Zeus Build And Env

Zeus: Build and Environment

Zeus is a React Native (RN) Bitcoin/Lightning mobile wallet. This skill is the runbook for recreating the development environment from nothing, understanding the postinstall chain that assembles the native layer, and avoiding the traps that break builds.

Jargon quick-reference (terms used below):

• LND: Lightning Network Daemon — a Lightning node implementation. Zeus embeds a mobile build of it ("embedded LND") compiled with gomobile (Go-to-mobile compiler) into Lndmobile.aar (Android archive) / Lndmobile.xcframework (iOS multi-arch framework bundle).
• LNC: Lightning Node Connect — Lightning Labs' encrypted-tunnel protocol for reaching a remote LND node. Shares the same Lndmobile binary.
• LDK Node: a self-contained Lightning node library from the Lightning Dev Kit project; second embedded-node option. Rust, exposed via uniffi (Mozilla's Rust FFI binding generator that emits matching Kotlin/Swift wrapper source).
• CDK: Cashu Dev Kit — Rust library for Cashu ecash wallets, also uniffi-based.
• Hermes: Meta's JS engine for RN (enabled here). New Architecture / Fabric: RN's rewritten native rendering/bridge layer (enabled here).
• CocoaPods / pod: iOS dependency manager; pod install generates the Xcode workspace's dependency project.

When to use / When NOT to use

Use this skill when you need to: install dependencies, understand or debug the postinstall chain, fix missing/failing native binaries, wire a new native module, or bring up a dev build on Android/iOS.

Do NOT use it for:

• Running the app day-to-day, connecting nodes, releases and reproducible builds (build.sh, Docker, APK signing) → zeus-run-and-operate
• yarn verify / jest / CI check anatomy, adding tests, transformIgnorePatterns details → zeus-validation-and-qa
• Runtime bugs once the app builds and boots → zeus-debugging-playbook
• Adding dependencies (requires maintainer discussion first), commit/PR rules → zeus-change-control
• Backend/RPC code structure → zeus-backends-and-capabilities; architecture rationale → zeus-architecture-contract

1) Prerequisites (verified 2026-07-06, master c5fd094fb, v13.1.3-alpha)

There is no .nvmrc, no .ruby-version, no .yarnrc. CONTRIBUTING.md says "Node.js (LTS version)" — the hard floor is the engines field.

2) The postinstall chain (order matters)

yarn install triggers (package.json scripts.postinstall):

node patches/index.mjs && rn-nodeify --install crypto,stream,dgram --hack && yarn run fetch-libraries && pod-install

Run each step manually if you need to re-do part of it. Skipping the chain leaves unpatched node_modules, missing shims, and missing native binaries — the app will fail to compile or crash at boot.

Step 1 — node patches/index.mjs (patch node_modules in place)

Four patches, each idempotent, each rewriting files inside node_modules/ (so they must re-run after every install):

Step 2 — rn-nodeify --install crypto,stream,dgram --hack (Node core-module shims)

rn-nodeify makes Node.js core modules (crypto, stream, dgram) usable in React Native. It regenerates:

• the react-native and browser alias maps at the bottom of package.json (crypto → react-native-crypto, stream → stream-browserify, dgram → react-native-udp, tls: false, readable-stream aliases)
• shim.js at the repo root (global Buffer/process polyfills), imported by index.js

Trap: hand edits to those alias maps or to shim.js are clobbered on the next yarn install. If skipped: Metro fails to resolve crypto/stream imports and the app crashes at JS boot.

Step 3 — yarn run fetch-libraries = bash fetch-libraries.sh (native binaries)

Downloads the pre-built native binaries that are gitignored (see .gitignore lines for Lndmobile.aar, Lndmobile.xcframework, cashudevkit.aar, cdkFFI.xcframework, zeus-cashu-restore.aar, zeusRestoreFFI.xcframework, jniLibs/, LDKNodeFFI.xcframework). All versions and SHA256 hashes live in fetch-libraries-versions.json — when bumping a binary, change version AND sha256 there, never inside the script.

Versions pinned at time of writing:

Behavior and caveats (all verified by reading the script):

• SHA256 enforcement: ALL downloads — binaries AND the uniffi source bindings (ios/CashuDevKit/CashuDevKit.swift, ios/CashuDevKit/zeus_cashu_restore.swift, android/app/src/main/java/uniffi/zeus_cashu_restore/zeus_cashu_restore.kt, pinned via the *BindingsSha256 fields) — hard-fail (exit 1) on checksum mismatch, always. An empty or malformed hash field in fetch-libraries-versions.json fails closed up front (the script validates every hash is 64-char hex before any download, because macOS sha256sum -c exits 0 on improperly formatted lines); never blank one to "fix" a checksum failure. (Before this hardening the bindings were curl'd from raw.githubusercontent.com tag URLs with no checksum; that supply-chain gap is closed.)
• jq() is not jq: the script defines a shell function literally named jq() that is a python3 -c one-liner reading the versions JSON. Don't grep-conclude the repo depends on the jq binary.
• Error noise is normal: the script has no set -e; on a fresh clone you will see sha256sum: ... No such file or directory and failed rm messages before each download, and on re-runs mkdir: ios/LndMobileLibZipFile: File exists (the directory doesn't exist on a truly fresh clone — its contents are gitignored). Only an explicit "checksum failed" + exit 1 is a real failure.
• If skipped: Android fails at Gradle time (missing .aar/.so); iOS fails at Xcode link time ("framework 'Lndmobile' not found" etc.).

Step 4 — pod-install (iOS pods)

The pod-install npm package runs CocoaPods for ios/. On non-macOS it prints "CocoaPods is only supported on darwin" and exits gracefully (this is why yarn install passes on ubuntu CI). Note react-native.config.js sets automaticPodsInstallation: false, so the RN CLI will NOT install pods for you — only this postinstall step (or a manual cd ios && pod install) does. If skipped: zeus.xcworkspace fails to build with missing-pod errors.

3) Vendoring rules (zeus_modules/)

zeus_modules/ holds vendored (checked-in) packages: @lightninglabs/lnc-core, @lightninglabs/lnc-rn, @remobile/react-native-qrcode-local-image, bc-bech32, bc-ur, ur, noble_ecc.ts.

• @lightninglabs/lnc-core IS in package.json dependencies via "file:zeus_modules/@lightninglabs/lnc-core".
• @lightninglabs/lnc-rn is NOT in package.json at all. It is vendored with its own committed node_modules/ and yarn.lock and imported by relative path (backends/LightningNodeConnect.ts: import LNC from '../zeus_modules/@lightninglabs/lnc-rn'). Never yarn add lnc-rn — you would get a second, unpatched copy and break the LNC backend.
• zeus_modules is excluded from all tooling: tsconfig.json exclude (along with node_modules, android, ios), eslint.config.js ignores, and .prettierignore. Code inside it is not held to repo lint/format/type standards; don't "fix" it in a normal PR.

4) Native-layer wiring

Android

• App source root: android/app/src/main/java/ with THREE package trees: com/zeus/ (bulk of modules — note MainApplication.kt lives here even though its declared package is app.zeusln.zeus; it also holds cashudevkit/, declared package app.zeusln.zeus.cashudevkit — another dir/package mismatch), app/zeusln/zeus/ (LdkNode, StealthMode, ZipUtils), and org/lightningdevkit/ldknode/ + uniffi/zeus_cashu_restore/ (uniffi bindings). The com/zeus/lnc-rn/ directory name contains a hyphen (nonstandard Java layout) — it is correct, don't "fix" it.
• Manual native-package registration: android/app/src/main/java/com/zeus/MainApplication.kt manually add(...)s 10 packages that RN autolinking cannot discover (they are app-local, not npm packages): MobileToolsPackage, LndMobilePackage, LndMobileToolsPackage, LndMobileScheduledSyncPackage, LncPackage, NostrConnectPackage, StealthModePackage, CashuDevKitPackage, LdkNodePackage, ZipUtilsPackage. A new app-local native module must be added here or NativeModules.YourModule is null at runtime.
• Binary consumption (android/app/build.gradle + android/build.gradle): Lndmobile.aar via the :lndmobile subproject and a flatDir repo; CDK and restore AARs via implementation files("../cdk/cashudevkit.aar") / files("../zeus-restore/zeus-cashu-restore.aar"); LDK Node via raw .so files in jniLibs/ plus the checked-in Kotlin binding android/app/src/main/java/org/lightningdevkit/ldknode/ldk_node.kt.
• Release APKs are split per ABI with versionCodeOverride = versionCode * 1000 + {1..4} — release mechanics belong to zeus-run-and-operate.

iOS

• Workspace: ios/zeus.xcworkspace (always open the workspace, not the .xcodeproj — pods live in a companion project).
• One Lndmobile.xcframework, shared by two modules, in a misleading directory: fetch-libraries.sh unzips it to ios/LncMobile/ (NOT ios/LndMobile/). The embedded-LND Swift layer (ios/LndMobile/Lnd.swift, LndMobile.swift: import Lndmobile) and the LNC layer (ios/LncMobile/LncModule.mm, which #imports the header straight out of the xcframework) both link against it; zeus.xcodeproj references it at path LncMobile/Lndmobile.xcframework.
• Podfile post_install appends to every pod's FRAMEWORK_SEARCH_PATHS: "$(SRCROOT)/Cdk", "$(SRCROOT)/ZeusRestore", "$(SRCROOT)/LncMobile", and floors IPHONEOS_DEPLOYMENT_TARGET at 13.4. Local podspecs ios/CashuDevKit.podspec and ios/ZeusCashuRestore.podspec are consumed as pod 'CashuDevKit', :path => '.' / pod 'ZeusCashuRestore', :path => '.'.
• Other frameworks: ios/LdkNodeMobile/LDKNodeFFI.xcframework (with checked-in binding ios/LdkNodeMobile/LDKNode.swift), ios/Cdk/cdkFFI.xcframework, ios/ZeusRestore/zeusRestoreFFI.xcframework; downloaded (sha256-pinned) Swift bindings land in ios/CashuDevKit/.

uniffi binding version-match rule

uniffi generates wrapper source (Kotlin/Swift) whose function/type checksums must match the compiled Rust library. In Zeus the two halves arrive by different routes:

• Checked into git (must be updated by hand when the binary version bumps): ldk_node.kt, LDKNode.swift.
• Downloaded by fetch-libraries.sh pinned to the same version tag AND sha256-pinned via the *BindingsSha256 fields in fetch-libraries-versions.json: CashuDevKit.swift, zeus_cashu_restore.swift, zeus_cashu_restore.kt. (CDK Android bindings ship inside the checksummed cashudevkit.aar.)

If binding source and binary versions diverge you get runtime symbol/checksum errors (uniffi aborts on API-checksum mismatch), not compile errors. When bumping ldk-node in fetch-libraries-versions.json, regenerate/replace the two checked-in binding files from the same release. When bumping cdk or zeus-cashu-restore, update the binary hashes AND the *BindingsSha256 fields from the same release in the same commit.

TypeScript wrapper layers (where JS meets native)

Tor

Tor support is react-native-nitro-tor 0.6.0 (normal npm dependency, autolinked; used via import { RnTor } from 'react-native-nitro-tor' in utils/TorUtils.ts). The old react-native-tor ZeusLN fork is retired — replaced in PR #3971 (commit a58b4cefc, merge c512ea687). Ignore any older notes about building/patching the Sifir react-native-tor fork; there is nothing to build.

5) Known traps

1. Android emulator localhost: emulator host rule — see zeus-run-and-operate §2 (the owner of the 10.0.2.2 fact).
2. Proto changes: proto/lightning.js + proto/lightning.d.ts are generated artifacts (checked in). After editing any proto/**/*.proto, run yarn gen-proto (pbjs/pbts from protobufjs-cli) and commit the regenerated pair.
3. Stale Android build state: yarn android:clean removes android/app/.cxx, android/build, then runs gradlew clean. Use it after NDK/Gradle/RN version changes or C++ codegen weirdness. yarn gradlew <task> is the repo shortcut for arbitrary Gradle tasks.
4. New ESM dependency breaks jest ("Unexpected token 'export'"): extend the jest transformIgnorePatterns whitelist in package.json — full anatomy in zeus-validation-and-qa.
5. Hermes + New Architecture are ON (android/gradle.properties: hermesEnabled=true, newArchEnabled=true; New Arch since RN 0.83.1 upgrade, commit d13ebc2cd). Consequences: pre-2026 Animated/layout patterns can crash Fabric, and Hermes regexes need input length caps — details and incident hashes in zeus-failure-archaeology / zeus-debugging-playbook.
6. Never hand-edit the react-native/browser alias maps in package.json or shim.js — rn-nodeify regenerates them (§2 step 2).
7. pod install didn't run automatically from the RN CLI: expected — automaticPodsInstallation: false in react-native.config.js; run npx pod-install or cd ios && pod install.
8. Checksum failure on a binary: means the release asset changed or the download was corrupted. Delete the cached artifact (paths in §2 step 3 table) and re-run yarn fetch-libraries. Do NOT blank the hash in fetch-libraries-versions.json (an empty hash fails closed anyway).
9. gradle.properties sets org.gradle.parallel=false — a reproducible-build requirement; don't flip it for speed in a PR.
10. New npm dependencies require maintainer discussion first (CONTRIBUTING.md) — see zeus-change-control before adding anything.

6) From-scratch bring-up checklists

Build/run steps below are labeled [source-read] = verified by reading package.json/CONTRIBUTING/README/CI usage, not executed in this session; everything else was executed read-only.

Common (both platforms)

1. Install Node ≥ 22.11 (24.x recommended to match CI) and Yarn classic: npm i -g yarn. [source-read]
2. Set up the React Native environment per the RN "Building Projects with Native Code" guide for your target platform (README, "Starting development").
3. git clone https://github.com/ZeusLN/zeus.git && cd zeus
4. yarn — runs install + the full postinstall chain of §2. Requires network access to GitHub releases; expect harmless first-run noise from fetch-libraries.sh. [source-read]
5. Sanity-check the toolchain-free gates: yarn tsc and yarn test should pass on a clean master checkout. [source-read; full gate anatomy in zeus-validation-and-qa]

Android

6. Install Android Studio with SDK Platform 36, build-tools 36.0.0, NDK 28.0.13004108 (Gradle will prompt/fetch NDK if missing). [source-read]
7. Start an emulator, or enable USB debugging on a device and confirm adb devices lists it.
8. Terminal A: yarn start (Metro bundler — RN's JS dev server).
9. Terminal B: yarn android (= react-native run-android): builds debug APK, installs, launches. [source-read]
10. Verify: app boots to the Wallet screen. To connect a node running on your machine, use host 10.0.2.2.
11. If the build fails on missing .aar/.so: re-run yarn fetch-libraries; on C++/codegen residue: yarn android:clean.

iOS (macOS only)

6. Install Xcode + command line tools; sudo gem install cocoapods or bundle install (Gemfile pins cocoapods ≥ 1.13, != 1.15.0/1.15.1). [source-read]
7. Pods were installed by postinstall; if not, cd ios && pod install && cd ...
8. Terminal A: yarn start.
9. Either yarn ios (= react-native run-ios) or open ios/zeus.xcworkspace in Xcode, select the zeus scheme + a simulator, hit Run. [source-read]
10. Verify: app boots to the Wallet screen; simulator can use 127.0.0.1 for local nodes (no 10.0.2.2 remap needed — that trap is Android-emulator-specific).
11. If linking fails with "framework not found" for Lndmobile/cdkFFI/zeusRestoreFFI/LDKNodeFFI: re-run yarn fetch-libraries then pod install (search paths come from the Podfile post_install, §4).

Provenance and maintenance

Facts verified 2026-07-06 against master c5fd094fb (v13.1.3-alpha) by direct file reads and read-only commands in this repo. Build/run commands not executed are labeled [source-read] above.

Re-verification one-liners for every volatile fact: