Volatile enrichment timescale as a function of orbital distance. In the inner disk (<10 au), volatiles sublimating at a depth of approximately 0.1 R_B (red line) are efficiently lost through convective mixing (τ_rec,con; dashed orange line). In the colder outer disk, volatiles sublimate at greater depths in the envelope: at a depth of 0.01 R_B (blue curve) volatiles are typically deposited in the radiative zone of the envelope where recycling timescales are long (τ_rec,ad; dashed light blue line), preventing material exchange. The dashed light blue line is truncated at 5 au, since we expect that the envelopes are prone to becoming fully convective in the inner disk (Fig. 13).