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How it works

Webhook payload schema

Dodo signs the canonicalized body with HMAC-SHA256 using the shared secret. Atlas rejects any payload that fails the 5-step verification or replays an already-seen invoice_id.

#[derive(Deserialize)]
pub struct DodoWebhookPayload {
    pub event:       String,      // "invoice.paid"
    pub invoice_id:  String,      // "inv_8c2..."
    pub amount:      u64,         // base units
    pub mint:        Pubkey,      // PUSD / USDC mint
    pub destination: Pubkey,      // treasury ATA
    pub memo:        Option<String>,
    pub signed_at:   i64,         // unix seconds — replay window anchor
    pub signature:   String,      // HMAC-SHA256 hex of canonicalized body
}

5-step verification

1. 1

   Canonicalize JSON

   Sort keys, drop whitespace. Hash input is the canonical byte string, not the wire body.

2. 2

   HMAC-SHA256 compute

   Compute HMAC-SHA256(secret, canonical_body) once. Reused for verify + audit log.

3. 3

   Constant-time compare

   Use subtle::ConstantTimeEq against the supplied hex signature — never == on bytes.

4. 4

   10-minute replay window

   Reject if now() - signed_at > 600s. Clock skew tolerance ±60s baked in.

5. 5

   Idempotency check

   Dedup by invoice_id in a 24h LRU. Duplicate webhooks accept silently — no double-settle.

Slot-rate pre-warm formula

The pre-warm target is the floor of the buffer ratio plus the slot-rate term — the yield Atlas expects to capture before the obligation deadline. This keeps the rebalance window open even when the idle buffer alone is short.

prewarm_target_pct  =  min( 100,  ⌊ (idle_buffer ÷ obligation) × 100 ⌋
                                 +  slot_rate_bps ÷ 100 )

slot_rate_bps        =  EMA₆₄(yield_bps_per_slot) × slots_until_deadline

• EMA₆₄ — 64-slot exponential moving average of realised yield bps per slot.
• slots_until_deadline — slots between now() and the payout's settlement target.
• Both terms are unit-checked; floors prevent off-by-one over-warming.

6 failure modes

Source

• atlas-payments/src/dodo.rs
• /treasury/<id>/payments — live connection panel