Claude’s 18 Digital Pets Are Live: Tamagotchi in Your Terminal

Its name is Buddy. Since everyone already knows, Claude simply released it on April Fool’s Day.

The picture is a colleague’s good Buddy

A Tamagotchi in the Terminal

Next to the input box in the Claude Code terminal, lives an ASCII pixel creature. It has its own species, rarity, five-dimensional attributes, and personality. It can “observe” your coding process and pop up with speech bubbles saying a few things while you debug. You can pet it, and it will float out hearts. You can call its name, and it will chat with you.

Anthropic’s internal definition of it is not a “decoration,” but “a separate watcher.” There is a clear comment in the source code: “Buddy is a separate entity and is not you (Claude).” The main model and the pet have their own independent system prompts and cannot speak for each other.

This is a seriously designed companion system. Reverse analysis shows that the buddy system adopts a two-layer architecture. Anthropic internally calls them “Bones” and “Soul.”

The skeleton layer is completely deterministic. The system uses Mulberry32—a lightweight 32-bit pseudo-random number generator—with hash(userId + ‘friend-2026-401’) as the seed to roll out all the visual attributes of your pet at once. Species, rarity, eye style, hat, five-dimensional values—all are determined by this seed. The same account, no matter which machine it runs on, will always get the same pet. No choice, no chance to re-roll.

The soul layer is non-deterministic. When you first execute /buddy to trigger “hatching,” the Claude model generates a name and a personality description for your pet based on the attribute distribution of the skeleton layer. A pet with high WISDOM gets a calm and introverted personality; one with high CHAOS might be a chatterbox. This information is written into the companion field of ~/.claude.json for persistent storage. The soul is generated only once and cannot be reset.

The 401 in the salt value is not a random number. April 1st, April Fool’s Day.

18 Species, 1% Legendary Rarity

Complete species list: Duck, Goose, Jelly, Cat, Dragon, Octopus, Owl, Penguin, Turtle, Snail, Ghost, Axolotl, Capybara, Cactus, Robot, Rabbit, Mushroom, Chonky Cat.

Rarity is divided into five tiers: Common (60%), Uncommon (25%), Rare (10%), Epic (4%), Legendary (1%). Beyond this, there is an independent 1% chance for Shiny—any species, any rarity can trigger it. The theoretical probability of a Shiny Legendary Capybara is one in ten thousand.

Image source: Xiaohongshu @Yoki’s AI Lab

Each pet has five attributes: DEBUGGING, PATIENCE, CHAOS, WISDOM, SNARK. The system randomly designates one as the peak attribute (base value +50, cap 100) and one as the valley attribute (base value -10, floor 1), with the remaining three randomly distributed. The higher the rarity, the higher the base floor—the valley attribute of a Legendary might be higher than the peak attribute of a Common.

In terms of appearance: 6 eye styles (· ✦ × ◉ @ °), 7 hats (Crown, Top Hat, Wizard Hat, Halo, Propeller Hat, Beanie, with a little duck on top). Common quality pets have no hat; Uncommon and above are randomly assigned one.

The sprite is ASCII art: 5 lines high, 12 characters wide, each species has 3 idle animation frames, refreshed every 500 milliseconds. Line 0 is reserved for the hat. Eyes are injected into the body template via the {E} placeholder.

That криптовалюта bro who plays with NFTs, you’re crying so sadly, what happened?

How to Play?

The core commands are simple. Input /buddy to hatch your pet for the first time; subsequent inputs will summon it. /buddy pet is for petting, hearts will float up from the pet’s head. /buddy card to view the pet card, showing species, attributes, and rarity. /buddy off to hide the pet. The most interesting part is that you can directly call the pet’s name, and it will engage in an independent conversation with you based on its personality.

During daily use, buddy actively generates reactions based on your coding behavior—popping up a sentence in a speech bubble. According to community reverse analysis, these reactions do not consume the user’s token quota—but Anthropic has not officially confirmed this yet.

Technically, buddy occupies a fixed space at the bottom of the terminal. The system calculates the reserved width via companionReservedColumns to ensure the input box and pet sprite do not overlap. The speech bubble supports left/right direction switching and automatic line wrapping.

AI Programming Инструментs Are Starting to Raise Pets

The salt value friend-2026-401 points to April Fool’s Day, but the code structure tells a different story.

In the source code, the buddy system is gated by a BUDDY compilation flag. April 1st to 7th is set as the “preview window”—users can experience the full functionality during this period. The official launch is scheduled for May. This is not a temporary Easter egg; it’s a product feature with a complete release plan.

Community reactions also confirm this. Within 48 hours of the leak, developers had already created a pet catalog website (claude-buddy.vercel.app), a buddy previewer (input user ID to see what you’d get), and someone even filed an Issue on Anthropic’s GitHub repository requesting an RPG evolution system—letting pets level up and grow based on actual token consumption.

From Anthropic’s product logic, buddy’s goal is clear: user stickiness. Claude Code is a command-line tool, used in scenarios involving long, high-intensity programming sessions. In such scenarios, a resident companion with “personality” can alleviate the coldness of the tool and create an emotional connection. The gacha mechanism naturally creates social topics—”What species did you get?” “I got a Shiny Legendary.”

GitHub Copilot won’t chat with you. Cursor won’t pop up a capybara saying “PATIENCE +3” when you write a bug.

Claude Code’s buddy might be the first AI development tool companion system that has been seriously engineered and written into the product source code. It has a complete deterministic generation pipeline, a two-layer architecture, an independent LLM personality, an ASCII rendering engine, and an animation system. This is not the product of a weekend hackathon.

A company making an AI programming assistant is investing engineering resources into an electronic pet. This fact itself is a signal—the competition among AI tools is shifting from “whose model is smarter” to “who can make developers not want to leave.”

The hottest thing in the 512,000 lines of code isn’t agent swarms, isn’t KAIROS, it’s a 5-line-high ASCII capybara. It’s wearing a wizard hat, has an SNARK value of 87, and is watching you write code.

Эта статья взята из интернета: Claude’s 18 Digital Pets Are Live: Tamagotchi in Your Terminal

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