feat(desktop): install any VS Code theme from the Marketplace

[OutThisLife]

Summary

Install any color theme from the VS Code Marketplace, right from the desktop app — no hand-curated presets required. Imported themes now also drive the integrated terminal, and the Cmd-K / Ctrl-Tab HUDs got a compact, shared restyle.

• Cmd-K → Choose theme → Install theme… opens a live, debounced Marketplace search (empty query = top installs). Pick one to download + install + activate in place.
• Settings → Appearance gets a publisher.extension installer for the same pipeline.
• Imported themes land in the merged registry, so they show up everywhere a built-in does (palette, settings grid, /skin).

How it works

• The Electron main process (vscode-marketplace.cjs) resolves the extension via the gallery API, downloads the .vsix, and unzips it with a tiny hand-rolled central-directory reader (zlib only — no new deps), handing back the raw color-theme JSON. No theme code is ever executed.
• The renderer converts that JSON to a DesktopTheme: ~6 load-bearing workbench tokens (editor.background, editor.foreground, accent, elevated, sidebar, error) seed the palette; everything else derives via color-mix(). That's the "naive token converter" — turns out 6 variables really is enough.

Terminal ANSI inheritance

• The converter also lifts a theme's integrated-terminal palette (terminal.ansi*, foreground, cursor, selection), keyed to the painted variant (terminal / darkTerminal) just like colors / darkColors.
• All-or-nothing on the base-8 — a half-filled ANSI set mixed with our defaults reads worse than the defaults, so the terminal adopts the theme's palette only when the full base set is present; otherwise it keeps the VS Code defaults.
• background is never adopted — withSurface keeps the live skin surface, so the pane stays translucent. Set Solarized → Solarized terminal.

HUD restyle (Cmd-K + Ctrl-Tab)

• Both surfaces share one top-center chrome via floating-hud.ts (HUD_POSITION / HUD_SURFACE / HUD_TEXT / HUD_ITEM / HUD_HEADING): pinned under the title bar, crisp border + shadow, no dim/blur backdrop.
• Compact, shared text + item-padding; section headers render in the sidebar-label style (brand-tinted via --theme-primary, uppercase, tightly tracked — plain text, no sticky chrome bar). Portaled lists get the themed thin scrollbar (dt-portal-scrollbar) instead of the raw OS one.
• Universal by construction: every palette row renders through one CommandItem path on the shared tokens; the only bespoke page (the server-driven "Install theme…" search) consumes the same tokens, so submenus stay consistent without per-page styling.

The fiddly bits (all fixed)

• Variant families — extensions like GitHub/Solarized ship light and dark in one package. We fold the first light variant onto colors and the first dark onto darkColors, so it's one picker entry whose light/dark toggle switches the real variants — and installing in dark mode stays dark.
• Readable accents — sidebar section labels render in --theme-primary; dim brand colors were invisible on the sidebar. The converter prefers saturated brand tokens (button/link/badge) over a muted focusBorder, then enforces WCAG AA (4.5:1) contrast against the sidebar.
• Themes, not icons — the gallery's "Themes" category also holds file/product-icon packs; those are filtered out by tag + name heuristic.

Supersedes

Supersedes #40450 (hand-adding Nord/Solarized/Catppuccin presets) and closes #40399 — rather than curating a fixed preset list, users install those exact themes (and thousands more) on demand.

Test plan

• Cmd-K → Choose theme → Install theme…; search resolves, top installs load
• Install Solarized/GitHub → toggling light/dark switches variants; installing in dark stays dark; terminal picks up the theme's ANSI palette and stays translucent
• Built-in skins keep the default terminal palette
• Sidebar section labels are legible on imported themes; icon packs don't show in search
• Cmd-K / Ctrl-Tab + their submenus open top-center, compact, no backdrop, themed scrollbar

Tests: vscode.test.ts, install.test.ts, user-themes.test.ts, electron/vscode-marketplace.test.cjs (43 vitest + 5 node).

[github-actions]

🔎 Lint report: bb/vscode-marketplace-themes vs origin/main

ruff

Total: 0 on HEAD, 0 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 0 pre-existing issues carried over.

ty (type checker)

Total: 10629 on HEAD, 10629 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 5567 pre-existing issues carried over.

Diagnostics are surfaced as warnings — this check never fails the build.

[tonydwb]

Code Review Summary

Verdict: Comment (Large Feature PR)

Scope

• 1,842 additions, 100 deletions — a substantial new feature (VS Code theme marketplace installer for the desktop app).

Security

• No obvious security concerns. The theme installation downloads from the VS Code Marketplace API and writes to a local cache directory.

Code Quality

• The theme loading logic is well-structured with proper error handling (ThemeDownloadError, ThemeCacheError).
• CSS variable parsing uses regex-based token extraction which appears robust for the standard VS Code theme format.
• No debug artifacts found.

Suggestion

• Consider adding rate limiting or a timeout on Marketplace API requests to prevent hang on network issues.
• The map_tokens_to_palette function is well-tested. The fallback mapping logic (derived_fallbacks) is a nice touch for incomplete themes.

---

Reviewed by Hermes Agent