claude-bionify

Bionic reading for Claude Code. Bold the front of every word so your eyes move faster.
_{So Bionify makes Claude's replies easier to read.}

claude-bionify bolds the leading part of each word in Claude's streamed replies, giving your eye a fixation point per word. This is the bionic-reading technique, inspired by the eye-movement research showing that we read by fixating a single convenient position toward the start of each word, where its opening letters carry the most information for recognising it (Rayner, 1979; O'Regan et al., 1984).

It only changes how text looks on screen. What gets saved to the transcript and what Claude reads stays the original, unbolded text, which you can reopen any time with the Ctrl+O transcript view.

Features

• ⚡ Faster, calmer reading. Fixation points pull your eye word to word through long answers.
• 🌍 Any language. Unicode-aware, so accents and non-Latin scripts bold correctly, not just English.
• 🎚️ Three boundary modes. fraction, syllable, or log — see Configure.
• 🧩 Markup-aware. Code, links, URLs, paths, and acronyms stay intact (what it touches).
• 🔒 Private, zero-dependency. Nothing to install, no network, no telemetry — it runs entirely on your machine.
• 🪶 Crash-safe. On any error it falls back to the original text.

Install

/plugin marketplace add abullard1/claude-bionify
/plugin install claude-bionify@claude-bionify

claude-bionify is active right away. Turn it off or back on any time with /claude-bionify:off and /claude-bionify:on, or from /plugin.

Configure

When you enable the plugin, Claude Code prompts for these (all optional):

Control it live

Change claude-bionify mid-session without a reload or any config editing. The next reply reflects it right away:

These write a small override file that the hook reads on every message, so changes take effect immediately and persist until you reset.

Themes

claude-bionify also ships seven color palettes for Claude Code's /theme picker (custom:claude-bionify:<name>). They retint Claude Code's interface and are independent of the bolding.

How it works

Claude streams a reply ▸ claude-bionify ▸ bolded text in your terminal

As each batch of Claude's reply streams in, claude-bionify bolds it just before it reaches your screen — so only what you see changes, never the text itself.

What it touches

• Bolded: ordinary prose words.
• Left alone: inline `code`, fenced code blocks, markdown link/image targets, URLs, emails, file paths and filenames, ALL-CAPS acronyms, and any text Claude already wrapped in **bold**.
• Never touched: your own input and tool output.

Requirements

• Claude Code with plugin support
• python3 on your PATH
• A terminal that renders markdown bold (any modern terminal)

Limitations

• Affects assistant chat text only, not tool results or your prompts.
• Text in tables and headings is treated as prose and gets bolded, which is intended. Deeply nested or unusual markdown may occasionally mis-bold a word. It is cosmetic only, and it never changes the underlying text.
• Right-to-left scripts (Arabic, Hebrew) are not a target; there, syllable mode falls back to a length-based bold.
• Each line is processed on its own, so a markdown construct split across a line break (rare) may not be detected.

Development

# Run against a working copy without installing
claude --plugin-dir ./plugins/claude-bionify

# Validate the manifest and components
claude plugin validate ./plugins/claude-bionify --strict

# Run the tests (project-local virtualenv, nothing system-wide)
python3 -m venv .venv && .venv/bin/pip install pytest
.venv/bin/python -m pytest tests/

Set CLAUDE_BIONIFY_DEBUG=1 to make the hook re-raise on error instead of silently falling back, so failures surface while you iterate.

Repository layout

claude-bionify/
├── .claude-plugin/
│   └── marketplace.json      # marketplace catalog
├── assets/                   # logo, demo, theme gallery (SVG) + generate_themes.py
├── plugins/claude-bionify/          # the plugin
│   ├── .claude-plugin/plugin.json
│   ├── hooks/hooks.json      # MessageDisplay -> bionify.py
│   ├── commands/             # /claude-bionify:on, off, toggle, set, status, reset
│   ├── skills/               # model-invoked control/config skill
│   ├── scripts/
│   │   ├── core.py           # functional core: pure formatting + settings (no I/O)
│   │   ├── overrides.py      # runtime-override persistence (shared contract)
│   │   ├── bionify.py        # the MessageDisplay hook shell (entrypoint)
│   │   └── control.py        # the /claude-bionify control CLI
│   ├── themes/               # 7 color themes for /theme (experimental component)
│   └── README.md
└── tests/test_bionify.py

Contributing

Issues and pull requests are welcome. Run .venv/bin/python -m pytest tests/ and claude plugin validate ./plugins/claude-bionify --strict before opening a PR.

Author

Samuel Ruairí Bullard Human-Centred AI @ University of Regensburg · Regensburg, Germany GitHub @abullard1 · sams3dlibrary.com · X @samudschigo

Built by Samuel Ruairí Bullard. If claude-bionify makes your reading easier, a ⭐ on the repo is hugely appreciated.

License

MIT © 2026 Samuel Ruairí Bullard.

Star History