Function resolve_agent_binary 

pub fn resolve_agent_binary() -> String

The binary path to write into agent configurations — MCP server command fields and agent hooks (#1873).

These outlive the running build just like the shell artifacts of #1851: a Scoop or Homebrew install runs from a versioned directory the next update removes, which left every configured MCP server pointing at a deleted binary. A stable launcher is used only when its target identity is verified (see stable_shell_binary); otherwise the exact binary is kept.