Compressed PDA Programs

Build Solana programs with compressed accounts via CPI to the Light System Program. No rent-exemption required.

When to use compressed PDAs

Per-user state (profiles, game state, credentials)
DePIN device registrations
Nullifier-based double-spend prevention
Infrequently accessed accounts

Choosing approach

| Criteria | Light-PDA (easy) | Compressed PDA (advanced) | |----------|-----------------|--------------------------| | When | Rent-free version of existing Anchor accounts | Custom compressed state with ZK proofs | | Skill | light-sdk (Anchor macro pattern) | This skill (solana-compression) | | Macro | #[light_account(init)] | LightAccount::new_init() manual CPI | | Dependencies | light-sdk, light-compressible | light-sdk, light-sdk-types |

If you just want rent-free Anchor accounts, use the light-sdk skill instead. This skill is for programs that require manual CPI to the Light System Program (custom compressed state, ZK proofs, address derivation).

Client-program interaction flow

 ├─ Client
 │  ├─ Get ValidityProof from RPC.
 │  ├─ pack accounts with PackedAccounts into PackedAddressTreeInfo and PackedStateTreeInfo.
 │  ├─ pack CompressedAccountMeta.
 │  ├─ Build Instruction from PackedAccounts and CompressedAccountMetas.
 │  └─ Send transaction.
 │
 └─ Custom Program
    ├─ CpiAccounts parse accounts consistent with PackedAccounts.
    ├─ LightAccount instantiates from CompressedAccountMeta.
    │
    └─ Light System Program CPI
       ├─ Verify ValidityProof.
       ├─ Update State Merkle tree.
       ├─ Update Address Merkle tree.
       └─ Complete atomic state transition.

Domain references

| Topic | Reference | |-------|-----------| | Program operations (create, update, close, burn, reinit) | references/compressed-pdas.md | | Client SDK (TypeScript + Rust) | references/client.md | | Nullifier PDAs (double-spend prevention) | references/nullifier-pdas.md | | Error codes (6000-16034) | references/error-codes.md |

Reference repos

Basic operations — create, update, close, reinit, burn (each with Anchor and Native variants)

Counter — full lifecycle (create, increment, decrement, reset, close):

counter/anchor — Anchor with Rust and TypeScript tests
counter/native — Native with light-sdk and Rust tests
counter/pinocchio — Pinocchio with light-sdk-pinocchio and Rust tests

Other examples:

create-and-update — Create and update with a single validity proof in one instruction
read-only — Create and read a compressed account onchain
account-comparison — Compressed vs regular Solana accounts

Nullifier:

nullifier-program — Rent-free PDA for duplicate execution prevention. SDK: light-nullifier-program | example client

Airdrop claim:

simple-claim — Compressed tokens decompressed to SPL on claim with cliff
merkle-distributor — SPL tokens with compressed PDA claim tracking, linear vesting, partial claims, clawback
example-token-distribution — Simple client-side distribution

ZK programs:

zk-id — Identity verification with Groth16 proofs
zk/nullifier — Simple nullifier creation program

Additional: examples-zk-compression — More ZK compression examples

Canonical source: program-examples README. If cloned locally, scope Read, Glob, Grep to these repositories and the current project directory only.

Workflow

Clarify intent
- Recommend plan mode, if it's not activated
- Use AskUserQuestion to resolve blind spots
- All questions must be resolved before execution
Identify references
- Match task to domain references and reference repos
- Locate relevant documentation and examples
Write plan file (YAML task format)
- Use AskUserQuestion for anything unclear — never guess or assume
- Identify blockers: permissions, dependencies, unknowns
- Plan must be complete before execution begins
Execute
- Use Task tool with subagents for parallel research
- Subagents load skills via Skill tool
- Track progress with TodoWrite
When stuck: ask to spawn a read-only subagent with Read, Glob, Grep, and DeepWiki MCP access, loading skills/ask-mcp. Scope reads to skill references, example repos, and docs.

Build and test

Required commands

Anchor programs:

anchor build
anchor test

Native programs:

cargo build-sbf
cargo test-sbf

Forbidden shortcuts

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

Failure recovery

On failure, spawn debugger agent with error context.

Loop rules:

Each debugger gets fresh context + previous debug reports
Each attempt tries something DIFFERENT
NEVER GIVE UP - keep spawning until fixed
Max 5 attempts per error

Do NOT proceed until all tests pass.

SDK references

| Package | Link | |---------|------| | light-sdk | docs.rs | | light-client | docs.rs | | @lightprotocol/stateless.js | API docs | | light-program-test | docs.rs |

DeepWiki fallback

If no matching pattern in reference repos:

mcp__deepwiki__ask_question("Lightprotocol/light-protocol", "How to {operation}?")

Security

This skill provides code patterns and documentation references only.

Declared dependencies. Devnet and mainnet examples require API_KEY (Helius or Triton RPC key) and read ~/.config/solana/id.json for the payer keypair. Neither is needed on localnet. In production, load both from a secrets manager.
Filesystem scope. Read, Glob, and Grep must be limited to the current project directory and the reference repos listed above. Do not read outside these paths.
Subagent scope. When stuck, the skill asks to spawn a read-only subagent with Read, Glob, Grep scoped to skill references, example repos, and docs.
Install source. npx skills add Lightprotocol/skills from Lightprotocol/skills.
Audited protocol. Light Protocol smart contracts are independently audited. Reports are published at github.com/Lightprotocol/light-protocol/tree/main/audits.