This paper constructs the G-L integer-charge microstructure system and defines the G fundamental particle as the underlying fermionic unit of cosmic matter. Secondary composite L-quark structures are formed by the coupling of G fundamental particles. The standard L-quark configurations for proton and neutron are presented. The configuration evolution mechanisms for proton-neutron transformation in β^- decay, β^+ decay and electron capture are fully revealed. A self-consistent novel framework for hadron microstructure is established without ad-hoc assumptions. Based on the microscopic mechanism of the 1022 keV threshold in proton β^+ decay, the Cui Charge Symmetry Threshold Conservation Law for β^+ Decay under Weak Interaction (CZ Law) is derived. Observations from deep inelastic scattering experiments can be interpreted as regional average charge effects inside nucleons, which are highly consistent with the G-L integer-charge model. Based on the G-L model, it is predicted that the X(2370) resonance discovered by BESIII is a brand-new hadronic state formed by many-body direct condensation of G fundamental particles. It opens a new theoretical paradigm for hadron spectroscopy and glueball physics.