feat(share): flat end-of-conversation band + split copy-link button - #6369

Share moves out of the buried "..." options menu into the header action row on
both entity pages, as PR #6369's SplitShareButton: the label copies the link and
the chevron drops the standard social list.

- New `EntityShareAction` wraps `ShareActions` with the entity's link/text/cid
  and logs `ShareTag`/`ShareSource` with the provider and origin. `display`
  defaults to the split control; `icon` keeps the icon-only trigger.
- Block leaves the row for the "..." menu, so the row is one Follow button plus
  identical secondary controls. Blocked is the exception: Unblock stays in the
  row, in the Follow slot that is empty then, and leaves the menu.
- The notification bell takes ButtonVariant.Float so the bell, the copy control
  and the "..." button read as one treatment.
- `CustomFeedOptionsMenu` gains `hideShare` so the in-menu Share entry is
  dropped where the visible control renders, never both.
- `SourceActions` gains `showShare`; only /sources/[source] passes it, so the
  post page highlights widget keeps its existing row.

No feature flag: this ships to everyone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Share moves out of the buried "..." options menu into the header action row on
both entity pages, as PR #6369's SplitShareButton: the label copies the link and
the chevron drops the standard social list.

- New `EntityShareAction` wraps `ShareActions` with the entity's link/text/cid
  and logs `ShareTag`/`ShareSource` with the provider and origin. `display`
  defaults to the split control; `icon` keeps the icon-only trigger.
- Block leaves the row for the "..." menu, so the row is one Follow button plus
  identical secondary controls. Blocked is the exception: Unblock stays in the
  row, in the Follow slot that is empty then, and leaves the menu.
- The notification bell takes ButtonVariant.Float so the bell, the copy control
  and the "..." button read as one treatment.
- `CustomFeedOptionsMenu` gains `hideShare` so the in-menu Share entry is
  dropped where the visible control renders, never both.
- `SourceActions` gains `showShare`; only /sources/[source] passes it, so the
  post page highlights widget keeps its existing row.

No feature flag: this ships to everyone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Share moves out of the buried "..." options menu into the header action row on
both entity pages, as PR #6369's SplitShareButton: the label copies the link and
the chevron drops the standard social list.

- New `EntityShareAction` wraps `ShareActions` with the entity's link/text/cid
  and logs `ShareTag`/`ShareSource` with the provider and origin. `display`
  defaults to the split control; `icon` keeps the icon-only trigger.
- Block leaves the row for the "..." menu, so the row is one Follow button plus
  identical secondary controls. Blocked is the exception: Unblock stays in the
  row, in the Follow slot that is empty then, and leaves the menu.
- The notification bell takes ButtonVariant.Float so the bell, the copy control
  and the "..." button read as one treatment.
- `CustomFeedOptionsMenu` gains `hideShare` so the in-menu Share entry is
  dropped where the visible control renders, never both.
- `SourceActions` gains `showShare`; only /sources/[source] passes it, so the
  post page highlights widget keeps its existing row.

No feature flag: this ships to everyone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

"Tsahi's button" is SplitShareButton from #6369 — copy link and a chevron
holding the networks, meeting at one hairline — wrapped by ShareBand, which
pairs it with a title and a line of copy. #6369 built it for exactly these two
surfaces: the band below an active discussion and the prompt after an upvote.

Neither PR landed. #6369 is closed and #6378 merged into it, so the components
exist on no branch that ships. They are carried here — ShareBand, ShareActions,
SplitShareButton, CopyStateIcon and the Origin they log against — and both
prompts now render through ShareBand rather than the pair of hand-rolled rows
I had built. If that stack revives, these two callers should collapse into its
EndOfConversationShare and the copies here should go.

The copy is theirs too, so the two bands read as one pair.

Testing: shared 382 suites / 2680 tests, webapp 81 / 644, extension 6 / 52,
package lint clean for shared and webapp. The ported ShareActions spec runs
green here as it does there.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Three controls inside the brief itself:

- The post page's highlight bar (#6556), scoped to a body container so a
  selection in the header or the preferences card never raises it.
- A copy icon per bullet and paragraph, carrying the text and the brief
  link, after #6350's copy-summary icon. Each one is labelled with what
  it copies, since a brief carries a column of them.
- A Snapshot on the Must know heading that captures its bullets as one
  card, with the claim before the colon as each line.

None of these can be declared in JSX: the body is a single `<Markdown
content={contentHtml} />`, so briefBodyBlocks reads the blocks back out
of the rendered DOM — which is also the most faithful source, being what
the reader is looking at — and the controls are portalled into them.
Hosts are marked and swept before each run, because Markdown re-renders
on its own for hover cards and the image modal.

The closing band is #6369's ShareBand with the briefing's copy, so it
cannot drift from the end-of-conversation band it was asked to match.

All of it sits behind `briefing_share_controls`, default false.

Mockup-to-eng-pass: 1

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

…o choose from

The Snapshot button becomes a Share button: the icon and label are the ones
people already recognise, and pressing it opens a menu that previews the
designed 1080² card before offering it.

The menu opens immediately with a skeleton rather than waiting on the render.
Rasterizing takes a second or two, and a control that does nothing visible for
that long reads as broken — so the capture is deferred a tick, letting the menu
paint first, and Copy link stays usable while the card is still rendering.

Seven layouts are up for review in Features/Snapshot/Menu styles, all live
against the same card: rows, rows-centred, an overlay pill on the card, a
compact no-preview variant, Tsahi's split button from #6369, and the two ways
the image can sit in the share modal — its own section or a single tile. The
`menuVariant` prop exists to serve that page and comes out with the losers.

The image is one action, not a mode over the sheet's other targets. A link needs
a destination, which is why there are twenty of them; an image does not, because
the OS share sheet and the clipboard are the destinations, and no web share
intent takes an image anyway. So the image owns its own action and the squads
and external tiles keep sharing the link — which is what keeps this on one
screen instead of two.

Pressing it hands the PNG to the native sheet where the platform takes files,
copies it to the clipboard otherwise (with a toast, since the clipboard has no
UI of its own), and downloads it only as a last resort.

Capture moves into `useSnapshotCapture` so the dropdown and the modal section
render from one implementation. Its `isActive` gate matters twice: a feed never
carries a 1080px card per item until someone asks to share, and because the
modal pre-renders on open, the click handler reaches `clipboard.write` with no
await in front of it — still inside the user gesture the clipboard requires.

Two surfaces had no card at all, from the #6579 and #6581 reviews:

- `FeedSnapshotCard` carries a shared feed's recipe — tags and source count —
  rather than its posts, which are a standing filter and would go stale.
- `AwardSnapshotCard` names the sender. It is the only status moment that comes
  from someone else, and a gift with no giver reads as self-congratulation.

Tsahi's `SplitShareButton` and `CopyStateIcon` come across from #6369 unchanged
apart from four additive props — `onOpenChange`, `header`, `menuLayout` and a
width override — so his grid is untouched when nobody passes them.

`SocialShareList`, `SocialShareButton` and `SocialShareContainer` gain optional
size and compact props, defaulting to today's values, so the dropdown can
tighten without moving anything else in the app.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Three controls inside the brief itself:

- The post page's highlight bar (#6556), scoped to a body container so a
  selection in the header or the preferences card never raises it.
- A copy icon per bullet and paragraph, carrying the text and the brief
  link, after #6350's copy-summary icon. Each one is labelled with what
  it copies, since a brief carries a column of them.
- A Snapshot on the Must know heading that captures its bullets as one
  card, with the claim before the colon as each line.

None of these can be declared in JSX: the body is a single `<Markdown
content={contentHtml} />`, so briefBodyBlocks reads the blocks back out
of the rendered DOM — which is also the most faithful source, being what
the reader is looking at — and the controls are portalled into them.
Hosts are marked and swept before each run, because Markdown re-renders
on its own for hover cards and the image modal.

The closing band is #6369's ShareBand with the briefing's copy, so it
cannot drift from the end-of-conversation band it was asked to match.

All of it sits behind `briefing_share_controls`, default false.

Mockup-to-eng-pass: 1

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Three controls inside the brief itself:

- The post page's highlight bar (#6556), scoped to a body container so a
  selection in the header or the preferences card never raises it.
- A copy icon per bullet and paragraph, carrying the text and the brief
  link, after #6350's copy-summary icon. Each one is labelled with what
  it copies, since a brief carries a column of them.
- A Snapshot on the Must know heading that captures its bullets as one
  card, with the claim before the colon as each line.

None of these can be declared in JSX: the body is a single `<Markdown
content={contentHtml} />`, so briefBodyBlocks reads the blocks back out
of the rendered DOM — which is also the most faithful source, being what
the reader is looking at — and the controls are portalled into them.
Hosts are marked and swept before each run, because Markdown re-renders
on its own for hover cards and the image modal.

The closing band is #6369's ShareBand with the briefing's copy, so it
cannot drift from the end-of-conversation band it was asked to match.

All of it sits behind `briefing_share_controls`, default false.

Mockup-to-eng-pass: 1

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Three controls inside the brief itself:

- The post page's highlight bar (#6556), scoped to a body container so a
  selection in the header or the preferences card never raises it.
- A copy icon per bullet and paragraph, carrying the text and the brief
  link, after #6350's copy-summary icon. Each one is labelled with what
  it copies, since a brief carries a column of them.
- A Snapshot on the Must know heading that captures its bullets as one
  card, with the claim before the colon as each line.

None of these can be declared in JSX: the body is a single `<Markdown
content={contentHtml} />`, so briefBodyBlocks reads the blocks back out
of the rendered DOM — which is also the most faithful source, being what
the reader is looking at — and the controls are portalled into them.
Hosts are marked and swept before each run, because Markdown re-renders
on its own for hover cards and the image modal.

The closing band is #6369's ShareBand with the briefing's copy, so it
cannot drift from the end-of-conversation band it was asked to match.

All of it sits behind `briefing_share_controls`, default false.

Mockup-to-eng-pass: 1

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

…placement

The seven menu layouts were there to pick one, and the buttons they were
picking between are not new — Share and Copy link already exist in the
app. What this PR is actually about is generating the card and deciding
where the control sits, so the exploration comes out:

- Features/Snapshot/Menu styles, and the menuVariant prop behind it
- SnapshotImageSection, which only the modal candidates rendered
- SplitShareButton and CopyStateIcon, which belong to #6369
- the optional size and compact props on SocialShareList,
  SocialShareButton and SocialShareContainer, added only for those
  candidates

SnapshotButton is a plain button again: press it and it shares the card.
Rendering starts on hover or focus rather than on mount, so a feed does
not carry a 1080px card per item — and because the render is already
done by the time the press lands, the clipboard still has the gesture it
needs. A press that arrives first waits for the render and downloads
instead, which is the one path the clipboard cannot take.

Two type fixes on SocialShareButton stay: the size map is indexed with
the full ButtonSize union, and the ref is passed to a Button that renders
as an anchor.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>