${B}$$^{0}$ − $\overline{B}$$^{0}$ entanglement for an ideal experiment for the direct $\textit{CP}$ violation $\phi$$_{3}$ ${/}$ $\gamma$ phase

${B}$$^{0}$ − $\overline{B}$$^{0}$ entanglement offers a conceptual alternative to the single charged $\textit{B}$-decay asymmetry for the measurement of the direct $\textit{CP}$-violating $\gamma$ ${/}$ $\phi$$_{3}$ phase. With $\textit{f = J / $\Psi$K$_{L}$ , J / $\Psi$K$_{S}$}$ and $\textit{g = (ππ)$^{0}$ , ($\rho$$_{L}$$\rho$}$$_{L}$)$^{0}$ , the 16 time-ordered double-decay rate intensities to $\textit{(f, g)}$ depend on the relative phase between the $\textit{f-}$ and $\textit{g-}$decay amplitudes given by $\gamma$ at tree level. Several constraining consistencies appear. An intrinsic accuracy of the method at the level of $\pm$1$^\circ$ could be achievable at Belle-II with an improved determination of the penguin amplitude to $\textit{g}$ channels from existing facilities.