Proposal: AffixIOGuardPlugin for host-side tool action proof #184

What

Community plugin: AffixIOGuardPlugin that gates sensitive tool calls via AffixIO on the host, same shelf as AgentGovernancePlugin / HITL samples.

Why AffixIO here

AffixIO proves a host-side ACTION completed (signed yes/no). PII stays on the host. Not person/age/KYC.

Sit: before an ADK agent runs a sensitive tool (spend, DB admin, destructive API), AffixIO can gate/prove the action on the host using before_tool_callback on BasePlugin.

Install

npm i affixio
npm i @affixio/[email protected]

MCP is local stdio.

Sketch

# google.adk_community.plugins.affixio_guard_plugin
class AffixIOGuardPlugin(BasePlugin):
    async def before_tool_callback(self, *, tool, tool_args, tool_context):
        # For allowlisted sensitive tools: require AffixIO host proof
        # Deny / short-circuit if unsigned or rejected
        ...

Would live under src/google/adk_community/plugins/ plus a small sample next to contributing/samples/agent_governance and hitl_approval.

Links

• https://www.affix-io.com/
• https://hub.affix-io.com/onboarding/

Offer

Happy to open a focused PR if maintainers want this shape. Prefer confirm fit first so we do not dump a heavy wrap.

Context

Kris / AffixIO. Looking for a light community integration, not a core ADK change (core already has BasePlugin tool callbacks).