---
argument-hint: <add_your_app_description>
description: Design a ZK App POC with rent-free nullifiers, compressed accounts, and Groth16 circuits
allowed-tools: [Bash, Read, Glob, Grep, Task, WebFetch]
---
Design a Solana program with tests that uses rent-free nullifiers, compressed accounts, and Groth16 circuits.
## Initial App Design
<ADD YOUR IDEA AND DESIGN HERE>
## Goal
Produce a **fully working POC** that builds and tests pass.
## Available commands
Via Bash tool:
- `cargo build-sbf`, `cargo test-sbf`, `cargo fmt`, `cargo clippy`
- `anchor build`, `anchor test`, `anchor deploy`
- `circom`, `snarkjs`, `solana`, `light`
## Documentation
- Nullifiers: https://zkcompression.com/zk/nullifiers
- Compressed Accounts with Poseidon Hashes: https://zkcompression.com/zk/compressed-account-zk
## Reference repos
program-examples/zk/zk-id/
├── programs/zk-id/src/
│ ├── lib.rs # create_issuer, add_credential, zk_verify_credential
│ └── verifying_key.rs # Groth16 key from circom trusted setup
├── circuits/
│ └── compressed_account_merkle_proof.circom # Merkle proof + nullifier circuit
└── tests/
└── zk-id.ts # Proof generation + on-chain verification
## Workflow
### Phase 1: Design application
**1.1 Define private state**
What data stays private? (credentials, balances, votes, etc.)
**1.2 Define public inputs**
What does the circuit prove publicly? (nullifier, merkle root, commitments)
**1.3 Define nullifier scheme**
nullifier = Poseidon(context, secret)
### Phase 2: Index reference implementation
grep -r "LightAccountPoseidon" program-examples/zk/
grep -r "Groth16Verifier" program-examples/zk/
grep -r "derive_address.*nullifier" program-examples/zk/
grep -r "read_state_merkle_tree_root" program-examples/zk/
Read matching files to understand patterns.
### Phase 3: Circuit development
**3.1 Write circom circuit**
Based on compressed_account_merkle_proof.circom:
- Merkle proof verification
- Nullifier computation
- Public input constraints
**3.2 Trusted setup**
circom circuit.circom --r1cs --wasm --sym
snarkjs groth16 setup circuit.r1cs pot_final.ptau circuit_0000.zkey
snarkjs zkey export verificationkey circuit_final.zkey verification_key.json
snarkjs zkey export solidityverifier circuit_final.zkey # adapt for Solana
**3.3 Add sensitive files to .gitignore**
*.zkey
*.ptau
*.r1cs
*_js/
### Phase 4: Program implementation
| Pattern | Function | Reference |
|---------|----------|-----------|
| Poseidon state | `LightAccountPoseidon::new_init()` | zk-id/lib.rs |
| Nullifier address | `derive_address([prefix, nullifier, ctx], tree, program)` | zk-id/lib.rs |
| Read root only | `read_state_merkle_tree_root()` | zk-id/lib.rs |
| Groth16 verify | `Groth16Verifier::new().verify()` | zk-id/lib.rs |
**Dependencies:**
[dependencies]
anchor-lang = "0.31.1"
light-sdk = { version = "0.17.1", features = ["anchor", "poseidon", "merkle-tree", "v2"] }
light-hasher = "5.0.0"
light-sdk-types = { version = "0.17.1", features = ["v2"] }
groth16-solana = { git = "https://github.com/Lightprotocol/groth16-solana", rev = "66c0dc87" }
[dev-dependencies]
light-program-test = "0.17.1"
light-client = "0.17.1"
### Phase 5: Build and test loop
**Required commands (no shortcuts):**
For Anchor programs: `anchor build && anchor test`
For Native programs: `cargo build-sbf && cargo test-sbf`
**NO shortcuts allowed:**
- Do NOT use `cargo build` (must use `cargo build-sbf`)
- Do NOT use `cargo test` (must use `cargo test-sbf`)
- Do NOT skip SBF compilation
- Tests MUST run against real BPF bytecode
**On failure:** Spawn debugger agent with error context.
**Loop rules:**
1. Each debugger gets fresh context + previous debug reports
2. Each attempt tries something DIFFERENT
3. **NEVER GIVE UP** - keep spawning until fixed
Do NOT proceed until all tests pass.
### Phase 6: Cleanup (only after tests pass)
rm -rf target/
## DeepWiki fallback
If no matching pattern in reference repos:
mcp__deepwiki__ask_question("Lightprotocol/light-protocol", "How to {operation}?")
