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Gemini harness

Use this guide when Gemini CLI is loading local extensions or embedded MCP server declarations and you want Guard to block changed extension surfaces before launch.

What Guard detectsDirect link to What Guard detects​

The Gemini adapter looks in:

  • ~/.gemini/extensions/*/gemini-extension.json
  • <workspace>/.gemini/extensions/*/gemini-extension.json
  • fallback global ~/.gemini/*/mcp_config.json

For each extension manifest Guard records:

  • the extension name
  • the publisher when present
  • the optional contextFileName
  • embedded MCP server definitions under mcpServers

Approval modelDirect link to Approval model​

Gemini currently uses the Guard approval center:

  • approval tier: approval-center
  • Guard scans Gemini extensions before launch
  • blocked changes go to the local approval center until Gemini exposes a richer native approval model

What Guard treats as an artifactDirect link to What Guard treats as an artifact​

Guard treats both of these as relevant launch inputs:

  • the extension manifest itself
  • any embedded MCP server declarations inside that manifest

That matters because a Gemini extension can change publisher metadata, context wiring, and runtime server commands in the same file.

Install and launch flowDirect link to Install and launch flow​

hol-guard detect gemini --json
hol-guard install gemini
hol-guard run gemini --dry-run
hol-guard run gemini
hol-guard approvals

Use a workspace or home directory with a real Gemini extension installed, then confirm:

  1. Guard detects the extension manifest
  2. embedded MCP server entries are listed in the detection output
  3. the first dry run records a receipt
  4. changed extension metadata routes to the approval center when policy blocks

Best fitDirect link to Best fit​

Gemini is a good Guard fit when you want:

  • extension-level trust before launch
  • publisher and context metadata recorded alongside MCP server definitions
  • a local approval-center path while Gemini-native approvals are still limited

Next guidesDirect link to Next guides​