Overview

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Architecture

┌─────────────┐   invoke('plugin:…|cmd')   ┌──────────────────┐   DuckBackend    ┌──────────┐
│   Webview   │ ─────────────────────────▶ │  better-duck-    │ ───────────────▶ │  DuckDB  │
│  (JS / TS)  │ ◀───── JSON rows / err ──── │  tauri (Rust)    │ ◀─── rows ─────  │ (vendored)│
└─────────────┘                            └──────────────────┘                  └──────────┘
   @better-duck/tauri                      capabilities + scope + Policy          better-duck-core
   Database class                          enforced before the backend runs

• Webview holds a Database handle and calls typed methods that invoke plugin commands.
• Plugin validates every call against the Tauri capability (which commands are allowed) and the scope + Policy (which values those commands may use), then runs DuckDB work on a blocking task so the async runtime is never blocked.
• DuckDB is compiled into the app via better-duck-core (vendored through better-duck-sys), so there is no system install to manage.

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How it fits together

• One backend, picked by a Cargo feature. backend-core (default) builds on better-duck-core; backend-diesel builds on better-duck-diesel (an r2d2 pool of DuckDbConnection + Diesel embed_migrations!). The webview command surface is identical either way — both engines implement the same DuckBackend trait, so your JS never changes. See Backends.
• A fixed command set, not arbitrary RPC. Every command is a #[tauri::command] and is listed in build.rs so Tauri can generate its allow-* / deny-* permissions.
• Two security layers: an init-time Rust Policy (mandatory) and declarative per-capability scope entries, both enforced before the backend touches DuckDB. See Security overview.

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The command set at a glance

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30-second quickstart

# src-tauri/Cargo.toml
[dependencies]
better-duck-tauri = { version = "0.1.0-beta.8", features = ["backend-core"] }

// src-tauri/src/main.rs
tauri::Builder::default()
    .plugin(better_duck_tauri::core::init()) // simplest; or ::diesel::init()
    .run(tauri::generate_context!())?;

{ "permissions": ["better-duck-tauri:default", "better-duck-tauri:allow-execute"] }

import Database from '@better-duck/tauri'

const db = await Database.load('duckdb:analytics.db') // or 'duckdb::memory:'
await db.execute('CREATE TABLE t (id INTEGER, name VARCHAR)')
await db.execute('INSERT INTO t VALUES ($1, $2)', [1, 'ada'])
const rows = await db.select('SELECT * FROM t WHERE id > $1', [0]) // [{ id: 1, name: 'ada' }]
await db.close()

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See also

• Installation — the Rust dependency, feature flags, and the JS package.
• Registration — tauri::Builder wiring, simple and configured.
• Security overview — the untrusted-webview threat model.
• Feature flags — how backend-core, backend-diesel, and arrow relate to the rest of the workspace.