[bobleer]

Summary

Selecting a session in an assistant's expanded history highlighted both the session and its parent assistant. Apply the existing project-workspace selection styles to assistants so the visible session owns the highlight, including while hovering the parent row. Restore the assistant highlight when its history is collapsed.

Type and Areas

Type: Bug fix / UI

Areas: Web UI sidebar styling

Motivation / Impact

Assistant rows now follow the same nested-selection behavior as ordinary workspace rows. Parent background, label emphasis, and icon color no longer compete with the selected child session.

Refreshed upstream main and inspected related open PRs, including drafts, before editing; no existing fix covered this missing assistant style rule.

Verification

• pnpm run check:web — passed, including type-check and Appearance/theme governance checks.
• pnpm --dir src/web-ui run test:run src/app/components/NavPanel/sections/workspaces/WorkspaceListSectionLayout.test.ts src/app/components/NavPanel/sections/workspaces/AssistantSessionHistory.test.tsx src/app/components/NavPanel/sections/workspaces/assistantSessionPreferences.test.ts — 19 tests passed.
• Local Chrome fixture using the compiled production stylesheet — reproduced the double highlight before the fix; verified selected-child, parent-hover, no-selected-child, and collapsed-history states after the fix.
• git diff --check — passed.

Reviewer Notes

AI-assisted; lightly tested. Browser verification used an isolated markup fixture, not the native application. Remote Workspace, Remote Control, Peer Device Mode, and Detached Dispatch were not exercised. This change only extends existing CSS selectors; it adds no runtime, persistence, or protocol changes.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.