Add x402 BCH payment support for HTTP requests

.github/workflows/opencode.yml

@@ -0,0 +1,45 @@
+name: opencode
+
+on:
+  pull_request:
+    types: [opened, synchronize, ready_for_review]
+  issue_comment:
+    types: [created]
+  pull_request_review_comment:
+    types: [created]
+
+jobs:
+  opencode:
+    if: |
+      github.event_name == 'pull_request' ||
+      contains(github.event.comment.body, ' /oc') ||
+      startsWith(github.event.comment.body, '/oc') ||
+      contains(github.event.comment.body, ' /opencode') ||
+      startsWith(github.event.comment.body, '/opencode')
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      contents: read
+      pull-requests: write
+      issues: read
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run opencode
+        uses: anomalyco/opencode/github@latest
+        env:
+          OPENCODE_API_KEY: ${{ secrets.OPENCODE_API_KEY }}
+        with:
+          model: opencode/kimi-k2.5

README.md

@@ -98,6 +98,37 @@ paytaca token send <address> <amount> --token <cat>  # Send fungible tokens
 paytaca token send-nft <address> --token <cat> --commitment <hex>  # Send an NFT
 ```
 
+### x402 Payments
+
+The x402 protocol enables HTTP payments via BCH. Some APIs (like nanogpt) require payment to access.
+
+```bash
+paytaca check <url>                 # Check if URL requires payment, shows estimated cost
+paytaca pay <url>                    # Make a paid HTTP request (handles 402 automatically)
+paytaca pay <url> --json             # JSON output (recommended for AI agents)
+paytaca pay <url> --dry-run          # Preview payment without executing
+paytaca pay <url> --method POST      # POST request with body
+paytaca pay <url> --body '{"prompt":"hello"}'
+```
+
+**Example workflow:**
+```bash
+paytaca check https://api.nanogpt.com/v1/complete --json
+# → {"paymentRequired": true, "estimatedCostSats": "100"}
+
+paytaca pay https://api.nanogpt.com/v1/complete --method POST --body '{"prompt":"hello"}'
+# → Handles 402 → pays → returns response
+```
+
+### AI Agent Integration
+
+```bash
+paytaca opencode                    # Install Paytaca x402 skill for OpenCode AI agents
+paytaca claude                      # Install Paytaca x402 skill for Claude Code agents
+```
+
+This enables AI agents to autonomously handle HTTP 402 payment responses when calling x402-enabled APIs.
+
 ## Network
 
 All commands default to **mainnet**. Pass `--chipnet` for testnet:
@@ -130,15 +161,23 @@ src/
     history.ts       transaction history (BCH and CashTokens)
     address.ts       HD address derivation (standard and z-prefix)
     token.ts         CashToken commands (list, info, send, send-nft)
+    pay.ts           x402 BCH payment handler for HTTP requests
+    check.ts         Check if URL requires x402 payment
+    opencode.ts      Install x402 skill for OpenCode AI agents
+    claude.ts        Install x402 skill for Claude Code AI agents
   wallet/
     index.ts         Wallet class, mnemonic gen/import/load
     bch.ts           BchWallet (balance, send, history, CashTokens)
     keys.ts          LibauthHDWallet (HD key derivation, token addresses)
+    x402.ts          X402Payer (BCH payment signing and verification)
   storage/
     keychain.ts      OS keychain wrapper (@napi-rs/keyring)
   utils/
     crypto.ts        pubkey -> CashAddress pipeline
     network.ts       Watchtower URLs, derivation paths
+    x402.ts          x402 header parsing, payment requirement selection
+  types/
+    x402.ts          x402 payment types (PaymentRequired, PaymentPayload, etc.)
 ```
 
 ## Key Dependencies
@@ -161,6 +200,22 @@ npm run build      # One-time build
 npm run clean      # Remove dist/
 ```
 
+## x402 Server
+
+A reference x402 server implementation is included for testing:
+
+```bash
+cd x402-server
+npm install
+npm run dev        # Start dev server on port 3001
+```
+
+The server implements the x402-bch v2.2 specification and provides:
+- `GET /api/quote` — Returns a quote (requires payment)
+- `POST /api/generate` — Text generation endpoint (requires payment)
+
+Useful for testing the `paytaca pay` workflow locally.
+
 ## License
 
 Copyright Paytaca Inc. 2021. All rights reserved. See [LICENSE](LICENSE) for details.