Agent Platform Architecture

Gemini platform Architecture and Engineering Guide

This skill is the reference system for designing, engineering, and validating enterprise-grade Gemini platform architectures across multi-project hierarchies, hybrid/cross-cloud networks, zero-trust identity boundaries, and inline safety/policy enforcement planes.

Usage Attribution

MUST READ: Before executing any gcloud, REST API, or MCP command, you MUST read and follow the instructions in Usage Attribution.

[!IMPORTANT] Architectural Scope and Reference Discipline: Use SKILL.md to select the target topology, egress mode, ingress pattern, and governance plane, then consult the authoritative references/*.md manual for exact CLI commands, REST/YAML schemas, Common Expression Language (CEL) expressions, and Python Agent Development Kit (ADK) runtime code (references/*.md is the single source of truth for all implementation syntax). When remote Model Context Protocol (MCP) tools (such as the Google Developer Knowledge MCP server or Google-managed MCP endpoints) are available, prefer remote MCP tool invocation over raw CLI/REST commands. Do not execute unrequested live mutations against customer projects when asked for architectural designs.

[!CAUTION] Human Approval Gate for Sensitive Operations: Always prompt the user for explicit confirmation before executing commands or applying configurations that grant permissive Identity and Access Management (IAM) bindings (roles/iap.egressor, roles/compute.networkUser, roles/networkservices.admin), modify Organization Policies (constraints/iam.managed.disableAccessPolicyBinding), update Unified Access Policy (UAP) or VPC Service Controls (VPC-SC) policies, or delete resources (REST DELETE ...?force=true or CLI --quiet).

Prerequisites, Authentication, Region, and Billing Setup

1. Google Cloud SDK, Authentication, and Project Setup:

   • Install the Google Cloud SDK (gcloud) and authenticate CLI and Application Default Credentials (gcloud auth login && gcloud auth application-default login, or set GOOGLE_APPLICATION_CREDENTIALS).

   • Select or create the target project (gcloud projects create {project_id} / gcloud config set project {project_id}), set the default region (gcloud config set compute/region {region}, defaulting to us-central1; see Google Cloud Locations), and enable required APIs:

     Copy

     gcloud services enable aiplatform.googleapis.com agentregistry.googleapis.com \
       agentidentity.googleapis.com agentidentitycredentials.googleapis.com \
       networkservices.googleapis.com networksecurity.googleapis.com iap.googleapis.com \
       modelarmor.googleapis.com compute.googleapis.com dns.googleapis.com \
       certificatemanager.googleapis.com servicenetworking.googleapis.com

2. Billing, Least-Privilege IAM, and Product Terminology:

   • Verify an active billing account is attached (gcloud billing projects describe {project_id} --format="value(billingEnabled)") across {host_project_id}, {gov_project_id}, {runtime_project_id}, and {mcp_project_id} (required even when evaluating free-tier allowances; review Google Cloud Pricing).

   • Grant explicit least-privilege IAM roles (roles/aiplatform.user, roles/networkservices.admin, roles/compute.networkAdmin, roles/compute.networkUser, roles/iap.egressor, or a custom role with networkservices.agentGateways.get,networkservices.agentGateways.use,networkservices.operations.get) rather than primitive roles/owner or roles/editor.

   • Use approved product names: Gemini platform, Agent Runtime (reasoningEngines), Agent Gateway (240.0.0.2:443), Agent Connectivity Template (ACT), Agent Registry, and Unified Access Policy (UAP Policy V2) / Semantic Governance Policy (SGP).

3-Phase Architect Workflow and Decision Tree

graph TD
    Start["Enterprise Gemini platform Architecture"] --> Q1{"1. Egress Destinations?"}
    Q1 -->|"RFC 1918 + Google APIs Only"| Priv["ACT: vpcEgress = PRIVATE_RANGES_ONLY<br/>• Direct Private Google Access (PGA)"]
    Q1 -->|"Public Internet, VPC-SC, or Non-RFC 1918 PUPI"| All["ACT: vpcEgress = ALL_TRAFFIC<br/>• 100% Egress via AGW VIP 240.0.0.2:443<br/>• Consolidate Core Google APIs FQDNs"]
    All --> Q2{"2. Layer 7 URL List or Cross-Cloud mTLS?"}
    Q2 -->|"No (Standard NAT)"| Nat["Direct Cloud NAT on PSC-I Subnet<br/>• ENDPOINT_TYPE_VM,ENDPOINT_TYPE_SWG"]
    Q2 -->|"Yes (Next-Hop SWP)"| Swp["Next-Hop SWP (NEXT_HOP_ROUTING_MODE) + PBR<br/>• Internal and Google API DEFAULT_ROUTING bypasses<br/>• Default route via SWP ILB IP<br/>• Exclude PSC-I from manual Cloud NAT"]

1. Phase 1 — Scope Verification and Architecture Discovery:

   • Scope Boundaries and Single-Region Discovery: Decline generic Google Cloud IAM/Compute/Storage debugging unrelated to the Gemini platform stack or requests to run broad multi-region live project scanning loops, pointing instead to gcloud ai reasoning-engines list --region={region}.

   • Architecture Design and Engineering: Identify the project hierarchy (Host, Governance Hub, Runtime Spoke, Tool/MCP Spoke), egress mode (ALL_TRAFFIC vs PRIVATE_RANGES_ONLY), policy plane (UAP V2, SGP, Model Armor), and target output format (topology specification, gcloud CLI commands, or REST/YAML manifests).

2. Phase 2 — Draft Architecture Plan and Resource Mapping:

   • Synthesize the topology diagram, project/VPC layout, IAM bootstrap matrix, and security controls using the Domain Router and Symptom Matrix, and map each manual's canonical REST/YAML schema and CLI commands into the target deployment artifacts.

3. Phase 3 — Post-Deployment and Audit Log Verification:

   • Pair every architecture design with the Post-Deployment and Cloud Audit Log Verification checklist (references/topologies_and_project_layouts.md) and runtime query validation (references/agent_runtime_and_identity.md).

Domain Router and Symptom Matrix

Each reference manual in references/ is the single source of truth for its domain's CLI commands, REST/YAML schemas, quotas, and CEL expressions. Always read the corresponding reference manual before generating configurations or answering domain-specific questions:

Supporting Public Documentation Links

• Agent Runtime Overview

• Agent Gateway Overview

• Policies Overview

• Agent Identity Overview

• Agent Registry Overview

• Deploy Agent Gateway Runtime

• Private Service Connect Interface