docs: online Texas Hold'em design spec (serverless, value-ready deal ladder)

[SethMorrowSoftware]

What this is

docs/holdem-spec.md — a pre-implementation design spec (plan, not as-built) for a serverless online no-limit Texas Hold'em game built on the OXT extension family:

• TorrentXT — rp1 peer messaging, DHT rendezvous (phantom swarms + short table codes), BEP44 signed standings
• SodiumXT — ed25519 identities, sealed lanes, hash commitments, and (the one new prerequisite) exposing libsodium's ristretto255 surface
• OnionXT — anonymous tables and onion-hosted deck oracle (optional)
• Box2Dxt Kit — spritesheet card animation (deal slides, squash-flips) and physical chips, per the performance playbook

Design highlights

• Deal protocol ladder: Level 0 (rotating host, entropy-committed shuffle — friendly tables) → Level 1 (non-playing deck oracle over an onion service) → Level 2: ristretto255 mental poker — commutative scalar masking, reveal-scalar showdown (no ZK proofs needed), publicly-visible duplicate detection, and a void-and-audit rule that makes cheating attributable, not just detectable.
• Hash-chained, signed transcript with per-street checkpoints; the game is a deterministic state machine over the log (reconnect, spectate, and dispute all reduce to replay).
• Countersigned settlement receipts as the only interface a future value layer may consume — requested because chips may someday carry real monetary value.
• Honest non-goals: regulatory compliance, collusion/bot detection, and ZK shuffle proofs (documented as the ceiling above Level 2, with DLEQ proofs as the named first hardening pass).
• Milestones M0 (hotseat) → M4 (hardening), test plan including an adversarial cheater-bot harness, and per-repo prerequisite work items (only SodiumXT has blocking native work; TorrentXT/OnionXT/Box2Dxt suffice as shipped).

Docs-only change: no code, no Kit edit (no sync/harness bump needed), no ABI impact. Verified clean of smart quotes.

🤖 Generated with Claude Code

https://claude.ai/code/session_01ARv3pRjgM2H9ga7ZYQmvhe