fix(markdown): align mention chip wrapping

[tellaho]

Category: fix
User Impact: Human and agent mentions now break across lines with the same cloned chip treatment as repository and permalink chips while preserving the conversation text rhythm.

Problem: Profile-backed rendered mentions sat inside an inline-flex popover trigger, unlike entity chips, so the wrapper interfered with true inline fragmentation. The browser-layout test measured text-range rows rather than the painted chip rectangles, allowing touching decorations to pass as “separate” fragments.

Solution: Keep the profile trigger interactive but override its layout to true inline, then give mention fragments 18px computed leading inside the message’s 20px prose rhythm. Chromium paints each fragment at 17px and advances it by 20px, leaving a visible gap between cloned rounded rectangles. The browser test now measures the chip’s own getClientRects() and asserts fragment count, height, gap, and step; entity links retain their existing 22px leading.

File changes

desktop/src/features/profile/ui/UserProfilePopover.tsx
Allows inline consumers to override the trigger wrapper’s layout without changing other profile-popover call sites.

desktop/src/shared/styles/globals/markdown.css
Keeps one shared wrapping-chip mechanic and gives mention decorations enough room to separate visibly within 20px prose.

desktop/src/shared/ui/markdown.test.mjs
Pins both rendered mentions and entity links to the shared wrapping-chip contract.

desktop/src/shared/ui/markdown/MarkdownMention.tsx
Makes the profile-popover trigger truly inline so the nested mention chip can fragment with surrounding prose.

desktop/src/shared/ui/mentionChip.ts
Keeps wrapping-inline-chip as the single contract for fragmenting decorated chips.

desktop/tests/e2e/mentions.spec.ts
Measures the painted chip rectangles, requires a positive fragment gap, and verifies the inline trigger remains mouse- and keyboard-operable.

desktop/tests/e2e/navigation.spec.ts
Keeps a wrapped repository chip as the control, asserting its existing 22px line height and fragment advance.

Reproduction steps

1. Open a channel in Buzz Desktop using dark theme.
2. Send a message containing a human mention and another containing an agent mention; both chips should remain aligned with adjacent text on a 20px line.
3. Render a collision-qualified mention in a narrow message width; it should break into separately decorated fragments exactly like another wrapping chip, while each fragment follows the 20px prose rhythm.
4. Render a long repository or permalink chip in the same constrained width; it should retain its roomier 22px fragment spacing.

Screenshot

The dark-theme production renderer shows the real qualified label (bob (npub1hv3…tpuc)) at an 8rem width. The two lines now paint as visibly separate rounded fragments rather than one continuous rectangle.

Validation

At commit 2b063e1b4ade30e11f1616269ad4ba4190366885:

• Pre-push desktop gates — file-size check, Biome/checks, typecheck, and 6,483 unit tests passed
• pnpm --dir desktop build — passed
• Focused Playwright coverage for single-line agent mention, single-line human mention, wrapped qualified mention including keyboard profile activation, and timeline mention click — 4 passed
• git diff --check — passed

[github-actions]

🔐 Codex Security Review

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