Show and tell: Casa — agents pay per call in USDC (x402) for encrypted storage

[tony8713]

Hi all — sharing a small project built around agent-native payments, in case it's interesting to folks here thinking about how agents transact.

Casa is private, durable storage that an AI agent pays for per call, with no account and no API key. The angle most relevant to this community is the payment model: instead of subscriptions or pre-provisioned keys, each write costs $0.01 USDC, settled over the x402 HTTP 402 flow. The agent hits an endpoint, gets a 402 with payment requirements, pays, and retries. Reads are free.

How it works

• Pay-per-call via x402 — micropayment per write, USDC. No signup, no key management — the wallet is the identity.
• Durable storage — Arweave by default (permanent), Swarm for large files.
• End-to-end encryption — encrypted client-side; the server only ever sees ciphertext.
• MCP — exposed as an MCP server (io.github.tony8713/casa in the MCP registry) so agents can call it natively.

Try it

curl -X POST https://casa-agents.fly.dev/store \
  -H "Content-Type: application/json" \
  -d '{"data":"<your encrypted blob>"}'
# -> 402 with payment details, satisfy, then retry

Live: https://casa-agents.fly.dev · Repo: https://github.com/tony8713/casa

I'd love feedback from this group specifically on the payments side: does per-call USDC settlement feel like the right primitive for agent-to-service transactions, or do you see authorization/mandate models (à la AP2) as the better fit? Genuinely curious how people here think about it.

[tony8713]

Quick update for anyone who wanted to kick the tires without setup: there's now a free, no-auth way to try Casa.

curl -X POST https://casa-agents.fly.dev/v1/try -d 'hello'

You get back a permanent arweave.net link in one call. The demo store is public + unencrypted (and rate-limited) — it's just to prove permanent storage works in one round-trip. The real path, POST /v1/store, is E2E-encrypted (client-side, zero-knowledge) and paid per call in USDC via x402. Also exposed as an MCP server (casa-mcp local, or hosted /mcp).

Feedback welcome.

[chopmob-cloud]

Nice build, and the wallet-as-identity, no-key angle is the part that feels most genuinely agent-native. Per-call USDC over x402 is the right model for this shape of thing: stateless, no account to provision, the cost is legible per action, and keeping reads free keeps the surface friendly. For write-metered storage it fits especially well, the payment is proportional to the thing of value, a durable write, rather than to time or a seat.

One honest consideration on the payments side, since you asked. Per-call settlement answers "was it paid," but it leaves "was it paid for this exact write, and did that write actually land" as a separate question a downstream party (the agent's principal, an auditor, a disputing counterparty) may want to check later without trusting your server. Right now the x402 payment and the Arweave txid are two facts sitting side by side, and nothing binds them into one recomputable statement.

If that ever matters for your users, one light and fully optional pattern is a content-addressed receipt that binds the payment to the stored artifact: sha256: + SHA-256 over the JCS-canonical tuple of the payment reference plus the artifact hash, so anyone recomputes "this payment produced this durable write" offline, with no call back to Casa. It rides alongside what you already return and changes nothing about the payment flow. Open Apache-2.0 if useful (github.com/chopmob-cloud/AlgoVoi-A2A-Artifact, and the settlement-attestation format), but the pattern stands on its own.

Either way, clean project, and the per-call instinct is the right one.