feat: add Sardis payment tools for ADK agents

contributing/tools/sardis/README.md

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+# Sardis Payment Tools for Google ADK
+
+Policy-controlled payments for AI agents built with [Google Agent Development Kit](https://google.github.io/adk-docs/).
+
+## Installation
+
+```bash
+pip install google-adk-community sardis
+```
+
+## Setup
+
+Set your environment variables:
+
+```bash
+export SARDIS_API_KEY="sk_..."
+export SARDIS_WALLET_ID="wal_..."
+```
+
+## Usage
+
+```python
+from google.adk.agents import Agent
+from google.adk_community.tools.sardis import (
+    sardis_pay, sardis_check_balance, sardis_check_policy,
+)
+
+agent = Agent(
+    model="gemini-2.0-flash",
+    name="payment_agent",
+    description="An agent that can make policy-controlled payments",
+    tools=[sardis_pay, sardis_check_balance, sardis_check_policy],
+)
+```
+
+## Available Tools
+
+| Tool | Description |
+|------|-------------|
+| `sardis_pay` | Execute a payment with policy guardrails |
+| `sardis_check_balance` | Check wallet balance and spending limits |
+| `sardis_check_policy` | Pre-check if a payment would be allowed |
+
+## Features
+
+- **Policy guardrails** — spending limits, merchant restrictions, category rules
+- **Non-custodial** — MPC wallets, no private keys stored
+- **Multi-chain** — Base, Polygon, Ethereum, Arbitrum, Optimism
+- **Stablecoin native** — USDC, USDT, EURC, PYUSD
+- **Full audit trail** — append-only ledger for compliance
+
+## Links
+
+- [Sardis Documentation](https://sardis.sh/docs)
+- [sardis-adk on PyPI](https://pypi.org/project/sardis-adk/)
+- [GitHub](https://github.com/EfeDurmaz16/sardis)

src/google/adk_community/tools/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.

src/google/adk_community/tools/sardis/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Sardis payment tools for Google ADK - policy-controlled AI agent payments."""
+
+from .sardis_tools import sardis_check_balance
+from .sardis_tools import sardis_check_policy
+from .sardis_tools import sardis_pay
+
+__all__ = [
+    "sardis_pay",
+    "sardis_check_balance",
+    "sardis_check_policy",
+]

src/google/adk_community/tools/sardis/sardis_tools.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Sardis payment tools for Google Agent Development Kit.
+
+These tools enable ADK agents to make policy-controlled payments through
+Sardis non-custodial MPC wallets.
+
+Installation:
+    pip install google-adk-community sardis
+
+Usage:
+    from google.adk.agents import Agent
+    from google.adk_community.tools.sardis import (
+        sardis_pay, sardis_check_balance, sardis_check_policy,
+    )
+
+    agent = Agent(
+        model="gemini-2.0-flash",
+        name="payment_agent",
+        tools=[sardis_pay, sardis_check_balance, sardis_check_policy],
+    )
+"""
+
+from __future__ import annotations
+
+import logging
+import os
+from typing import Optional
+
+logger = logging.getLogger("google_adk." + __name__)
+
+
+def sardis_pay(
+    recipient: str,
+    amount: str,
+    token: str = "USDC",
+    chain: str = "base",
+    memo: Optional[str] = None,
+) -> dict:
+  """Execute a policy-controlled payment via Sardis.
+
+  Args:
+    recipient: Destination wallet address or Sardis wallet ID.
+    amount: Amount to send as a decimal string (e.g. "10.00").
+    token: Token symbol (USDC, EURC, USDT, PYUSD). Default: USDC.
+    chain: Chain to execute on (base, polygon, ethereum, arbitrum,
+      optimism). Default: base.
+    memo: Optional human-readable memo for the payment.
+
+  Returns:
+    A dict with keys: status, transaction_id, tx_hash, amount, token, chain.
+  """
+  try:
+    from sardis import SardisClient
+  except ImportError:
+    return {
+        "status": "error",
+        "error": "sardis package required. Install with: pip install sardis",
+    }
+
+  api_key = os.environ.get("SARDIS_API_KEY")
+  wallet_id = os.environ.get("SARDIS_WALLET_ID")
+  if not api_key:
+    return {
+        "status": "error",
+        "error": "SARDIS_API_KEY environment variable not set.",
+    }
+  if not wallet_id:
+    return {
+        "status": "error",
+        "error": "SARDIS_WALLET_ID environment variable not set.",
+    }
+
+  client = SardisClient(api_key=api_key)
+  result = client.payments.send(
+      wallet_id, to=recipient, amount=float(amount), token=token,
+      purpose=memo or "Payment",
+  )
+  return {
+      "status": "APPROVED" if result.success else "BLOCKED",
+      "transaction_id": getattr(result, "tx_id", ""),
+      "message": getattr(result, "message", ""),
+      "amount": amount,
+      "token": token,
+      "chain": chain,
+  }
+
+
+def sardis_check_balance(
+    token: str = "USDC",
+) -> dict:
+  """Check the balance of a Sardis wallet.
+
+  Args:
+    token: Token symbol to check (e.g. "USDC"). Default: USDC.
+
+  Returns:
+    A dict with keys: balance, remaining, token.
+  """
+  try:
+    from sardis import SardisClient
+  except ImportError:
+    return {"status": "error", "error": "sardis package required."}
+
+  api_key = os.environ.get("SARDIS_API_KEY")
+  wallet_id = os.environ.get("SARDIS_WALLET_ID")
+  if not api_key or not wallet_id:
+    return {"status": "error", "error": "SARDIS_API_KEY and SARDIS_WALLET_ID required."}
+
+  client = SardisClient(api_key=api_key)
+  balance = client.wallets.get_balance(wallet_id, token=token)
+  return {
+      "balance": str(balance.balance),
+      "remaining": str(balance.remaining),
+      "token": token,
+  }
+
+
+def sardis_check_policy(
+    amount: str,
+    merchant: str,
+) -> dict:
+  """Check if a payment would be allowed by spending policy.
+
+  Args:
+    amount: Amount to check as a decimal string (e.g. "250.00").
+    merchant: Merchant or recipient to check against policy rules.
+
+  Returns:
+    A dict with keys: allowed (bool), reason (str).
+  """
+  try:
+    from sardis import SardisClient
+  except ImportError:
+    return {"status": "error", "error": "sardis package required."}
+
+  api_key = os.environ.get("SARDIS_API_KEY")
+  wallet_id = os.environ.get("SARDIS_WALLET_ID")
+  if not api_key or not wallet_id:
+    return {"status": "error", "error": "SARDIS_API_KEY and SARDIS_WALLET_ID required."}
+
+  client = SardisClient(api_key=api_key)
+  balance = client.wallets.get_balance(wallet_id)
+  amt = float(amount)
+  if amt > balance.remaining:
+    return {
+        "allowed": False,
+        "reason": f"Amount ${amt} exceeds remaining limit ${balance.remaining}",
+    }
+  if amt > balance.balance:
+    return {
+        "allowed": False,
+        "reason": f"Amount ${amt} exceeds balance ${balance.balance}",
+    }
+  return {
+      "allowed": True,
+      "reason": f"Payment of ${amt} to {merchant} would be allowed",
+  }

tests/unittests/tools/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.

tests/unittests/tools/sardis/__init__.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.

tests/unittests/tools/sardis/test_sardis_tools.py

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+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for Sardis payment tools."""
+
+from unittest.mock import MagicMock, patch
+
+from google.adk_community.tools.sardis.sardis_tools import (
+    sardis_check_balance,
+    sardis_check_policy,
+    sardis_pay,
+)
+
+
+def test_sardis_pay_missing_api_key(monkeypatch):
+  monkeypatch.delenv("SARDIS_API_KEY", raising=False)
+  monkeypatch.delenv("SARDIS_WALLET_ID", raising=False)
+  result = sardis_pay(recipient="0xABC", amount="10.00")
+  assert result["status"] == "error"
+
+
+def test_sardis_check_balance_missing_key(monkeypatch):
+  monkeypatch.delenv("SARDIS_API_KEY", raising=False)
+  result = sardis_check_balance()
+  assert result["status"] == "error"
+
+
+def test_sardis_check_policy_missing_key(monkeypatch):
+  monkeypatch.delenv("SARDIS_API_KEY", raising=False)
+  result = sardis_check_policy(amount="100.00", merchant="openai")
+  assert result["status"] == "error"