feat(wallet): Ark protocol support via barkd sidecar

barkd (Ark wallet daemon, pinned 0.3.0, checksum-verified release binary)
packaged as an installable app; thin HTTP bridge in wallet/ark_client.rs
mirrors the fedimint_client pattern — the bark SDK stays out of the node
binary. wallet.ark-* RPCs cover status/balance/address/send/invoice/
board/offboard/history/configure; Ark movements merge into the unified
ecash history (kind="ark") and spendable Ark sats into total_sats.
Signet defaults (Second's public Ark server) until Ark matures.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/api/rpc/ark.rs

@@ -0,0 +1,223 @@
+//! Ark protocol RPCs — bridge to the `barkd` sidecar.
+//!
+//! Companion to the Cashu RPCs in [`super::wallet`] and the Fedimint RPCs in
+//! [`super::fedimint`]. Holding VTXOs, joining rounds and unilateral exits are
+//! delegated to the barkd container via [`crate::wallet::ark_client::ArkClient`];
+//! here we expose the node's JSON-RPC surface. barkd keeps its own movement
+//! history, so unlike Fedimint there is no local transaction log.
+
+use super::RpcHandler;
+use crate::wallet::ark_client::{self, ArkClient};
+use anyhow::Result;
+
+impl RpcHandler {
+    /// `wallet.ark-status` — sidecar reachability, wallet fingerprint, network
+    /// and Ark server parameters. Soft-fails into `available: false` so the
+    /// settings UI can render an install/enable hint instead of an error.
+    pub(super) async fn handle_wallet_ark_status(&self) -> Result<serde_json::Value> {
+        let config = ark_client::load_config(&self.config.data_dir).await;
+        let client = match ArkClient::from_node(&self.config.data_dir).await {
+            Ok(c) => c,
+            Err(_) => {
+                return Ok(serde_json::json!({
+                    "available": false,
+                    "wallet_ready": false,
+                    "config": config,
+                }))
+            }
+        };
+        // Make sure the wallet exists before reporting (idempotent, cheap once
+        // created).
+        let _ = ark_client::ensure_wallet(&self.config.data_dir).await;
+
+        let wallet = client.wallet_info().await.ok();
+        let info = client.ark_info().await.ok();
+        Ok(serde_json::json!({
+            "available": true,
+            "wallet_ready": wallet.is_some(),
+            "wallet": wallet,
+            "ark_info": info,
+            "config": config,
+        }))
+    }
+
+    /// `wallet.ark-balance` — off-chain (spendable + pending) and on-chain
+    /// sats. Soft-fails to zeros so unified balances still render.
+    pub(super) async fn handle_wallet_ark_balance(&self) -> Result<serde_json::Value> {
+        let client = match ArkClient::from_node(&self.config.data_dir).await {
+            Ok(c) => c,
+            Err(_) => {
+                return Ok(serde_json::json!({
+                    "balance_sats": 0,
+                    "spendable_sats": 0,
+                    "pending_sats": 0,
+                    "onchain_sats": 0,
+                }))
+            }
+        };
+        let bal = client.balance().await.unwrap_or_else(|_| serde_json::json!({}));
+        let sat = |key: &str| bal.get(key).and_then(|v| v.as_u64()).unwrap_or(0);
+        let spendable = sat("spendable_sat");
+        let pending = sat("pending_in_round_sat")
+            + sat("pending_board_sat")
+            + sat("pending_lightning_send_sat")
+            + sat("claimable_lightning_receive_sat")
+            + bal.get("pending_exit_sat").and_then(|v| v.as_u64()).unwrap_or(0);
+        let onchain = client
+            .onchain_balance()
+            .await
+            .ok()
+            .and_then(|b| {
+                b.get("total_sat")
+                    .or_else(|| b.get("confirmed_sat"))
+                    .and_then(|v| v.as_u64())
+            })
+            .unwrap_or(0);
+        Ok(serde_json::json!({
+            "balance_sats": spendable,
+            "spendable_sats": spendable,
+            "pending_sats": pending,
+            "onchain_sats": onchain,
+        }))
+    }
+
+    /// `wallet.ark-address` — fresh Ark (`tark1…`) receive address; pass
+    /// `{"onchain": true}` for an on-chain boarding address instead.
+    pub(super) async fn handle_wallet_ark_address(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let _ = ark_client::ensure_wallet(&self.config.data_dir).await;
+        let client = ArkClient::from_node(&self.config.data_dir).await?;
+        let onchain = params
+            .as_ref()
+            .and_then(|p| p.get("onchain"))
+            .and_then(|v| v.as_bool())
+            .unwrap_or(false);
+        let address = if onchain {
+            client.onchain_address().await?
+        } else {
+            client.ark_address().await?
+        };
+        Ok(serde_json::json!({ "address": address, "onchain": onchain }))
+    }
+
+    /// `wallet.ark-send` — pay an Ark address, BOLT11 invoice, LNURL or
+    /// lightning address from Ark funds.
+    pub(super) async fn handle_wallet_ark_send(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let params = params.ok_or_else(|| anyhow::anyhow!("Missing params"))?;
+        let destination = params
+            .get("destination")
+            .and_then(|v| v.as_str())
+            .map(str::trim)
+            .filter(|s| !s.is_empty())
+            .ok_or_else(|| anyhow::anyhow!("Missing destination"))?;
+        // Optional for BOLT11 invoices that carry their own amount.
+        let amount_sats = params.get("amount_sats").and_then(|v| v.as_u64());
+        if amount_sats == Some(0) {
+            return Err(anyhow::anyhow!("Amount must be greater than zero"));
+        }
+        let comment = params.get("comment").and_then(|v| v.as_str());
+
+        let client = ArkClient::from_node(&self.config.data_dir).await?;
+        let movement = client.send(destination, amount_sats, comment).await?;
+        Ok(serde_json::json!({
+            "sent": true,
+            "movement": movement,
+        }))
+    }
+
+    /// `wallet.ark-invoice` — BOLT11 invoice that lands as Ark funds when paid.
+    pub(super) async fn handle_wallet_ark_invoice(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let params = params.ok_or_else(|| anyhow::anyhow!("Missing params"))?;
+        let amount_sats = params
+            .get("amount_sats")
+            .and_then(|v| v.as_u64())
+            .filter(|&v| v > 0)
+            .ok_or_else(|| anyhow::anyhow!("Missing amount_sats"))?;
+
+        let _ = ark_client::ensure_wallet(&self.config.data_dir).await;
+        let client = ArkClient::from_node(&self.config.data_dir).await?;
+        let res = client.lightning_invoice(amount_sats).await?;
+        Ok(res)
+    }
+
+    /// `wallet.ark-board` — lift on-chain funds into Ark VTXOs. Omitting
+    /// `amount_sats` boards everything.
+    pub(super) async fn handle_wallet_ark_board(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let amount_sats = params
+            .as_ref()
+            .and_then(|p| p.get("amount_sats"))
+            .and_then(|v| v.as_u64());
+        if amount_sats == Some(0) {
+            return Err(anyhow::anyhow!("Amount must be greater than zero"));
+        }
+        let client = ArkClient::from_node(&self.config.data_dir).await?;
+        let res = client.board(amount_sats).await?;
+        Ok(res)
+    }
+
+    /// `wallet.ark-offboard` — collaboratively move all VTXOs back on-chain,
+    /// optionally to a provided address (defaults to the wallet's own).
+    pub(super) async fn handle_wallet_ark_offboard(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let address = params
+            .as_ref()
+            .and_then(|p| p.get("address"))
+            .and_then(|v| v.as_str())
+            .map(str::trim)
+            .filter(|s| !s.is_empty());
+        let client = ArkClient::from_node(&self.config.data_dir).await?;
+        let res = client.offboard_all(address).await?;
+        Ok(res)
+    }
+
+    /// `wallet.ark-history` — barkd movements mapped to the unified
+    /// transaction shape (kind = "ark"), newest first.
+    pub(super) async fn handle_wallet_ark_history(&self) -> Result<serde_json::Value> {
+        let mut transactions = ark_client::load_ark_txs(&self.config.data_dir).await;
+        transactions.sort_by(|a, b| b.timestamp.cmp(&a.timestamp));
+        Ok(serde_json::json!({ "transactions": transactions }))
+    }
+
+    /// `wallet.ark-configure` — set the Ark server / esplora / network used
+    /// when the barkd wallet is (re)created. Does NOT migrate an existing
+    /// wallet: barkd binds a wallet to its Ark server at creation.
+    pub(super) async fn handle_wallet_ark_configure(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let params = params.ok_or_else(|| anyhow::anyhow!("Missing params"))?;
+        let mut config = ark_client::load_config(&self.config.data_dir).await;
+        for (key, field) in [
+            ("network", &mut config.network as &mut String),
+            ("ark_server", &mut config.ark_server),
+            ("esplora", &mut config.esplora),
+        ] {
+            if let Some(v) = params.get(key).and_then(|v| v.as_str()) {
+                let v = v.trim();
+                if !v.is_empty() {
+                    *field = v.to_string();
+                }
+            }
+        }
+        if !matches!(config.network.as_str(), "signet" | "mainnet" | "regtest") {
+            return Err(anyhow::anyhow!(
+                "network must be one of: signet, mainnet, regtest"
+            ));
+        }
+        ark_client::save_config(&self.config.data_dir, &config).await?;
+        Ok(serde_json::json!({ "config": config }))
+    }
+}

core/archipelago/src/api/rpc/dispatcher.rs

@@ -258,6 +258,17 @@ impl RpcHandler {
             "wallet.fedimint-leave" => self.handle_wallet_fedimint_leave(params).await,
             "wallet.fedimint-balance" => self.handle_wallet_fedimint_balance().await,
 
+            // Ark protocol (via barkd sidecar)
+            "wallet.ark-status" => self.handle_wallet_ark_status().await,
+            "wallet.ark-balance" => self.handle_wallet_ark_balance().await,
+            "wallet.ark-address" => self.handle_wallet_ark_address(params).await,
+            "wallet.ark-send" => self.handle_wallet_ark_send(params).await,
+            "wallet.ark-invoice" => self.handle_wallet_ark_invoice(params).await,
+            "wallet.ark-board" => self.handle_wallet_ark_board(params).await,
+            "wallet.ark-offboard" => self.handle_wallet_ark_offboard(params).await,
+            "wallet.ark-history" => self.handle_wallet_ark_history().await,
+            "wallet.ark-configure" => self.handle_wallet_ark_configure(params).await,
+
             // Container registries
             "registry.list" => self.handle_registry_list().await,
             "registry.add" => self.handle_registry_add(params).await,

core/archipelago/src/api/rpc/mod.rs

@@ -1,4 +1,5 @@
 mod analytics;
+mod ark;
 mod auth;
 mod backup_rpc;
 mod bitcoin;

core/archipelago/src/api/rpc/wallet.rs

@@ -1,5 +1,5 @@
 use super::RpcHandler;
-use crate::wallet::{ecash, fedimint_client, profits};
+use crate::wallet::{ark_client, ecash, fedimint_client, profits};
 use anyhow::Result;
 
 /// A Cashu token (NUT-00 `cashuA`/`cashuB`, or our legacy `cashuSend_` form)
@@ -21,13 +21,16 @@ impl RpcHandler {
                 Ok(client) => client.total_balance_sats().await.unwrap_or(0),
                 Err(_) => 0,
             };
+        // Spendable Ark (barkd) balance, same best-effort contract.
+        let ark_sats = ark_client::spendable_sats_or_zero(&self.config.data_dir).await;
         Ok(serde_json::json!({
             // `balance_sats` stays Cashu-only for back-compat; `total_sats` is the
-            // spendable amount across Cashu + Fedimint.
+            // spendable amount across Cashu + Fedimint + Ark.
             "balance_sats": cashu_sats,
             "cashu_sats": cashu_sats,
             "fedimint_sats": fedimint_sats,
-            "total_sats": cashu_sats + fedimint_sats,
+            "ark_sats": ark_sats,
+            "total_sats": cashu_sats + fedimint_sats + ark_sats,
             "proof_count": wallet.proofs.iter().filter(|p| !p.spent && !p.reserved).count(),
             "mint_url": wallet.mint_url,
         }))
@@ -181,6 +184,8 @@ impl RpcHandler {
         let wallet = ecash::load_wallet(&self.config.data_dir).await?;
         let mut transactions = wallet.transactions;
         transactions.extend(fedimint_client::load_fedimint_txs(&self.config.data_dir).await);
+        // Ark movements from barkd (kind="ark"), best-effort like Fedimint.
+        transactions.extend(ark_client::load_ark_txs(&self.config.data_dir).await);
         // Sort by RFC-3339 timestamp descending (string compare is valid for
         // same-offset RFC-3339), newest first.
         transactions.sort_by(|a, b| b.timestamp.cmp(&a.timestamp));