Hedera · HTS Capability Tokens

The bet

"Give the agent your API key" is the wrong shape. The right shape is a capability token: scoped, expiring, spend-capped, network-allowlisted, replay-protected.

Implementation

• Every mandate is minted as an HTS fungible token (hedera_token_id) via a small Node signer service — @hashgraph/sdk cannot run inside edge runtimes, so writes go through Node.
• Fields enforced deterministically outside the model:
• scope — string prefix match
• spend_cap_tinybar — hard ceiling
• expires_at — hard deadline
• allowlist_addresses — recipient allowlist
• network_allowlist — chain allowlist (hedera-testnet only for now)
• replay_nonce — one-shot
• Reads (balances, HCS messages, token state) run directly against https://testnet.mirrornode.hedera.com/api/v1/*.
• A user can revoke a capability from the Payments page.

Env vars

• HEDERA_OPERATOR_ID (0.0.xxxxxx)
• HEDERA_OPERATOR_KEY (DER-encoded ED25519)
• HEDERA_NETWORK=testnet

Win condition

• The judge tries to spend past the cap on stage. It fails before the LLM is even consulted.