Solana Cross-Program Invocations: Patterns & Principles — Forge College

Do you know how Solana programs safely and predictably call one another? Choosing the right cross-program invocation (CPI) pattern drives security, composability, and the client responsibilities that determine runtime success. What you'll learn: This lesson compares common CPI patterns and explains when each is appropriate for template-based Solana programs. You will learn what a CPI is, how it differs from a client-issued transaction, and how instruction composition and AccountMeta flags (signer/writable) shape runtime access checks. The lesson walks through three practical patterns — delegation, orchestration, and proxy/composite — and shows how calling conventions change which program or client must supply accounts and signatures. Finally, you will learn how invocation ordering and simple performance tradeoffs affect latency and cost when composing CPIs, and how to read a program template to identify the pattern and client-side expectations. Who this is for: Intermediate Solana developers who already understand basic accounts, transactions, and template debugging practices. Ideal for engineers validating client-program interactions and designing multi-program instruction flows. Key topics covered: - What a cross-program invocation (CPI) is and how it behaves like a synchronous internal call - AccountMeta flags, signer/writable responsibilities, and how instruction composition enforces runtime checks - Delegation pattern: when a callee performs work with caller-supplied accounts - Orchestration pattern: coordinator programs that sequence CPIs and own account provisioning - Proxy/composite pattern: composing instructions to external programs (example: token program) and signer delegation - Invocation ordering, latency, and simple performance tradeoffs for CPI composition Ready to design predictable, maintainable CPIs and map client responsibilities with confidence? Learn more at https://www.forge.college/