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open-coder-ai/verify-mcp-allowlist

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Gates MCP servers against .chock/mcp-allowlist.json, empty by default (name, launcher with exact args, or url host). Shell guard refuses <agent> mcp add and shell writes of MCP configs or the allowlist unless listed. Script gate (commit, tool use, turn end) reads 13 client configs: a server off the list, or with other command, args or url host, refuses; unpinned or shell launchers, http, literal credentials, old versions only warn. Misses: aliases, scripts, gitignored files, other clients. [Shell guard: Session-enforced by the PreToolUse hook under com.github.copilot/ in clients that read that namespace (documented for VS Code agent mode); a client that ignores it, as the Agent Plugins spec tells generic clients to, gets the advisory skill only. The hook needs git, a usable bash and a Python 3.11+ (python3, python or py, whichever actually runs). With no working Python it exits 2; without git or bash, fail-open clients allow silently and fail-closed clients refuse matched commands. If the guard itself crashes or times out, the hook asks for confirmation rather than allowing silently -- VS Code agent mode honours that ask and it overrides the client's own auto-approve. Write gate: Session-enforced at the turn's end by a Stop hook; needs git and a Python 3.11+. This client records no file-writing tool vocabulary, so the write itself is not judged: what the turn actually left on disk is re-read, and a construct a rule denies is refused then, however it was written. With no working Python the hook exits 2; without git, fail-open clients allow silently. A gate that cannot reach a decision refuses rather than allowing one it never judged. Enforcement at every commit and in CI still needs chock installed in the repo. Both halves: Enforces only in a client that reads the com.github.copilot namespace and tells the hook where the package lives; a client that exports no plugin-root variable (VS Code's agent-plugin format exports none) runs the hook, which then exits 0 and checks nothing; a root that is set but lacks the bundled hook exits 2 and refuses the call.]