Solana program scaffold

Solana Program Scaffold

Bootstrap an Anchor-based Solana program with current conventions. Covers workspace layout, PDA derivation, SOL-vs-SPL dual instruction patterns, #[derive(Accounts)] constraints, testing, and deployment.

When to use

• Starting a new Solana program from scratch.
• Adding instructions to an existing Anchor program and wanting a consistent account/PDA/testing pattern.
• Standardizing a quick-prototype program that has drifted.
• Migrating a native Rust program to Anchor (or vice versa — but almost always prefer Anchor).

Before you start

Decide:

1. Anchor vs native Rust. Default to Anchor 0.31+. Native Rust is only worth it for extreme byte-level optimization or when Anchor's IDL constraints don't fit. This skill assumes Anchor.
2. SOL, SPL, or both? Programs that accept value typically need both a SOL flow and an SPL flow. Anchor encourages these as parallel instruction variants (place_bet_sol / place_bet_spl) rather than a single polymorphic instruction.
3. PDA strategy. Which accounts are PDAs? What seeds identify them? Common patterns: singleton ([b"factory"]), indexed ([b"item", counter.to_le_bytes()]), per-user ([b"user_account", user.key().as_ref()]).
4. Randomness source. If the program needs randomness, decide now: SlotHashes sysvar (provably fair, cheap, manipulable by validators within a slot), Switchboard VRF (true randomness, paid), or commit-reveal (no extra deps, but requires two transactions).
5. Testing model. Anchor's default is TypeScript/Mocha via anchor test. Good for integration-level. For Rust-native unit tests, add a tests/ Cargo target. LiteSVM / Bankrun give much faster in-memory testing than the built-in solana-test-validator.

Authoring workflow

1. Init the workspace. anchor init my-program gives you programs/, tests/, Anchor.toml. Commit the scaffold before writing anything.
2. Decide your account types first — #[account] structs in src/state.rs. Every PDA stores its own bump for safe re-derivation.
3. Write instructions as modules under src/instructions/. One file per instruction. Each exports an Accounts struct and a handler function.
4. Register instructions in lib.rs inside the #[program] module. Keep lib.rs as a dispatch table — no business logic here.
5. Custom errors in src/errors.rs via #[error_code]. Reference them inline in constraints: constraint = cond @ MyError::Variant.
6. Tests in tests/ — TypeScript via the Anchor client, with the IDL loaded from target/idl/<program>.json.
7. Deployment — anchor build, verify binary size, deploy with solana program deploy or anchor deploy. For mainnet, transfer upgrade authority to a multisig / hardware wallet after initial deploy.

Non-negotiable rules

• Every PDA stores its bump on its account and re-derives with that exact bump. Never re-derive a PDA without storing the bump — it's expensive and error-prone.
• Every account constraint in #[derive(Accounts)] has an attributed error. constraint = foo == bar @ MyError::NotBar — not bare constraint = foo == bar. Unattributed constraints produce opaque ConstraintRaw errors that are miserable to debug.
• Dual SOL/SPL instructions stay parallel, not unified. If your program accepts both, keep place_bet_sol and place_bet_spl as separate instructions with separate account contexts. A single polymorphic instruction that branches on mint == Pubkey::default() looks cleaner but breaks Anchor's type guarantees.
• owner checks are constraints, not runtime if statements. Put them in #[derive(Accounts)], not in the handler body.
• Never use Clock::get()?.unix_timestamp or block.timestamp-equivalent as randomness. Use SlotHashes sysvar or Switchboard VRF.
• Sign your deployment transactions with a local keypair you keep offline for mainnet. --keypair ~/.config/solana/id.json for devnet is fine; a production upgrade authority should be a hardware wallet or multisig.
• Binary size matters. target/deploy/<program>.so over ~200 KB risks hitting per-slot compute limits and incurs painful rent. Strip with RUSTFLAGS="-C strip=symbols" if you're close.

References

• Anchor workspace setup — init, Cargo.toml features, Anchor.toml, lib.rs shape.
• PDA patterns — singleton, indexed, per-user, vault PDAs; storing and verifying bumps.
• Accounts and constraints — #[derive(Accounts)] attributes, constraint-with-error pattern, ownership + state validation.
• SOL vs SPL token flows — why they're parallel, how to structure vault PDAs for SPL, mint discrimination.
• On-chain randomness — SlotHashes sysvar pattern, limitations, when to use Switchboard VRF instead.
• Testing with the TypeScript Anchor client — IDL-based client, PDA derivation from TS, smoke tests vs unit tests, LiteSVM alternative.
• Deployment and upgrade authority — build → verify size → deploy → initialize → transfer authority.