fix: add idempotency keys to all Stripe mutation calls

Co-authored-by: userAdityaa <aditya.chaudhary1558@gmail.com>
Co-committed-by: userAdityaa <aditya.chaudhary1558@gmail.com>

backend/README.md

@@ -74,13 +74,20 @@ Public exceptions:
 - `GET /tenants` — list tenants (admin)
 - `POST /tenants` — idempotently ensure a tenant row exists for the current auth pubkey (creates Stripe customer + tenant on first call, returns existing tenant otherwise)
 - `GET /tenants/:pubkey` — get tenant (admin or same tenant)
-- `PUT /tenants/:pubkey/billing` — update tenant `nwc_url` (admin or same tenant)
-- `GET /relays` — list relays (`?tenant=<pubkey>` allowed for admin only)
+- `PUT /tenants/:pubkey` — update tenant `nwc_url` (admin or same tenant)
+- `GET /tenants/:pubkey/relays` — list tenant relays (admin or same tenant)
+- `GET /relays` — list relays (admin)
 - `POST /relays` — create relay (admin or relay tenant)
 - `GET /relays/:id` — get relay (admin or relay tenant)
+- `GET /relays/:id/members` — list relay members from zooid (admin or relay tenant)
 - `PUT /relays/:id` — update relay (admin or relay tenant)
+- `GET /relays/:id/activity` — list relay activity (admin or relay tenant)
 - `POST /relays/:id/deactivate` — deactivate relay (admin or relay tenant)
-- `GET /invoices` — list invoices (`?tenant=<pubkey>` allowed for admin only)
+- `POST /relays/:id/reactivate` — reactivate relay (admin or relay tenant)
+- `GET /tenants/:pubkey/invoices` — list tenant invoices (admin or same tenant)
+- `GET /invoices/:id` — get invoice (admin or same tenant)
+- `GET /invoices/:id/bolt11` — get invoice bolt11 (admin or same tenant)
+- `GET /tenants/:pubkey/stripe/session` — create Stripe customer portal session (admin or same tenant)
 
 ## API Auth Model
 

backend/migrations/0002_hot_path_indexes.sql

@@ -0,0 +1,11 @@
+CREATE INDEX IF NOT EXISTS idx_tenant_stripe_customer_id
+ON tenant (stripe_customer_id);
+
+CREATE INDEX IF NOT EXISTS idx_relay_tenant_id
+ON relay (tenant, id);
+
+CREATE INDEX IF NOT EXISTS idx_relay_tenant_status_plan
+ON relay (tenant, status, plan);
+
+CREATE INDEX IF NOT EXISTS idx_activity_resource_type_resource_id_created_at_id
+ON activity (resource_type, resource_id, created_at DESC, id DESC);

backend/spec/api.md

@@ -9,6 +9,7 @@ Members:
 - `query: Query`
 - `command: Command`
 - `billing: Billing`
+- `infra: Infra`
 
 Notes:
 
@@ -103,6 +104,14 @@ Notes:
 - Authorizes admin or relay owner
 - Return `data` is a single relay struct from `query.get_relay`
 
+## `async fn list_relay_members(...) -> Response`
+
+- Serves `GET /relays/:id/members`
+- Authorizes admin or relay owner
+- For unsynced relays, returns an empty member list without calling zooid
+- For synced relays, proxies the member list from zooid via `infra`
+- Return `data` is `{ members }`
+
 ## `async fn create_relay(...) -> Response`
 
 - Serves `POST /relays`
@@ -117,6 +126,7 @@ Notes:
 - Serves `PUT /relays/:id`
 - Authorizes admin or relay owner
 - Validates/prepares the relay data to be saved using `prepare_relay`
+- If the requested plan changes to a plan with a finite member limit and the current member count exceeds that limit, return a `422` with `code=member-limit-exceeded`
 - Updates the given relay using `command.update_relay`
 - If relay is a duplicate by subdomain, return a `422` with `code=subdomain-exists`
 - Return `data` is a single relay struct.
@@ -132,7 +142,7 @@ Notes:
 
 - Serves `POST /relays/:id/deactivate`
 - Authorizes admin or relay owner
-- If relay is already inactive, return a `400` with `code=relay-is-inactive`
+- If relay status is `inactive` or `delinquent`, return a `400` with `code=relay-is-inactive`
 - Call `command.deactivate_relay`
 - Return `data` is empty
 

backend/spec/billing.md

@@ -26,12 +26,15 @@ Members:
 
 Manages the Stripe subscription and subscription items for a relay's tenant. Only paid (non-free) relays interact with Stripe. Free-only tenants have no subscription. Must be idempotent.
 
+Stripe uses **pay-in-advance** by default: when a subscription is first created, Stripe immediately generates an open invoice for the current period. The `invoice.created` webhook fires shortly after and `handle_invoice_created` attempts payment.
+
 - Fetch the relay and tenant associated with the `activity`
-- **If relay plan is `free`**: if the relay has a `stripe_subscription_item_id`, delete it via the Stripe API and call `command.delete_relay_subscription_item`. Then check cleanup (below). Return early.
-- **If relay is `inactive`**: if the relay has a `stripe_subscription_item_id`, delete it via the Stripe API and call `command.delete_relay_subscription_item`. Then check cleanup (below). Return early.
+- **If relay plan is `free`**: if the relay has a `stripe_subscription_item_id`, delete it via the Stripe API and call `command.delete_relay_subscription_item`. Then run downgrade proration validation by previewing the upcoming invoice and logging proration lines/amounts. Then check cleanup (below). Return early.
+- **If relay is `inactive` or `delinquent`**: if the relay has a `stripe_subscription_item_id`, delete it via the Stripe API and call `command.delete_relay_subscription_item`. Then check cleanup (below). Return early.
 - **If relay is `active` and on a paid plan**:
   - **Ensure subscription exists**: If the tenant has no `stripe_subscription_id`, create a Stripe subscription for the customer with `collection_method: "charge_automatically"` and the relay's price as the first item. Save the subscription ID via `command.set_tenant_subscription` and the item ID via `command.set_relay_subscription_item`. Return early.
   - **Sync the subscription item**: If the tenant already has a subscription, create or update the relay's Stripe subscription item to the plan's `stripe_price_id` via the Stripe API, then call `command.set_relay_subscription_item`.
+  - **Downgrade validation**: when changing an existing subscription item, detect if the new plan amount is lower than the current one. If yes, preview the upcoming Stripe invoice and log proration line/amount details to validate expected credit/proration behavior.
 - **Clean up empty subscription**: After any item deletion, check if the tenant has any remaining active paid relays. If none and the tenant has a `stripe_subscription_id`, cancel the Stripe subscription immediately and call `command.clear_tenant_subscription`.
 
 ## `pub fn handle_webhook(&self, payload: &str, signature: &str) -> Result<()>`
@@ -44,6 +47,7 @@ Manages the Stripe subscription and subscription items for a relay's tenant. Onl
   - `invoice.overdue` -> `self.handle_invoice_overdue`
   - `customer.subscription.updated` -> `self.handle_subscription_updated`
   - `customer.subscription.deleted` -> `self.handle_subscription_deleted`
+  - `payment_method.attached` -> `self.handle_payment_method_attached`
 - Unknown event types are ignored (return Ok)
 
 ## `pub async fn stripe_list_invoices(&self, customer_id: &str) -> Result<Value>`
@@ -66,16 +70,37 @@ Manages the Stripe subscription and subscription items for a relay's tenant. Onl
 - Creates a Stripe Customer Portal session for the given customer
 - Returns the portal session URL
 
+## `pub async fn pay_outstanding_nwc_invoices(&self, tenant: &Tenant) -> Result<()>`
+
+Called when a tenant first sets their NWC URL (via `PUT /tenants/:pubkey`). Attempts to pay any currently open invoices for the tenant using their NWC wallet, so that invoices created before NWC was configured are not left unpaid.
+
+- If `tenant.nwc_url` is empty, return early.
+- List all Stripe invoices for `tenant.stripe_customer_id` via `stripe_list_invoices`.
+- For each invoice with `status == "open"` and `amount_due > 0`:
+  - Attempt NWC payment via `nwc_pay_invoice`.
+  - On success: call `stripe_pay_invoice_out_of_band` and `command.clear_tenant_nwc_error`.
+  - On failure: call `command.set_tenant_nwc_error` and log the error; continue to the next invoice.
+
+## `pub async fn pay_outstanding_card_invoices(&self, tenant: &Tenant) -> Result<()>`
+
+Attempts Stripe-side collection for open invoices when the tenant has a card on file.
+
+- If tenant has no card payment method, return early.
+- List all Stripe invoices for `tenant.stripe_customer_id`.
+- For each invoice with `status == "open"` and `amount_due > 0`:
+  - Call Stripe `POST /v1/invoices/:id/pay` to retry collection using the card on file.
+  - Log and continue on failures.
+
 ## `fn handle_invoice_created(&self, invoice: &Invoice)`
 
-Attempts to pay a new subscription invoice. Payment priority:
+Attempts to pay a new subscription invoice. Because Stripe defaults to pay-in-advance, this webhook fires immediately when a subscription is created (i.e. when a paid relay is added or a plan is upgraded). Payment priority:
 
 1. **NWC auto-pay**: If the tenant has a `nwc_url`:
    - Create a bolt11 Lightning invoice for the invoice amount using `self.nwc_url` (the receiving/system wallet)
    - Pay the bolt11 invoice using the tenant's `nwc_url` (the spending/tenant wallet)
    - If payment succeeds: call Stripe `POST /v1/invoices/:id/pay` with `paid_out_of_band: true`. Clear `nwc_error` via `command.clear_tenant_nwc_error`.
    - If payment fails: set `nwc_error` on tenant via `command.set_tenant_nwc_error`. Fall through to next option.
-2. **Card on file**: If the tenant has a payment method on the Stripe customer, do nothing — Stripe will charge automatically.
+2. **Card on file**: If the tenant has a payment method on the Stripe customer, do nothing here — Stripe will charge automatically for this invoice attempt.
 3. **Manual payment**: If neither NWC nor card is available, send a DM via `robot.send_dm` notifying the tenant that payment is due with a link to the application for manual Lightning payment.
 
 Skip invoices with `amount_due` of 0.
@@ -85,7 +110,7 @@ Skip invoices with `amount_due` of 0.
 - Look up tenant by `stripe_customer_id`
 - If tenant has `past_due_at` set:
   - Clear `past_due_at` via `command.clear_tenant_past_due`
-  - Find all `inactive` relays for the tenant that were deactivated due to non-payment (i.e. relays on paid plans that are inactive)
+  - Find all `delinquent` relays on paid plans for the tenant (relays marked delinquent by the billing system due to non-payment)
   - Reactivate each one via `command.activate_relay`
 
 ## `fn handle_invoice_payment_failed(&self, invoice: &Invoice)`
@@ -98,7 +123,7 @@ Skip invoices with `amount_due` of 0.
 ## `fn handle_invoice_overdue(&self, invoice: &Invoice)`
 
 - Look up tenant by `stripe_customer_id`
-- Deactivate all active relays on paid plans via `command.deactivate_relay`
+- Mark all active relays on paid plans as delinquent via `command.mark_relay_delinquent` (sets status to `delinquent`, distinct from user-initiated `deactivate_relay`)
 - Send a DM via `robot.send_dm` notifying the tenant that their paid relays have been deactivated due to non-payment
 
 ## `fn handle_subscription_updated(&self, subscription: &Subscription)`
@@ -106,9 +131,14 @@ Skip invoices with `amount_due` of 0.
 - Look up tenant by `stripe_customer_id`
 - If subscription status is `canceled` or `unpaid`:
   - Clear `stripe_subscription_id` via `command.clear_tenant_subscription`
-  - Deactivate all active paid relays for the tenant via `command.deactivate_relay`
+  - Mark all active paid relays as delinquent via `command.mark_relay_delinquent`
 
 ## `fn handle_subscription_deleted(&self, subscription: &Subscription)`
 
 - Look up tenant by `stripe_customer_id`
 - Clear `stripe_subscription_id` via `command.clear_tenant_subscription`
+
+## `fn handle_payment_method_attached(&self, stripe_customer_id: &str)`
+
+- Look up tenant by `stripe_customer_id`
+- Call `pay_outstanding_card_invoices` so invoices that were due before card setup are retried immediately

backend/spec/command.md

@@ -44,6 +44,14 @@ Notes:
 
 - Sets relay status to `inactive`
 - Logs activity as `(deactivate_relay, relay_id)`
+- Used for user/admin-initiated deactivation only
+
+## `pub fn mark_relay_delinquent(&self, relay: &Relay) -> Result<()>`
+
+- Sets relay status to `delinquent`
+- Logs activity as `(deactivate_relay, relay_id)`
+- Used exclusively by the billing system when a relay's subscription becomes past due
+- `delinquent` relays are automatically reactivated via `activate_relay` when payment is received
 
 ## `pub fn activate_relay(&self, relay: &Relay) -> Result<()>`
 

backend/spec/infra.md

@@ -15,12 +15,15 @@ Members:
 ## `pub async fn start(self)`
 
 - Subscribes to `command.notify`
+- On startup, schedules delayed sync retries for relays whose `sync_error` is non-empty.
 - Loops on `rx.recv()`, calling `handle_activity` for each received `Activity`.
 
 ## `async fn handle_activity(&self, activity: &Activity)`
 
-- For `create_relay`, `update_relay`, `activate_relay`, or `deactivate_relay` activity, calls `sync_and_report`.
-- All other activity types are ignored (e.g. `fail_relay_sync`, `complete_relay_sync`).
+- For `create_relay`, `update_relay`, `activate_relay`, or `deactivate_relay` activity, calls `sync_and_report` immediately.
+- For `fail_relay_sync`, schedules a delayed retry using exponential backoff based on consecutive failures for the relay.
+- Retry scheduling stops after the configured max attempts to avoid infinite retry loops.
+- Other activity types are ignored (e.g. `complete_relay_sync`).
 
 ## `async fn sync_and_report(&self, relay: &Relay, is_new: bool)`
 

backend/spec/models.md

@@ -69,7 +69,7 @@ A relay is a nostr relay owned by a `tenant` and hosted by the attached zooid in
 - `subdomain` - the relay's subdomain
 - `plan` - the relay's plan
 - `stripe_subscription_item_id` (nullable) - the Stripe subscription item id. Only set for relays on paid plans.
-- `status` - `active|inactive`. Only `active` relays count toward billing.
+- `status` - one of `active|inactive|delinquent`. Only `active` relays count toward billing. `delinquent` is set by the billing system when a relay's subscription becomes past due; `inactive` is set when a user or admin manually deactivates a relay.
 - `synced` - whether the relay has been successfully synced to zooid at least once.
 - `sync_error` - a string indicating any errors encountered when synchronizing.
 - `info_name` - the relay's name

backend/src/api.rs

@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use anyhow::anyhow;
+use anyhow::{Result, anyhow};
 use axum::{
     Json, Router,
     extract::{Path, State},
@@ -14,6 +14,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::billing::{Billing, InvoiceLookupError};
 use crate::command::Command;
+use crate::infra::Infra;
 use crate::models::{
     RELAY_STATUS_ACTIVE, RELAY_STATUS_DELINQUENT, RELAY_STATUS_INACTIVE, Relay, Tenant,
 };
@@ -27,6 +28,7 @@ pub struct Api {
     query: Query,
     command: Command,
     billing: Billing,
+    infra: Infra,
 }
 
 async fn stripe_webhook(
@@ -117,7 +119,7 @@ fn map_invoice_lookup_error(error: InvoiceLookupError) -> ApiError {
 }
 
 impl Api {
-    pub fn new(query: Query, command: Command, billing: Billing) -> Self {
+    pub fn new(query: Query, command: Command, billing: Billing, infra: Infra) -> Self {
         let host = std::env::var("HOST").unwrap_or_else(|_| "127.0.0.1".to_string());
         let admins = std::env::var("ADMINS")
             .unwrap_or_default()
@@ -131,6 +133,7 @@ impl Api {
             query,
             command,
             billing,
+            infra,
         }
     }
 
@@ -148,6 +151,7 @@ impl Api {
             .route("/tenants/:pubkey/relays", get(list_tenant_relays))
             .route("/relays", get(list_relays).post(create_relay))
             .route("/relays/:id", get(get_relay).put(update_relay))
+            .route("/relays/:id/members", get(list_relay_members))
             .route("/relays/:id/activity", get(list_relay_activity))
             .route("/relays/:id/deactivate", post(deactivate_relay))
             .route("/relays/:id/reactivate", post(reactivate_relay))
@@ -251,22 +255,24 @@ impl Api {
         }
     }
 
-    fn prepare_relay(&self, mut relay: Relay) -> anyhow::Result<Relay> {
-        if !relay
-            .subdomain
-            .chars()
-            .all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-')
-        {
-            return Err(anyhow!("invalid-subdomain"));
+    async fn fetch_relay_members(&self, relay: &Relay) -> Result<Vec<String>> {
+        if relay.synced == 0 {
+            return Ok(Vec::new());
         }
 
-        let plan = Query::get_plan(&relay.plan).ok_or_else(|| anyhow!("invalid-plan"))?;
+        self.infra.list_relay_members(&relay.id).await
+    }
+
+    fn prepare_relay(&self, mut relay: Relay) -> std::result::Result<Relay, RelayValidationError> {
+        validate_subdomain_label(&relay.subdomain)?;
+
+        let plan = Query::get_plan(&relay.plan).ok_or(RelayValidationError::InvalidPlan)?;
 
         if !plan.blossom && relay.blossom_enabled == 1 {
-            return Err(anyhow!("premium-feature"));
+            return Err(RelayValidationError::PremiumFeature);
         }
         if !plan.livekit && relay.livekit_enabled == 1 {
-            return Err(anyhow!("premium-feature"));
+            return Err(RelayValidationError::PremiumFeature);
         }
 
         if relay.schema.is_empty() {
@@ -289,6 +295,96 @@ impl Api {
     }
 }
 
+const SUBDOMAIN_LABEL_MAX_LEN: usize = 63;
+const RESERVED_SUBDOMAIN_LABELS: [&str; 2] = ["api", "admin"];
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum SubdomainValidationError {
+    Empty,
+    TooLong,
+    Reserved,
+    EdgeHyphen,
+    InvalidCharacters,
+}
+
+impl SubdomainValidationError {
+    fn code(self) -> &'static str {
+        match self {
+            Self::Empty => "subdomain-empty",
+            Self::TooLong => "subdomain-too-long",
+            Self::Reserved => "subdomain-reserved",
+            Self::EdgeHyphen => "subdomain-invalid-hyphen",
+            Self::InvalidCharacters => "subdomain-invalid-characters",
+        }
+    }
+
+    fn message(self) -> &'static str {
+        match self {
+            Self::Empty => "subdomain is required",
+            Self::TooLong => "subdomain must be 63 characters or fewer",
+            Self::Reserved => "subdomain is reserved",
+            Self::EdgeHyphen => "subdomain cannot start or end with a hyphen",
+            Self::InvalidCharacters => {
+                "subdomain may only contain lowercase letters, numbers, and hyphens"
+            }
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum RelayValidationError {
+    InvalidPlan,
+    PremiumFeature,
+    Subdomain(SubdomainValidationError),
+}
+
+impl RelayValidationError {
+    fn code(self) -> &'static str {
+        match self {
+            Self::InvalidPlan => "invalid-plan",
+            Self::PremiumFeature => "premium-feature",
+            Self::Subdomain(reason) => reason.code(),
+        }
+    }
+
+    fn message(self) -> &'static str {
+        match self {
+            Self::InvalidPlan => "plan not found",
+            Self::PremiumFeature => "feature requires a paid plan",
+            Self::Subdomain(reason) => reason.message(),
+        }
+    }
+}
+
+impl From<SubdomainValidationError> for RelayValidationError {
+    fn from(value: SubdomainValidationError) -> Self {
+        Self::Subdomain(value)
+    }
+}
+
+fn validate_subdomain_label(subdomain: &str) -> std::result::Result<(), SubdomainValidationError> {
+    if subdomain.is_empty() {
+        return Err(SubdomainValidationError::Empty);
+    }
+    if subdomain.len() > SUBDOMAIN_LABEL_MAX_LEN {
+        return Err(SubdomainValidationError::TooLong);
+    }
+    if subdomain.starts_with('-') || subdomain.ends_with('-') {
+        return Err(SubdomainValidationError::EdgeHyphen);
+    }
+    if RESERVED_SUBDOMAIN_LABELS.contains(&subdomain) {
+        return Err(SubdomainValidationError::Reserved);
+    }
+    if !subdomain
+        .chars()
+        .all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-')
+    {
+        return Err(SubdomainValidationError::InvalidCharacters);
+    }
+
+    Ok(())
+}
+
 fn ok<T: Serialize>(status: StatusCode, data: T) -> Response {
     (status, Json(OkResponse { data, code: "ok" })).into_response()
 }
@@ -316,6 +412,14 @@ fn parse_bool_default(value: i64, default: i64) -> i64 {
     }
 }
 
+fn relay_validation_error_response(error: RelayValidationError) -> Response {
+    err(
+        StatusCode::UNPROCESSABLE_ENTITY,
+        error.code(),
+        error.message(),
+    )
+}
+
 fn map_unique_error(err: &anyhow::Error) -> Option<&'static str> {
     let sqlx_err = err.downcast_ref::<sqlx::Error>()?;
     let sqlx::Error::Database(db_err) = sqlx_err else {
@@ -577,6 +681,40 @@ async fn list_relay_activity(
     }
 }
 
+async fn list_relay_members(
+    State(state): State<AppState>,
+    headers: HeaderMap,
+    Path(id): Path<String>,
+) -> std::result::Result<Response, ApiError> {
+    let auth = state.api.extract_auth_pubkey(&headers)?;
+
+    let relay = match state.api.query.get_relay(&id).await {
+        Ok(Some(r)) => r,
+        Ok(None) => return Ok(err(StatusCode::NOT_FOUND, "not-found", "relay not found")),
+        Err(e) => {
+            return Ok(err(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "internal",
+                &e.to_string(),
+            ));
+        }
+    };
+
+    state.api.require_admin_or_tenant(&auth, &relay.tenant)?;
+
+    match state.api.fetch_relay_members(&relay).await {
+        Ok(members) => Ok(ok(
+            StatusCode::OK,
+            serde_json::json!({ "members": members }),
+        )),
+        Err(e) => Ok(err(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "internal",
+            &e.to_string(),
+        )),
+    }
+}
+
 async fn create_relay(
     State(state): State<AppState>,
     headers: HeaderMap,
@@ -608,27 +746,9 @@ async fn create_relay(
     };
 
     relay = match state.api.prepare_relay(relay) {
-        Err(e) if e.to_string() == "invalid-plan" => {
-            return Ok(err(
-                StatusCode::UNPROCESSABLE_ENTITY,
-                "invalid-plan",
-                "plan not found",
-            ));
-        }
         Ok(r) => r,
-        Err(e) if e.to_string() == "premium-feature" => {
-            return Ok(err(
-                StatusCode::UNPROCESSABLE_ENTITY,
-                "premium-feature",
-                "feature requires a paid plan",
-            ));
-        }
-        Err(_) => {
-            return Ok(err(
-                StatusCode::UNPROCESSABLE_ENTITY,
-                "invalid-relay",
-                "relay validation failed",
-            ));
+        Err(e) => {
+            return Ok(relay_validation_error_response(e));
         }
     };
 
@@ -674,10 +794,13 @@ async fn update_relay(
 
     state.api.require_admin_or_tenant(&auth, &relay.tenant)?;
 
+    let current_plan = relay.plan.clone();
+    let requested_plan = payload.plan.clone();
+
     if let Some(v) = payload.subdomain {
         relay.subdomain = v;
     }
-    if let Some(v) = payload.plan {
+    if let Some(v) = requested_plan.clone() {
         relay.plan = v;
     }
     if let Some(v) = payload.info_name {
@@ -712,30 +835,44 @@ async fn update_relay(
     }
 
     relay = match state.api.prepare_relay(relay) {
-        Err(e) if e.to_string() == "invalid-plan" => {
-            return Ok(err(
-                StatusCode::UNPROCESSABLE_ENTITY,
-                "invalid-plan",
-                "plan not found",
-            ));
-        }
         Ok(r) => r,
-        Err(e) if e.to_string() == "premium-feature" => {
-            return Ok(err(
-                StatusCode::UNPROCESSABLE_ENTITY,
-                "premium-feature",
-                "feature requires a paid plan",
-            ));
-        }
-        Err(_) => {
-            return Ok(err(
-                StatusCode::UNPROCESSABLE_ENTITY,
-                "invalid-relay",
-                "relay validation failed",
-            ));
+        Err(e) => {
+            return Ok(relay_validation_error_response(e));
         }
     };
 
+    let plan_changed = requested_plan
+        .as_deref()
+        .is_some_and(|requested| requested != current_plan);
+
+    if plan_changed {
+        let selected_plan = Query::get_plan(&relay.plan).expect("validated plan must exist");
+        if let Some(limit) = selected_plan.members {
+            let current_members = match state.api.fetch_relay_members(&relay).await {
+                Ok(members) => members.len() as i64,
+                Err(e) => {
+                    return Ok(err(
+                        StatusCode::INTERNAL_SERVER_ERROR,
+                        "internal",
+                        &e.to_string(),
+                    ));
+                }
+            };
+
+            if current_members > limit {
+                let message = format!(
+                    "relay has {current_members} members, which exceeds the {} plan limit of {limit}",
+                    selected_plan.name.to_lowercase()
+                );
+                return Ok(err(
+                    StatusCode::UNPROCESSABLE_ENTITY,
+                    "member-limit-exceeded",
+                    &message,
+                ));
+            }
+        }
+    }
+
     match state.api.command.update_relay(&relay).await {
         Ok(()) => Ok(ok(StatusCode::OK, relay)),
         Err(e) => {
@@ -945,12 +1082,29 @@ async fn update_tenant(
     state.api.require_admin_or_tenant(&auth, &pubkey)?;
     let mut tenant = state.api.get_tenant_or_404(&pubkey).await?;
 
+    let nwc_previously_empty = tenant.nwc_url.is_empty();
     if let Some(nwc_url) = payload.nwc_url {
         tenant.nwc_url = nwc_url;
     }
 
     match state.api.command.update_tenant(&tenant).await {
-        Ok(()) => Ok(ok(StatusCode::OK, tenant)),
+        Ok(()) => {
+            // When NWC is first connected, attempt to pay any outstanding open invoices.
+            if nwc_previously_empty && !tenant.nwc_url.is_empty() {
+                let billing = state.api.billing.clone();
+                let tenant_clone = tenant.clone();
+                tokio::spawn(async move {
+                    if let Err(e) = billing.pay_outstanding_nwc_invoices(&tenant_clone).await {
+                        tracing::error!(
+                            error = %e,
+                            pubkey = %tenant_clone.pubkey,
+                            "pay_outstanding_nwc_invoices failed after NWC setup"
+                        );
+                    }
+                });
+            }
+            Ok(ok(StatusCode::OK, tenant))
+        }
         Err(e) => Ok(err(
             StatusCode::INTERNAL_SERVER_ERROR,
             "internal",

backend/src/billing.rs

@@ -17,6 +17,9 @@ type HmacSha256 = Hmac<Sha256>;
 const STRIPE_API: &str = "https://api.stripe.com/v1";
 const COINBASE_SPOT_API: &str = "https://api.coinbase.com/v2/prices";
 const WEBHOOK_TOLERANCE_SECS: i64 = 300;
+const MANUAL_LIGHTNING_PAYMENT_DM: &str = "Payment is due for your relay subscription. Please visit the application to complete a manual Lightning payment.";
+const NWC_ERROR_DM_PREFIX: &str = "NWC auto-payment failed:";
+const NWC_ERROR_DM_MAX_CHARS: usize = 240;
 
 #[derive(Debug)]
 pub enum InvoiceLookupError {
@@ -80,7 +83,6 @@ pub struct Billing {
     nwc_url: String,
     stripe_secret_key: String,
     stripe_webhook_secret: String,
-    btc_quote_api_base: String,
     http: reqwest::Client,
     query: Query,
     command: Command,
@@ -98,13 +100,10 @@ impl Billing {
         if stripe_webhook_secret.trim().is_empty() {
             panic!("missing STRIPE_WEBHOOK_SECRET environment variable");
         }
-        let btc_quote_api_base =
-            std::env::var("BTC_PRICE_API_BASE").unwrap_or_else(|_| COINBASE_SPOT_API.to_string());
         Self {
             nwc_url,
             stripe_secret_key,
             stripe_webhook_secret,
-            btc_quote_api_base,
             http: reqwest::Client::new(),
             query,
             command,
@@ -167,6 +166,8 @@ impl Billing {
                 self.command
                     .delete_relay_subscription_item(&relay.id)
                     .await?;
+                self.validate_downgrade_proration(&tenant, "free-plan-downgrade")
+                    .await;
             }
             self.cleanup_empty_subscription(&tenant.pubkey).await?;
             return Ok(());
@@ -206,8 +207,28 @@ impl Billing {
         // Sync the subscription item: create or update
         let subscription_id = tenant.stripe_subscription_id.as_ref().unwrap();
         let item_id = if let Some(ref existing_item_id) = relay.stripe_subscription_item_id {
-            self.stripe_update_subscription_item(existing_item_id, stripe_price_id)
-                .await?
+            let is_downgrade = self
+                .is_subscription_item_downgrade(existing_item_id, plan.amount)
+                .await
+                .unwrap_or_else(|error| {
+                    tracing::warn!(
+                        error = %error,
+                        relay_id = %relay.id,
+                        "failed to determine relay plan downgrade direction"
+                    );
+                    false
+                });
+
+            let updated_item_id = self
+                .stripe_update_subscription_item(existing_item_id, stripe_price_id)
+                .await?;
+
+            if is_downgrade {
+                self.validate_downgrade_proration(&tenant, "paid-plan-downgrade")
+                    .await;
+            }
+
+            updated_item_id
         } else {
             self.stripe_create_subscription_item(subscription_id, stripe_price_id)
                 .await?
@@ -275,6 +296,10 @@ impl Billing {
                 let customer = obj["customer"].as_str().unwrap_or_default();
                 self.handle_subscription_deleted(customer).await?;
             }
+            "payment_method.attached" => {
+                let customer = obj["customer"].as_str().unwrap_or_default();
+                self.handle_payment_method_attached(customer).await?;
+            }
             _ => {}
         }
 
@@ -334,6 +359,8 @@ impl Billing {
             return Ok(());
         };
 
+        let mut nwc_error_for_dm: Option<String> = None;
+
         // 1. NWC auto-pay: if the tenant has a nwc_url
         if !tenant.nwc_url.is_empty() {
             match self
@@ -350,6 +377,14 @@ impl Billing {
                     self.command
                         .set_tenant_nwc_error(&tenant.pubkey, &error_msg)
                         .await?;
+                    tracing::warn!(
+                        error = %e,
+                        tenant_pubkey = %tenant.pubkey,
+                        stripe_customer_id,
+                        invoice_id,
+                        "nwc auto-payment failed for invoice.created"
+                    );
+                    nwc_error_for_dm = summarize_nwc_error_for_dm(&error_msg);
                     // Fall through to next option
                 }
             }
@@ -364,12 +399,8 @@ impl Billing {
         }
 
         // 3. Manual payment: send a DM
-        self.robot
-            .send_dm(
-                &tenant.pubkey,
-                "Payment is due for your relay subscription. Please visit the application to complete a manual Lightning payment.",
-            )
-            .await?;
+        let dm_message = manual_lightning_payment_dm(nwc_error_for_dm.as_deref());
+        self.robot.send_dm(&tenant.pubkey, &dm_message).await?;
 
         Ok(())
     }
@@ -492,6 +523,103 @@ impl Billing {
         Ok(())
     }
 
+    async fn handle_payment_method_attached(&self, stripe_customer_id: &str) -> Result<()> {
+        if stripe_customer_id.is_empty() {
+            return Ok(());
+        }
+
+        let Some(tenant) = self
+            .query
+            .get_tenant_by_stripe_customer_id(stripe_customer_id)
+            .await?
+        else {
+            return Ok(());
+        };
+
+        self.pay_outstanding_card_invoices(&tenant).await?;
+        Ok(())
+    }
+
+    async fn is_subscription_item_downgrade(
+        &self,
+        item_id: &str,
+        next_plan_amount: i64,
+    ) -> Result<bool> {
+        let Some(current_price_id) = self.stripe_get_subscription_item_price_id(item_id).await?
+        else {
+            return Ok(false);
+        };
+
+        let Some(current_plan_amount) = Self::plan_amount_from_price_id(&current_price_id) else {
+            return Ok(false);
+        };
+
+        Ok(next_plan_amount < current_plan_amount)
+    }
+
+    fn plan_amount_from_price_id(price_id: &str) -> Option<i64> {
+        Query::list_plans().into_iter().find_map(|plan| {
+            if plan.stripe_price_id.as_deref() == Some(price_id) {
+                Some(plan.amount)
+            } else {
+                None
+            }
+        })
+    }
+
+    async fn validate_downgrade_proration(&self, tenant: &crate::models::Tenant, context: &str) {
+        match self
+            .stripe_preview_upcoming_invoice(
+                &tenant.stripe_customer_id,
+                tenant.stripe_subscription_id.as_deref(),
+            )
+            .await
+        {
+            Ok(upcoming) => {
+                let lines = upcoming["lines"]["data"]
+                    .as_array()
+                    .cloned()
+                    .unwrap_or_default();
+                let proration_lines = lines
+                    .iter()
+                    .filter(|line| line["proration"].as_bool().unwrap_or(false))
+                    .count();
+                let amount_due = upcoming["amount_due"]
+                    .as_i64()
+                    .unwrap_or_else(|| upcoming["total"].as_i64().unwrap_or(0));
+                let currency = upcoming["currency"].as_str().unwrap_or("usd");
+                let preview_id = upcoming["id"].as_str().unwrap_or_default();
+
+                tracing::info!(
+                    tenant_pubkey = %tenant.pubkey,
+                    stripe_customer_id = %tenant.stripe_customer_id,
+                    context,
+                    preview_id,
+                    proration_lines,
+                    amount_due,
+                    currency,
+                    "validated Stripe proration preview for downgrade"
+                );
+
+                if proration_lines == 0 {
+                    tracing::warn!(
+                        tenant_pubkey = %tenant.pubkey,
+                        context,
+                        "downgrade proration preview has no proration lines; verify in Stripe dashboard"
+                    );
+                }
+            }
+            Err(error) => {
+                tracing::warn!(
+                    error = %error,
+                    tenant_pubkey = %tenant.pubkey,
+                    context,
+                    "failed to fetch downgrade proration preview"
+                );
+            }
+        }
+    }
+
     // --- Public API helpers ---
 
     pub async fn get_invoice_with_tenant(
@@ -515,11 +643,13 @@ impl Billing {
     pub async fn stripe_create_customer(&self, tenant_pubkey: &str) -> Result<String> {
         let short_pubkey: String = tenant_pubkey.chars().take(12).collect();
         let display_name = format!("Caravel tenant {short_pubkey}");
+        let idempotency_key = self.idempotency_key(&["create_customer", tenant_pubkey]);
 
         let resp = self
             .http
             .post(format!("{STRIPE_API}/customers"))
             .bearer_auth(&self.stripe_secret_key)
+            .header("Idempotency-Key", idempotency_key)
             .form(&[
                 ("name", display_name.as_str()),
                 ("metadata[tenant_pubkey]", tenant_pubkey),
@@ -599,6 +729,93 @@ impl Billing {
         Ok(invoice_response.invoice)
     }
 
+    pub async fn pay_outstanding_nwc_invoices(&self, tenant: &crate::models::Tenant) -> Result<()> {
+        if tenant.nwc_url.is_empty() {
+            return Ok(());
+        }
+
+        let invoices = self
+            .stripe_list_invoices(&tenant.stripe_customer_id)
+            .await?;
+        let invoices_arr = invoices.as_array().cloned().unwrap_or_default();
+
+        for invoice in &invoices_arr {
+            let status = invoice["status"].as_str().unwrap_or_default();
+            let amount_due = invoice["amount_due"].as_i64().unwrap_or(0);
+            let invoice_id = invoice["id"].as_str().unwrap_or_default();
+            let currency = invoice["currency"].as_str().unwrap_or("usd");
+
+            if status != "open" || amount_due == 0 || invoice_id.is_empty() {
+                continue;
+            }
+
+            match self
+                .nwc_pay_invoice(amount_due, currency, &tenant.nwc_url)
+                .await
+            {
+                Ok(()) => {
+                    if let Err(e) = self.stripe_pay_invoice_out_of_band(invoice_id).await {
+                        tracing::error!(
+                            error = %e,
+                            invoice_id,
+                            "failed to mark invoice paid out of band"
+                        );
+                    } else {
+                        let _ = self.command.clear_tenant_nwc_error(&tenant.pubkey).await;
+                    }
+                }
+                Err(e) => {
+                    let error_msg = format!("{e}");
+                    tracing::error!(
+                        error = %e,
+                        invoice_id,
+                        "nwc payment failed for outstanding invoice"
+                    );
+                    let _ = self
+                        .command
+                        .set_tenant_nwc_error(&tenant.pubkey, &error_msg)
+                        .await;
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    async fn pay_outstanding_card_invoices(&self, tenant: &crate::models::Tenant) -> Result<()> {
+        if !self
+            .stripe_has_payment_method(&tenant.stripe_customer_id)
+            .await?
+        {
+            return Ok(());
+        }
+
+        let invoices = self
+            .stripe_list_invoices(&tenant.stripe_customer_id)
+            .await?;
+        let invoices_arr = invoices.as_array().cloned().unwrap_or_default();
+
+        for invoice in &invoices_arr {
+            let status = invoice["status"].as_str().unwrap_or_default();
+            let amount_due = invoice["amount_due"].as_i64().unwrap_or(0);
+            let invoice_id = invoice["id"].as_str().unwrap_or_default();
+
+            if status != "open" || amount_due == 0 || invoice_id.is_empty() {
+                continue;
+            }
+
+            if let Err(error) = self.stripe_pay_invoice(invoice_id).await {
+                tracing::error!(
+                    error = %error,
+                    invoice_id,
+                    "failed to retry card payment for outstanding invoice"
+                );
+            }
+        }
+
+        Ok(())
+    }
+
     pub async fn stripe_create_portal_session(&self, customer_id: &str) -> Result<String> {
         let resp = self
             .http
@@ -619,15 +836,30 @@ impl Billing {
 
     // --- Stripe API helpers ---
 
+    fn idempotency_key(&self, parts: &[&str]) -> String {
+        let mut mac = HmacSha256::new_from_slice(self.stripe_secret_key.as_bytes())
+            .expect("HMAC accepts any key length");
+        for (i, part) in parts.iter().enumerate() {
+            if i > 0 {
+                mac.update(b":");
+            }
+            mac.update(part.as_bytes());
+        }
+        hex::encode(mac.finalize().into_bytes())
+    }
+
     async fn stripe_create_subscription(
         &self,
         customer_id: &str,
         price_id: &str,
     ) -> Result<(String, String)> {
+        let idempotency_key =
+            self.idempotency_key(&["create_subscription", customer_id, price_id]);
         let resp = self
             .http
             .post(format!("{STRIPE_API}/subscriptions"))
             .bearer_auth(&self.stripe_secret_key)
+            .header("Idempotency-Key", idempotency_key)
             .form(&[
                 ("customer", customer_id),
                 ("collection_method", "charge_automatically"),
@@ -654,10 +886,13 @@ impl Billing {
         subscription_id: &str,
         price_id: &str,
     ) -> Result<String> {
+        let idempotency_key =
+            self.idempotency_key(&["create_subscription_item", subscription_id, price_id]);
         let resp = self
             .http
             .post(format!("{STRIPE_API}/subscription_items"))
             .bearer_auth(&self.stripe_secret_key)
+            .header("Idempotency-Key", idempotency_key)
             .form(&[("subscription", subscription_id), ("price", price_id)])
             .send()
             .await?;
@@ -676,10 +911,13 @@ impl Billing {
         item_id: &str,
         price_id: &str,
     ) -> Result<String> {
+        let idempotency_key =
+            self.idempotency_key(&["update_subscription_item", item_id, price_id]);
         let resp = self
             .http
             .post(format!("{STRIPE_API}/subscription_items/{item_id}"))
             .bearer_auth(&self.stripe_secret_key)
+            .header("Idempotency-Key", idempotency_key)
             .form(&[("price", price_id)])
             .send()
             .await?;
@@ -715,10 +953,56 @@ impl Billing {
         Ok(())
     }
 
-    async fn stripe_pay_invoice_out_of_band(&self, invoice_id: &str) -> Result<()> {
+    async fn stripe_pay_invoice(&self, invoice_id: &str) -> Result<()> {
+        let idempotency_key = self.idempotency_key(&["pay_invoice", invoice_id]);
         self.http
             .post(format!("{STRIPE_API}/invoices/{invoice_id}/pay"))
             .bearer_auth(&self.stripe_secret_key)
+            .header("Idempotency-Key", idempotency_key)
+            .send()
+            .await?
+            .error_for_status()?;
+
+        Ok(())
+    }
+
+    async fn stripe_get_subscription_item_price_id(&self, item_id: &str) -> Result<Option<String>> {
+        let resp = self
+            .http
+            .get(format!("{STRIPE_API}/subscription_items/{item_id}"))
+            .bearer_auth(&self.stripe_secret_key)
+            .send()
+            .await?;
+
+        let body: serde_json::Value = resp.error_for_status()?.json().await?;
+        Ok(body["price"]["id"].as_str().map(ToString::to_string))
+    }
+
+    async fn stripe_preview_upcoming_invoice(
+        &self,
+        customer_id: &str,
+        subscription_id: Option<&str>,
+    ) -> Result<serde_json::Value> {
+        let mut req = self
+            .http
+            .get(format!("{STRIPE_API}/invoices/upcoming"))
+            .bearer_auth(&self.stripe_secret_key)
+            .query(&[("customer", customer_id)]);
+
+        if let Some(subscription_id) = subscription_id {
+            req = req.query(&[("subscription", subscription_id)]);
+        }
+
+        let body: serde_json::Value = req.send().await?.error_for_status()?.json().await?;
+        Ok(body)
+    }
+
+    async fn stripe_pay_invoice_out_of_band(&self, invoice_id: &str) -> Result<()> {
+        let idempotency_key = self.idempotency_key(&["pay_invoice_oob", invoice_id]);
+        self.http
+            .post(format!("{STRIPE_API}/invoices/{invoice_id}/pay"))
+            .bearer_auth(&self.stripe_secret_key)
+            .header("Idempotency-Key", idempotency_key)
             .form(&[("paid_out_of_band", "true")])
             .send()
             .await?
@@ -805,7 +1089,7 @@ impl Billing {
     }
 
     async fn fetch_btc_spot_price(&self, currency: &str) -> Result<f64> {
-        fetch_btc_spot_price_from_base(&self.http, &self.btc_quote_api_base, currency).await
+        fetch_btc_spot_price_from_base(&self.http, COINBASE_SPOT_API, currency).await
     }
 
     fn currency_minor_exponent(currency: &str) -> Result<u8> {
@@ -849,6 +1133,31 @@ pub async fn fetch_btc_spot_price_from_base(
     Ok(amount)
 }
 
+fn summarize_nwc_error_for_dm(error: &str) -> Option<String> {
+    let normalized = error.split_whitespace().collect::<Vec<_>>().join(" ");
+    if normalized.is_empty() {
+        return None;
+    }
+
+    if normalized.chars().count() <= NWC_ERROR_DM_MAX_CHARS {
+        return Some(normalized);
+    }
+
+    let prefix_len = NWC_ERROR_DM_MAX_CHARS.saturating_sub(3);
+    let mut truncated = normalized.chars().take(prefix_len).collect::<String>();
+    truncated.push_str("...");
+    Some(truncated)
+}
+
+fn manual_lightning_payment_dm(nwc_error: Option<&str>) -> String {
+    match nwc_error {
+        Some(error) if !error.is_empty() => {
+            format!("{MANUAL_LIGHTNING_PAYMENT_DM}\n\n{NWC_ERROR_DM_PREFIX} {error}")
+        }
+        _ => MANUAL_LIGHTNING_PAYMENT_DM.to_string(),
+    }
+}
+
 pub fn fiat_minor_to_msats_from_quote(
     amount_due_minor: i64,
     currency: &str,
@@ -1146,4 +1455,5 @@ mod tests {
         assert_eq!(billing.stripe_secret_key, "sk_test_dummy");
         assert_eq!(billing.stripe_webhook_secret, "whsec_test_dummy");
     }
+
 }

backend/src/infra.rs

@@ -1,10 +1,15 @@
 use anyhow::Result;
 use nostr_sdk::prelude::*;
+use std::time::Duration;
 
 use crate::command::Command;
-use crate::models::{Activity, Relay, RELAY_STATUS_DELINQUENT, RELAY_STATUS_INACTIVE};
+use crate::models::{Activity, RELAY_STATUS_DELINQUENT, RELAY_STATUS_INACTIVE, Relay};
 use crate::query::Query;
 
+const RELAY_SYNC_RETRY_BASE_DELAY_SECS: u64 = 30;
+const RELAY_SYNC_RETRY_MAX_DELAY_SECS: u64 = 15 * 60;
+const RELAY_SYNC_RETRY_MAX_ATTEMPTS: usize = 6;
+
 #[derive(Clone)]
 pub struct Infra {
     api_url: String,
@@ -18,14 +23,22 @@ pub struct Infra {
 }
 
 impl Infra {
-    pub fn new(query: Query, command: Command) -> Self {
+    pub fn new(query: Query, command: Command) -> Result<Self> {
         let api_url = std::env::var("ZOOID_API_URL").unwrap_or_default();
         let relay_domain = std::env::var("RELAY_DOMAIN").unwrap_or_default();
         let livekit_url = std::env::var("LIVEKIT_URL").unwrap_or_default();
         let livekit_api_key = std::env::var("LIVEKIT_API_KEY").unwrap_or_default();
         let livekit_api_secret = std::env::var("LIVEKIT_API_SECRET").unwrap_or_default();
         let api_secret = std::env::var("ZOOID_API_SECRET").unwrap_or_default();
-        Self {
+
+        if api_url.trim().is_empty() {
+            anyhow::bail!("missing ZOOID_API_URL");
+        }
+        if api_secret.trim().is_empty() {
+            anyhow::bail!("missing ZOOID_API_SECRET");
+        }
+
+        Ok(Self {
             api_url,
             relay_domain,
             livekit_url,
@@ -34,12 +47,16 @@ impl Infra {
             api_secret,
             query,
             command,
-        }
+        })
     }
 
     pub async fn start(self) {
         let mut rx = self.command.notify.subscribe();
 
+        if let Err(e) = self.schedule_startup_retries().await {
+            tracing::error!(error = %e, "failed to schedule relay sync retries on startup");
+        }
+
         loop {
             match rx.recv().await {
                 Ok(activity) => {
@@ -58,15 +75,84 @@ impl Infra {
     async fn handle_activity(&self, activity: &Activity) -> Result<()> {
         let needs_sync = should_sync_relay_activity(activity.activity_type.as_str());
 
-        if needs_sync {
-            let Some(relay) = self.query.get_relay(&activity.resource_id).await? else {
-                return Ok(());
-            };
-
-            let is_new = relay.synced == 0;
-            self.sync_and_report(&relay, is_new).await;
+        if !needs_sync || activity.resource_type != "relay" {
+            return Ok(());
         }
 
+        if activity.activity_type == "fail_relay_sync" {
+            self.schedule_relay_sync_retry(&activity.resource_id, "activity")
+                .await?;
+            return Ok(());
+        }
+
+        let Some(relay) = self.query.get_relay(&activity.resource_id).await? else {
+            return Ok(());
+        };
+
+        let is_new = relay.synced == 0;
+        self.sync_and_report(&relay, is_new).await;
+
+        Ok(())
+    }
+
+    async fn schedule_startup_retries(&self) -> Result<()> {
+        let relays = self.query.list_relays_with_sync_error().await?;
+
+        for relay in relays {
+            self.schedule_relay_sync_retry(&relay.id, "startup").await?;
+        }
+
+        Ok(())
+    }
+
+    async fn schedule_relay_sync_retry(&self, relay_id: &str, source: &str) -> Result<()> {
+        let activities = self.query.list_activity_for_relay(relay_id).await?;
+        let consecutive_failures = consecutive_sync_failures(&activities);
+
+        let Some(delay) = relay_sync_retry_delay(consecutive_failures) else {
+            tracing::warn!(
+                relay = relay_id,
+                consecutive_failures,
+                max_attempts = RELAY_SYNC_RETRY_MAX_ATTEMPTS,
+                "relay sync retries exhausted; awaiting manual intervention"
+            );
+            return Ok(());
+        };
+
+        tracing::info!(
+            relay = relay_id,
+            source,
+            consecutive_failures,
+            delay_secs = delay.as_secs(),
+            "scheduled relay sync retry"
+        );
+
+        let relay_id = relay_id.to_string();
+        let infra = self.clone();
+
+        tokio::spawn(async move {
+            tokio::time::sleep(delay).await;
+
+            if let Err(e) = infra.retry_relay_sync(&relay_id).await {
+                tracing::error!(relay = %relay_id, error = %e, "relay sync retry task failed");
+            }
+        });
+
+        Ok(())
+    }
+
+    async fn retry_relay_sync(&self, relay_id: &str) -> Result<()> {
+        let Some(relay) = self.query.get_relay(relay_id).await? else {
+            return Ok(());
+        };
+
+        if relay.sync_error.trim().is_empty() {
+            tracing::debug!(relay = %relay.id, "skip relay sync retry; relay has no sync_error");
+            return Ok(());
+        }
+
+        let is_new = relay.synced == 0;
+        self.sync_and_report(&relay, is_new).await;
         Ok(())
     }
 
@@ -96,6 +182,28 @@ impl Infra {
         Ok(auth)
     }
 
+    pub async fn list_relay_members(&self, relay_id: &str) -> Result<Vec<String>> {
+        let client = reqwest::Client::new();
+        let base = self.api_url.trim_end_matches('/');
+        let url = format!("{base}/relay/{relay_id}/members");
+        let auth = self.nip98_auth(&url, HttpMethod::GET).await?;
+
+        let response = client
+            .get(&url)
+            .header("Authorization", auth)
+            .send()
+            .await?;
+
+        if !response.status().is_success() {
+            let status = response.status();
+            let body = response.text().await.unwrap_or_default();
+            anyhow::bail!("zooid members returned {status}: {body}");
+        }
+
+        let body = response.text().await?;
+        parse_relay_members_response(&body)
+    }
+
     async fn sync_relay(&self, relay: &Relay, is_new: bool) -> Result<()> {
         let client = reqwest::Client::new();
         let base = self.api_url.trim_end_matches('/');
@@ -125,7 +233,9 @@ impl Infra {
         );
 
         let url = format!("{}/relay/{}", base, relay.id);
-        let auth = self.nip98_auth(&url, zooid_sync_http_method(is_new)).await?;
+        let auth = self
+            .nip98_auth(&url, zooid_sync_http_method(is_new))
+            .await?;
 
         let request = if is_new {
             client.post(&url)
@@ -156,6 +266,34 @@ fn zooid_sync_http_method(is_new: bool) -> HttpMethod {
     }
 }
 
+fn parse_relay_members_response(body: &str) -> Result<Vec<String>> {
+    let value: serde_json::Value = serde_json::from_str(body)?;
+
+    if let Some(members) = members_from_value(&value) {
+        return Ok(members);
+    }
+    if let Some(members) = value.get("members").and_then(members_from_value) {
+        return Ok(members);
+    }
+    if let Some(members) = value
+        .get("data")
+        .and_then(|data| data.get("members"))
+        .and_then(members_from_value)
+    {
+        return Ok(members);
+    }
+
+    anyhow::bail!("zooid members response missing members array")
+}
+
+fn members_from_value(value: &serde_json::Value) -> Option<Vec<String>> {
+    let values = value.as_array()?;
+    values
+        .iter()
+        .map(|value| value.as_str().map(ToString::to_string))
+        .collect()
+}
+
 fn relay_sync_body(
     relay: &Relay,
     host: String,
@@ -198,6 +336,28 @@ fn relay_sync_body(
 fn should_sync_relay_activity(activity_type: &str) -> bool {
     matches!(
         activity_type,
-        "create_relay" | "update_relay" | "activate_relay" | "deactivate_relay"
+        "create_relay" | "update_relay" | "activate_relay" | "deactivate_relay" | "fail_relay_sync"
     )
 }
+
+fn consecutive_sync_failures(activities: &[Activity]) -> usize {
+    activities
+        .iter()
+        .take_while(|activity| activity.activity_type == "fail_relay_sync")
+        .count()
+}
+
+fn relay_sync_retry_delay(consecutive_failures: usize) -> Option<Duration> {
+    let retry_attempt = consecutive_failures.max(1);
+    if retry_attempt > RELAY_SYNC_RETRY_MAX_ATTEMPTS {
+        return None;
+    }
+
+    let exponent = (retry_attempt - 1).min(31);
+    let multiplier = 1u64 << exponent;
+    let delay_secs = RELAY_SYNC_RETRY_BASE_DELAY_SECS
+        .saturating_mul(multiplier)
+        .min(RELAY_SYNC_RETRY_MAX_DELAY_SECS);
+
+    Some(Duration::from_secs(delay_secs))
+}

backend/src/main.rs

@@ -33,8 +33,8 @@ async fn main() -> Result<()> {
     let query = Query::new(pool.clone());
     let command = Command::new(pool);
     let billing = Billing::new(query.clone(), command.clone(), robot.clone());
-    let infra = Infra::new(query.clone(), command.clone());
-    let api = Api::new(query, command, billing.clone());
+    let infra = Infra::new(query.clone(), command.clone())?;
+    let api = Api::new(query, command, billing.clone(), infra.clone());
 
     let host = std::env::var("HOST").unwrap_or_else(|_| "127.0.0.1".to_string());
     let port: u16 = std::env::var("PORT")

backend/src/query.rs

@@ -94,6 +94,23 @@ impl Query {
         Ok(rows)
     }
 
+    pub async fn list_relays_with_sync_error(&self) -> Result<Vec<Relay>> {
+        let rows = sqlx::query_as::<_, Relay>(
+            "SELECT id, tenant, schema, subdomain, plan, stripe_subscription_item_id,
+                     status, sync_error,
+                     info_name, info_icon, info_description,
+                     policy_public_join, policy_strip_signatures,
+                     groups_enabled, management_enabled, blossom_enabled,
+                     livekit_enabled, push_enabled, synced
+              FROM relay
+              WHERE TRIM(sync_error) != ''
+              ORDER BY id",
+        )
+        .fetch_all(&self.pool)
+        .await?;
+        Ok(rows)
+    }
+
     pub async fn list_relays_for_tenant(&self, tenant_id: &str) -> Result<Vec<Relay>> {
         let rows = sqlx::query_as::<_, Relay>(
             "SELECT id, tenant, schema, subdomain, plan, stripe_subscription_item_id,

frontend/src/components/ConfirmDialog.tsx

@@ -0,0 +1,151 @@
+import { For, Show, createEffect, createSignal } from "solid-js"
+import Modal from "@/components/Modal"
+
+type ConfirmDialogProps = {
+  open: boolean
+  title: string
+  description: string
+  /** Optional bullet points shown in a warning box below the description */
+  details?: string[]
+  confirmLabel: string
+  busyLabel?: string
+  busy?: boolean
+  tone?: "danger" | "primary"
+  onConfirm: () => void | Promise<void>
+  onClose: () => void
+}
+
+const TONE_STYLES: Record<NonNullable<ConfirmDialogProps["tone"]>, string> = {
+  danger: "bg-red-600 text-white hover:bg-red-700",
+  primary: "bg-blue-600 text-white hover:bg-blue-700",
+}
+
+const DETAIL_BOX_STYLES: Record<NonNullable<ConfirmDialogProps["tone"]>, string> = {
+  danger: "border-amber-200 bg-amber-50 text-amber-800",
+  primary: "border-blue-200 bg-blue-50 text-blue-800",
+}
+
+type ConfirmDialogSnapshot = {
+  title: string
+  description: string
+  details?: string[]
+  confirmLabel: string
+  busyLabel?: string
+  busy: boolean
+  tone: NonNullable<ConfirmDialogProps["tone"]>
+}
+
+export default function ConfirmDialog(props: ConfirmDialogProps) {
+  const [snapshot, setSnapshot] = createSignal<ConfirmDialogSnapshot>({
+    title: props.title,
+    description: props.description,
+    details: props.details ? [...props.details] : undefined,
+    confirmLabel: props.confirmLabel,
+    busyLabel: props.busyLabel,
+    busy: props.busy ?? false,
+    tone: props.tone ?? "primary",
+  })
+
+  createEffect(() => {
+    if (!props.open) return
+
+    setSnapshot({
+      title: props.title,
+      description: props.description,
+      details: props.details ? [...props.details] : undefined,
+      confirmLabel: props.confirmLabel,
+      busyLabel: props.busyLabel,
+      busy: props.busy ?? false,
+      tone: props.tone ?? "primary",
+    })
+  })
+
+  const content = () => props.open
+    ? {
+        title: props.title,
+        description: props.description,
+        details: props.details,
+        confirmLabel: props.confirmLabel,
+        busyLabel: props.busyLabel,
+        busy: props.busy ?? false,
+        tone: props.tone ?? "primary",
+      }
+    : snapshot()
+  const tone = () => content().tone
+  const confirmText = () => content().busy ? (content().busyLabel ?? content().confirmLabel) : content().confirmLabel
+
+  function handleClose() {
+    if (props.busy) return
+    props.onClose()
+  }
+
+  function handleConfirm() {
+    if (props.busy) return
+    void props.onConfirm()
+  }
+
+  return (
+    <Modal
+      open={props.open}
+      onClose={handleClose}
+      wrapperClass="fixed inset-0 z-50 flex items-center justify-center bg-black/50 p-4"
+      panelClass="w-full max-w-md rounded-2xl bg-white shadow-xl overflow-hidden"
+    >
+      <div class="px-6 pt-6 pb-4 border-b border-gray-100">
+        <div class="flex items-start justify-between gap-3">
+          <div>
+            <h2 class="text-lg font-semibold text-gray-900">{content().title}</h2>
+          </div>
+          <button
+            type="button"
+            onClick={handleClose}
+            disabled={content().busy}
+            class="shrink-0 rounded p-1 text-gray-400 hover:bg-gray-100 hover:text-gray-700 disabled:cursor-not-allowed disabled:opacity-50"
+            aria-label="Close"
+          >
+            <svg class="w-5 h-5" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+              <path d="M18 6L6 18M6 6l12 12" />
+            </svg>
+          </button>
+        </div>
+      </div>
+
+      <div class="px-6 py-4">
+        <div class="space-y-3 text-left">
+          <p class="text-sm text-gray-600">{content().description}</p>
+          <Show when={content().details && content().details!.length > 0}>
+            <ul class={`w-full rounded-lg border px-4 py-3 space-y-1.5 ${DETAIL_BOX_STYLES[tone()]}`}>
+              <For each={content().details}>
+                {(item) => (
+                  <li class="flex items-start gap-2 text-sm">
+                    <span class="mt-0.5 shrink-0 select-none">•</span>
+                    <span>{item}</span>
+                  </li>
+                )}
+              </For>
+            </ul>
+          </Show>
+        </div>
+      </div>
+
+      <div class="px-6 py-4 flex justify-end gap-3 border-t border-gray-100">
+        <button
+          type="button"
+          onClick={handleClose}
+          disabled={content().busy}
+          class="rounded-lg border border-gray-300 px-4 py-2 text-sm text-gray-700 transition-colors hover:bg-gray-50 disabled:cursor-not-allowed disabled:opacity-50"
+        >
+          Cancel
+        </button>
+        <button
+          type="button"
+          onClick={handleConfirm}
+          disabled={content().busy}
+          class={`rounded-lg px-4 py-2 text-sm font-medium transition-colors disabled:cursor-not-allowed disabled:opacity-50 ${TONE_STYLES[tone()]}`}
+        >
+          {confirmText()}
+        </button>
+      </div>
+    </Modal>
+  )
+}

frontend/src/components/PaymentDialog.tsx

@@ -3,7 +3,6 @@ import QRCode from "qrcode"
 import Modal from "@/components/Modal"
 import PaymentSetup from "@/components/PaymentSetup"
 import { getInvoice, getInvoiceBolt11 } from "@/lib/api"
-import { tenantNeedsPaymentSetup } from "@/lib/hooks"
 
 type PayStatus = "idle" | "loading" | "success" | "error"
 type Bolt11Status = "idle" | "loading" | "ready" | "error"
@@ -26,8 +25,8 @@ export default function PaymentDialog(props: PaymentDialogProps) {
   const [bolt11Error, setBolt11Error] = createSignal("")
   const [payStatus, setPayStatus] = createSignal<PayStatus>("idle")
   const [payError, setPayError] = createSignal("")
-  const [showSetup, setShowSetup] = createSignal(false)
   const [showPaymentSetup, setShowPaymentSetup] = createSignal(false)
+  const [setupSaved, setSetupSaved] = createSignal(false)
 
   async function loadBolt11() {
     if (!props.invoice.id) return
@@ -63,7 +62,6 @@ export default function PaymentDialog(props: PaymentDialogProps) {
       const invoice = await getInvoice(props.invoice.id)
       if (invoice.status === "paid") {
         setPayStatus("success")
-        tenantNeedsPaymentSetup().then(needs => setShowSetup(needs)).catch(() => {})
       } else {
         setPayStatus("error")
         setPayError("Payment not yet confirmed. Please try again after sending.")
@@ -81,7 +79,6 @@ export default function PaymentDialog(props: PaymentDialogProps) {
     setBolt11Error("")
     setBolt11("")
     setQrDataUrl("")
-    setShowSetup(false)
     props.onClose()
   }
 
@@ -160,6 +157,15 @@ export default function PaymentDialog(props: PaymentDialogProps) {
                     </button>
                   </div>
                 </Show>
+                <div class="text-center pt-1">
+                  <button
+                    type="button"
+                    onClick={() => setShowPaymentSetup(true)}
+                    class="text-sm text-blue-600 hover:text-blue-700"
+                  >
+                    Set up payment method instead
+                  </button>
+                </div>
               </Show>
             </div>
           }
@@ -172,15 +178,13 @@ export default function PaymentDialog(props: PaymentDialogProps) {
             </div>
             <p class="text-sm font-medium text-gray-900">Payment confirmed!</p>
             <p class="text-xs text-gray-500">Thank you. Your account is up to date.</p>
-            <Show when={showSetup()}>
-              <button
-                type="button"
-                onClick={() => setShowPaymentSetup(true)}
-                class="mt-2 text-sm font-medium text-blue-600 hover:text-blue-700"
-              >
-                Set up automatic payments
-              </button>
-            </Show>
+            <button
+              type="button"
+              onClick={() => setShowPaymentSetup(true)}
+              class="mt-2 text-sm font-medium text-blue-600 hover:text-blue-700"
+            >
+              Set up automatic payments
+            </button>
           </div>
         </Show>
       </div>
@@ -228,7 +232,14 @@ export default function PaymentDialog(props: PaymentDialogProps) {
     </Modal>
     <PaymentSetup
       open={showPaymentSetup()}
-      onClose={() => setShowPaymentSetup(false)}
+      onClose={() => {
+        setShowPaymentSetup(false)
+        if (setupSaved()) {
+          setSetupSaved(false)
+          props.onClose()
+        }
+      }}
+      onSaved={() => setSetupSaved(true)}
     />
     </>
   )

frontend/src/components/PaymentSetup.tsx

@@ -9,6 +9,7 @@ type Tab = "nwc" | "card"
 type PaymentSetupProps = {
   open: boolean
   onClose: () => void
+  onSaved?: () => void
 }
 
 export default function PaymentSetup(props: PaymentSetupProps) {
@@ -27,6 +28,7 @@ export default function PaymentSetup(props: PaymentSetupProps) {
     try {
       await updateActiveTenant({ nwc_url: url })
       setSaved(true)
+      props.onSaved?.()
     } catch (e) {
       setError(e instanceof Error ? e.message : "Failed to save wallet connection")
     } finally {
@@ -64,7 +66,7 @@ export default function PaymentSetup(props: PaymentSetupProps) {
         <div class="flex items-start justify-between gap-3">
           <div>
             <h2 class="text-lg font-semibold text-gray-900">Set Up Payments</h2>
-            <p class="text-sm text-gray-500 mt-1">Choose how you'd like to pay for your relay.</p>
+            <p class="text-sm text-gray-500 mt-1">Choose how you'd like to pay once invoices are issued for your relay.</p>
           </div>
           <button
             type="button"
@@ -144,7 +146,7 @@ export default function PaymentSetup(props: PaymentSetupProps) {
                 <line x1="1" y1="10" x2="23" y2="10" />
               </svg>
             </div>
-            <p class="text-sm text-gray-600">Add a payment card via Stripe to enable automatic billing.</p>
+            <p class="text-sm text-gray-600">Add a payment card via Stripe to enable automatic billing. If an invoice is currently due, we will retry collection after card setup.</p>
             <button
               type="button"
               onClick={openPortal}

frontend/src/components/RelayDetailCard.tsx

@@ -2,6 +2,7 @@ import { A } from "@solidjs/router"
 import { Show, createEffect, createSignal, onCleanup } from "solid-js"
 import type { Relay, PlanId } from "@/lib/api"
 import menuDotsIcon from "@/assets/menu-dots-2.svg"
+import ConfirmDialog from "@/components/ConfirmDialog"
 import Field from "@/components/Field"
 import PricingTable from "@/components/PricingTable"
 import ToggleButton from "@/components/ToggleButton"
@@ -51,8 +52,8 @@ type RelayDetailCardProps = {
   currentMembers?: number
   showTenant?: boolean
   editHref?: string
-  onDeactivate?: () => void
-  onReactivate?: () => void
+  onDeactivate?: () => void | Promise<void>
+  onReactivate?: () => void | Promise<void>
   deactivating?: boolean
   reactivating?: boolean
   onTogglePublicJoin?: () => void
@@ -76,6 +77,7 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
   }
   const [menuOpen, setMenuOpen] = createSignal(false)
   const [plan, setPlan] = createSignal<PlanId>(props.relay.plan)
+  const [pendingAction, setPendingAction] = createSignal<"deactivate" | "reactivate" | null>(null)
 
   let menuContainerRef: HTMLDivElement | undefined
 
@@ -86,6 +88,24 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
   }
   const planLimited = () => (props.enforcePlanLimits ?? true) && r().plan === "free"
   const showPlanActions = () => props.showPlanActions ?? true
+  const actionBusy = () => pendingAction() === "deactivate" ? !!props.deactivating : pendingAction() === "reactivate" ? !!props.reactivating : false
+  const relayLabel = () => r().info_name || r().subdomain
+  const confirmTitle = () => pendingAction() === "deactivate" ? "Deactivate relay?" : "Reactivate relay?"
+  const confirmDescription = () => pendingAction() === "deactivate"
+    ? `${relayLabel()} will be taken offline immediately.`
+    : `${relayLabel()} will come back online and start accepting connections.`
+  const confirmDetails = () => pendingAction() === "deactivate"
+    ? [
+        "All client connections will be dropped immediately.",
+        "Members will be unable to read from or publish to the relay.",
+        "Scheduled and automated tasks (billing, syncing) will be paused.",
+        "All relay data, settings, and members are preserved, nothing is deleted.",
+        "You can reactivate at any time from this page.",
+      ]
+    : undefined
+  const confirmLabel = () => pendingAction() === "deactivate" ? "Yes, deactivate" : "Yes, reactivate"
+  const confirmBusyLabel = () => pendingAction() === "deactivate" ? "Deactivating..." : "Reactivating..."
+  const confirmTone = () => pendingAction() === "deactivate" ? "danger" : "primary"
 
   async function changePlan(plan: PlanId) {
     setPlan(plan)
@@ -97,6 +117,29 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
     }
   }
 
+  function openActionDialog(action: "deactivate" | "reactivate") {
+    setMenuOpen(false)
+    setPendingAction(action)
+  }
+
+  function closeActionDialog() {
+    if (actionBusy()) return
+    setPendingAction(null)
+  }
+
+  async function confirmAction() {
+    const action = pendingAction()
+    if (!action) return
+
+    if (action === "deactivate") {
+      await props.onDeactivate?.()
+    } else {
+      await props.onReactivate?.()
+    }
+
+    setPendingAction(null)
+  }
+
   createEffect(() => {
     if (!menuOpen()) return
 
@@ -128,7 +171,7 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
       <div class="flex items-start justify-between gap-4">
         <div class="flex items-start gap-4 min-w-0">
           <Show when={r().info_icon}>
-            <img src={r().info_icon} alt="" class="w-14 h-14 rounded-xl object-cover flex-shrink-0 border border-gray-200" />
+            <img src={r().info_icon} alt="" class="w-14 h-14 rounded-xl object-cover shrink-0 border border-gray-200" />
           </Show>
           <div class="min-w-0">
             <div class="flex items-center gap-3 flex-wrap">
@@ -148,7 +191,7 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
         </div>
 
         <Show when={props.editHref && (props.onDeactivate || props.onReactivate)}>
-          <div class="relative flex-shrink-0" ref={menuContainerRef}>
+          <div class="relative shrink-0" ref={menuContainerRef}>
             <button
               type="button"
               class="inline-flex h-9 w-9 items-center justify-center rounded-lg border border-gray-200 hover:bg-gray-50"
@@ -177,8 +220,7 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
                   type="button"
                   class="block w-full text-left px-3 py-2 text-sm text-red-600 hover:bg-red-50 disabled:opacity-50"
                   onClick={() => {
-                    setMenuOpen(false)
-                    props.onDeactivate?.()
+                    openActionDialog("deactivate")
                   }}
                   disabled={props.deactivating}
                 >
@@ -190,8 +232,7 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
                   type="button"
                   class="block w-full text-left px-3 py-2 text-sm text-blue-600 hover:bg-blue-50 disabled:opacity-50"
                   onClick={() => {
-                    setMenuOpen(false)
-                    props.onReactivate?.()
+                    openActionDialog("reactivate")
                   }}
                   disabled={props.reactivating}
                 >
@@ -346,6 +387,19 @@ export default function RelayDetailCard(props: RelayDetailCardProps) {
           </Show>
         </DetailSection>
       </Show>
+
+      <ConfirmDialog
+        open={pendingAction() !== null}
+        title={confirmTitle()}
+        description={confirmDescription()}
+        details={confirmDetails()}
+        confirmLabel={confirmLabel()}
+        busyLabel={confirmBusyLabel()}
+        busy={actionBusy()}
+        tone={confirmTone()}
+        onConfirm={confirmAction}
+        onClose={closeActionDialog}
+      />
     </div>
   )
 }

frontend/src/components/RelayForm.tsx

@@ -1,6 +1,7 @@
 import { createEffect, createMemo, createSignal, For } from "solid-js"
 import type { Relay } from "@/lib/hooks"
 import { slugify } from "@/lib/slugify"
+import { validateSubdomainLabel } from "@/lib/subdomain"
 import { setToastMessage } from "@/components/Toast"
 import { plans } from "@/lib/state"
 
@@ -31,6 +32,12 @@ export default function RelayForm(props: RelayFormProps) {
       return
     }
 
+    const subdomainError = validateSubdomainLabel(subdomain())
+    if (subdomainError) {
+      setToastMessage(subdomainError)
+      return
+    }
+
     setToastMessage("")
     setSubmitting(true)
 

frontend/src/lib/api.ts

@@ -241,6 +241,10 @@ export function getRelay(id: string) {
   return callApi<undefined, Relay>("GET", `/relays/${id}`)
 }
 
+export function listRelayMembers(id: string) {
+  return callApi<undefined, { members: string[] }>("GET", `/relays/${id}/members`)
+}
+
 export function listRelayActivity(id: string) {
   return callApi<undefined, { activity: Activity[] }>("GET", `/relays/${id}/activity`)
 }

frontend/src/lib/hooks.ts

@@ -2,7 +2,6 @@ import { createEffect, createResource, createSignal, onCleanup } from "solid-js"
 import { getProfilePicture } from "applesauce-core/helpers/profile"
 import { createOutboxMap, selectOptimalRelays, setFallbackRelays } from "applesauce-core/helpers/relay-selection"
 import { includeMailboxes } from "applesauce-core/observable"
-import { Relay as NostrRelay, RelayManagement } from "applesauce-relay"
 import { map, of } from "rxjs"
 import {
   createRelay,
@@ -12,12 +11,14 @@ import {
   getTenant,
   listRelayActivity,
   listRelays,
+  listTenantInvoices,
   listTenantRelays,
   listTenants,
   updateRelay,
   updateTenant,
   type Activity,
   type CreateRelayInput,
+  type Invoice,
   type Relay,
   type Tenant,
   type UpdateRelayInput,
@@ -137,14 +138,12 @@ export async function tenantNeedsPaymentSetup(): Promise<boolean> {
   return !tenant.nwc_url && !tenant.stripe_subscription_id
 }
 
-export async function getRelayMembers(url: string) {
-  const management = new RelayManagement(new NostrRelay(url), account()!.signer)
-
-  try {
-    return await management.listAllowedPubkeys()
-  } catch {
-    return []
-  }
+export async function getLatestOpenInvoice(): Promise<Invoice | null> {
+  const invoices = await listTenantInvoices(account()!.pubkey)
+  const open = invoices
+    .filter(inv => inv.status === "open" && inv.amount_due > 0)
+    .sort((a, b) => b.period_start - a.period_start)
+  return open[0] ?? null
 }
 
-export type { Activity, Relay, Tenant }
+export type { Activity, Invoice, Relay, Tenant }

frontend/src/lib/subdomain.ts

@@ -0,0 +1,22 @@
+const SUBDOMAIN_LABEL_MAX_LEN = 63
+const RESERVED_SUBDOMAIN_LABELS = new Set(["api", "admin"])
+
+export function validateSubdomainLabel(subdomain: string): string | null {
+  if (subdomain.length === 0) {
+    return "subdomain is required"
+  }
+  if (subdomain.length > SUBDOMAIN_LABEL_MAX_LEN) {
+    return "subdomain must be 63 characters or fewer"
+  }
+  if (subdomain.startsWith("-") || subdomain.endsWith("-")) {
+    return "subdomain cannot start or end with a hyphen"
+  }
+  if (RESERVED_SUBDOMAIN_LABELS.has(subdomain)) {
+    return "subdomain is reserved"
+  }
+  if (!/^[a-z0-9-]+$/.test(subdomain)) {
+    return "subdomain may only contain lowercase letters, numbers, and hyphens"
+  }
+
+  return null
+}

frontend/src/lib/useRelayToggles.ts

@@ -1,7 +1,7 @@
 import { createSignal } from "solid-js"
-import { updateRelayById, deactivateRelayById, reactivateRelayById, tenantNeedsPaymentSetup, type Relay } from "@/lib/hooks"
+import { updateRelayById, deactivateRelayById, reactivateRelayById, getLatestOpenInvoice, type Relay } from "@/lib/hooks"
 import { setToastMessage } from "@/components/Toast"
-import type { PlanId } from "@/lib/api"
+import type { Invoice, PlanId } from "@/lib/api"
 
 function toBool(value: number | undefined, fallback: boolean): boolean {
   if (value === 0) return false
@@ -30,7 +30,7 @@ export default function useRelayToggles(
   { refetch, mutate }: RelayActions,
 ) {
   const [busy, setBusy] = createSignal(false)
-  const [needsPaymentSetup, setNeedsPaymentSetup] = createSignal(false)
+  const [pendingInvoice, setPendingInvoice] = createSignal<Invoice | undefined>()
 
   async function updateRelay(next: Relay, previous: Relay) {
     mutate(next)
@@ -101,8 +101,8 @@ export default function useRelayToggles(
     }
 
     if (plan !== "free") {
-      const needs = await tenantNeedsPaymentSetup()
-      if (needs) setNeedsPaymentSetup(true)
+      const invoice = await getLatestOpenInvoice()
+      if (invoice) setPendingInvoice(invoice)
     }
   }
 
@@ -116,5 +116,5 @@ export default function useRelayToggles(
     onToggleLivekitSupport: () => toggle("livekit_enabled", relay()?.plan !== "free"),
   }
 
-  return { busy, handleDeactivate, handleReactivate, handleUpdatePlan, needsPaymentSetup, clearNeedsPaymentSetup: () => setNeedsPaymentSetup(false), toggles }
+  return { busy, handleDeactivate, handleReactivate, handleUpdatePlan, pendingInvoice, clearPendingInvoice: () => setPendingInvoice(undefined), toggles }
 }

frontend/src/pages/admin/AdminRelayDetail.tsx

@@ -1,11 +1,12 @@
 import { useParams } from "@solidjs/router"
-import { Show } from "solid-js"
+import { createResource, Show } from "solid-js"
 import BackLink from "@/components/BackLink"
 import PageContainer from "@/components/PageContainer"
 import RelayDetailCard from "@/components/RelayDetailCard"
 import ResourceState from "@/components/ResourceState"
 import useMinLoading from "@/components/useMinLoading"
 import ActivityFeed from "@/components/ActivityFeed"
+import { listRelayMembers } from "@/lib/api"
 import { useRelay, useRelayActivity } from "@/lib/hooks"
 import useRelayToggles from "@/lib/useRelayToggles"
 
@@ -13,6 +14,15 @@ export default function AdminRelayDetail() {
   const params = useParams()
   const relayId = () => params.id ?? ""
   const [relay, { refetch, mutate }] = useRelay(relayId)
+  const [members] = createResource(relayId, async (id) => {
+    if (!id) return []
+
+    try {
+      return (await listRelayMembers(id)).members
+    } catch {
+      return []
+    }
+  })
   const loading = useMinLoading(() => relay.loading && !relay())
   const [activity] = useRelayActivity(relayId)
   const { busy, handleDeactivate, handleReactivate, toggles } = useRelayToggles(relayId, relay, { refetch, mutate })
@@ -26,6 +36,7 @@ export default function AdminRelayDetail() {
           <div class="space-y-6 mb-6">
             <RelayDetailCard
               relay={r()}
+              currentMembers={members()?.length}
               showTenant
               editHref={`/admin/relays/${params.id}/edit`}
               onDeactivate={handleDeactivate}

frontend/src/pages/relays/RelayDetail.tsx

@@ -1,27 +1,59 @@
 import { useParams } from "@solidjs/router"
-import { createMemo, createResource, Show } from "solid-js"
+import { createMemo, createResource, createSignal, Show } from "solid-js"
 import BackLink from "@/components/BackLink"
 import PageContainer from "@/components/PageContainer"
+import PaymentDialog from "@/components/PaymentDialog"
 import PaymentSetup from "@/components/PaymentSetup"
 import RelayDetailCard from "@/components/RelayDetailCard"
 import ResourceState from "@/components/ResourceState"
 import useMinLoading from "@/components/useMinLoading"
 import ActivityFeed from "@/components/ActivityFeed"
-import { getRelayMembers, useRelay, useRelayActivity } from "@/lib/hooks"
+import { listRelayMembers } from "@/lib/api"
+import { getLatestOpenInvoice, useRelay, useRelayActivity, useTenant } from "@/lib/hooks"
 import useRelayToggles from "@/lib/useRelayToggles"
+import { plans } from "@/lib/state"
 
 export default function RelayDetail() {
   const params = useParams()
   const relayId = () => params.id ?? ""
   const [relay, { refetch, mutate }] = useRelay(relayId)
-  const relayUrl = createMemo(() => {
-    const subdomain = relay()?.subdomain
-    return subdomain ? `wss://${subdomain}.spaces.coracle.social` : undefined
+  const [members] = createResource(relayId, async (id) => {
+    if (!id) return []
+
+    try {
+      return (await listRelayMembers(id)).members
+    } catch {
+      return []
+    }
   })
-  const [members] = createResource(relayUrl, getRelayMembers)
   const loading = useMinLoading(() => relay.loading && !relay())
   const [activity] = useRelayActivity(relayId)
-  const { busy, handleDeactivate, handleReactivate, handleUpdatePlan, needsPaymentSetup, clearNeedsPaymentSetup, toggles } = useRelayToggles(relayId, relay, { refetch, mutate })
+  const { busy, handleDeactivate, handleReactivate, handleUpdatePlan, pendingInvoice, clearPendingInvoice, toggles } = useRelayToggles(relayId, relay, { refetch, mutate })
+
+  const [tenant, { refetch: refetchTenant }] = useTenant()
+  const [paymentSetupOpen, setPaymentSetupOpen] = createSignal(false)
+  const [invoiceDialogOpen, setInvoiceDialogOpen] = createSignal(false)
+  const [paymentBannerDismissed, setPaymentBannerDismissed] = createSignal(false)
+
+  const isPaidRelay = createMemo(() => {
+    const r = relay()
+    if (!r) return false
+    const plan = plans().find(p => p.id === r.plan)
+    return !!(plan && plan.amount > 0)
+  })
+
+  const [openInvoice, { refetch: refetchOpenInvoice }] = createResource(
+    isPaidRelay,
+    async (paid) => paid ? getLatestOpenInvoice() : null
+  )
+
+  const showPaymentNudge = createMemo(() => {
+    if (paymentBannerDismissed()) return false
+    if (!isPaidRelay()) return false
+    const t = tenant()
+    if (!t) return false
+    return !t.nwc_url
+  })
 
   return (
     <PageContainer>
@@ -30,9 +62,47 @@ export default function RelayDetail() {
       <Show when={!loading() && relay()}>
         {(r) => (
           <div class="space-y-6 mb-6">
+            <Show when={showPaymentNudge()}>
+              <div class="rounded-lg border border-amber-200 bg-amber-50 p-4 flex items-start justify-between gap-4">
+                <div class="min-w-0">
+                  <p class="text-sm font-medium text-amber-800">Payment setup recommended</p>
+                  <p class="text-sm text-amber-700 mt-1">
+                    This relay is on a paid plan. Invoices are due when your subscription starts. Set up NWC or Stripe for automatic payments, or pay open invoices via Lightning.
+                  </p>
+                </div>
+                <div class="flex items-center gap-3 shrink-0">
+                  <Show when={openInvoice()}>
+                    <button
+                      type="button"
+                      onClick={() => setInvoiceDialogOpen(true)}
+                      class="text-sm font-medium text-amber-800 underline hover:text-amber-900 whitespace-nowrap"
+                    >
+                      Pay invoice
+                    </button>
+                  </Show>
+                  <button
+                    type="button"
+                    onClick={() => setPaymentSetupOpen(true)}
+                    class="text-sm font-medium text-amber-800 underline hover:text-amber-900 whitespace-nowrap"
+                  >
+                    Set up payments
+                  </button>
+                  <button
+                    type="button"
+                    onClick={() => setPaymentBannerDismissed(true)}
+                    aria-label="Dismiss"
+                    class="text-amber-500 hover:text-amber-800 shrink-0"
+                  >
+                    <svg class="w-4 h-4" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                      <path d="M18 6L6 18M6 6l12 12" />
+                    </svg>
+                  </button>
+                </div>
+              </div>
+            </Show>
             <RelayDetailCard
               relay={r()}
-              currentMembers={members.length}
+              currentMembers={members()?.length}
               editHref={`/relays/${params.id}/edit`}
               onDeactivate={handleDeactivate}
               onReactivate={handleReactivate}
@@ -45,9 +115,37 @@ export default function RelayDetail() {
           </div>
         )}
       </Show>
+      <Show when={pendingInvoice()}>
+        {(inv) => (
+          <PaymentDialog
+            invoice={inv()}
+            open={true}
+            onClose={() => {
+              clearPendingInvoice()
+              void refetchTenant()
+              void refetchOpenInvoice()
+            }}
+          />
+        )}
+      </Show>
+      <Show when={openInvoice()}>
+        {(inv) => (
+          <PaymentDialog
+            invoice={inv()!}
+            open={invoiceDialogOpen()}
+            onClose={() => {
+              setInvoiceDialogOpen(false)
+              void refetchOpenInvoice()
+            }}
+          />
+        )}
+      </Show>
       <PaymentSetup
-        open={needsPaymentSetup()}
-        onClose={clearNeedsPaymentSetup}
+        open={paymentSetupOpen()}
+        onClose={() => {
+          setPaymentSetupOpen(false)
+          void refetchTenant()
+        }}
       />
     </PageContainer>
   )

frontend/src/pages/relays/RelayEdit.tsx

@@ -1,7 +1,6 @@
 import { useNavigate, useParams } from "@solidjs/router"
 import { Show } from "solid-js"
 import RelayForm, { type RelayFormValues } from "@/components/RelayForm"
-import { slugify } from "@/lib/slugify"
 import BackLink from "@/components/BackLink"
 import PageContainer from "@/components/PageContainer"
 import ResourceState from "@/components/ResourceState"
@@ -18,7 +17,7 @@ export default function RelayEdit(props: { basePath?: string; title?: string })
 
   async function handleSubmit(values: RelayFormValues) {
     await updateRelayById(relayId(), {
-      subdomain: slugify(values.subdomain),
+      subdomain: values.subdomain,
       info_name: values.info_name.trim(),
       info_icon: values.info_icon.trim(),
       info_description: values.info_description.trim(),

frontend/src/pages/relays/RelayNew.tsx

@@ -1,14 +1,15 @@
-import { createSignal } from "solid-js"
+import { createSignal, Show } from "solid-js"
 import { useNavigate } from "@solidjs/router"
 import BackLink from "@/components/BackLink"
 import PageContainer from "@/components/PageContainer"
-import PaymentSetup from "@/components/PaymentSetup"
+import PaymentDialog from "@/components/PaymentDialog"
 import RelayForm, { type RelayFormValues } from "@/components/RelayForm"
-import { createRelayForActiveTenant, tenantNeedsPaymentSetup } from "@/lib/hooks"
+import { createRelayForActiveTenant, getLatestOpenInvoice } from "@/lib/hooks"
+import type { Invoice } from "@/lib/api"
 
 export default function RelayNew() {
   const navigate = useNavigate()
-  const [showPaymentSetup, setShowPaymentSetup] = createSignal(false)
+  const [pendingInvoice, setPendingInvoice] = createSignal<Invoice | undefined>()
   let createdRelayId = ""
 
   async function handleSubmit(values: RelayFormValues) {
@@ -16,9 +17,9 @@ export default function RelayNew() {
     createdRelayId = relay.id
 
     if (values.plan !== "free") {
-      const needs = await tenantNeedsPaymentSetup()
-      if (needs) {
-        setShowPaymentSetup(true)
+      const invoice = await getLatestOpenInvoice()
+      if (invoice) {
+        setPendingInvoice(invoice)
         return
       }
     }
@@ -27,7 +28,7 @@ export default function RelayNew() {
   }
 
   function handleDialogClose() {
-    setShowPaymentSetup(false)
+    setPendingInvoice(undefined)
     navigate(`/relays/${createdRelayId}`)
   }
 
@@ -41,10 +42,15 @@ export default function RelayNew() {
         submitLabel="Create Relay"
         submittingLabel="Creating..."
       />
-      <PaymentSetup
-        open={showPaymentSetup()}
-        onClose={handleDialogClose}
-      />
+      <Show when={pendingInvoice()}>
+        {(inv) => (
+          <PaymentDialog
+            invoice={inv()}
+            open={true}
+            onClose={handleDialogClose}
+          />
+        )}
+      </Show>
     </PageContainer>
   )
 }