Wagner (3), Tristan und Isolde, part 2

Here is a postscript, as it were, to the previous post. Eric Chafe observes that "the first of the dream chords of 'O sink hernieder' [reappears at the end] leading the duet to pass over into the f# tonality of Brangaene's warning" (2008, 268). Here are the two passages—beginning:

. . .  and ending:

In a later scene between Tristan and Kurwenal, the dominant ninth chord becomes thoroughly embedded in the full Tristan motive/phrase:

Finally, in the climax of Isolde's "Liebestod," the determined (and extended) progress toward the structural dominant and the 6 1/2 bars of the subsequent F# bass (as V in B major) support multiple rapid statements of the Tristan motive that eventually lead to the V9 of the cadence from the first page of the Prelude (but now in a major key). I have aligned the two cadences in a sketch below the score.

Reference:
Eric Chafe, The Tragic and the Ecstatic: The Musical Revolution of Wagner's Tristan und Isolde (2008).