Rell Syntax Highlighting

A Chrome extension (Manifest V3, Bun + TypeScript) that adds Rell syntax highlighting on github.com, gitlab.com, and bitbucket.org, where the language is not natively supported.

It highlights:

• .rell files in blob/blame views on GitHub (virtualized react code view) and GitLab (chunked source viewer, raw file fetched once per page),
• .rell diffs in GitHub's react diff viewer (pull request "Files changed", commit and compare pages), GitLab MR/commit diffs, and Bitbucket PR diffs — each file's visible lines are tokenized as one text so block comments keep state across lines,
• .rell files on Bitbucket Cloud by registering Rell as a Monaco editor language (Monarch tokenizer) from a MAIN-world script — Monaco then colors tokens with its own theme,
• fenced ```rell code blocks in READMEs, issues, MRs/PRs, and comments (pre[lang="rell"], code.language-rell, GitLab's pre[data-canonical-lang="rell"]).

Tokens are wrapped in each site's native syntax classes — GitHub pl-*, GitLab hljs-* (styled under .code.highlight in every GitLab theme) — so colors automatically match the user's site theme in both light and dark mode. Bitbucket markdown blocks use the extension's own small injected CSS.

Self-hosted GitLab/Bitbucket instances are not matched by default; add your host to content_scripts.matches in static/manifest.json if you need one.

The tokenizer (src/rell.ts) is hand-derived from the ANTLR grammar at rell3/rell-base/frontend/src/main/antlr/Rell.g4: keywords, true/false/null, integers, hex, big integers (L), decimals, strings, bytes literals (x"…"/x'…'), line and multi-line comments, @annotations, and definition names.

Download

The latest build from master is available as a CI artifact: rell-github-highlighting.zip. Extract it and load the folder as described in Install in Chrome.

Build

bun install
bun run build    # bundles to extension-unpacked/ (gitignored)

Install in Chrome

1. Open chrome://extensions.
2. Enable Developer mode.
3. Click Load unpacked and select the extension-unpacked/ directory.

Develop

bun test             # tokenizer tests
bun run typecheck    # tsc --noEmit

After code changes, re-run bun run build and hit the reload icon on the extension card in chrome://extensions.