<p>Initial-anode-free lithium metal batteries offer the potential for high energy density and simplified manufacturing, positioning as a transformative platform for sustainable energy storage. However, their implementation is hindered by the low reversibility of lithium plating/stripping. Herein, we propose a dynamic integrated interface engineering strategy that incorporates an Ag-based multifunctional initiator into the electrolyte. This additive consists of Ag⁺ paired with anions capable of generating Lewis acids, enabling electrode-electrolyte interfacial coupling through in situ polymerization, while simultaneously enhancing the lithiophilicity of current collectors via Ag⁺-driven in situ deposition. The controlled release of the additive regulates the solvation structure, leading to the solid electrolyte interphase with an inverted organic-rich inner/inorganic-rich outer architecture, which represents a deliberate departure from conventional models. The anion anchoring effect reinforces the self-healing capability of the interphase, ensuring the construction of fast Li-ion transport pathways and a durable protective barrier, realizing highly stable operation of initially&#xa0;anode-free quasi-solid-state batteries. Specifically, the Cu | |LiFePO₄ cell exhibits 90% capacity retention after 200 cycles at 0.1 C, and a 2 Ah-level pouch cell delivers a specific energy of 467 Wh kg⁻¹ based on total cell weight. This work provides an effective unified approach to address multiple interfacial challenges in initially&#xa0;anode-free lithium batteries.</p>