feat(briefing): share controls on the briefing surfaces

[tomeredlich]

Stacked on snapshot-post-page-variations (#6556). Adds share controls to the two briefing surfaces — the list at /briefing and the briefing itself — all behind briefing_share_controls, default false.

Snapshot of the briefing as an object is deliberately out. The premise behind it does not survive a read of the code: a brief is a normal post at /posts/{slug} (BriefListItem.tsx), so a link resolves for the recipient, and useSharePost.copyLink already shortens it and tags it with ReferralCampaignKey.SharePost. The one image that earns its place is the Must know card, whose payload is the bullets rather than the brief.

The briefing header

BriefPostHeaderActions wrapped its cluster in hidden laptop:block, and BriefPostContent is the only caller passing showShareButton — so a working, tracked copy button existed and was invisible at the widths where most briefings are read. The wrapper is gone, a share arrow joins it for the popover on desktop and the native sheet on mobile, and the settings gear moves to Tertiary so the three read at one weight. BriefPostHeader's kicker row gains a shrink guard, since it never had to survive a narrow row while the actions were desktop-only.

The /briefing rows

#6353's pairing: copy and the share arrow in one container after the CardLink with relative z-1, or the full-bleed overlay swallows the clicks. The text column drops w-full — it claimed the whole card and pushed the controls past its border — and rows without controls keep their original DOM.

Inside the briefing

• The post page's highlight bar, 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. Each is labelled with what it copies.
• A Snapshot on the Must know heading that captures that section's bullets as one card.
• A closing band, which is feat(share): flat end-of-conversation band + split copy-link button #6369's ShareBand with the briefing's copy.

The body is a single <Markdown content={contentHtml} />, so none of the three in-body controls can be declared in JSX. briefBodyBlocks.ts reads the blocks back out of the rendered DOM — also the most faithful source, being what the reader sees — and the controls are portalled into them. Hosts are marked with data-brief-control and swept before each run, because Markdown re-renders on its own for hover cards and the image modal.

Notes for review

• The Must know lookup matches on heading text, so it is English- and format-dependent: if briefs ship other section names, that button stops appearing (the per-block copy icons degrade individually). A backend anchor would be the durable fix.
• Nothing renders with the flag off, and no existing DOM changes on that path.

🤖 Generated with Claude Code

Copy confirmation

All four copy controls here — the header, the list row and one per body block — confirm on the button that was pressed: the icon swaps to the upvote button's filled avocado arrow and spins through copy-confirm, the same 0.4s curve as its spinAndScale, off under prefers-reduced-motion.

Two of them had no way to know a copy had landed: useSharePost was discarding useCopyPostLink's flag. It now returns isCopying, available to every consumer. CopyStateIcon takes the glyph it rests on, so a link control keeps its link icon rather than switching to a clipboard.

Review links

• Preview: https://claude-snapshot-briefing-preview.preview.app.daily.dev/briefing
• Storybook: Vercel skips the Storybook build on this branch. The matching surface page is Features/Snapshot/Surfaces/Briefing on feat(snapshot): square share images for every daily.dev surface #6544's build: https://storybook-git-snapshot-share-images-dailydotdev.vercel.app/?path=/story/features-snapshot-surfaces-briefing--variations

Preview domain

https://claude-snapshot-briefing-preview.preview.app.daily.dev

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Project	Deployment	Actions	Updated
daily-webapp	Ready	Preview	Sep 3, 2026 1:27pm UTC

1 Skipped Deployment

Project	Deployment	Actions	Updated
storybook	Ignored		Sep 3, 2026 1:27pm UTC