**Grace Universal (G):** Grace is the universal external operator that reverses sign-state decoherence without destroying the information substrate. It is the unique solution to the Self-Flip Impossibility Theorem.
The [[075_D9.1_Grace-Operator-Definition|Grace operator]] acts on the [[010_D2.1_Logos-Field-Definition|Logos field]] \chi coupled to an agent state \psi:
Where the sign states are eigenstates of \hat{\sigma}:
Definition (Grace Operator): Let (\mathcal{H}, \hat{\sigma}) be a Hilbert space with sign operator \hat{\sigma}^2 = \mathbb{I}, \hat{\sigma}^\dagger = \hat{\sigma}. A Grace operator is a linear map \hat{G}: \mathcal{H} \to \mathcal{H} satisfying:
1. Anticommutation: \{\hat{G}, \hat{\sigma}\} = \hat{G}\hat{\sigma} + \hat{\sigma}\hat{G} = 0
2. Non-unitarity: \hat{G}^\dagger\hat{G} \neq \mathbb{I}
3. Sign-flip: \hat{\sigma}\hat{G}|\psi_-\rangle = +\hat{G}|\psi_-\rangle (maps \sigma=-1 eigenspace to \sigma=+1 eigenspace)