# Password Vault — Agent Context

## Project Overview

An offline-first, single-file password manager built with **Svelte 5** (runes-based reactivity). All data is encrypted in-browser with AES-256-GCM and stored in IndexedDB. The production build is a single `dist/index.html` with zero network dependencies — it works from `file://`, USB, or any static server.

## Architecture

```
src/
├── App.svelte                  # Root component — routes between LockScreen, MainLayout
├── main.js                     # Entry point
├── components/
│   ├── LockScreen.svelte       # Master password setup + unlock UI
│   ├── MainLayout.svelte       # Shell: sidebar + content area
│   ├── Sidebar.svelte          # Group list + search bar
│   ├── EntryList.svelte        # Credential entries grid
│   ├── EntryForm.svelte        # Create/edit credential form
│   ├── EntryDetail.svelte      # View single entry (copy password/username)
│   ├── PasswordGenerator.svelte# Configurable password generator
│   └── ImportExport.svelte     # JSON import/export with merge/replace
├── lib/
│   ├── crypto/crypto.js        # Web Crypto API: PBKDF2 key derivation, AES-GCM encrypt/decrypt, password generator
│   ├── storage/db.js           # IndexedDB layer (idb wrapper): entries, groups, meta stores
│   ├── models/schema.js        # Data models: CredentialEntry, Group; validation; ID generation
│   └── stores/
│       ├── app.svelte.js       # AppStore: $state(isUnlocked, encryptionKey, salt)
│       ├── security.svelte.js  # Auto-lock timer, visibility change, beforeunload cleanup
│       └── search.svelte.js    # Reactive search state
```

## Key Design Decisions

- **Svelte 5 runes** — Use `$state`, `$derived`, `$effect`. Props-based event passing (no Svelte events). Event handler attributes are all lower-case (e.g. oninput)
- **No external crypto libraries** — Uses the browser's native Web Crypto API exclusively.
- **Key never persisted** — Encryption key lives only in `$state` memory; cleared on lock, tab switch, or page close.
- **Single-file build** — `vite-plugin-singlefile` inlines all JS/CSS; post-build script inlines favicon.
- **IndexedDB via `idb`** — Three stores: `entries`, `groups`, `meta`. Only `encryptedPassword` is encrypted at rest; titles, usernames, URLs, and notes are plaintext for searchability.
- **PBKDF2 key derivation** — 600,000 iterations, SHA-256, 256-bit AES-GCM key.

## Encryption Flow

```
Master Password → PBKDF2 (600k iters, 16-byte salt) → AES-256-GCM Key → encrypt/decrypt credentials
```

Password verification uses a test payload (random string encrypted at vault creation). On unlock, the entered password derives a key that must successfully decrypt the test payload.

## Scripts

| Command | Description |
|---|---|
| `npm run dev` | Vite dev server with HMR on `:5173` |
| `npm run build` | Production build → `dist/index.html` (single self-contained file) |
| `npm run preview` | Preview production build |
| `npm run test` | Vitest (watch mode) |
| `npm run test:run` | Vitest (single run) |

## Testing

- Framework: **Vitest** with **jsdom** environment
- Test setup: `tests/setup.js` (fake-indexeddb polyfill)
- Test files: `tests/lib/stores/*.test.js`
- Run with `npm run test` or `npm run test:run`

## Security Notes

- Only `encryptedPassword` is encrypted at rest; other fields (title, username, URL, notes) are plaintext in IndexedDB.
- `testPlaintext` for password verification is stored unencrypted in the `meta` store.
- Auto-lock triggers on tab visibility change and 5-minute inactivity.
- Clipboard auto-clears after 15 seconds.
- No browser fingerprinting or anti-keylogger protections.