Rust in Ente

                         ┌───────────────────────────────────────┐
                         │            rust/core/                 │
                         │        (ente-core crate)              │
                         │                                       │
                         │   Pure Rust - NO FFI annotations      │
                         │   Stateless business logic            │
                         │   Fully testable with cargo test      │
                         └───────────────────────────────────────┘
                                           │
              ┌────────────────────────────┼────────────────────────────┐
              │                            │                            │
              ▼                            ▼                            ▼
┌───────────────────────────┐ ┌───────────────────────────┐ ┌────────────────────────┐
│  mobile/packages/rust/    │ │   web/packages/wasm/      │ │      rust/cli/         │
│    (ente_rust crate)      │ │    (ente-wasm crate)      │ │                        │
│                           │ │                           │ │  CLI binary, depends   │
│  Shared #[frb] wrappers   │ │  #[wasm_bindgen] wrappers │ │  on ente-core          │
│  for all mobile apps      │ │  for all web apps         │ │                        │
└───────────────────────────┘ └───────────────────────────┘ └────────────────────────┘
         │    │                            │
         │    └──────────────┐             │
         ▼                   ▼             ▼
┌─────────────────┐   ┌────────────┐   ┌───────────────────────────┐
│   Photos App    │   │ Other apps │   │        Web Apps           │
│                 │   │ (Auth ...) │   │   (Photos, Auth, etc.)    │
└─────────────────┘   └────────────┘   └───────────────────────────┘
         ▲
         │
┌───────────────────────────┐
│ mobile/apps/photos/rust/  │
│  (ente_photos_rust crate) │
│                           │
│  App-specific #[frb]:     │
│  usearch, ML, etc.        │
└───────────────────────────┘

Contents (this repo)

rust/core/ (ente-core) - shared, pure Rust code used by clients (crypto + auth, plus small HTTP/URL helpers).
rust/cli/ (ente-rs) - Rust CLI.
rust/ensu/ - LLM chat stack (see rust/ensu/README.md).

Directory Structure

rust/
├── cli/                          # CLI package (ente-rs)
│   ├── src/
│   │   └── main.rs
│   ├── Cargo.toml
│   └── Cargo.lock
│
├── core/                         # Pure Rust shared logic (ente-core)
│   ├── src/
│   │   ├── lib.rs
│   │   ├── crypto/
│   │   └── auth/
│   ├── docs/
│   │   ├── crypto.md
│   │   └── auth.md
│   └── Cargo.toml
│
└── ensu/                         # LLM chat stack (see rust/ensu/README.md)

rust/uniffi/                      # UniFFI bindings for core crypto/auth + ensu
├── core/
└── ensu/

web/packages/wasm/                # WASM bindings (lives in web workspace)
├── src/
│   └── lib.rs                    # #[wasm_bindgen] wrappers around ente-core
├── Cargo.toml                    # crate name: ente-wasm
├── package.json                  # includes wasm-pack as devDependency
└── pkg/                          # generated output (gitignored)

mobile/packages/rust/             # Shared FRB bindings for all mobile apps
├── rust/
│   ├── src/
│   │   └── api/                  # #[frb] wrappers around ente-core
│   └── Cargo.toml                # crate name: ente_rust
├── lib/                          # Generated Dart bindings
└── pubspec.yaml                  # Flutter plugin package

mobile/apps/photos/rust/          # Photos app-specific FRB bindings
├── src/
│   ├── lib.rs
│   └── api/                      # #[frb] app-specific code (usearch, ML)
│       └── *.rs
└── Cargo.toml                    # crate name: ente_photos_rust

Crates:

ente-core - shared business logic (pure Rust, no FFI)
- Docs: rust/core/docs/crypto.md, rust/core/docs/auth.md
ente-rs - CLI binary
ente-wasm - wasm-bindgen wrappers for web
ente_rust - shared FRB wrappers for mobile (Dart class: EnteRust)
ente_photos_rust - Photos app-specific FRB (Dart class: EntePhotosRust)

Tooling

wasm-bindgen

A Rust library that provides the #[wasm_bindgen] attribute macro. When you annotate a function with #[wasm_bindgen], it:

Marks the function for export to JavaScript
Handles type conversions between Rust and JS (e.g., String ↔ JS string, i64 ↔ BigInt)
Generates metadata that the wasm-bindgen CLI uses to create JS/TS glue code

wasm-pack

A CLI tool that orchestrates the WASM build process:

Runs cargo build --target wasm32-unknown-unknown
Invokes wasm-bindgen CLI to generate JS/TS bindings from the compiled WASM
Outputs everything to a pkg/ directory ready for npm/bundlers

wasm-pack is installed via npm as a devDependency, so yarn install handles it.

Flutter Rust Bridge (FRB)

Used for Flutter integration. FRB is used on two crates:

ente_rust (mobile/packages/rust/) - Shared wrappers around ente-core, used by multiple mobile apps (Photos, Auth, etc.)
ente_photos_rust (mobile/apps/photos/rust/) - Photos app-specific functionality (usearch, ML)

Both depend on ente-core and use #[frb] annotations to generate Dart bindings.

Development

Commands

ente-core (rust/core/):

cargo fmt        # format
cargo clippy     # lint
cargo build      # build
cargo test       # test

ente-cli (rust/cli/):

cargo fmt        # format
cargo clippy     # lint
cargo build      # build
cargo test       # test
cargo run -- --help

ente-wasm (web/packages/wasm/):

yarn install     # installs wasm-pack
yarn build       # runs wasm-pack build --target bundler

Or from web/ root:

yarn build:wasm  # builds the WASM package

[!TIP]

For active Rust development, use watch mode in a separate terminal:
sh
cargo install cargo-watch
cd web/
cargo watch -w ../rust/core -w packages/wasm/src -s "yarn build:wasm"

ente_rust (mobile/packages/rust/):

cargo install flutter_rust_bridge_codegen
flutter_rust_bridge_codegen generate

flutter_rust_bridge_codegen generate needs to be run either manually (or in watch mode, flutter_rust_bridge_codegen generate --watch) whenever the Rust source changes to get the bindings to update.

ente_photos_rust (mobile/apps/photos/rust/):

flutter_rust_bridge_codegen generate
flutter test