The Great Day of Judgment: complete repair and receiving the reward.
The cycle's terminus is the Great Day of Judgment (Yom HaDin HaGadol) — the eschatological hinge at which the cosmic register is revealed and the bestowal completes.
Op. 79 names the cosmic-temporal endpoint of the cycle. The Great Day of Judgment is when the registration Op. 78 named is revealed; the repair is complete; the reward is received. Klach treats this as a structural-temporal fact, not just a poetic anticipation.
The Great Day of Judgment is located structurally at the end of the cycle. After six thousand years of human service (Op. 137), the cosmic register holds the complete record of what was done; the cosmic structures hold the complete repair; the bestowal is ready to complete. The Great Day is the moment of revelation: the concealed government's record becomes operationally visible; the rule of unity (Op. 30) replaces the rule of good-and-evil; the bestowal flows in its complete form.
This is not a moment of fear in the rabbinic-eschatological sense, where the prospect of judgment hangs as a threat over the unprepared. It is the moment of fulfillment — when the cycle's purpose, set up at Op. 3, is operationally consummated. The Great Day of Judgment is the bestowal of the ultimate good, presented as the operationally complete reward to those whose service has earned it.
Op. 137 (six thousand years culminating in complete repair for ever to eternity) operationalises the Great Day at the temporal scale. Op. 138 (the closing benediction) is the operational moment at which the cycle's terminus becomes operationally complete.