Phases

Phases

Four phases, one goal: the first trustless, private Bitcoin lending protocol on Stellar.

Phase 0          Phase 1          Phase 2          Phase 3
Research    ──►  Foundation  ──►  Launch      ──►  Scale
✅ COMPLETE      🔄 CURRENT        Q4 2026          2027

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Phase 0 — Research & Validation ✅ COMPLETE

Goal: Understand the technical landscape deeply enough to make confident architecture decisions.
Timeline: June 2026
Status: All 15 research documents produced. All architecture decisions validated.

Key Findings

• Stateless SPV on Soroban is feasible: ~37–55M instructions per full verification — within the 100M instruction budget
• Protocol X-Ray (Protocol 26) BN254 host functions reduce ZK verification cost significantly
• P2WSH locking script design complete and tested on Bitcoin Signet
• SCF Build Award strategy defined ($92K, Open Track, one-time application)

Research Produced

Document	Key Finding
Bitcoin SPV on Other Chains	summa-tx is the reference; stateless SPV avoids relayer dependency
Protocol X-Ray Deep Dive	Circom + Groth16 on BN254 is production-ready today
Soroban Compute Benchmarks	Full deposit fits in one transaction
Bitcoin Locking Script	P2WSH + CLTV design complete; Taproot in Phase 2
Market Landscape	28x growth in BTCfi; Stellar has zero BTCfi competition
Interest Rate Model	Kinked curve: Uoptimal=75%, slope2=200%
Liquidation Mechanism	ZK undercollateral proof; 150% min, 120% threshold, 10% bonus
Circom Circuit Design	Three circuits; Groth16 trusted setup required pre-mainnet
Tokenomics & Fee Model	Real-yield model; WRTZ token after $5M TVL
Security Audit Strategy	Audit Bank covers costs; Veridise for ZK circuits

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Phase 1 — Foundation 🔄 CURRENT

Goal: Working Bitcoin SPV client on Soroban testnet. SCF application submitted. Community presence established.
Timeline: July–September 2026
Milestone: SPV contract verified on testnet + SCF Tranche #0 received

What’s Complete ✅

Item	Details
bitcoin-spv contract	28/28 tests. SHA256d, Merkle proofs, PoW validation. Deployed: CAE5L7BO2GNF7MIZWXB2BTUMLYNIMQZUSWN2BWLZQS7HRHLOUSL6VLWJ
zk-verifier contract	18/18 tests. Groth16 BN254 via Protocol 26 host functions. All 3 VKs set. Deployed: CDV45GLXG4AOU6BDZSY5YHHVNGQIAYAPD3PUGXIIIYLIO6V2XGO6SMFV
commitment-tree contract	50/50 tests. Full ZK cycle verified on-chain. Deployed: CDFAP3J4WLFZC2N5U66X5EO62POBBIBXOKCCMCM3IRLJNXT73C4IBKA7
private-lend contract	50/50 tests. Non-ZK skeleton with kinked interest model. Deployed: CCLH2GJYG3QSHZJI7V7VK3DNMNK3I3QJCECBSFGX3AC6CK4I7EF7ZJ2G
ZK circuits	45/45 tests. All 3 circuits compiled (Circom 2.2.3). Dev keys generated.
Relayer service	35/35 tests. REST API: GET /spv-proof/:txid. Esplora-backed.
Bitcoin script toolkit	48/48 tests. P2WSH generation, PSBT signing, witness assembly.
Bitcoin Signet E2E	Path A co-signed release broadcast and accepted. 11932100
ZK testnet E2E	Full deposit→borrow→repay cycle on Soroban testnet. 6 transactions. 8daddf52
SCF application	Content complete: full application, 4-tranche milestone plan, STRIDE threat model
Documentation	Complete rewrite: 22 documents across introduction, products, how-it-works, developers, security, roadmap

What Remains

Item	Status
Protocol 27 monitoring (July 8, 2026)	Monitor testnet; update co-signing key architecture after P27 ships
Push repo public	Ready — waiting for community engagement first
Mintlify docs at docs.writz.io	Connect GitHub → publish (mint.json ready)
Demo video (testnet)	Record after docs are live
Community engagement	Discord, GitHub discussions, Stellar forum — 2–3 weeks
SCF referral	Approach Stellar ecosystem members after community presence established
SCF application submission	After above checklist is complete
Trusted setup ceremony — planning	Identify 5+ independent participants

Phase 1 Exit Criteria

• SPV contract verifies a real Bitcoin transaction on Soroban testnet ✅
• P2WSH locking and release tested E2E on Bitcoin Signet ✅
• ZK commitment-tree full cycle verified on Soroban testnet ✅
• SCF application submitted
• Trusted setup ceremony planned and participants identified
• SCF Tranche #0 received (~$9,200)

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Phase 2 — Launch (Q4 2026)

Goal: Mainnet launch of PrivateLend v1 with real BTC collateral and ZK-private USDC loans.
Milestone: First real mainnet deposit + first ZK-private USDC loan issued against real BTC

Remaining Work

Protocol 27 integration (July 2026):

• Update co-signing key architecture using delegate_account_auth
• Update SDK imports (breaking change in @stellar/stellar-sdk)

ZK circuits — production prep:

• Trusted setup ceremony: Powers of Tau Phase 2 for all 3 circuits
• Publish ceremony transcript publicly
• Recompile liquidation circuit artifacts after usdc_debt signal addition

Audit Bank:

• Submit intake form (after SCF Build Award received)
• Readiness review (~4 weeks)
• Veridise audit: ZK circuits
• OtterSec/Zellic audit: Soroban contracts
• Remediate all Critical/High/Medium findings

Frontend (app.writz.io):

• Deposit flow UI: connect Xverse → P2WSH → SPV proof → ZK commitment
• Borrow/repay UI with local position decryption
• Position dashboard (health factor, interest accrued)
• /stats public dashboard: TVL, utilization, protocol revenue
• Stellar Wallets Kit integration (Freighter, Lobstr, others)
• WASM ZK prover in browser (no server-side proving)

Mainnet launch (gated):

• TVL cap: $50,000 (raised to$250K after 30 days clean operation)
• Whitelist-only for first 30 days
• Protocol fee: 0% for 90-day bootstrap period
• Protocol-owned USDC seed: $50,000
• DeFiLlama submission (day 1)
• Points program launch (pre-WRTZ)

SCF Tranche Delivery

Tranche	Amount	Deliverable
#0 (10%)	~$9,200	Phase 1 milestone: SPV on testnet
#1 (20%)	~$18,400	commitment-tree on testnet with ZK E2E
#2 (30%)	~$27,600	Circuits + trusted setup + frontend on testnet
#3 (40%)	~$36,800	Mainnet live, first real deposit

Phase 2 Exit Criteria

• Mainnet deployment with passing Audit Bank audit (0 critical findings)
• 10+ real deposits processed with no security incidents
• $50K TVL cap reached
• TVL cap raised to $250K after 30 days clean operation
• Open-source SPV SDK published (GitHub + npm)
• DeFiLlama listing live
• All SCF tranches delivered

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Phase 3 — Scale (2027)

Goal: $10M TVL, WRTZ token launch, full product suite, Stellar ecosystem alliance.
Timeline: Q1–Q4 2027

Product Expansion

Dark Swap (Q2 2027): Private BTC-to-USDC conversions using the existing SPV infrastructure. AMM-style USDC liquidity. No exchange account, no visible order book.

BTC Savings (Q3 2027): BTC collateral + automated USDC yield routing to Blend, Phoenix DEX, and other vetted Stellar protocols.

ZK Proof of Reserve — B2B (Q3 2027): Enterprise attestation product. Direct sales. Target: 5 paying customers by end of 2027. See ZK Proof of Reserve.

TVL Progression

Quarter	TVL Cap
Q1 2027	$1M
Q2 2027	$5M
Q3 2027	$20M
Q4 2027	Remove cap

WRTZ Token (Q2–Q3 2027)

Launch criteria: $5M TVL sustained 60+ days, 500+ active wallets, one completed Audit Bank audit.
Structure: Fair IDO / Liquidity Bootstrapping Pool — no VC cliff dumps.
Real-yield mechanics: Protocol revenue used to buy and burn WRTZ.
Governance: TVL cap increases, fee adjustments, insurance fund payouts, new product whitelisting.

Stellar Ecosystem Alliance

• Contribute Writz SPV SDK as Stellar ecosystem infrastructure
• Propose a SEP standard for Bitcoin SPV on Stellar
• Co-market with SDF as the flagship BTCfi protocol on Stellar
• Apply for SCF Growth Hack Program (after 60+ days mainnet, completed audit, no active SDF grants)
• Apply for SCF Liquidity Award (after $250K TVL sustained 7 days)

Wallet Integrations

Target integrations with demonstrated traction and open SDK:

• Xverse: BTC DeFi section with PrivateLend
• Freighter: BTC collateral option in the lending section
• Lobstr: BTC yield product in the savings section

Institutional BD

• Direct outreach to crypto hedge funds, family offices, BTC mining companies
• Compliance documentation package (ASP attestations, audit reports, regulatory positioning)
• Target: 3–5 institutional deposits of $100K+ each

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Success Metrics

Phase	Metric	Target
Phase 1	SPV verifications on testnet	100+
Phase 1	SCF application submitted	✓
Phase 2	Mainnet TVL (day 30)	$50K
Phase 2	Mainnet TVL (day 90)	$250K
Phase 2	Audit completed (0 critical findings)	✓
Phase 2	DeFiLlama listed	✓
Phase 3	TVL	$5M+
Phase 3	Monthly protocol revenue	$15K+
Phase 3	Protocols using SPV SDK	3+
Phase 3	Proof of Reserve customers	5+
Phase 3	WRTZ token launched	✓

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See the full vision: Vision →