G-type shallow-contact binaries are Roche-lobe-filling systems that share a thin common-convective envelope, with a fill-out factor typically below 20%. The study of such systems provides key insights into magnetic activity in shallow convective envelopes. As an exemplary case, V719 Her is a short-period (P ≈ 0401) shallow-contact binary of spectral type G3. Precise TESS photometry reveals continuously varying and asymmetric light curves of V719 Her. Our comprehensive study, based on long-term photometric and spectroscopic data, confirms V719 Her is a totally eclipsing system exhibiting spot activity. The light curve variations were successfully modeled by introducing an evolving cool spot on the more massive component. By analyzing 1274 new eclipse timings along with archival data, a secular period increase accompanied by a cyclic variation of about 45 yr is found. The long-term period increase suggests mass transfer from the less massive component to its companion, leading to orbital expansion as predicted by the Thermal Relaxation Oscillation (TRO) theory. Among 57 collected G-type shallow-contact binaries, 31 targets (including V719 Her) observed by LAMOST show Hα emission, indicating chromospheric activity. With its increasing period and clear magnetic activity signatures, V719 Her stands as an ideal object for testing TRO theory and magnetic activity in shallow-contact binaries.

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