Solana session intent specification

[lgalabru]

Specification draft for MPP session intent, driving an implementation that will the audited and maintained by Solana Foundation (not ready for review)

[alexanderattar]

Closed #200 to move things here. I went through the draft and had a few questions.

The lean voucher makes sense to me if channelId is always treated as the authoritative commitment to payer, recipient, asset, and program state. Does that imply the verifier is expected to resolve channel state onchain, or is there an intended offchain-only verification path?

Are you aiming for one canonical channel program, or would any program that implements this instruction set and state model be compatible?

I noticed metering is entirely server-side in this draft, with the voucher only authorizing cumulative payment. Was that intentional?

I had also written up sections on replay protection, crash safety for distributed servers, and Ed25519 instruction introspection that may be worth pulling into this draft if useful.

[lgalabru]

Thanks @alexanderattar, appreciate your help!
The server verifies vouchers off-chain during the session (signature check, monotonicity, balance — no RPC needed per request). The channel state is resolved on-chain only at open (to confirm the deposit landed) and at settle/close (to claim funds). This is the same as Tempo — off-chain during streaming, on-chain at settlement boundaries.

Any compatible program with the spec should be usable, this is why we're proposing channelProgram in the challenge: different programs could offer different trade-offs (grace period length, supported tokens, compression, etc.). The spec defines the logical interface; implementations vary.

[github-actions]

Spec Preview

Spec	Changed
draft-card-charge-00	Yes
draft-httpauth-payment-00	Yes
draft-lightning-charge-00	Yes
draft-lightning-session-00	Yes
draft-payment-discovery-00	Yes
draft-payment-intent-charge-00	Yes
draft-payment-transport-mcp-00	Yes
draft-solana-charge-00	Yes
draft-solana-session-00	-
draft-stripe-charge-00	Yes
draft-tempo-charge-00	Yes
draft-tempo-session-00	Yes

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