Relation between f_esc and observable quantities (emission-line EW and β_UV) in the picket-fence model. The top panel shows the variation of f_esc in the β_UV–EW(Hα) parameter space for different stellar ages, with the observational result of LACES104037-bulk overplotted. The bottom panel illustrates that f_esc and stellar age are fully degenerate when only emission-line EWs are considered. Hα and [O III] are the two emission lines observable for LACES104037-LyC, and in the EW-based parameter space, variations in age and f_esc trace the same evolutionary locus. The pixel-by-pixel measurements of LACES104037-bulk (with emission-line S/N > 10 per pixel) and the observational result of LACES104037-LyC are both overplotted, revealing a pronounced gap between the two. We note that our models include only a young stellar population, while the observed optical continuum may contain a contribution from an older stellar population (see the stellar population parameters derived from SED fitting in Table 2). As a result, the observed EWs should be regarded as lower limits relative to the intrinsic EWs of the young stellar component.