`nix/templates/harness/` is cited from `send_allow.rs` and twice from
`mcp_config.rs`, in the present tense, as where the NixOS module writes
the send allow-list, writes the extra-MCP spec, and defines the MCP http
port default. There is no such directory — `nix/templates/` holds only
`agent.nix` and `ruth.nix`.
All three describe things that live in `nix/agent-modules/mcp.nix`:
send-allow.json is written at :230, extra-mcp.json at :228, and the
`hyperhive.mcp.httpPort` option is declared at :143.
These are the mechanical half of #3923, which explicitly carved the
repointing out from the question of whether the reference gate should
widen. Nothing here changes that question.
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