Pushstr

Private, relay-backed messaging over Nostr. Pushstr ships as a browser extension (Firefox/Chrome) and a Flutter mobile app backed by a Rust core.

Features

• NIP-04 DMs (kind 4).
• NIP-59 giftwrap DMs (kind 1059 + sealed rumor kind 13 + inner kind 14) using NIP-44 v2.
• Legacy giftwrap compatibility for older clients.
• Read receipts (between Pushstr clients).
• Ordered delivery hints via per-recipient sequence tags and gap placeholders.
• Encrypted attachments via Blossom-compatible uploads with inline previews.
• Per-contact DM mode toggle (04 vs giftwrap).
• Multi-relay delivery with retry/backoff and relay cooldown.
• JSON profile backup/import (mobile + extension).
• Optimistic send in extension UI.
• Streamlined settings: actions, key management, backup/restore, connectivity toggle.
• Extension sidebar refresh (settings in header, edit nickname, wider contacts pane).
• Extension settings aligned to mobile sections with active/all profile backups.

Architecture

• UI: Flutter (mobile), HTML/CSS/JS (extension).
• Crypto/relays: Rust (nostr-sdk), exposed via flutter_rust_bridge.
• Extension crypto: WASM bundle (built from wasm_crypto).
• Rust handles message normalization, receipt parsing, and FIFO send ordering; Dart/JS focus on UI.

Repo Layout

• src/ extension source
• dist/ extension build output
• manifest.chrome.json MV3 manifest for Chrome
• mobile/ Flutter app
• pushstr_rust/ Rust core
• wasm_crypto/ WASM crypto build
• documentation/pushstr_fsd.md functional spec

Requirements

• Node 18+ and npm
• Rust (stable)
• Flutter 3.10+ and Android SDK (Xcode for iOS)
• wasm-pack for the extension WASM build
• flutter_rust_bridge_codegen

Build and Run

Browser Extension

From repo root:

# if currently in /wasm_crypto
cd ..

npm install
cd wasm_crypto
wasm-pack build --release --target web --out-dir ../src --out-name wasm_crypto
npm run patch:wasm

# Firefox (MV2)
npm run package

# Chrome (MV3)
MANIFEST_FILE=manifest.chrome.json npm run package

Outputs:

• Build output in dist/
• Packaged zip at pushstr.zip

Load the unpacked extension:

• Chrome: chrome://extensions -> Load unpacked -> select dist/
• Firefox: about:debugging -> This Firefox -> Load Temporary Add-on -> select pushstr.zip

Mobile (Android/iOS)

Optional Rust rebuild (FFI + native libs):

flutter_rust_bridge_codegen generate --config-file flutter_rust_bridge.yaml
cd pushstr_rust
cargo ndk -t arm64-v8a -t armeabi-v7a -o ../mobile/android/app/src/main/jniLibs build --release

Run Flutter:

cd mobile
flutter pub get
flutter run

APK build:

flutter build apk --release
flutter install --use-application-binary build/app/outputs/flutter-apk/app-release.apk

Troubleshooting

• If messages do not appear, reload extension, verify relays and check background logs (background.js).
• If giftwrap appears but content is missing, confirm inner kind 14 is plaintext (NIP-59 compatible).
• If the extension shows a new npub after reload, the extension ID likely changed.

Documentation

• Functional spec: documentation/pushstr_fsd.md
• Mobile notes: MOBILE_APP_GUIDE.md, MOBILE_APP_SUMMARY.md

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Images

Desktop extension

Mobile app