Prerequisite challenge.

Objective.

This challenge is not a test of your existing Solana or Anchor knowledge.

We're interested in understanding how you approach an unfamiliar codebase, set up a working development environment, learn independently, and communicate your understanding of a system. Feel free to use documentation, AI, tutorials, or any other resources available to you.

You will be provided with:

• An Anchor-based Vault program.
• The interface (IDL) for our registration program

Before you start.

Set up your environment.

You'll need Rust, the Solana CLI, and Anchor installed. You can follow this tutorial:
https://solana.com/developers/bootcamp/solana-crashcourse/set-up-your-solana-environment
For getting a basic understanding for how to use anchor locally:
https://www.anchor-lang.com/docs/quickstart/local

Look at some basic Solana concepts.

You don't need to know these in depth to start (we will get to that once the cohort starts), but knowing what the words mean will make the code much easier to read:

• ProgramA smart contract on Solana. The Vault program is one.
• AnchorA Rust framework that removes much of the boilerplate involved in writing Solana programs.
• AccountWhere Solana stores data. Programs themselves are stateless, so the state lives in accounts that get passed into each instruction.
• InstructionA single callable action in a program, such as deposit or withdraw.
• PDA (Program Derived Address)A PDA is used to enable our program to "sign" transactions with a Public Key derived from some kind of deterministic seed. This is then combined with an additional "bump" which is a single additional byte that is generated to "bump" this Public Key off the elliptic curve. This means that there is no matching Private Key for this Public Key, as if there were a matching private key and someone happened to possess it, they would be able to sign on behalf of the program, creating security concerns.
• CPI (Cross-Program Invocation)One program calling another program from inside its own instruction. That's what Step 2 is about.
• IDL (Interface Definition Language)Similar to the concept of ABI in other ecosystems, an IDL specifies a program's public interface. Though not mandatory, most programs on Solana do have an IDL, and it is the primary way we typically interact with programs on Solana. It defines a Solana program's account structures, instructions, and error codes. IDLs are .json files, so they can be used to generate client-side code, such as Typescript type definitions, for ease of use.

1. Understand the Vault Program.

   Github link : Vault program

   The repository contains the Anchor vault program along with tests implemented in both Litesvm (Rust) and TypeScript. To interact with the registration program on devnet in the next step, we will focus on the TypeScript tests.

   Read through the Vault program that is given to you and develop a high-level understanding of how it works.

   By the end of this step, you should understand:

   • The purpose of each instruction.
   • The accounts involved.
   • How program state changes over time.
   • The overall flow of the application.

   You'll notice that the withdraw function includes accounts such as Application_account and Application_program, which are currently unused and not needed for Withdraw instruction. This leads directly to Step 2.

2. Extend the program.

   Modify the Vault program by extending the withdraw instruction to perform a Cross-Program Invocation (CPI) to our registration program. All the necessary functions and Account struct needed to perform the CPI to call initialize has already been imported.

   The registration program records:

   • GitHub username

   Deploy the modified program and run anchor test.

   It's important that you deploy the program and not call the program we have deployed, because we will verify that the CPI is not done using our program or a direct call to the registration program. Keep in mind that you can do only one registration per wallet.

   Success criteria: After a successful withdrawal, the registration program should successfully record your details.

3. Create an architecture diagram.

   Create a simple architecture diagram that explains how the Vault program works. You can use any tool of your choice, including Excalidraw, draw.io, or others.

   Assume your audience is a new engineer joining the project. Your diagram should clearly communicate the important accounts, instructions, and overall flow of the program.

4. Record a video.

   Record a video (maximum 3 minutes) explaining your architecture diagram. Use any tool you like, and upload it to Youtube, make sure we can access it and captions are available.

   Focus on explaining the overall design and flow of the program rather than walking through the code line by line. Resolution and production quality don't matter, so record on whatever device you have, including your phone, as long as we can hear you clearly. What we're really evaluating is how well you communicate your understanding of the challenge.

Deliverables.

Submit the following:

• Modified Vault program containing the verification CPI, in a public Github repository.
• Architecture diagram.
• Video (maximum 3 minutes).

Evaluation criteria.

We'll be evaluating:

• Your ability to learn independently.
• Your ability to follow instructions and complete the challenge.
• Your ability to understand and extend an existing codebase.
• Your ability to communicate technical concepts clearly.

Getting help.

Use any resource you like, including AI, video tutorials, and documentation. There's a list of useful resources below.

You can also ask questions in Discord. You're part of a community now, and it's a supportive one, so help each other out. That's a big part of how this cohort works. If you are not already on our Discord server, here is a link to join: https://discord.gg/q5AtXM3Ak.

Useful resources.

• Solana docs, start here: https://solana.com/docs
• Solana core concepts, accounts, PDAs, CPIs: https://solana.com/docs/core
• Anchor documentation: https://www.anchor-lang.com/docs
• Solana Stack Exchange, for specific questions: https://solana.stackexchange.com

Objective.

This is the final part of the Builders Cohort prerequisite, submitted alongside your Vault Program Challenge. It front-loads the foundation of your Capstone (Deliverable 1: the Letter of Intent). Before week one, we want to get you moving so we can all hit the ground running. You need to sketch a product idea and state why it has product market fit and why you are the right person to build it. The point is to arrive capstone-ready to let us form teams faster by knowing what each cadet wants to build and why.

Keep in mind that this is just a starting point, and you are not tied to it. When you submit your capstone assignment during the cohort, you may keep this idea, merge it with a teammate's, or replace it entirely. That said, the more concrete it is, and the less you change it, the more you refine it instead of replace it, the faster you will move through the course.

Scope: the four building categories.

Your idea should fit one of the following four categories. The examples are kick-starters, not the menu. Each one has hundreds of unique opportunities.

1. Real World Assets (RWAs): automated yield strategies on tokenized commodities, decentralized carry-trade and credit protocols, structured credit pools backed by invoices or revenue-share agreements.
2. Tokenization: institutional equities and bonds (pre-IPO pools, compliant stock tokens), oracle-verified commodity vaults, on-chain SPVs that fractionalize private equity or venture debt.
3. Payments: hyper-local stablecoins for regional rails, crypto-native merchant rails that bypass interchange fees via instant settlement, off-grid privacy and proof-of-presence settlement systems.
4. Collectibles: phygitals and vaulted assets, provenance and fractional-ownership protocols using non-transferable metadata, on-chain escrow state machines for safe physical redemption.

Deliverables.

Keep the whole thing to roughly half a page to one page. Clear and specific beats long.

Submit a google doc containing the following:

1. Category: name which of the four categories your idea falls under.
2. Concept overview (2 to 5 sentences): what you are building. Someone reading only this should understand the product.
3. Value proposition and product-market fit (1 paragraph): the problem, who has it, and why your approach fits real demand. Be concrete about the pain you remove.
4. Founder-market fit (a few sentences): your background, technical skills, motivation, and any network or edge that makes you the right person to build this.

How it feeds the capstone.

This will expand into the full LOI, which will build on this by researching target markets and use cases, competitors, actors, and atomic on-chain use cases, all refined through AI red-teaming once you have this framework down. This pre-work is the seed. Get the idea and the fit right now, and the rest of the capstone builds on solid ground.