Premium pricing for stamp pool feature

[crtahlin]

Summary

The stamp pool feature provides low-latency stamp provisioning (instant vs 1+ minute for regular purchases). This premium service incurs additional costs for the gateway operator:

• Pre-purchased stamps tie up capital
• TTL costs continue even if stamps aren't used
• Risk of unused stamps expiring

This warrants premium pricing or access control.

Options to Consider

Option 1: Premium x402 Pricing (Simplest)

• Charge higher prices for /api/v1/pool/acquire endpoint
• Use existing x402 pricing mechanisms
• Add X402_POOL_MARKUP_PERCENT config (e.g., 100% = 2x regular price)

Option 2: Subscriber Tiers

• Free tier: Regular stamp purchase only (1+ minute latency)
• Premium tier: Access to stamp pool (instant)
• Requires account/subscription system

Option 3: Hybrid

• Pool access available to all, but at premium price
• Subscribers get pool access at regular price

Implementation Notes

• Start with Option 1 (premium pricing) as it requires minimal changes
• Subscriber tiers can be added in Phase 2+ of x402 integration
• Consider rate limiting pool access per-IP or per-wallet

Related

• Stamp Pool PR: Add stamp pool feature for low-latency stamp provisioning (Issue #63) #64
• x402 Integration Plan: See docs/x402-operator-guide.md

Acceptance Criteria

• Decision documented on pricing model
• Premium pricing implemented for pool endpoints
• Configuration options for operators to set markup