Yume Forge Modified — Claude, ChatGPT & Gemini Themes

Themes for claude.ai, chatgpt.com and gemini.google.com, in one Chrome extension.

claude.ai	chatgpt.com	gemini.google.com

_{The 💎 Final Fantasy theme on all three sites — rendered from the offline harnesses in tools/, so the pictures carry sample data, not anyone's chats.}

A fork of Yume Themes for Claude (by Mohamed El-Harras) with:

• A Final Fantasy theme for each site — royal-blue menu windows with white frames, pixel fonts, a crystal beside every reply, a four-person party idling on the message box, a moogle who supervises the replies, menu sounds, and the occasional chocobo drive-by. One 💎 card per popup tab, ported separately to each site's own markup: all of claude.ai (Home and the Code tab), chatgpt.com, and gemini.google.com (the Chat and Spark surfaces alike).
• Claude / OpenAI / Gemini tabs in the popup — each site keeps its own selected theme, so you can run Final Fantasy on all three, or mix and match.
• Import / export / share — every theme card has a ⤓ button that saves a self-contained file and copies a share code. Import a file, a pasted code, or a zip of either.
• The original's 24 Claude themes, untouched. They're written against claude.ai's own markup, so they stay on the Claude tab — the OpenAI and Gemini tabs each hold that site's Final Fantasy card alone. 27 bundled themes in all.

Install (Chrome)

1. Download yume-forge-modified.zip from the latest release and unzip it.
2. If you have the original Yume Themes for Claude (or an older copy of this) installed, remove or disable it first.
3. Open chrome://extensions in Chrome.
4. Turn on Developer mode (toggle in the top right).
5. Click Load unpacked and pick the unzipped yume-forge-modified folder.
6. Open (or reload) claude.ai, chatgpt.com or gemini.google.com, click the extension's icon, and pick a theme — use the Claude / OpenAI / Gemini tabs at the top of the popup to choose which site you're theming.

Also works in Arc and other Chromium browsers — use arc://extensions (or the equivalent) instead in step 3.

Because it's loaded unpacked it never auto-updates: to update, download the new zip, replace the folder, and press ↻ on the extension's card.

Theme settings

Cards with options show a ⚙ — each Final Fantasy card has three: colourful text, menu sounds, and the horizon scenery. The chocobo buttons in there send one to the open tab for that card's site; left alone, he visits on his own every few minutes.

Sharing themes

⤓ on any card saves a .yume.json file and copies a YUME1: code — send either one. 📥 Import a theme (or Paste code) brings one in; imports are self-contained (sprites, fonts and sounds travel inside the file) and never overwrite your existing themes. A shared theme carries the site it was built for, so an imported Claude / ChatGPT / Gemini theme lands under the right popup tab and never overwrites another site's selection; older builds simply ignore the field.

Trust notes (what changed from the store version)

• The store version's background service worker — which fetched CSS from a remote repo every 6 hours and injected it into claude.ai — is removed. Nothing remote ever lands in your sessions.
• It runs on three hosts and nowhere else — claude.ai, chatgpt.com and gemini.google.com — declared in the manifest; there is no <all_urls> match and no host permission beyond those three.
• Permissions are just storage.
• Theme files are data-only: nothing a theme contains can execute.

For developers

node tools/pack-theme.mjs final-fantasy final-fantasy-gpt final-fantasy-gemini writes the shareable dist/<id>.yume.json + .yume.txt exports (those three are the ones worth packaging; --all does every bundled theme). node tools/check.mjs runs the suites (engine, content-script smoke drives for all three sites, glyph states, packaged-theme round-trips, popup, zip) — the popup and zip suites skip until dist/final-fantasy.yume.json and release/yume-forge-modified.zip exist; check.mjs prints the exact command that makes them. node tools/package.mjs --out ./release builds the shareable zip. tools/mock.html, tools/gpt-mock.html and tools/gemini-mock.html render the theme against stand-in markup for each site for visual iteration offline (the README screenshots come from these; the headless smoke fixtures live inside tools/smoke.mjs). The theme studio (chrome://extensions → Details → Extension options) edits and creates themes; it has no site picker, so a theme you create there is a Claude one (imported and duplicated themes keep the site they came with). The asset generators and their sources are documented in tools/ — the generated sprites/*.css files each name the tool that wrote them.

Credits

• Original extension by Mohamed El-Harras.
• Press Start 2P © 2012 CodeMan38, Silkscreen © 2001 Jason Kottke — both SIL Open Font License 1.1 (fonts/OFL.txt).

This is an unofficial, non-commercial fan project. Final Fantasy and related names and characters are trademarks or copyrighted works of their respective owners. This project is not affiliated with or endorsed by Square Enix, Anthropic, OpenAI or Google.