" },
             if self.ingest { "on" } else { "off" },
+            self.checkout_methods_str(),
             self.match_mode,
             set(self.mnemonic.is_some()),
             set(self.wallet_password.is_some()),
@@ -527,6 +557,35 @@ impl Config {
     }
 }
 
+/// Parse `GP_CHECKOUT_METHODS` (comma list of `nostr`/`slatepack`) into the two
+/// display flags. Parsing is lenient: tokens are trimmed, lowercased, and
+/// unknown tokens are ignored with a warning. Unset (`None`) enables both, which
+/// preserves the historical default of showing every available method. If a set
+/// value parses to no known methods, both are enabled (a checkout must offer at
+/// least one way to pay) and a warning is logged.
+fn parse_checkout_methods(raw: Option<String>) -> (bool, bool) {
+    let Some(raw) = raw else {
+        return (true, true);
+    };
+    let mut nostr = false;
+    let mut slatepack = false;
+    for tok in raw.split(',') {
+        match tok.trim().to_lowercase().as_str() {
+            "" => {}
+            "nostr" => nostr = true,
+            "slatepack" => slatepack = true,
+            other => log::warn!("GP_CHECKOUT_METHODS: ignoring unknown method `{other}`"),
+        }
+    }
+    if !nostr && !slatepack {
+        log::warn!(
+            "GP_CHECKOUT_METHODS enabled no known methods; defaulting to both (nostr,slatepack)"
+        );
+        return (true, true);
+    }
+    (nostr, slatepack)
+}
+
 /// Parse an `on`/`off` flag with a default.
 fn parse_bool(
     get: &dyn Fn(&str) -> Option<String>,
@@ -637,6 +696,36 @@ mod tests {
         assert_eq!(cfg.match_mode, MatchMode::Derived);
     }
 
+    #[test]
+    fn checkout_methods_default_and_parsing() {
+        // Unset: both methods on (unchanged historical behavior).
+        let cfg = load(&[]).unwrap();
+        assert!(cfg.checkout_nostr);
+        assert!(cfg.checkout_slatepack);
+
+        // Single method selects only that method.
+        let cfg = load(&[("GP_CHECKOUT_METHODS", "nostr")]).unwrap();
+        assert!(cfg.checkout_nostr);
+        assert!(!cfg.checkout_slatepack);
+
+        let cfg = load(&[("GP_CHECKOUT_METHODS", "slatepack")]).unwrap();
+        assert!(!cfg.checkout_nostr);
+        assert!(cfg.checkout_slatepack);
+
+        // Both, order/whitespace/case insensitive, unknown tokens ignored.
+        let cfg = load(&[("GP_CHECKOUT_METHODS", " Slatepack , NOSTR ,bogus,")]).unwrap();
+        assert!(cfg.checkout_nostr);
+        assert!(cfg.checkout_slatepack);
+
+        // Empty or all-garbage parses to no methods -> defaults to both.
+        let cfg = load(&[("GP_CHECKOUT_METHODS", "")]).unwrap();
+        assert!(cfg.checkout_nostr);
+        assert!(cfg.checkout_slatepack);
+        let cfg = load(&[("GP_CHECKOUT_METHODS", "lightning, bitcoin")]).unwrap();
+        assert!(cfg.checkout_nostr);
+        assert!(cfg.checkout_slatepack);
+    }
+
     #[test]
     fn tls_rustls_requires_cert_and_key() {
         assert!(load(&[("GP_TLS", "rustls")]).is_err());

crates/gp-server/src/checkout.rs

@@ -58,9 +58,17 @@ pub struct CheckoutInfo {
 pub fn build_info(inv: &Invoice, cfg: &Config, slatepack_addr: Option<&str>) -> CheckoutInfo {
     let relays = gp_nostr::relays::resolve(&cfg.relays);
     let recipient_pubkey = inv.recipient_pubkey.clone().unwrap_or_default();
-    let (npub, nprofile) = match PublicKey::from_hex(&recipient_pubkey) {
+    // The Nostr (Goblin Wallet) method is only surfaced when the operator has it
+    // enabled (`GP_CHECKOUT_METHODS`). Disabled, the nprofile/npub/QR are left
+    // empty and the template omits the whole section. This gates only the hosted
+    // PAGE display; the connector API and ingest are unaffected.
+    let (npub, nprofile) = if cfg.checkout_nostr {
+        match PublicKey::from_hex(&recipient_pubkey) {
             Ok(pk) => (gp_nostr::npub_of(pk), gp_nostr::nprofile(pk, &relays)),
             Err(_) => (String::new(), String::new()),
+        }
+    } else {
+        (String::new(), String::new())
     };
     // The QR carries a pay-URI so a scanning wallet can auto-fill the amount
     // (and memo). The human-readable nprofile/npub strings on the page are
@@ -76,8 +84,10 @@ pub fn build_info(inv: &Invoice, cfg: &Config, slatepack_addr: Option<&str>) ->
     // QR carries the bare address (a Grin wallet reads no amount from it, so
     // the page states the amount to send in text next to it). No address means
     // no wallet loaded: the page simply omits the Slatepack option.
+    // The Slatepack method needs both operator opt-in (`GP_CHECKOUT_METHODS`)
+    // and a loaded wallet: an enabled method that cannot work is simply hidden.
     let (slatepack_address, slatepack_qr_svg) = match slatepack_addr {
-        Some(addr) if !addr.is_empty() => {
+        Some(addr) if cfg.checkout_slatepack && !addr.is_empty() => {
             let qr = qr::svg(addr, cfg.qr_logo_href()).unwrap_or_default();
             (Some(addr.to_string()), Some(qr))
         }
@@ -384,6 +394,71 @@ mod tests {
         assert!(blank.slatepack_qr_svg.is_none());
     }
 
+    #[test]
+    fn checkout_nostr_disabled_hides_nostr_section() {
+        // GP_CHECKOUT_METHODS=slatepack: the Nostr method is off, so build_info
+        // leaves the nprofile/npub empty and the page omits the Nostr section
+        // while still showing the Slatepack one.
+        let inv = invoice(Some(1_500_000_000), None);
+        let mut cfg = Config::default();
+        cfg.checkout_nostr = false;
+        cfg.checkout_slatepack = true;
+        let info = build_info(&inv, &cfg, Some("grin1qtestaddress"));
+        assert!(info.nprofile.is_empty(), "nprofile empty when nostr off");
+        assert!(info.npub.is_empty(), "npub empty when nostr off");
+        assert_eq!(info.slatepack_address.as_deref(), Some("grin1qtestaddress"));
+
+        let page = PayPage {
+            info,
+            is_open: true,
+            is_paid: false,
+            is_expired: false,
+        };
+        let html = page.render().unwrap();
+        assert!(
+            !html.contains("Pay with Goblin Wallet"),
+            "Nostr section absent when checkout_nostr=false"
+        );
+        assert!(
+            html.contains("Pay by Slatepack"),
+            "Slatepack section still present"
+        );
+    }
+
+    #[test]
+    fn checkout_slatepack_disabled_hides_slatepack_section() {
+        // GP_CHECKOUT_METHODS=nostr: the Slatepack method is off, so even with a
+        // wallet address available, build_info drops it and the page omits the
+        // Slatepack section while still showing the Nostr one.
+        let inv = invoice(Some(1_500_000_000), None);
+        let mut cfg = Config::default();
+        cfg.checkout_nostr = true;
+        cfg.checkout_slatepack = false;
+        let info = build_info(&inv, &cfg, Some("grin1qtestaddress"));
+        assert!(
+            info.slatepack_address.is_none(),
+            "slatepack dropped when method off"
+        );
+        assert!(info.slatepack_qr_svg.is_none());
+        assert!(!info.nprofile.is_empty(), "nprofile present when nostr on");
+
+        let page = PayPage {
+            info,
+            is_open: true,
+            is_paid: false,
+            is_expired: false,
+        };
+        let html = page.render().unwrap();
+        assert!(
+            html.contains("Pay with Goblin Wallet"),
+            "Nostr section present"
+        );
+        assert!(
+            !html.contains("Pay by Slatepack"),
+            "Slatepack section absent when checkout_slatepack=false"
+        );
+    }
+
     #[test]
     fn amount_invoice_encodes_amount() {
         // 1.5 GRIN → nostr:<nprofile>?amount=1.5

templates/pay.html

@@ -21,6 +21,7 @@
   {% else %}
     <p class="status open">Waiting for payment&#8230;</p>
 
+    {% if !info.nprofile.is_empty() %}
     <section class="pay-method">
       <h2>Pay with Goblin Wallet</h2>
       <div class="qr">{{ info.qr_svg|safe }}</div>
@@ -28,6 +29,7 @@
       <label for="nprofile">Payment address (nprofile)</label>
       <textarea id="nprofile" class="copybox" rows="3" readonly>{{ info.nprofile }}</textarea>
     </section>
+    {% endif %}
 
     {% if let Some(grin1) = info.slatepack_address %}
     <section class="pay-method">