diff --git a/locales/de.yml b/locales/de.yml
index 9204e4ae..82b5d4eb 100644
--- a/locales/de.yml
+++ b/locales/de.yml
@@ -683,6 +683,15 @@ goblin:
     title: "%{n} Rechnungen bestätigen"
     blurb: "Stelle %{n} Zahlungsanforderungen über je %{amount} an %{name} — insgesamt %{total}. Jede Anforderung erhält ihre eigene neue Zahlungsadresse."
     approve: "Bestätigen"
+  login:
+    title: "Anmelden"
+    headline: "Bei %{domain} anmelden?"
+    identity: "Anmelden als"
+    explain: "Dies signiert eine einmalige Anmeldeanfrage. Dein Schlüssel wird nicht geteilt, und die Seite kann nicht in deinem Namen handeln."
+    pass_prompt: "Gib dein Wallet-Passwort ein, um dich anzumelden."
+    confirm: "Anmelden"
+    sent: "Bei %{domain} angemeldet"
+    failed: "%{domain} war nicht erreichbar. Die Anmeldung wurde nicht zugestellt."
   identities:
     title: "Identitäten"
     switch_hint: "Identität wechseln"
diff --git a/locales/en.yml b/locales/en.yml
index 0f7fe7b2..b39d994b 100644
--- a/locales/en.yml
+++ b/locales/en.yml
@@ -683,6 +683,15 @@ goblin:
     title: "Approve %{n} invoices"
     blurb: "Issue %{n} payment requests of %{amount} each to %{name} — %{total} in total. Each request gets its own fresh payment address."
     approve: "Approve"
+  login:
+    title: "Sign in"
+    headline: "Sign in to %{domain}?"
+    identity: "Signing in as"
+    explain: "This signs a one-time login request. It does not share your key or let the site act as you."
+    pass_prompt: "Enter your wallet password to sign in."
+    confirm: "Sign in"
+    sent: "Signed in to %{domain}"
+    failed: "Could not reach %{domain}. The sign-in was not delivered."
   identities:
     title: "Identities"
     switch_hint: "Switch identity"
diff --git a/locales/fr.yml b/locales/fr.yml
index 4ee1f455..4cd7091e 100644
--- a/locales/fr.yml
+++ b/locales/fr.yml
@@ -683,6 +683,15 @@ goblin:
     title: "Approuver %{n} factures"
     blurb: "Émettre %{n} demandes de paiement de %{amount} chacune à %{name} — %{total} au total. Chaque demande reçoit sa propre adresse de paiement."
     approve: "Approuver"
+  login:
+    title: "Connexion"
+    headline: "Se connecter à %{domain} ?"
+    identity: "Se connecter en tant que"
+    explain: "Ceci signe une demande de connexion à usage unique. Votre clé n'est pas partagée et le site ne peut pas agir en votre nom."
+    pass_prompt: "Saisissez le mot de passe de votre portefeuille pour vous connecter."
+    confirm: "Se connecter"
+    sent: "Connecté à %{domain}"
+    failed: "Impossible de joindre %{domain}. La connexion n'a pas été transmise."
   identities:
     title: "Identités"
     switch_hint: "Changer d'identité"
diff --git a/locales/ru.yml b/locales/ru.yml
index 5b0460dd..827d98af 100644
--- a/locales/ru.yml
+++ b/locales/ru.yml
@@ -683,6 +683,15 @@ goblin:
     title: "Подтвердить %{n} счетов"
     blurb: "Выставить %{n} запросов на оплату по %{amount} каждый для %{name} — всего %{total}. Каждый запрос получает свой новый платёжный адрес."
     approve: "Подтвердить"
+  login:
+    title: "Вход"
+    headline: "Войти на %{domain}?"
+    identity: "Войти как"
+    explain: "Будет подписан одноразовый запрос на вход. Ваш ключ не передаётся, и сайт не сможет действовать от вашего имени."
+    pass_prompt: "Введите пароль кошелька, чтобы войти."
+    confirm: "Войти"
+    sent: "Выполнен вход на %{domain}"
+    failed: "Не удалось связаться с %{domain}. Вход не был выполнен."
   identities:
     title: "Личности"
     switch_hint: "Сменить личность"
diff --git a/locales/tr.yml b/locales/tr.yml
index 35d7cbf3..2cb6eb62 100644
--- a/locales/tr.yml
+++ b/locales/tr.yml
@@ -683,6 +683,15 @@ goblin:
     title: "%{n} faturayı onayla"
     blurb: "%{name} için her biri %{amount} olan %{n} ödeme isteği düzenle — toplam %{total}. Her istek kendi yeni ödeme adresini alır."
     approve: "Onayla"
+  login:
+    title: "Giriş yap"
+    headline: "%{domain} sitesine giriş yapılsın mı?"
+    identity: "Giriş yapılacak kimlik"
+    explain: "Bu, tek seferlik bir giriş isteğini imzalar. Anahtarın paylaşılmaz ve site senin adına işlem yapamaz."
+    pass_prompt: "Giriş yapmak için cüzdan parolanı gir."
+    confirm: "Giriş yap"
+    sent: "%{domain} girişi yapıldı"
+    failed: "%{domain} adresine ulaşılamadı. Giriş iletilemedi."
   identities:
     title: "Kimlikler"
     switch_hint: "Kimlik değiştir"
diff --git a/locales/zh-CN.yml b/locales/zh-CN.yml
index 379156e9..cbdb174f 100644
--- a/locales/zh-CN.yml
+++ b/locales/zh-CN.yml
@@ -683,6 +683,15 @@ goblin:
     title: "批准 %{n} 张发票"
     blurb: "向 %{name} 发出 %{n} 个付款请求，每个 %{amount}，共 %{total}。每个请求都有自己全新的收款地址。"
     approve: "批准"
+  login:
+    title: "登录"
+    headline: "登录 %{domain}？"
+    identity: "登录身份"
+    explain: "这将签署一次性的登录请求。不会分享你的密钥，网站也无法以你的身份行事。"
+    pass_prompt: "输入钱包密码以登录。"
+    confirm: "登录"
+    sent: "已登录 %{domain}"
+    failed: "无法连接 %{domain}，登录未送达。"
   identities:
     title: "身份"
     switch_hint: "切换身份"
diff --git a/src/gui/views/goblin/mod.rs b/src/gui/views/goblin/mod.rs
index 9b91f773..7283081f 100644
--- a/src/gui/views/goblin/mod.rs
+++ b/src/gui/views/goblin/mod.rs
@@ -137,6 +137,12 @@ pub struct GoblinWalletView {
 	back_hint: Option<std::time::Instant>,
 	/// A batch invoice request awaiting approval (count=N deep link).
 	batch_invoice: Option<BatchInvoiceState>,
+	/// A "Sign in with Goblin" login request awaiting approval (deep link or
+	/// scanned QR), including the callback POST once approved. While this is
+	/// `Some`, every new incoming login URI is ignored (one at a time).
+	login: Option<LoginState>,
+	/// Quiet toast for the login outcome: text and when it appeared.
+	login_toast: Option<(String, std::time::Instant)>,
 }
 
 /// Whether the per-identity cue is drawn on activity rows (owner-approved). The
@@ -269,6 +275,8 @@ impl Default for GoblinWalletView {
 			min_conf_edit: String::new(),
 			back_hint: None,
 			batch_invoice: None,
+			login: None,
+			login_toast: None,
 		}
 	}
 }
@@ -348,6 +356,40 @@ const MIN_CONF_MODAL: &str = "goblin_min_conf_modal";
 /// one approval for N payment requests, each on its own fresh proof address.
 const BATCH_INVOICE_MODAL: &str = "goblin_batch_invoice_modal";
 
+/// Id of the "Sign in with Goblin" approval modal: the user reviews the
+/// requesting domain, picks the signing identity, and confirms with the
+/// wallet password before the one-time challenge is signed.
+const LOGIN_MODAL: &str = "goblin_login_modal";
+
+/// A pending, untouched login approval expires after this many seconds (the
+/// modal closes and the request is dropped).
+const LOGIN_EXPIRY_SECS: u64 = 120;
+
+/// The login callback POST gives up after this many seconds.
+const LOGIN_POST_TIMEOUT_SECS: u64 = 15;
+
+/// One pending "Sign in with Goblin" approval. Single-use by construction:
+/// once the event is signed (`posting`), or on cancel/expiry, the state is
+/// dropped and only a fresh URI can start another.
+struct LoginState {
+	/// The validated request (challenge, domain, callback).
+	uri: crate::nostr::loginuri::LoginUri,
+	/// The CHOSEN signing identity (pubkey hex); defaults to the active one.
+	selected: String,
+	/// When the request arrived, for the [`LOGIN_EXPIRY_SECS`] deadline.
+	created: std::time::Instant,
+	/// Wallet password typed into the modal; cleared as soon as consumed.
+	pass: String,
+	/// The typed password did not verify: show the wrong-password line. The
+	/// request itself stays pending (a typo never consumes it).
+	wrong_pass: bool,
+	/// The event is signed and the callback POST is in flight; the request is
+	/// consumed either way once the worker reports back.
+	posting: bool,
+	/// Result slot the POST worker thread fills.
+	result: std::sync::Arc<std::sync::Mutex<Option<Result<(), String>>>>,
+}
+
 /// A password-gated identity action the modal executes. Switching no longer uses
 /// the modal (it is instant and local); only these need the wallet password.
 #[derive(Clone)]
@@ -619,8 +661,14 @@ impl GoblinWalletView {
 			self.settings_page = SettingsPage::Main;
 			self.advanced = AdvancedState::default();
 			self.identity_switch = IdentitySwitchState::default();
+			self.login = None;
+			self.login_toast = None;
 		}
 
+		// Transient login-outcome toast (drawn as a Foreground area, so it rides
+		// above whatever surface or overlay is showing).
+		self.login_toast_ui(ui.ctx());
+
 		// A pending payment deep link (`goblin:` / `nostr:` pay URI, routed here
 		// from an OS launch/open) opens a prefilled send-review flow — the exact
 		// destination a scanned checkout QR lands on. A BATCH invoice-request
@@ -668,6 +716,76 @@ impl GoblinWalletView {
 			});
 		}
 
+		// A pending "Sign in with Goblin" request (deep link or scanned QR,
+		// already fully validated at the dispatch site). One approval at a
+		// time: while one is pending (modal open or POST in flight), any new
+		// incoming login request is dropped; re-triggering needs a fresh URI.
+		if let Some(login) = crate::take_pending_login() {
+			if self.login.is_none() {
+				if let Some(active) = wallet.active_nostr_pubkey() {
+					// The approval takes over from any open scan/send flow.
+					self.send = None;
+					self.login = Some(LoginState {
+						uri: login,
+						selected: active,
+						created: std::time::Instant::now(),
+						pass: String::new(),
+						wrong_pass: false,
+						posting: false,
+						result: std::sync::Arc::new(std::sync::Mutex::new(None)),
+					});
+					Modal::new(LOGIN_MODAL)
+						.position(ModalPosition::CenterTop)
+						.title(t!("goblin.login.title"))
+						.show();
+				}
+			}
+		}
+		// An untouched approval dies after 2 minutes: modal closed, request
+		// dropped. The signed-and-posting phase is governed by the POST
+		// timeout instead, so it is exempt here.
+		let login_expired = matches!(&self.login, Some(st)
+			if !st.posting && st.created.elapsed().as_secs() >= LOGIN_EXPIRY_SECS);
+		if login_expired {
+			self.login = None;
+			if Modal::opened() == Some(LOGIN_MODAL) {
+				Modal::close();
+			}
+		}
+		// Poll the callback POST; the request is consumed either way and the
+		// outcome shows as a quiet toast (distinct success/failure strings).
+		let mut login_outcome = None;
+		if let Some(st) = &self.login {
+			if st.posting {
+				login_outcome = st
+					.result
+					.lock()
+					.unwrap()
+					.take()
+					.map(|res| (res, st.uri.domain.clone()));
+				if login_outcome.is_none() {
+					ui.ctx().request_repaint();
+				}
+			}
+		}
+		if let Some((res, domain)) = login_outcome {
+			let text = match res {
+				Ok(()) => t!("goblin.login.sent", domain => domain).to_string(),
+				Err(e) => {
+					log::warn!("sign-in callback failed: {e}");
+					t!("goblin.login.failed", domain => domain).to_string()
+				}
+			};
+			self.login_toast = Some((text, std::time::Instant::now()));
+			self.login = None;
+		}
+		// The sign-in approval modal itself.
+		if Modal::opened() == Some(LOGIN_MODAL) {
+			Modal::ui(ui.ctx(), cb, |ui, modal, cb| {
+				self.login_modal_content(ui, modal, wallet, cb);
+			});
+		}
+
 		// Send flow takes the full surface when active.
 		if let Some(send) = &mut self.send {
 			let done = send.ui(ui, wallet, cb, &mut self.avatars);
@@ -5881,6 +5999,309 @@ impl GoblinWalletView {
 		}
 	}
 
+	/// Content of the "Sign in with Goblin" approval modal: the requesting
+	/// domain up top, the signing identity (a picker when several are held;
+	/// the truncated npub is always visible as the anchor), a one-line plain
+	/// explanation, the wallet password, and uniform paired Cancel / Sign in
+	/// buttons. Approving signs the one-time kind-22242 challenge with the
+	/// CHOSEN identity's key and POSTs it to the callback off the UI thread;
+	/// a wrong password stays in the modal without consuming the request.
+	fn login_modal_content(
+		&mut self,
+		ui: &mut egui::Ui,
+		modal: &Modal,
+		wallet: &Wallet,
+		cb: &dyn PlatformCallbacks,
+	) {
+		let Some(st) = self.login.as_mut() else {
+			Modal::close();
+			return;
+		};
+		if st.posting {
+			// Already signed and in flight; nothing left to gate here.
+			Modal::close();
+			return;
+		}
+		let domain = st.uri.domain.clone();
+		let identities = wallet.nostr_identities();
+		let mut go = false;
+		let mut cancel = false;
+		ui.vertical_centered(|ui| {
+			ui.add_space(6.0);
+			// Headline with the requesting domain prominent.
+			ui.label(
+				RichText::new(t!("goblin.login.headline", domain => domain.clone()))
+					.size(17.0)
+					.color(Colors::title(false)),
+			);
+			ui.add_space(10.0);
+			// The signing identity. Display precedence is the switcher's:
+			// private tag, else bare claimed name, else truncated npub — and
+			// the truncated npub is ALWAYS shown as the anchor.
+			ui.label(
+				RichText::new(t!("goblin.login.identity"))
+					.size(13.0)
+					.color(Colors::gray()),
+			);
+			ui.add_space(6.0);
+			if identities.len() > 1 {
+				// Identity picker: the held-identities list, tap to choose
+				// which one signs. Defaults to the active identity.
+				for id in &identities {
+					let selected = st.selected == id.pubkey_hex;
+					let title = id.display();
+					let short = data::short_npub(&id.pubkey_hex);
+					let row = ui
+						.scope(|ui| {
+							ui.horizontal(|ui| {
+								ui.add_space(4.0);
+								ui.label(
+									RichText::new(if selected {
+										crate::gui::icons::CHECK_CIRCLE
+									} else {
+										crate::gui::icons::CIRCLE
+									})
+									.size(18.0)
+									.color(if selected {
+										Colors::green()
+									} else {
+										Colors::gray()
+									}),
+								);
+								ui.add_space(8.0);
+								ui.vertical(|ui| {
+									if title != short {
+										ui.label(
+											RichText::new(&title)
+												.size(15.0)
+												.color(Colors::text(false)),
+										);
+									}
+									ui.label(
+										RichText::new(&short).size(12.5).color(Colors::gray()),
+									);
+								});
+							});
+						})
+						.response
+						.rect;
+					let hit = ui.interact(
+						row,
+						egui::Id::from(modal.id).with(("login_id", id.pubkey_hex.as_str())),
+						Sense::click(),
+					);
+					if hit
+						.on_hover_cursor(egui::CursorIcon::PointingHand)
+						.clicked()
+					{
+						st.selected = id.pubkey_hex.clone();
+					}
+					ui.add_space(4.0);
+				}
+			} else if let Some(id) = identities.first() {
+				let title = id.display();
+				let short = data::short_npub(&id.pubkey_hex);
+				if title != short {
+					ui.label(RichText::new(&title).size(15.0).color(Colors::text(false)));
+				}
+				ui.label(RichText::new(&short).size(12.5).color(Colors::gray()));
+			}
+			ui.add_space(10.0);
+			// One plain line on what approving does (and does not do).
+			ui.label(
+				RichText::new(t!("goblin.login.explain"))
+					.size(13.0)
+					.color(Colors::gray()),
+			);
+			ui.add_space(10.0);
+			// The wallet password gates the signature, mirroring the identity
+			// password modal (masked field, same wrong-password line).
+			ui.label(
+				RichText::new(t!("goblin.login.pass_prompt"))
+					.size(16.0)
+					.color(Colors::gray()),
+			);
+			ui.add_space(10.0);
+			let mut field = TextEdit::new(egui::Id::from(modal.id).with("login_pass")).password();
+			field.ui(ui, &mut st.pass, cb);
+			if field.enter_pressed {
+				go = true;
+			}
+			if st.pass.is_empty() {
+				st.wrong_pass = false;
+			} else if st.wrong_pass {
+				ui.add_space(10.0);
+				ui.label(
+					RichText::new(t!("goblin.advanced.wrong_password"))
+						.size(16.0)
+						.color(Colors::red()),
+				);
+			}
+			ui.add_space(12.0);
+		});
+		ui.scope(|ui| {
+			ui.spacing_mut().item_spacing = egui::Vec2::new(8.0, 0.0);
+			ui.columns(2, |columns| {
+				columns[0].vertical_centered_justified(|ui| {
+					View::button(
+						ui,
+						t!("modal.cancel"),
+						Colors::white_or_black(false),
+						|| {
+							cancel = true;
+						},
+					);
+				});
+				columns[1].vertical_centered_justified(|ui| {
+					View::button(
+						ui,
+						t!("goblin.login.confirm"),
+						Colors::white_or_black(false),
+						|| {
+							go = true;
+						},
+					);
+				});
+			});
+			ui.add_space(6.0);
+		});
+		if cancel {
+			// Cancel drops the request: it is single-use, no retry.
+			self.login = None;
+			Modal::close();
+			return;
+		}
+		if go {
+			let (pass, selected) = match self.login.as_ref() {
+				Some(st) => (st.pass.clone(), st.selected.clone()),
+				None => return,
+			};
+			if pass.is_empty() {
+				return;
+			}
+			if !wallet.verify_nostr_password(&pass) {
+				// Wrong password: stay in the modal, request NOT consumed.
+				if let Some(st) = self.login.as_mut() {
+					st.wrong_pass = true;
+				}
+				return;
+			}
+			// The chosen identity's unlocked in-memory keys, from the running
+			// service (the Build-145 model: every held identity is unlocked).
+			let keys = wallet.nostr_service().and_then(|s| {
+				s.recv_snapshot()
+					.into_iter()
+					.find(|h| h.keys.public_key().to_hex() == selected)
+					.map(|h| h.keys)
+			});
+			let Some(keys) = keys else {
+				// No running service / identity gone: drop the request.
+				self.login = None;
+				Modal::close();
+				return;
+			};
+			let st = self.login.as_mut().unwrap();
+			st.pass.clear();
+			st.wrong_pass = false;
+			match crate::nostr::loginuri::build_login_event(
+				&keys,
+				&st.uri.challenge,
+				&st.uri.domain,
+			) {
+				Ok(event) => {
+					// Signed: the request is consumed from here on, whatever
+					// the POST outcome. Deliver off the UI thread with the
+					// shared HTTP client and a hard timeout.
+					st.posting = true;
+					let callback = st.uri.callback.clone();
+					let slot = st.result.clone();
+					std::thread::spawn(move || {
+						let res = match tokio::runtime::Builder::new_current_thread()
+							.enable_all()
+							.build()
+						{
+							Ok(rt) => rt.block_on(async {
+								let post =
+									crate::nostr::loginuri::post_login_event(&callback, &event);
+								match tokio::time::timeout(
+									std::time::Duration::from_secs(LOGIN_POST_TIMEOUT_SECS),
+									post,
+								)
+								.await
+								{
+									Ok(r) => r,
+									Err(_) => Err("timeout".to_string()),
+								}
+							}),
+							Err(e) => Err(e.to_string()),
+						};
+						*slot.lock().unwrap() = Some(res);
+					});
+					Modal::close();
+				}
+				Err(e) => {
+					// Signing failed (never expected): consume the request and
+					// surface the quiet failure toast.
+					log::error!("login event signing failed: {e}");
+					self.login_toast = Some((
+						t!("goblin.login.failed", domain => domain).to_string(),
+						std::time::Instant::now(),
+					));
+					self.login = None;
+					Modal::close();
+				}
+			}
+		}
+	}
+
+	/// Draw the transient login-outcome toast: the same quiet pill as the back
+	/// hint (solid soft pill, no border, small dim text), bottom-anchored,
+	/// non-blocking, fading out.
+	fn login_toast_ui(&mut self, ctx: &egui::Context) {
+		const SHOW_SECS: f32 = 3.5;
+		let Some((text, at)) = &self.login_toast else {
+			return;
+		};
+		let elapsed = at.elapsed().as_secs_f32();
+		if elapsed >= SHOW_SECS {
+			self.login_toast = None;
+			return;
+		}
+		let text = text.clone();
+		let t = theme::tokens();
+		// Fade over the final 0.5s.
+		let alpha = ((SHOW_SECS - elapsed) / 0.5).clamp(0.0, 1.0);
+		let font = FontId::new(13.0, fonts::regular());
+		egui::Area::new(egui::Id::new("goblin_login_toast"))
+			.order(egui::Order::Foreground)
+			.anchor(
+				egui::Align2::CENTER_BOTTOM,
+				Vec2::new(0.0, -(View::get_bottom_inset() + 92.0)),
+			)
+			.interactable(false)
+			.show(ctx, |ui| {
+				let galley = ui
+					.painter()
+					.layout_no_wrap(text, font.clone(), t.surface_text_dim);
+				let pad = Vec2::new(16.0, 10.0);
+				let size = galley.size() + pad * 2.0;
+				let (rect, _) = ui.allocate_exact_size(size, Sense::hover());
+				ui.painter().rect(
+					rect,
+					CornerRadius::same((size.y / 2.0) as u8),
+					t.surface2.gamma_multiply(alpha),
+					Stroke::NONE,
+					egui::StrokeKind::Inside,
+				);
+				ui.painter().galley(
+					rect.min + pad,
+					galley,
+					t.surface_text_dim.gamma_multiply(alpha),
+				);
+			});
+		ctx.request_repaint_after(std::time::Duration::from_millis(50));
+	}
+
 	/// Inline username-claim widget (availability check + registration).
 	fn claim_ui(&mut self, ui: &mut egui::Ui, wallet: &Wallet, cb: &dyn PlatformCallbacks) {
 		let t = theme::tokens();
diff --git a/src/gui/views/goblin/send.rs b/src/gui/views/goblin/send.rs
index 05605091..6c9c5ac1 100644
--- a/src/gui/views/goblin/send.rs
+++ b/src/gui/views/goblin/send.rs
@@ -239,6 +239,17 @@ impl SendFlow {
 	/// handler so both spell the same destination. `now` seeds the search-box
 	/// debounce.
 	fn apply_scan(&mut self, text: &str, wallet: &Wallet, now: f64) {
+		// A "Sign in with Goblin" login URI is grabbed BEFORE any pay parsing
+		// (mirroring the deep-link dispatcher): it is never a payment, and a
+		// login-shaped payload that fails validation is dropped entirely. A
+		// valid one is stashed for the Goblin surface, whose per-frame router
+		// closes this flow and opens the approval modal.
+		if crate::nostr::loginuri::is_login_shaped(text) {
+			if let Some(login) = crate::nostr::loginuri::parse(text) {
+				crate::set_pending_login(login);
+			}
+			return;
+		}
 		// Proof-on-request context (frozen contract 4.1) rides alongside the
 		// recipient/amount/memo routing and is independent of whether we land on
 		// Review or Search, so pull it from the same pure parse. `order` is a
diff --git a/src/gui/views/wallets/content.rs b/src/gui/views/wallets/content.rs
index bbfe733e..d2b4ec50 100644
--- a/src/gui/views/wallets/content.rs
+++ b/src/gui/views/wallets/content.rs
@@ -491,11 +491,24 @@ impl WalletsContent {
 		if !Content::is_dual_panel_mode(ui.ctx()) && Content::is_network_panel_open() {
 			Content::toggle_network_panel();
 		}
-		// Route a Goblin payment deep link (`goblin:` / `nostr:` pay URI) to the
-		// send-review flow instead of the slatepack message handler: stash it for
-		// the Goblin surface to open, and select/open the wallet with NO message
-		// so the surface shows. Same destination as scanning a checkout QR.
+		// Dispatch order is explicit: the `login` keyword is checked FIRST, so a
+		// `goblin:login?...` deep link can never fall through to the pay path
+		// (and a pay URI is never login-shaped: an npub/nprofile recipient
+		// always starts `npub1`/`nprofile1`). A login-shaped URI that fails
+		// validation is dropped entirely: no modal, no send, no message.
+		//
+		// Then a Goblin payment deep link (`goblin:` / `nostr:` pay URI) routes
+		// to the send-review flow instead of the slatepack message handler:
+		// stash it for the Goblin surface to open, and select/open the wallet
+		// with NO message so the surface shows. Same destination as scanning a
+		// checkout QR.
 		let data = match data {
+			Some(d) if crate::nostr::loginuri::is_login_shaped(&d) => {
+				if let Some(login) = crate::nostr::loginuri::parse(&d) {
+					crate::set_pending_login(login);
+				}
+				None
+			}
 			Some(d) if crate::nostr::payuri::is_pay_uri(&d) => {
 				crate::set_pending_pay_uri(d);
 				None
diff --git a/src/lib.rs b/src/lib.rs
index 6e025d42..921862da 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -559,6 +559,13 @@ lazy_static! {
 	/// slatepack message handler. Consumed by the Goblin view once a wallet is
 	/// open and showing.
 	static ref PENDING_PAY_URI: Arc<RwLock<Option<String>>> = Arc::new(RwLock::new(None));
+	/// A pending, already-VALIDATED "Sign in with Goblin" login request
+	/// (`goblin:login?...` deep link or QR), waiting for the Goblin surface to
+	/// open its approval modal. Only a fully validated [`nostr::loginuri::LoginUri`]
+	/// is ever stashed here; rejected login URIs are dropped at the dispatch
+	/// site and never reach the UI.
+	static ref PENDING_LOGIN: Arc<RwLock<Option<nostr::loginuri::LoginUri>>> =
+		Arc::new(RwLock::new(None));
 }
 
 /// Stash a payment deep link for the Goblin surface to open (see
@@ -573,6 +580,19 @@ pub fn take_pending_pay_uri() -> Option<String> {
 	PENDING_PAY_URI.write().take()
 }
 
+/// Stash a VALIDATED login request for the Goblin surface to open its approval
+/// modal (see [`take_pending_login`]). The most recent request wins here; the
+/// surface itself ignores new requests while one approval is already pending.
+pub fn set_pending_login(login: nostr::loginuri::LoginUri) {
+	*PENDING_LOGIN.write() = Some(login);
+}
+
+/// Take (and clear) a pending login request, if any. The Goblin wallet view
+/// polls this each frame and opens the sign-in approval modal for it.
+pub fn take_pending_login() -> Option<nostr::loginuri::LoginUri> {
+	PENDING_LOGIN.write().take()
+}
+
 /// Callback from Java code with passed data.
 #[allow(dead_code)]
 #[allow(non_snake_case)]
diff --git a/src/nostr/loginuri.rs b/src/nostr/loginuri.rs
new file mode 100644
index 00000000..556692ec
--- /dev/null
+++ b/src/nostr/loginuri.rs
@@ -0,0 +1,445 @@
+// Copyright 2026 The Goblin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! "Sign in with Goblin" login-URI parser and one-time login-event signer.
+//!
+//! A site (magick.market) asks the wallet to approve a one-time login by
+//! handing it a challenge over either the `goblin:` deep-link scheme or the
+//! equivalent `nostr:` QR payload:
+//!
+//! ```text
+//! goblin:login?c=<64-hex nonce>&d=<domain>&cb=<https callback URL>
+//! nostr:login?c=<64-hex nonce>&d=<domain>&cb=<https callback URL>
+//! ```
+//!
+//! On approval the wallet signs a kind-22242 event (content empty, tags
+//! `[["challenge", c], ["domain", d]]`) with the CHOSEN identity's key and
+//! POSTs it to the callback as `{"event": <event-json>}`. The signed event
+//! proves control of the key for this one nonce; it shares no secret and
+//! grants the site no capability to act as the user.
+//!
+//! Parsing is PURE and fail-closed over UNTRUSTED input, mirroring
+//! [`crate::nostr::payuri`] (same scheme handling, same percent-decoding,
+//! first occurrence of a duplicate param wins). A login-shaped URI that fails
+//! validation is REJECTED as a whole — it is never fed to the pay path and it
+//! never opens an approval modal. The `login` keyword cannot collide with a
+//! pay recipient: a bech32 npub/nprofile always starts `npub1`/`nprofile1`.
+
+use super::payuri::{percent_decode, strip_pay_scheme};
+use nostr_sdk::{Event, EventBuilder, Keys, Kind, Tag, TagKind};
+
+/// Total payload byte cap, same bar as the pay-URI parser.
+const MAX_URI_LEN: usize = 4096;
+/// Domain byte cap (a DNS name is at most 253 bytes).
+const MAX_DOMAIN_LEN: usize = 253;
+/// Callback URL byte cap.
+const MAX_CALLBACK_LEN: usize = 2048;
+
+/// The nostr event kind of a signed login challenge (NIP-42 client auth).
+pub const LOGIN_EVENT_KIND: u16 = 22242;
+
+/// A validated login request: the one-time challenge nonce, the requesting
+/// domain the user approves, and the HTTPS callback the signed event is
+/// POSTed to. Only constructed by [`parse`], so holding one means every field
+/// already passed validation.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct LoginUri {
+	/// The one-time challenge nonce, exactly 64 hex chars.
+	pub challenge: String,
+	/// The requesting domain, shown to the user for approval.
+	pub domain: String,
+	/// The callback URL the signed event is delivered to: `https://...`, or
+	/// `http://localhost[:port]...` for development.
+	pub callback: String,
+}
+
+/// True when `scanned` carries a Goblin scheme with the `login` keyword, i.e.
+/// it is a login request (valid or not) and must NEVER be fed to the pay
+/// path. The dispatcher checks this BEFORE [`super::payuri::is_pay_uri`]; a
+/// shaped-but-invalid login URI is then dropped entirely (no modal, no send).
+pub fn is_login_shaped(scanned: &str) -> bool {
+	let text = scanned.trim();
+	if text.len() > MAX_URI_LEN {
+		return false;
+	}
+	match strip_pay_scheme(text) {
+		Some(rest) => {
+			let head = rest.split('?').next().unwrap_or("");
+			head.eq_ignore_ascii_case("login")
+		}
+		None => false,
+	}
+}
+
+/// Parse a login URI. `Some` only when EVERY field validates: `c` is exactly
+/// 64 hex chars, `d` is non-empty, and `cb` is `https://` (or
+/// `http://localhost[:port]` for dev). Anything else is `None` and the whole
+/// request is ignored. Pure, total, no I/O.
+pub fn parse(scanned: &str) -> Option<LoginUri> {
+	let text = scanned.trim();
+	if text.len() > MAX_URI_LEN || text.as_bytes().contains(&0) {
+		return None;
+	}
+	let rest = strip_pay_scheme(text)?;
+	let (head, query) = rest.split_once('?')?;
+	if !head.eq_ignore_ascii_case("login") {
+		return None;
+	}
+	let mut challenge = None;
+	let mut domain = None;
+	let mut callback = None;
+	for pair in query.split('&') {
+		let Some((key, val)) = pair.split_once('=') else {
+			continue; // valueless / malformed segment, ignore
+		};
+		match key {
+			// First occurrence wins, matching the pay-URI convention, so a
+			// second `cb=` can never override a validated one.
+			"c" if challenge.is_none() => challenge = Some(val),
+			"d" if domain.is_none() => domain = Some(val),
+			"cb" if callback.is_none() => callback = Some(val),
+			// Unknown params are ignored for forward-compat.
+			_ => {}
+		}
+	}
+	let challenge = validate_challenge(challenge?)?;
+	let domain = validate_domain(domain?)?;
+	let callback = validate_callback(callback?)?;
+	Some(LoginUri {
+		challenge,
+		domain,
+		callback,
+	})
+}
+
+/// The challenge nonce must be exactly 64 hex chars (a 32-byte value): wrong
+/// length or any non-hex char rejects the whole URI.
+fn validate_challenge(raw: &str) -> Option<String> {
+	let decoded = String::from_utf8_lossy(&percent_decode(raw)).into_owned();
+	if decoded.len() == 64 && decoded.chars().all(|c| c.is_ascii_hexdigit()) {
+		Some(decoded)
+	} else {
+		None
+	}
+}
+
+/// The domain must be non-empty, printable ASCII without spaces, and within
+/// DNS length bounds. It is DISPLAY data (the user approves it by eye) and a
+/// tag value, never a route, so a shape check is enough.
+fn validate_domain(raw: &str) -> Option<String> {
+	let decoded = String::from_utf8_lossy(&percent_decode(raw)).into_owned();
+	let decoded = decoded.trim();
+	if decoded.is_empty()
+		|| decoded.len() > MAX_DOMAIN_LEN
+		|| !decoded.chars().all(|c| c.is_ascii_graphic())
+	{
+		return None;
+	}
+	Some(decoded.to_string())
+}
+
+/// The callback must be `https://...`, or `http://localhost[:port]...` as the
+/// one development exception. Everything else (plain http, ftp, garbage)
+/// rejects the whole URI so a signed event can never be posted somewhere
+/// unexpected in the clear.
+fn validate_callback(raw: &str) -> Option<String> {
+	let decoded = String::from_utf8_lossy(&percent_decode(raw)).into_owned();
+	let decoded = decoded.trim();
+	if decoded.len() > MAX_CALLBACK_LEN || decoded.bytes().any(|b| b < 0x20 || b == 0x7f) {
+		return None;
+	}
+	if let Some(rest) = strip_prefix_ignore_case(decoded, "https://") {
+		if !rest.is_empty() {
+			return Some(decoded.to_string());
+		}
+		return None;
+	}
+	if let Some(rest) = strip_prefix_ignore_case(decoded, "http://") {
+		if is_localhost_authority(rest) {
+			return Some(decoded.to_string());
+		}
+	}
+	None
+}
+
+/// Strip a case-insensitive ASCII prefix.
+fn strip_prefix_ignore_case<'a>(s: &'a str, prefix: &str) -> Option<&'a str> {
+	let n = prefix.len();
+	match s.get(..n) {
+		Some(head) if head.eq_ignore_ascii_case(prefix) => Some(&s[n..]),
+		_ => None,
+	}
+}
+
+/// True when the URL remainder after `http://` names exactly `localhost`,
+/// optionally with a `:port` (a valid non-zero u16), followed by nothing or a
+/// `/ ? #` delimiter. `localhost.evil.com` and friends do NOT pass.
+fn is_localhost_authority(rest: &str) -> bool {
+	let authority_end = rest
+		.find(|c| c == '/' || c == '?' || c == '#')
+		.unwrap_or(rest.len());
+	let authority = &rest[..authority_end];
+	let (host, port) = match authority.split_once(':') {
+		Some((h, p)) => (h, Some(p)),
+		None => (authority, None),
+	};
+	if !host.eq_ignore_ascii_case("localhost") {
+		return false;
+	}
+	match port {
+		None => true,
+		Some(p) => {
+			!p.is_empty()
+				&& p.chars().all(|c| c.is_ascii_digit())
+				&& p.parse::<u16>().map(|n| n > 0).unwrap_or(false)
+		}
+	}
+}
+
+/// Build and sign the one-time login event with the CHOSEN identity's keys:
+/// kind 22242, empty content, tags exactly
+/// `[["challenge", challenge], ["domain", domain]]`, `created_at` now. The
+/// signature proves control of the key for this one nonce; nothing secret
+/// leaves the wallet.
+pub fn build_login_event(keys: &Keys, challenge: &str, domain: &str) -> Result<Event, String> {
+	EventBuilder::new(Kind::Custom(LOGIN_EVENT_KIND), "")
+		.tags(vec![
+			Tag::custom(TagKind::custom("challenge"), [challenge.to_string()]),
+			Tag::custom(TagKind::custom("domain"), [domain.to_string()]),
+		])
+		.sign_with_keys(keys)
+		.map_err(|e| e.to_string())
+}
+
+/// POST the signed login event to the callback as `{"event": <event-json>}`.
+/// Goes through the app's shared [`crate::http::HttpClient`], so it follows
+/// the exact same transport policy (proxy settings included) as every other
+/// clearnet call. The caller wraps this in its own timeout.
+pub async fn post_login_event(callback: &str, event: &Event) -> Result<(), String> {
+	let body = serde_json::json!({ "event": event }).to_string();
+	let req = hyper::Request::builder()
+		.method(hyper::Method::POST)
+		.uri(callback)
+		.header("Content-Type", "application/json")
+		.header("User-Agent", "goblin-wallet")
+		.body(http_body_util::Full::new(bytes::Bytes::from(body)))
+		.map_err(|e| e.to_string())?;
+	let resp = crate::http::HttpClient::send(req)
+		.await
+		.map_err(|e| e.to_string())?;
+	let status = resp.status().as_u16();
+	if (200..300).contains(&status) {
+		Ok(())
+	} else {
+		Err(format!("callback returned status {status}"))
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	/// A well-formed 64-hex challenge nonce.
+	const C: &str = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+	/// A real, valid bech32 npub (the Goblin news key), for the pay-vs-login
+	/// dispatch tests.
+	const NPUB: &str = "npub15gsytqvs5c78u83yv2agl4twjkk6qgem7gtwe2agu7s90tkelxys0xxely";
+
+	fn valid_uri(scheme: &str) -> String {
+		format!("{scheme}login?c={C}&d=magick.market&cb=https://magick.market/api/login")
+	}
+
+	#[test]
+	fn valid_goblin_and_nostr_login_accepted() {
+		for scheme in ["goblin:", "nostr:"] {
+			let out = parse(&valid_uri(scheme)).expect("valid login URI must parse");
+			assert_eq!(out.challenge, C);
+			assert_eq!(out.domain, "magick.market");
+			assert_eq!(out.callback, "https://magick.market/api/login");
+		}
+	}
+
+	#[test]
+	fn scheme_and_keyword_case_insensitive() {
+		let uri = format!("GOBLIN:LOGIN?c={C}&d=magick.market&cb=https://magick.market/cb");
+		let out = parse(&uri).expect("uppercase scheme/keyword must parse");
+		assert_eq!(out.domain, "magick.market");
+		assert!(is_login_shaped(&uri));
+	}
+
+	#[test]
+	fn challenge_must_be_exactly_64_hex() {
+		// Wrong length: 63, 65, empty.
+		for bad in [&C[..63], &format!("{C}0")[..], ""] {
+			let uri = format!("goblin:login?c={bad}&d=magick.market&cb=https://m.m/cb");
+			assert_eq!(parse(&uri), None, "expected c={bad:?} to be rejected");
+		}
+		// Right length, non-hex chars.
+		let bad = format!("{}zz", &C[..62]);
+		let uri = format!("goblin:login?c={bad}&d=magick.market&cb=https://m.m/cb");
+		assert_eq!(parse(&uri), None, "non-hex challenge must be rejected");
+	}
+
+	#[test]
+	fn empty_domain_rejected() {
+		let uri = format!("goblin:login?c={C}&d=&cb=https://magick.market/cb");
+		assert_eq!(parse(&uri), None);
+		// Whitespace-only after decode is also empty.
+		let uri = format!("goblin:login?c={C}&d=%20%20&cb=https://magick.market/cb");
+		assert_eq!(parse(&uri), None);
+	}
+
+	#[test]
+	fn missing_params_rejected() {
+		assert_eq!(
+			parse(&format!("goblin:login?d=m.m&cb=https://m.m/cb")),
+			None
+		);
+		assert_eq!(
+			parse(&format!("goblin:login?c={C}&cb=https://m.m/cb")),
+			None
+		);
+		assert_eq!(parse(&format!("goblin:login?c={C}&d=m.m")), None);
+		assert_eq!(parse("goblin:login"), None);
+		assert_eq!(parse("goblin:login?"), None);
+	}
+
+	#[test]
+	fn non_localhost_http_callback_rejected() {
+		for bad in [
+			"http://magick.market/cb",
+			"http://localhost.evil.com/cb",
+			"http://evillocalhost/cb",
+			"http://localhost:0/cb",
+			"http://localhost:99999/cb",
+			"http://localhost:12a/cb",
+		] {
+			let uri = format!("goblin:login?c={C}&d=magick.market&cb={bad}");
+			assert_eq!(parse(&uri), None, "expected cb={bad:?} to be rejected");
+		}
+	}
+
+	#[test]
+	fn ftp_and_garbage_callback_rejected() {
+		for bad in [
+			"ftp://magick.market/cb",
+			"javascript:alert(1)",
+			"m.m/cb",
+			"",
+		] {
+			let uri = format!("goblin:login?c={C}&d=magick.market&cb={bad}");
+			assert_eq!(parse(&uri), None, "expected cb={bad:?} to be rejected");
+		}
+	}
+
+	#[test]
+	fn localhost_callback_accepted_for_dev() {
+		for ok in [
+			"http://localhost:3000/api/login",
+			"http://localhost/cb",
+			"http://localhost:3000",
+		] {
+			let uri = format!("goblin:login?c={C}&d=magick.market&cb={ok}");
+			let out = parse(&uri).unwrap_or_else(|| panic!("expected cb={ok:?} accepted"));
+			assert_eq!(out.callback, ok);
+		}
+	}
+
+	#[test]
+	fn percent_encoded_callback_decoded() {
+		let cb = "https%3A%2F%2Fmagick.market%2Fapi%2Flogin%3Fs%3D1";
+		let uri = format!("goblin:login?c={C}&d=magick.market&cb={cb}");
+		let out = parse(&uri).expect("encoded cb must parse");
+		assert_eq!(out.callback, "https://magick.market/api/login?s=1");
+	}
+
+	#[test]
+	fn duplicate_params_first_wins() {
+		let uri = format!(
+			"goblin:login?c={C}&c={}&d=magick.market&d=evil.com&cb=https://magick.market/cb&cb=https://evil.com/cb",
+			"f".repeat(64)
+		);
+		let out = parse(&uri).expect("must parse");
+		assert_eq!(out.challenge, C);
+		assert_eq!(out.domain, "magick.market");
+		assert_eq!(out.callback, "https://magick.market/cb");
+	}
+
+	#[test]
+	fn pay_uri_is_not_login_and_login_is_not_pay() {
+		// Dispatch contract: the router checks is_login_shaped() FIRST, then
+		// falls through to the pay path. A pay URI must never look
+		// login-shaped, and a login URI must never be classified as anything
+		// but login (valid or dropped).
+		let pay = format!("goblin:{NPUB}?amount=1.5");
+		assert!(!is_login_shaped(&pay));
+		assert_eq!(parse(&pay), None);
+		// The pay parser still handles it exactly as before.
+		let parsed = crate::nostr::payuri::parse(&pay);
+		assert_eq!(parsed.recipient, NPUB);
+		assert_eq!(parsed.amount.as_deref(), Some("1.5"));
+
+		// A login URI IS login-shaped (so the router grabs it before the pay
+		// path can see it), whether or not its params validate.
+		let login = valid_uri("goblin:");
+		assert!(is_login_shaped(&login));
+		assert!(parse(&login).is_some());
+		let broken = "goblin:login?c=nothex&d=m.m&cb=https://m.m/cb";
+		assert!(is_login_shaped(broken));
+		assert_eq!(parse(broken), None);
+		// Non-goblin schemes and bare payloads are not login-shaped at all.
+		assert!(!is_login_shaped("bitcoin:login?c=x"));
+		assert!(!is_login_shaped("login?c=x"));
+		assert!(!is_login_shaped(""));
+	}
+
+	#[test]
+	fn whitespace_trimmed_and_oversize_rejected() {
+		let uri = format!("  {}  ", valid_uri("nostr:"));
+		assert!(parse(&uri).is_some());
+		let huge = format!(
+			"goblin:login?c={C}&d=magick.market&cb=https://m.m/{}",
+			"a".repeat(5000)
+		);
+		assert_eq!(parse(&huge), None);
+		assert!(!is_login_shaped(&huge));
+	}
+
+	#[test]
+	fn login_event_signed_by_the_chosen_identity() {
+		// Two held identities; the user picks the NON-active one. The event
+		// must verify against exactly that key.
+		let active = Keys::generate();
+		let chosen = Keys::generate();
+		let before = nostr_sdk::Timestamp::now().as_u64();
+		let event = build_login_event(&chosen, C, "magick.market").expect("sign");
+		let after = nostr_sdk::Timestamp::now().as_u64();
+
+		assert_eq!(event.kind.as_u16(), LOGIN_EVENT_KIND);
+		assert_eq!(event.content, "");
+		let tags: Vec<Vec<String>> = event.tags.iter().map(|t| t.as_slice().to_vec()).collect();
+		assert_eq!(
+			tags,
+			vec![
+				vec!["challenge".to_string(), C.to_string()],
+				vec!["domain".to_string(), "magick.market".to_string()],
+			]
+		);
+		let ts = event.created_at.as_u64();
+		assert!(ts >= before && ts <= after, "created_at must be now");
+		assert!(event.verify().is_ok(), "signature must verify");
+		assert_eq!(event.pubkey, chosen.public_key());
+		assert_ne!(event.pubkey, active.public_key());
+	}
+}
diff --git a/src/nostr/mod.rs b/src/nostr/mod.rs
index 53b4bde8..3f2c820e 100644
--- a/src/nostr/mod.rs
+++ b/src/nostr/mod.rs
@@ -48,4 +48,5 @@ pub use client::{HeldIdentityKeys, NostrProfile, NostrService, send_phase};
 pub mod avatar;
 pub mod nip05;
 
+pub mod loginuri;
 pub mod payuri;
diff --git a/src/nostr/payuri.rs b/src/nostr/payuri.rs
index 7428e4af..1b441677 100644
--- a/src/nostr/payuri.rs
+++ b/src/nostr/payuri.rs
@@ -189,8 +189,10 @@ fn validate_count(raw: &str) -> Option<u32> {
 
 /// Strip a case-insensitive payment scheme prefix (`goblin:` or `nostr:`),
 /// returning the remainder. Byte-safe against a leading multibyte char (the
-/// `text.get(..n)` guards against a `[..n]` slice panic).
-fn strip_pay_scheme(text: &str) -> Option<&str> {
+/// `text.get(..n)` guards against a `[..n]` slice panic). Crate-visible so the
+/// login-URI parser (see [`crate::nostr::loginuri`]) shares the exact same
+/// scheme handling.
+pub(crate) fn strip_pay_scheme(text: &str) -> Option<&str> {
 	for scheme in PAY_SCHEMES {
 		let n = scheme.len();
 		if let Some(head) = text.get(..n) {
@@ -348,7 +350,8 @@ fn truncate_on_char_boundary(s: String, max: usize) -> String {
 /// byte; a stray `%` or a non-hex escape is passed through literally. No new
 /// dependency — the wallet has no direct percent-encoding crate and this is a
 /// few lines. `+` is left literal (RFC-3986 query, not form-encoding).
-fn percent_decode(s: &str) -> Vec<u8> {
+/// Crate-visible so the login-URI parser decodes identically.
+pub(crate) fn percent_decode(s: &str) -> Vec<u8> {
 	let bytes = s.as_bytes();
 	let mut out = Vec::with_capacity(bytes.len());
 	let mut i = 0;