Advanced Miden Development: Source-Guided Context Engineering

Development Approach

1. Plan Mode First

For any non-trivial smart contract application, start in Plan Mode before writing code.

• Explore Miden source repos to understand existing patterns
• Design the account/note architecture and present it to the user before implementing
• Identify which standard components can be reused vs what needs to be custom
• Map out the note flow: which accounts exist, what notes flow between them, what storage each needs

Rule of thumb: if the task involves more than one contract or a pattern not covered by the basic skills, plan first.

2. Verification-Driven Development

This is the single highest-leverage practice for AI-assisted Miden development.

Build loop: After every contract edit, run cargo miden build --manifest-path contracts/<name>/Cargo.toml --release. The project's build hook does this automatically. If the build fails:

1. Read the error message
2. Translate obvious SDK migration errors first:
   • .as_u64() -> .as_canonical_u64()
   • Recipient::compute(...) -> note::build_recipient(...)
   • Value -> StorageValue<T>
   • StorageMap -> StorageMap<K, V>
3. Search the source repos for a working example of the pattern that failed
4. Adapt the working pattern to your use case
5. Rebuild

Test loop: Write tests alongside contracts. Run full repo checks with cargo make test (or cargo test -p integration --release for a faster integration-only loop). When tests fail:

1. Check the error — is it a build error, a runtime assertion, or a proof failure?
2. For assertion failures: check felt arithmetic (modular wrapping) and storage slot naming
3. For unexpected behavior: compare your code against the closest working example in source repos

Never submit code that doesn't compile and pass tests. The verification loop is your quality guarantee.

3. Context Engineering with Source Repos

The basic skills (rust-sdk-patterns, rust-sdk-testing-patterns, miden-concepts, rust-sdk-pitfalls) cover standard patterns. For anything beyond those patterns, Miden's source repositories are the knowledge base.

How to use source repos effectively:

• Don't load entire repos into context. Use sub-agents to explore — they search, read relevant files, and summarize findings without filling the main conversation context.
• Read source files only when you need a specific answer (progressive disclosure)
• Look for working examples first, then adapt. Working code that compiles is more reliable than documentation.
• When you find a useful pattern in source, extract just what you need — the exact API call, the exact data layout, the exact test setup.

Using sub-agents for exploration:

• Launch an explore sub-agent with a specific question: "Find how P2ID output notes are created in the miden-bank repository"
• The sub-agent searches, reads the relevant files, and returns a focused summary
• Your main context stays clean for implementation

4. Iterative Multi-Stage Development

Break complex applications into stages. Complete each before starting the next:

1. Design (Plan Mode) — Architecture, note flows, storage design
2. Implement accounts — Component structs, storage, methods
3. Implement notes — Note scripts, cross-component calls, input parsing
4. Implement tx scripts — Initialization, admin operations
5. Write tests — MockChain setup, multi-step execution, state verification
6. Integrate — Connect pieces, end-to-end test

When stuck at any stage: search the source repos for a similar working pattern. Adapt it, don't guess.

---

Miden Source Repository Map

Clone these repos alongside your project for reference. Claude will explore them when needed for advanced patterns.

# Required: contains standard note types and account components
git clone --depth 1 --branch main https://github.com/0xMiden/miden-base.git ../miden-base

# Required: contains SDK, compiler, and 12 working examples
git clone --depth 1 --branch main https://github.com/0xMiden/compiler.git ../compiler

# Required: contains client API for deployment and chain interaction
git clone --depth 1 --branch main https://github.com/0xMiden/miden-client.git ../miden-client

# Recommended: complete working banking app with advanced patterns in the `examples/miden-bank` folder of the tutorials repo
git clone --branch main https://github.com/0xMiden/tutorials.git ../tutorials

Note: These commands clone the stable main branch. Only use --branch next if the user explicitly requests the experimental/upcoming version of the compiler or source repos.

compiler/ — The Rust-to-MASM Compiler

Contains the SDK that powers #[component], #[note], and #[tx_script] macros.

• examples/ — 12 working examples covering every SDK pattern: account components, note scripts, transaction scripts, authentication components, wallets, faucets, storage. These are the most reliable reference for "how to write X" questions.

WARNING: Stay in examples/ only. Do NOT explore compiler internals (sdk/, codegen/, etc.) — they are implementation details that will confuse the agent and lead to incorrect code.

Explore when: Writing any new contract type, finding working code examples for patterns not covered by skills.

miden-base/ — Protocol Layer and Standard Library

Contains the protocol specification, standard components, and standard note types.

• crates/miden-standards/ — Standard note types (P2ID, P2IDE, SWAP, BURN, MINT) and standard account components (BasicWallet, BasicFungibleFaucet, authentication components). Explore to understand note flow patterns and data layouts.
• crates/miden-protocol/asm/kernels/transaction/ — The MASM transaction kernel. Every Rust SDK function (e.g., native_account::add_asset, output_note::create, faucet::mint) maps to a procedure defined here. Start with api.masm to find the procedure signature and stack contract, then read the implementation in lib/ (e.g., lib/output_note.masm, lib/account.masm, lib/epilogue.masm). Useful for understanding exactly what happens under the hood -- for example, whether a function touches the vault, what the conservation check compares, or how note assets are tracked.
• crates/miden-tx/ — Rust execution engine (executor, prover, host). Orchestrates transaction execution but rarely needed for understanding contract behavior. Explore only if debugging execution infrastructure or host-level behavior.
• crates/miden-testing/ — MockChain implementation internals. Explore when you need to understand testing infrastructure beyond what the testing-patterns skill covers.

Note: Standard components (BasicWallet, etc.) are MASM-only and not callable from Rust SDK (see compiler#936). Explore miden-standards to understand note flows and data layouts, not for finding callable Rust APIs.

Explore when: Understanding note flows, P2ID/SWAP/faucet data layouts, or what SDK functions actually do under the hood (via the kernel MASM).

miden-client/ — Client Library

Contains the Rust API for deploying contracts and interacting with the Miden network.

• Rust client for building transactions, syncing state, managing accounts and notes
• CLI tool source code for reference on client usage patterns

Explore when: Deploying contracts to testnet, submitting transactions, syncing state, managing notes on-chain.

miden-bank/ — Working Example Application

A complete banking application built with the Rust SDK. Demonstrates advanced patterns that go beyond the basic skills.

• Multiple contract types working together (account, deposit note, withdraw note, tx script)
• Advanced patterns: StorageMap<K, V> + StorageValue<T> composition, felt arithmetic safety, cross-component calls, P2ID output note creation from within contracts
• Multi-step integration tests with output note verification

Explore when: Building multi-contract applications, understanding how pieces fit together, seeing a complete working app end-to-end.

---

What to Explore for Each Contract Type

Building This	Explore These Repos	What to Look For
Account component with storage	compiler/ examples, miden-bank/ contracts	StorageMap<K, V> / StorageValue<T> patterns, pub method signatures
Note script	compiler/ examples, miden-bank/ contracts	#[note_script] pattern, cross-component calls, note storage parsing
Transaction script	compiler/ examples, miden-bank/ contracts	#[tx_script] pattern, Account binding import
Authentication component	compiler/ examples	Auth component patterns (NoAuth, Falcon512, ECDSA)
Faucet (token minting)	compiler/ examples	BasicFungibleFaucet example, mint/burn pattern
P2ID output notes	miden-bank/ contracts, miden-base/ standards (data layouts)	note::build_recipient, script root, output_note creation
Swap notes	miden-base/ standards (data layouts)	SwapNote data layout, tag construction, payback flow
Multi-step tests	miden-bank/ integration tests	Init → operate → verify flow, output note verification
Client deployment	miden-client/	TransactionRequestBuilder, sync, submit patterns
SDK function internals	miden-base/ kernel (crates/miden-protocol/asm/kernels/transaction/)	api.masm for procedure signatures, lib/*.masm for implementations

---

Common Advanced Patterns

These patterns go beyond what the basic skills cover. For each, the source repos contain working implementations.

Multi-Component Accounts

Accounts can include standard components (BasicWallet, authentication) alongside custom logic at account creation time. Standard components are MASM-only (not callable from Rust), but they are composed into accounts via the testing/deployment infrastructure. The compiler/ examples show how to compose accounts with multiple components.

Output Note Creation from Contracts

Create output notes (like P2ID) from within contract code. Requires building a recipient with note::build_recipient(serial_num, script_root, storage) and then using output_note::create(...). The miden-bank/ withdraw pattern demonstrates this end-to-end.

Note Storage Protocol

Notes carry storage data as a Vec<Felt> baked at creation time. The #[note] macro generates a TryFrom<&[Felt]> for the note struct via the FromFeltRepr trait, so the #[note_script] method receives the deserialized note as self (by value); the script reads typed fields with self.<field> and never indexes the raw Felt slice.
Attached assets are separate and should be read with active_note::get_assets().

Atomic Swaps

The standard SwapNote in miden-base/ creates a payback P2ID note automatically when consumed. Explore the SwapNote builder to understand tag construction, storage layout, and the payback mechanism.

Account Initialization

Use #[tx_script] to initialize accounts before they accept operations. The miden-bank/ init-tx-script calls account.initialize() to set an initialization flag, which is checked before every operation.

Token Creation (Faucets)

Faucet accounts mint and burn fungible or non-fungible tokens. The compiler/ fungible-faucet example and miden-base/ BasicFungibleFaucet standard component show how to create and manage tokens.

P2ID with Expiration (P2IDE)

Send assets with a deadline — the sender can reclaim after the block height passes. The compiler/ p2ide-note example and miden-base/ P2IDE standard show the timelock pattern.

---

Source: 0xMiden/compiler — distributed by TomeVault.