For developers: mapping concepts to the SDK

This page is the bridge from Architecture and main components to the canonical PoD SDK documentation on GitHub. It repeats a few facts on purpose so engineers can verify mental models quickly.

For a guided first implementation, read Tutorials: building Privacy on Demand (PoD) dApps to pick the integration model, then follow Tutorial: private Adder on Sepolia for a primitive-only Solidity + TypeScript walkthrough (Sepolia presets).

Official reading order (SDK)

The upstream docs recommend:

1. Privacy dApps on any EVM chain with COTI PoD

2. Getting started

3. Writing privacy contracts on Ethereum

4. TypeScript integration (UX development)

Then deep dives:

• Async execution

• MPC library (PodLib)

• Examples with description

• Contract references: Data types, Patterns and checklist, Request builder and remote calls, Fees, gas, and oracle

Component → source file map

Concept (this book)	Where it lives in the SDK docs / repo
Inbox	IInbox.sol and cross-domain flow in the domain model diagram.
Callback guard	InboxUser.sol (onlyInbox) — see Features.
PodLib	PodLib.sol and width-specific libraries (PodLib64, PodLib128, PodLib256).
PodUser / presets	PodUser.sol, network mixins such as PodUserSepolia.sol in Getting started.
Types (it*, ct*, gt*)	MpcCore.sol and Data types.
Custom COTI calls	MpcAbiCodec.sol and the custom mode section of Writing privacy contracts.
Client crypto	coti-pod-crypto.ts via CotiPodCrypto (TypeScript integration).

Implementation checklist (condensed)

Derived from the SDK’s Writing privacy contracts and Async execution:

1. Classify data — public metadata vs it* inputs vs ct* outputs vs internal gt* (COTI-only).

2. Pick integration mode — PodLib helpers vs custom MpcAbiCodec + COTI contract.

3. Model async state — persist requestId, track pending/completed/failed.

4. Harden callbacks — onlyInbox, correct abi.decode tuple, validate peer context when applicable.

5. Configure routing safely — gated configure / configureCoti / inbox updates.

6. Budget fees — understand msg.value and callbackFeeLocalWei; use Inbox fee views where available (Fees doc).

7. Test failure paths — spoofed callback must revert, error callbacks must mark failures, decrypt integration must match widths.

Relationship to native COTI “build” documentation

If you build directly on COTI V2 with precompiles and private types, start from Build on COTI. PoD adds the Inbox-mediated cross-chain angle; many cryptographic ideas rhyme, but deployment and UX differ.

Package install

npm install "@coti/pod-sdk"

See Getting started for Solidity imports and the contract MyApp is PodLib, PodUserSepolia pattern.