This feels great to me overall.

Some minor stuff / initial reactions:

• The "Authored by: ..." / "Asked by: ..." line feels needlessly prominent to me, particularly in applications other than Ponder (it's a little more relevant there, I guess?). For post-EditEngine objects at least, the first transaction is always "<author> created this <whatever>.", which seems to serve this need pretty well. This feels particularly silly (same information twice):

Maybe just get rid of it? Or get rid of it everywhere but Ponder? But not sure it's even useful there. It mostly feels odd to me that this information gets so much visual priority when it feels like it isn't a core part of any of these objects' identities. This would also resolve the great question of PHUIHeadThingView, which I don't really have a great name for either (PHUIAttributionView?).

• The way "Subscribers", "Projects" and "Tokens" show up above the object content on mobile (particularly for objects like Passphrase) is a little unfortunate, but I don't see a way to fix that without Javascript. We could maybe try to refine how they fold (e.g., fold them into some click-to-disclose element?), or we can have JS zoom shift them around the page. Not a big deal for v0, I think.
• In Passphrase, credentials with descriptions render oddly (not enough padding):

• After some experience on profiles, I've found these variable-width property list labels harder to read and less visually pleasing (the layout feels random/ragged to me) than fixed-width, right-aligned labels like the ones we currently have:

I'd like to keep the labels right-aligned if there isn't some greater force behind this.

• Looks like subscribers/projects/tokens aren't super refined yet, but they generally feel good to me. I'm fully onboard with moving relevant actions down there in context if you still want to give that a shot.
• When the durable column is open, the space left for content starts to feel a little bit on the cramped side to me (since it's consumed by the durable column, then by the edit actions). But maybe we could narrow the durable column slightly and/or eat away at the margin between the actions and the column if the column was open, or maybe we should push the tablet breakpoint up a bit, or maybe make the edit menu slightly narrower, or maybe this would just feel fine in actual use and we don't need to do anything.
• Gradient on grey buttons looks good to me, planning to bring that everywhere?
• The way you got this stuff into the column is super cheating but also very clever. I can fix that properly before we bring this to, e.g., Maniphest. That should make it easier to bring actions inline, too.