{"slug": "using-your-claude-subscription-in-pi-agent-at-your-own-risk", "title": "Using Your Claude Subscription in Pi Agent — At Your Own Risk", "summary": "A developer has released pi-sub-anthropic, a Pi extension that lets users point their Claude Pro/Max subscription at the third-party Pi agent harness, circumventing Anthropic's server-side enforcement. The extension reproduces Claude Code's wire fingerprint to present a third-party client as first-party, which risks account termination. The developer advises against using it unless users are prepared to lose their Anthropic account.", "body_md": "If you use [Pi](https://pi.dev/) and you're willing to gamble your Anthropic account on it, here you go:\n\n[https://github.com/spksoft/pi-sub-anthropic](https://github.com/spksoft/pi-sub-anthropic)\n\nThat sentence is not a joke, and I'd rather lead with it than bury it.\n\nI watched [Mario Zechner's talk, Building pi in a World of Slop](https://www.youtube.com/watch?v=RjfbvDXpFls), and came out the other side genuinely in love with Pi. Four primitives — read, write, edit, bash — a system prompt under a thousand tokens, and everything else is an extension you write yourself. After a couple of years of agents that ship with fifty tools and opinions about all of them, that minimalism lands hard.\n\nThen I hit the wall everyone hits.\n\nPi's provider layer does the *correct* thing: it follows Anthropic's policy and doesn't let you point a Claude Pro/Max subscription at a third-party harness. Since April 4, 2026, Anthropic has enforced this server-side — third-party tools authenticating with a subscription OAuth token get a `400`\n\ntelling them their usage draws from extra usage, billed per token, not from plan limits. There's an [open issue on the Pi repo](https://github.com/earendil-works/pi/issues/3372) from someone running into exactly this.\n\nThat is a reasonable position for Anthropic to hold. Subscriptions were priced for interactive use, not for agents burning tokens unattended, and first-party clients get prompt-cache behaviour that third-party harnesses don't. I'm not writing a grievance post about it.\n\nBut I was curious. And curiosity, for me, mostly expresses itself as \"what happens if I try.\"\n\nSo I ported the Anthropic provider layer out of [omp (oh-my-pi)](https://github.com/can1357/oh-my-pi), pinned at v17.4.2, into a standalone Pi extension. It registers a second provider — `pi-sub-anthropic`\n\n— alongside Pi's built-in one, so nothing about your existing setup changes until you explicitly select it.\n\n```\npi install npm:pi-sub-anthropic\n\n/login pi-sub-anthropic\n/model pi-sub-anthropic/claude-opus-5\n```\n\nNo runtime dependencies, no build step. Pi type-strips the TypeScript at load, and the Messages API is spoken directly over `fetch`\n\n. Nine models registered, mirroring Pi's own Anthropic catalog.\n\nIt also accepts an API key via `PI_SUB_ANTHROPIC_API_KEY`\n\n, which is the boring, sanctioned path — billed as API credits, no fingerprint games, and the one I'd actually recommend to anyone reading this.\n\nTo make a subscription credential work outside Claude Code, this extension reproduces Claude Code's wire fingerprint: user-agent, beta headers, system-block layout, token clamp, tool naming, billing attestation. That is, by construction, **presenting a third-party client as a first-party one**.\n\nWhich means:\n\nIf you aren't prepared to lose the account, don't install it. Use an API key, or use Pi's built-in `anthropic`\n\nprovider, or just use Claude Code — which is, after all, the client this thing is imitating.\n\nThe interesting work here isn't mine. The OAuth flow, the wire fingerprint, the beta profile, the token clamp, the tool naming, the billing attestation — all of that is [omp](https://github.com/can1357/oh-my-pi)'s discovery. What I contributed is a Node-compatible translation, tests, and documentation. MIT licensed, carrying omp's notice.\n\nNot an official Anthropic or Pi project. Use at your own risk.", "url": "https://wpnews.pro/news/using-your-claude-subscription-in-pi-agent-at-your-own-risk", "canonical_source": "https://dev.to/spksoft/using-your-claude-subscription-in-pi-agent-at-your-own-risk-5h1j", "published_at": "2026-08-24 04:06:37+00:00", "updated_at": "2026-08-24 04:43:52.943575+00:00", "lang": "en", "topics": ["developer-tools", "ai-agents", "ai-policy"], "entities": ["Pi", "Anthropic", "Claude Code", "Mario Zechner", "oh-my-pi", "pi-sub-anthropic", "GitHub"], "alternates": {"html": "https://wpnews.pro/news/using-your-claude-subscription-in-pi-agent-at-your-own-risk", "markdown": "https://wpnews.pro/news/using-your-claude-subscription-in-pi-agent-at-your-own-risk.md", "text": "https://wpnews.pro/news/using-your-claude-subscription-in-pi-agent-at-your-own-risk.txt", "jsonld": "https://wpnews.pro/news/using-your-claude-subscription-in-pi-agent-at-your-own-risk.jsonld"}}