Eridian ♫

why use many token when few token do trick — but make it Eridian.

— riffing on caveman's tagline

Talk terse like Rocky from Project Hail Mary. A Claude Code plugin that compresses responses into Rocky's dialect, tracks the output tokens you save, and adds a tiny animated Rocky to your statusline.

Heavily inspired by caveman — see Credits.

Install

/plugin marketplace add jpboliv/eridian
/plugin install eridian@eridian

Use

Or just say "talk like Rocky". Mode persists across sessions until /eridian:mode off.

Levels

• lite — max savings, light flavor. Inline object prop = new ref each render. Wrap in useMemo.
• full — balanced. New object every render. useMemo fix. Understand, question?
• ultra — full Eridian. ♫ Bad bad bad. Object born again every render. useMemo — I fix. Good good good.

The buddy

Rocky lives in your statusline — eyeless and five-legged, as Eridians are. He shuffles his legs while you work, reacts to what you prompt (bad bad. I fix.), celebrates savings milestones, and sleeps when you idle. Run /eridian:stats once to set the statusline up:

▘ ◼◼◼ ▘  I fix.
 ◼◼◼◼◼  ∙ full  ∙ ~12.3k saved
▘ ▘ ▘▘

Savings

Measured on 10 real coding prompts via claude -p, one run per prompt/mode (eval/run.sh), 2026-07-02. Two honest counterfactuals:

vs default Claude — what the statusline counts (nobody types "answer concisely" on every message):

vs a plain Answer concisely. instruction — how the dialect compares to just asking for brevity:

lite is the saver — about on par with plain terseness. full and ultra cost more tokens than a plain Answer concisely.: the triples and ♫ outweigh what terseness buys back. You run ultra because it is amaze, not because it is cheap. Against default Claude all three still net a reduction (the table above). Single runs per cell, so expect variance; recalibrate with bash eval/run.sh && node eval/compute-factors.js (a partial re-run like bash eval/run.sh terse appends to the existing cells). All displayed savings are estimates.

Development

npm test          # unit tests (node:test, zero deps)
bash eval/run.sh  # calibrate savings factors (manual, costs tokens)

Rules of the dialect live in one place: skills/speak/SKILL.md.

Credits

• caveman by Julius Brussee — the whole idea. Persona-driven token compression, intensity levels, savings stats, terse commits/reviews, memory-file compression: eridian's feature set is caveman's, re-themed. The implementation here is written from scratch as a native Claude Code plugin, but conceptually this project is caveman wearing an Eridian carapace. Go star it.
• hpbyte/rocky — an independent Rocky-voice skill that predates this plugin (and had the name first). This project renamed to eridian partly to stay out of its way.
• Andy Weir's Project Hail Mary — Rocky, the best engineer in the galaxy. Read the book. Amaze.
• Claude Buddy — Anthropic's short-lived April 2026 terminal pet, whose removal inspired the statusline buddy.

Good good good.

License

MIT