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+# Solution: LP-0005 — Private Balance Attestation
+
+**Submitted by:** Tranquil-Flow
+
+## Summary
+
+This submission implements a reusable private token balance attestation primitive for Logos Execution Zone (LEZ) private balance commitments. A presenter can prove that a committed private token balance satisfies `balance >= threshold` without revealing the Nullifier Public Key (`npk`), exact balance, private account identity, or private witness data.
+
+The package includes:
+
+- a RISC0 guest circuit and host proof-artifact verification path;
+- privacy-preserving public journal and statement types;
+- context binding to prevent replay across gates;
+- presenter identity binding to prevent proof forwarding/theft;
+- an off-chain Logos Messaging verifier path;
+- a Rust verifier-program model for LEZ-style on-chain access grants;
+- deterministic error codes;
+- a Basecamp GUI artifact;
+- SPEL/IDL and TypeScript SDK facade;
+- three integration contracts and benchmark evidence;
+- a narrated demo video.
+
+## Repository
+
+- **Repo:** https://github.com/Tranquil-Flow/lp-0005-private-balance-attestation
+- **License:** MIT
+- **Narrated demo video:** https://youtu.be/x0BYf8bLRII
+
+## Live-deployment and maintainer-accepted evidence status
+
+This submission is ready for review as a packaged, testable evaluator bundle. The public repository is published, the narrated demo is attached, and the standalone `consumer-demo/` proves the integration surface from a clean consumer crate.
+
+The LEZ verifier path is represented by the Rust verifier-program model plus deployment manifest rather than a fabricated public testnet program id. Per maintainer clarification, testable packaged evidence is acceptable for this requirement; if reviewers still require chain-native telemetry or a public testnet id, the repository keeps the deployment manifest fields isolated so those values can be added without changing the proof interface.
+
+## Approach
+
+### RISC0 threshold proof
+
+The proof relation targets the LEZ private account commitment format:
+
+```text
+SHA256(npk || program_owner || balance || nonce || SHA256(data))
+```
+
+The private witness contains the balance-side private data. The public statement exposes only threshold, Merkle root, context binding, presenter binding, and proof id. The circuit rejects below-threshold witnesses before journaling.
+
+Evidence:
+
+- `methods/guest/`
+- `core/`
+- `host/`
+- `artifacts/lp0005-proof/manifest.txt`
+- `submission/deployment/risc0-proof-artifacts.json`
+- `scripts/validate-proof-artifacts.sh`
+
+### Privacy boundary
+
+The public journal is designed not to reveal raw `npk`, exact balance, account identity, or presenter secret material. Receipt/journal verification checks the public statement and the privacy-preserving journal boundary.
+
+Evidence:
+
+- `submission/PRIVACY_SECURITY.md`
+- `core/tests/guest_boundary.rs`
+- `host/tests/host_boundary.rs`
+
+### Context and identity binding
+
+The proof binds to a context id so it cannot be replayed across gates. It also binds to `presenter_pub`, derived as:
+
+```text
+presenter_pub = SHA256("lp0005:presenter-ed25519" || ed25519_verifying_key)
+```
+
+The off-chain and verifier-program paths require an active Ed25519 presenter challenge signature, preventing a copied proof from being reused by a third party.
+
+Evidence:
+
+- `messaging/`
+- `verifier-program/`
+- `cargo run -q -p lp0005-balance-messaging --bin lp0005-messaging-demo -- --forwarded-attack`
+
+## Success Criteria Checklist
+
+- [x] RISC0 circuit for `balance >= N` over the LEZ commitment format.
+- [x] Privacy: public outputs do not reveal `npk`, exact balance, or account identity.
+- [x] Context binding to prevent replay across gates.
+- [x] Identity binding / proof-forwarding resistance.
+- [x] Off-chain verifier library and Logos Messaging-style envelope path.
+- [x] Rust verifier-program model for LEZ-style on-chain access grants.
+- [x] Deterministic error codes for invalid proofs and graceful failures.
+- [x] SDK/CLI facade and demo binaries.
+- [x] Basecamp GUI artifact with local loadability.
+- [x] SPEL/IDL interface artifacts.
+- [x] Benchmarks and CU budget estimates.
+- [x] Narrated demo video.
+- [x] Public GitHub repository URL published.
+- [x] Verifier-program evidence accepted as a testable packaged model per maintainer clarification; live LEZ ID can be added if strictly requested.
+- [x] Standalone consumer integration demo attached under `consumer-demo/` per maintainer clarification that any demonstrated/testable path is acceptable.
+
+## FURPS Self-Assessment
+
+### Functionality
+
+The primitive supports private threshold access proofs, off-chain recipient-side verification, and LEZ-style verifier-program access grants with idempotent access records and deterministic rejection codes.
+
+### Usability
+
+Users and evaluators can run the demo script, inspect the Basecamp GUI artifact, and use the SDK/interface files to understand proof generation and verification flows.
+
+### Reliability
+
+Invalid proofs fail with deterministic errors including context mismatch, presenter mismatch, expired challenge, and occupied access record conflicts. The CI safe-lane and validators exercise core, messaging, verifier, GUI, interface, integration, and package checks.
+
+### Performance
+
+Benchmark evidence is in `submission/BENCHMARKS.md` and `submission/benchmark-results.json`. The current CU numbers are portable verifier-model estimates; replace them with chain-native sequencer telemetry after live testnet deployment if required.
+
+### Supportability
+
+The code is split into small crates/modules:
+
+- `core/` shared statement/journal/proof relation logic
+- `methods/` RISC0 guest package
+- `host/` receipt/proof-artifact verification
+- `messaging/` off-chain envelope verification
+- `verifier-program/` LEZ-style verifier semantics
+- `interfaces/` SPEL/IDL/SDK facade
+- `basecamp-app/` GUI artifact
+- `integrations/` integration contracts
+- `submission/` technical write-up, privacy notes, benchmarks, manifests
+
+## Supporting materials
+
+- Demo video: https://youtu.be/x0BYf8bLRII
+- Technical write-up: `submission/TECHNICAL_WRITEUP.md`
+- Privacy/security write-up: `submission/PRIVACY_SECURITY.md`
+- Benchmarks: `submission/BENCHMARKS.md`, `submission/benchmark-results.json`
+- Integration guide: `submission/INTEGRATIONS.md`
+- Final audit: `FINAL_SUBMISSION_AUDIT.md`
+
+## Reproducibility commands
+
+```bash
+bash scripts/validate-proof-artifacts.sh artifacts/lp0005-proof
+cargo test -p lp0005-balance-core --test guest_boundary -- --nocapture
+cargo test -p lp0005-balance-messaging -- --nocapture
+cargo test -p lp0005-verifier-program -- --nocapture
+python3 scripts/benchmark-safe-lane.py
+python3 scripts/validate-submission-package.py
+python3 scripts/validate-basecamp-gui.py
+python3 scripts/validate-interfaces.py
+python3 scripts/validate-integrations.py
+```
+
+## Terms & Conditions
+
+By submitting this solution, I confirm that I have read and agree to the [Terms & Conditions](../TERMS.md).