copass-google-agents 1.0.4

Copass agent primitives for Google Vertex AI Agent Engine (ADK)

copass-google-agents

Google Vertex AI Agent Engine (ADK) backend for Copass. Depends on copass-core-agents, which owns the vendor-neutral primitives (BaseAgent, AgentTool, AgentBackend ABC, events, AgentScope, registries, etc.) shared across every provider-specific Copass SDK.

This package owns the Google-specific piece — GoogleAgentBackend and the CopassGoogleAgent convenience subclass — and re-exports the core primitives for one-line dev imports. Either of these works for consumers:

from copass_google_agents import BaseAgent, CopassGoogleAgent  # convenient
# or
from copass_core_agents import BaseAgent                       # explicit boundary
from copass_google_agents import CopassGoogleAgent

Pairs with Copass's server-side router — both sides import the same code so the agent runtime is a single codepath, whether the agent runs in the dev's process or server-side via Copass's Router endpoint.

Status: scaffold (v0.1.0). Constructors, type surface, and public imports are in place. GoogleAgentBackend.run / GoogleAgentBackend.stream / deploy_adk_agent / adk_event_to_agent_events currently raise NotImplementedError. Implementation lands in a follow-up pass.

Install

pip install copass-google-agents

Requires google-cloud-aiplatform[agent_engines,adk]>=1.148.1 (which pulls in google-adk>=1.31). Uses Application Default Credentials (ADC) — run gcloud auth application-default login locally, or set GOOGLE_APPLICATION_CREDENTIALS / attach a service account.

Architecture

Agent Engine diverges from Claude Managed Agents in one important way: ADK agents are pre-deployed resources (projects/{p}/locations/{l}/reasoningEngines/{id}) and their tools are baked in at deploy time. You cannot pass tools per-run.

To preserve Copass's AgentToolResolver runtime-plug model, copass-google-agents deploys ADK agents carrying a single copass_dispatch(tool_name, arguments) function tool. At run time that proxy calls back into your Copass service, which hosts the real resolver and invokes the right tool for the current user.

So:

• GoogleAgentBackend is session-only — streams queries against a pre-deployed engine.
• deploy_adk_agent (ops helper) is the one-time setup that wires the proxy tool into a new ADK agent resource.
• Zero client-side tools is the expected case. CopassGoogleAgent defaults to an empty AgentToolRegistry.

Quickstart (planned — not functional in the scaffold)

import os
from copass_google_agents import (
    AgentInvocationContext,
    AgentScope,
    CopassGoogleAgent,
)

agent = CopassGoogleAgent(
    identity="support",
    system_prompt="You are a support agent.",
    project=os.environ["GOOGLE_CLOUD_PROJECT"],
    reasoning_engine_id=os.environ["COPASS_REASONING_ENGINE_ID"],
)

ctx = AgentInvocationContext(scope=AgentScope(user_id="u-123"))
result = await agent.run(
    messages=[{"role": "user", "content": "Hello"}],
    context=ctx,
)
print(result.final_text)

Streaming (planned)

from copass_google_agents import (
    AgentFinish,
    AgentTextDelta,
    AgentToolCall,
    AgentToolResult,
)

async for evt in agent.stream(messages, context=ctx):
    match evt:
        case AgentTextDelta(text=chunk):
            print(chunk, end="", flush=True)
        case AgentToolCall(name=name):
            print(f"\n[tool-call] {name}")
        case AgentToolResult(name=name):
            print(f"\n[tool-result] {name}")
        case AgentFinish(stop_reason=reason, session_id=sid):
            print(f"\n[finish] {reason} session={sid}")

Multi-turn continuation (planned)

Agent Engine sessions hold conversation state. Capture AgentFinish.session_id and thread it back on the next turn:

from copass_google_agents import SESSION_ID_HANDLE

ctx2 = AgentInvocationContext(
    scope=AgentScope(user_id="u-123"),
    handles={SESSION_ID_HANDLE: prior_session_id},
)

Deploying an ADK agent (planned)

from copass_google_agents.deploy import deploy_adk_agent

engine = deploy_adk_agent(
    display_name="support-agent",
    project="my-gcp-project",
    system_prompt="You are a support agent...",
    copass_api_url="https://api.copass.id",
)
print(engine.resource_name)  # feed into CopassGoogleAgent(reasoning_engine_id=...)

The deployed engine no longer bakes a fixed API key. Per-call authentication flows through the ADK session: the calling Copass server populates state["copass_api_key"] on each session via async_create_session(state={...}); the proxy tool reads it from tool_context.state on every invocation.

License

MIT.