demos: add remote signing coordinator

Author: darioAnongba

demos/remote-signing-coordinator/.env.example

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+COORDINATOR_LISTEN=127.0.0.1:8091
+COORDINATOR_API_URL=http://127.0.0.1:8091
+
+TAP_TRANSPORT=grpc
+TAPD_HOST=localhost:10029
+TAPD_REST_URL=https://localhost:8089
+TAPD_NETWORK=regtest
+TAPD_TLS_PATH=.tapd/alice/tls.cert
+TAPD_MACAROON_PATH=.tapd/alice/admin.macaroon
+TAPD_TLS_INSECURE=false

demos/remote-signing-coordinator/.gitignore

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+.env
+.tapd/
+server/remote-signing-coordinator

demos/remote-signing-coordinator/README.md

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+# Remote Signing Coordinator
+
+This demo is a local coordinator for Taproot Assets Issuances that need an
+external signing device. It uses the Go SDK on the server side and a
+Next.js/Tailwind dashboard for the browser workflow.
+
+The dashboard does not talk to `tapd` directly. The Go server connects to
+`tapd`, starts an SDK issuer call, pauses when the SDK asks for an external
+Issuance signature, exposes the unsigned virtual PSBT for review, accepts the
+signed virtual PSBT, and then lets the SDK finalize the Issuance.
+
+## Requirements
+
+- Docker with Compose
+- Go, using the version required by this repository
+- Node.js with Yarn 4 through Corepack
+
+If Corepack is not enabled yet:
+
+```bash
+corepack enable
+```
+
+## Quick Start
+
+From this directory:
+
+```bash
+cd dashboard
+yarn install
+yarn regtest
+yarn dev
+```
+
+Open the dashboard at:
+
+```text
+http://127.0.0.1:3000
+```
+
+`yarn regtest` starts the repository integration-test regtest stack and exports
+Alice and Bob `tapd` credentials into `.tapd/`. The default `.env` values point
+the coordinator at Alice on regtest.
+
+Stop the regtest stack with:
+
+```bash
+yarn regtest:down
+```
+
+## Commands
+
+Run from `dashboard/`:
+
+| Command | Purpose |
+| --- | --- |
+| `yarn dev` | Run the Go coordinator and dashboard together |
+| `yarn server` | Run only the Go coordinator |
+| `yarn dashboard` | Run only the Next.js dashboard |
+| `yarn regtest` | Start the pinned regtest stack and export creds |
+| `yarn regtest:down` | Stop the pinned regtest stack |
+| `yarn test` | Typecheck, lint, build dashboard, build server |
+
+## Configuration
+
+Defaults live in `.env.example`. Running any demo command creates `.env` from
+that file if it does not exist.
+
+| Variable | Default |
+| --- | --- |
+| `COORDINATOR_LISTEN` | `127.0.0.1:8091` |
+| `COORDINATOR_API_URL` | `http://127.0.0.1:8091` |
+| `TAP_TRANSPORT` | `grpc` |
+| `TAPD_HOST` | `localhost:10029` |
+| `TAPD_REST_URL` | `https://localhost:8089` |
+| `TAPD_NETWORK` | `regtest` |
+| `TAPD_TLS_PATH` | `.tapd/alice/tls.cert` |
+| `TAPD_MACAROON_PATH` | `.tapd/alice/admin.macaroon` |
+| `TAPD_TLS_INSECURE` | `false` |
+
+Relative paths are resolved from this demo directory, so the default credential
+paths work after `corepack yarn regtest`.
+
+## Flow
+
+1. Enter the external Issuance key descriptor: account xpub, master
+   fingerprint, and full child derivation path, such as
+   `m/86'/1'/0'/0/0` on regtest.
+2. Start either a new Asset or a new Issuance for an existing AssetRef.
+3. The server calls the SDK issuer with an external signer callback.
+4. The SDK stages and funds the Issuance, then returns a signing request.
+5. The dashboard presents the SDK review fields:
+   - the virtual PSBT authorizes a new Issuance
+   - the AssetRef being affected
+   - the amount by which supply increases
+   - the Issuance key descriptor
+   - the script key that controls the minted Asset
+   - the anchor outpoint that commits the Issuance
+6. Sign the virtual PSBT externally.
+7. Paste the signed virtual PSBT into the dashboard.
+8. The SDK submits the signature, seals the batch, and finalizes the Issuance.
+
+State is kept in memory. Restarting the Go coordinator clears sessions.

demos/remote-signing-coordinator/dashboard/.gitignore

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+.next/
+node_modules/
+out/
+dist/
+build/
+.yarn/
+!.yarn/releases/
+*.tsbuildinfo

demos/remote-signing-coordinator/dashboard/.yarnrc.yml

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+nodeLinker: node-modules

demos/remote-signing-coordinator/dashboard/eslint.config.mjs

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+import { defineConfig, globalIgnores } from "eslint/config";
+import nextVitals from "eslint-config-next/core-web-vitals";
+import nextTs from "eslint-config-next/typescript";
+
+const eslintConfig = defineConfig([
+  ...nextVitals,
+  ...nextTs,
+  globalIgnores([
+    ".next/**",
+    "node_modules/**",
+    "out/**",
+    "dist/**",
+    "build/**",
+    "next-env.d.ts",
+  ]),
+]);
+
+export default eslintConfig;

demos/remote-signing-coordinator/dashboard/go.mod

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+module github.com/lightninglabs/tap-sdk/demos/remote-signing-coordinator/dashboard
+
+go 1.25.7

demos/remote-signing-coordinator/dashboard/next-env.d.ts

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+/// <reference types="next" />
+/// <reference types="next/image-types/global" />
+import "./.next/types/routes.d.ts";
+
+// NOTE: This file should not be edited
+// see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

demos/remote-signing-coordinator/dashboard/next.config.ts

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+import { dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+import type { NextConfig } from "next";
+
+const apiUrl = process.env.COORDINATOR_API_URL ?? "http://127.0.0.1:8091";
+const root = dirname(fileURLToPath(import.meta.url));
+
+const nextConfig: NextConfig = {
+  allowedDevOrigins: ["127.0.0.1", "localhost"],
+  turbopack: {
+    root,
+  },
+  async rewrites() {
+    return [
+      {
+        source: "/api/:path*",
+        destination: `${apiUrl}/api/:path*`,
+      },
+    ];
+  },
+};
+
+export default nextConfig;

demos/remote-signing-coordinator/dashboard/package.json

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+{
+  "name": "@lightninglabs/tap-remote-signing-dashboard",
+  "version": "0.1.0",
+  "private": true,
+  "packageManager": "yarn@4.13.0",
+  "scripts": {
+    "dev": "concurrently -n server,dashboard -c cyan,magenta \"yarn server\" \"yarn dashboard\"",
+    "dashboard": "cd .. && ./scripts/ensure-env.sh && cd dashboard && dotenv -e ../.env -- next dev -p 3000",
+    "server": "cd .. && ./scripts/ensure-env.sh && go run ./server",
+    "server:build": "cd .. && go build -o ./server/remote-signing-coordinator ./server",
+    "regtest": "cd ../../.. && make itest-up && cd demos/remote-signing-coordinator && ./scripts/export-tapd-creds.sh",
+    "regtest:down": "cd ../../.. && make itest-down",
+    "build": "next build",
+    "start": "cd .. && ./scripts/ensure-env.sh && cd dashboard && dotenv -e ../.env -- next start -p 3000",
+    "lint": "eslint",
+    "typecheck": "tsc --noEmit",
+    "test": "yarn typecheck && yarn lint && yarn build && yarn server:build",
+    "clean": "rm -rf node_modules .next out dist build ../server/remote-signing-coordinator"
+  },
+  "dependencies": {
+    "concurrently": "9.2.1",
+    "dotenv-cli": "11.0.0",
+    "lucide-react": "1.14.0",
+    "next": "16.2.6",
+    "react": "19.2.6",
+    "react-dom": "19.2.6"
+  },
+  "devDependencies": {
+    "@tailwindcss/postcss": "4.3.0",
+    "@types/node": "25.7.0",
+    "@types/react": "19.2.14",
+    "@types/react-dom": "19.2.3",
+    "eslint": "9.39.4",
+    "eslint-config-next": "16.2.6",
+    "tailwindcss": "4.3.0",
+    "typescript": "6.0.3"
+  }
+}