Client appearance profile: export/import JSON + optional sync (VS Code Settings Sync–style)

[devarfeen]

Summary

I use T3 Code on multiple desktops (Mac, Windows/WSL) against the same WSL server. Environment settings already follow the server, but UI appearance (fonts, typography sizes, many Appearance toggles, custom themes beyond environment defaults) is per device in browser storage (t3code:client-settings:v1 and related t3code:* keys), as documented in appearance.md.

Themes can be synced manually today via ThemeFile v1 JSON import/export (with version: 1). Fonts and the rest of Appearance cannot without copying Electron storage or re-clicking every control on each machine.

I'd like a first-class, human-readable profile file and optional account or server sync, similar in spirit to VS Code Settings Sync, without asking users to hack local databases.

This extends discussion #16899 (server-stored client settings). I'd like portable export/import as phase 1, before server or T3 Connect sync.

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Problem (concrete use case)

1. I tune Appearance on Windows: theme (often custom), typography (interface, prompt, code, terminal), font smoothing, separate fonts, etc.
2. On Mac, same environment — server settings match, but UI looks different because client prefs are local.
3. Theme JSON export → import on another machine works (with version: 1).
4. No equivalent for fonts and other Appearance prefs.

Related: #19094, #6405, #16899, #16468.

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Proposal (staged)

Phase 1 — Portable profile file

Add ClientAppearanceProfile v1:

• version: 1
• Typography + appearance fields from ClientSettingsSchema that users expect to match across their machines
• Optional theme section: active theme / halves + embedded ThemeFile v1 entries

UI: Settings → Appearance — Export profile / Import profile (like theme import).

Exclude: window bounds, device-specific browser/desktop prefs, environment settings.json keys.

Phase 2 — Server-backed profile (#16899)

Server document + local cache; import from localStorage on first connect.

Phase 3 — T3 Connect account sync

Optional signed-in profile blob (distinct from environment sync in #21294).

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Questions for maintainers

1. One profile file vs split (themes vs appearance)?
2. Which keys sync vs stay local (as in Store appearance and behavior settings on the server that serves the web app #16899 / A rule for which settings the client owns and which the environment owns #19593)?
3. Remote clients: desktop profile on the app, not only t3 theme set on server ([Bug]: Paired desktop client ignores the server's published environment themes #19842).

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Why Phase 1 alone helps

Dotfiles/scp/manual sync — same workflow that already works for themes — without LevelDB copying or new backend.

Happy to help with a focused PR if Phase 1 scope is approved (CONTRIBUTING).