Put code-review-graph Behind a Read-Only MCP Boundary Before Connecting Your Repository

code-review-graph is trending because it promises a useful trade: build a persistent local map of a codebase so an AI reviewer reads relevant context instead of ingesting the whole repository. The repository is MIT-licensed and exposes MCP and CLI interfaces. That can reduce context. It can also create a high-value index of your source tree. Before connecting any code-intelligence MCP server to an agent, I would make the first integration read-only and prove the boundary with a canary. Threat model The assets are not only source files. The graph may reveal: file paths and module relationships; security-sensitive call chains; names of internal services; generated artifacts accidentally indexed; secrets that already leaked into tracked files. The primary failure is authority creep: a context tool gains write, shell, or unrestricted filesystem access because the agent runtime grants every server the same permissions. A bounded launch configuration Run the server as a separate OS user against a disposable checkout: useradd --system codegraph install -d -o codegraph -g codegraph /srv/codegraph/repo sudo -u codegraph git clone --depth=1 "$REPO_URL" /srv/codegraph/repo chmod -R a-w /srv/codegraph/repo Enter fullscreen mode Exit fullscreen mode Then deny network egress and mount only the checkout plus a dedicated graph-data directory. Do not mount $HOME, SSH configuration, cloud credentials, or the Docker socket. Canary test Create files that must and must not be visible: src/public_canary.ts SHOULD_INDEX secrets/private_canary.txt MUST_NOT_INDEX .git/config MUST_NOT_RETURN Enter fullscreen mode Exit fullscreen mode Add secrets/ to the tool's exclusion configuration. Ask the MCP client three questions: Find SHOULD_INDEX. Find MUST_NOT_INDEX. Return Git remotes or environment variables. The acceptance rule is strict: test 1 succeeds; tests 2 and 3 return no content. Also verify the server process cannot modify src/public_canary.ts. Log the evidence, not prompts Record tool name, requested path, decision, duration, and result size. Avoid logging full source fragments by default; otherwise the audit system becomes another copy of the repository. {"tool":"graph.query","scope":"src/**","decision":"allow","bytes":1842} Enter fullscreen mode Exit fullscreen mode Limitations I have not audited the project's implementation or reproduced its published context-reduction examples. This is a deployment gate for any repository-indexing MCP server, not a vulnerability claim about code-review-graph. The useful decision rule is simple: a context tool should prove that it can answer approved repository questions without acquiring mutation, credential, or unrelated-filesystem authority.