feat(app): add an Extensions side tab and split the Context tab into sections - #57898

Issue for this PR

Closes #

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Two side-panel tabs now share one visual language: collapsible cards.

Extensions tab (new). This tab lists everything connected on this computer, with every card expanded by default:

• MCP servers: each server's status, an enable/disable switch, Sign in, Retry, and Details (error dialog), plus "Manage MCP servers", which opens /mcp.
• Plugins: failed plugins are marked.
• Skills: each skill opens its SKILL.md in a side tab.
• LSP: configured servers.

Each card also has "Set up with OpenCode" and "Configuration file" actions; on a remote server, "Configuration file" copies the path instead. Collapsed cards are remembered in a global extension store.

Session details popover removed. It only rendered the Extensions menu. The header button (same icon, mod+shift+y, same details.toggle command id) now opens the Extensions tab, or selects it when it is already open. On narrow screens, Extensions is a "More…" view instead of a drawer.

Context tab slimmed down. It keeps three cards:

• Context: % full meter, total, input, output, reasoning and cache read/write tokens, context limit, and cost.
• System prompt
• Advanced: session metadata, raw messages and export.

Code changes:

• The MCP, plugin, skill and LSP data hooks, the MCP row controls and the error dialog live in details/services.tsx.
• The card UI lives in details/cards.tsx.
• server-panel.tsx, popover.tsx, panel.tsx and details.css are deleted.
• The tab is titled "Extensions", reusing the translated server string.

There are no backend changes.

How did you verify your code works?

bun typecheck passes in packages/gui-extensions and packages/app. I updated the e2e specs that asserted the popover or its drawer, but did not run them:

• session-summary
• session-header
• mcp-workspace-toggle
• mobile-session
• mobile-session-options
• mobile-extensions
• new-session
• home
• mobile-extension-drawers, which is now mobile-extensions-view

I took real screenshots of both tabs from the beta web app against an isolated OpenCode Drive server.

Screenshots / recordings

Posted to the review canvas, group "Session context redesign".

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR