# Client Architecture (Tauri)

**Verified against:** commit `5630aa1`, 2026-08-04

Desktop client built on Tauri v2: a TypeScript webview (~42k LOC, vanilla TS —
no UI framework) plus ~4.7k LOC of Rust across 16 modules. State lives in a
hand-rolled reactive store (`src/lib/store.ts`: immutable updates,
microtask-batched notifications, selector subscriptions). Components are
factory functions returning `{ element, mount, destroy }` built with the
`@lib/dom` helpers; a 2-page state machine (`src/lib/router.ts`) switches
between the Connect and Main pages.

> `docs/client-architecture.md` is a 15-line redirect stub kept for old links;
> this document is the client architecture reference. The abandoned SolidJS
> beachhead that used to live under `src/components/solid/` was fully removed
> (audit A-2026-07-12, closed 2026-07-19).

## D7 — Module map

```mermaid
flowchart TB
    subgraph boot ["Bootstrap"]
        MAIN["main.ts<br/>page orchestration, auth wiring,<br/>appearance pre-render"]
    end

    subgraph rust ["Rust (src-tauri)"]
        TOFU["tofu.rs<br/>shared TOFU core:<br/>3 rustls verifiers + pure decide"]
        WSP["ws_proxy.rs<br/>WSS proxy"]
        HTP["http_proxy.rs<br/>loopback TCP→TLS REST tunnel"]
        LKP["livekit_proxy.rs<br/>loopback TLS tunnel (pin required)"]
        CRED["credentials.rs + secret_store.rs<br/>OS keychain + verified fallback"]
        PTT["ptt.rs<br/>push-to-talk polling"]
        UPDC["update_commands.rs<br/>self-hosted updater"]
        SET["commands.rs<br/>settings + cert/identity pin stores"]
    end

    subgraph comm ["Communication layer (src/lib)"]
        API["api.ts<br/>REST client via httpProxy.ts<br/>(TOFU-pinned Rust tunnel)"]
        WSC["ws.ts<br/>reconnect w/ backoff, seq replay,<br/>generation counters, cert-tofu events"]
        DISP["dispatcher.ts<br/>34 msg types → store mutators"]
        LKS["livekitSession.ts (1.4k LOC)<br/>voice state machine"]
        LKE["livekitE2EE.ts<br/>key-holder election, room-key<br/>wrap/unwrap, peer verification"]
    end

    subgraph state ["Stores (9 singletons)"]
        AUTH2["auth"]
        CHAN["channels<br/>(incl. roles)"]
        MSG["messages"]
        MEM["members"]
        VOICE["voice"]
        DM["dm"]
        BLK["blocks"]
        EMO["emoji"]
        UIS["ui"]
    end

    subgraph ui ["UI (imperative DOM)"]
        CP["ConnectPage<br/>profiles + health polling"]
        MP["MainPage<br/>SidebarArea / ChatArea /<br/>15 controllers"]
        COMP["~60 component files<br/>message-list, settings tabs,<br/>voice widgets, overlays"]
    end

    MAIN --> CP
    MAIN --> MP
    MAIN --> API
    MAIN --> WSC
    WSC --> WSP
    API --> HTP
    WSP --> TOFU
    HTP --> TOFU
    LKP --> TOFU
    WSC --> DISP
    DISP --> AUTH2 & CHAN & MSG & MEM & VOICE & DM & BLK & EMO & UIS
    state --> ui
    LKS --> LKP
    LKS --> LKE
    VOICE --> LKS
    MP --> COMP
    WSP --> SRV["Go server"]
    HTP --> SRV
    CRED -.-> MAIN
    UPDC -.-> MAIN

    %% cross-store coupling (audit finding)
    AUTH2 -.->|clearAuth → leaveVoice| VOICE
    VOICE -.-> MEM
```

**What this shows.** Data flows one way in the happy path: WS frame → Rust
`ws_proxy` → `ws.ts` → `dispatcher.ts` → store mutators → subscribed components
re-render. All three network paths — WebSocket, REST, and LiveKit — terminate
TLS inside Rust proxies that share one TOFU core (`tofu.rs`): the WS and HTTP
proxies use a capture-then-decide verifier, and the LiveKit proxy refuses to
start without an existing pin. Deciding never writes a pin — a first
connection is *rejected* and surfaced to the user as a blocking trust prompt
before any pin is stored (the former auto-pin-on-first-use behavior was
removed in the 2026-07-22 security remediation). The remaining dashed edges
mark cross-store coupling (auth→voice→members) — known structural debt, not
yet scheduled.

### Key mechanisms

| Concern | Where | How |
|---------|-------|-----|
| Reconnect | `src/lib/ws.ts` | Exponential backoff (cap 30s), heartbeat 30s, `last_seq` replay + bounded dedup set, generation counter invalidates stale listeners |
| Cert trust | `src-tauri/src/tofu.rs` (shared by `ws_proxy.rs`, `http_proxy.rs`, `livekit_proxy.rs`) | TOFU with explicit consent: fingerprints stored per host in `certs.json`, but *deciding never writes a pin* — first use and mismatch both reject the connection and emit a `cert-tofu` event; the TS side shows a blocking modal (`CertMismatchModal.ts`) and only an explicit Accept stores/updates the pin. The updater uses a fourth, host-scoped verifier (pin for the OwnCord host, WebPKI for GitHub). |
| Voice E2EE identity | `src/lib/identity.ts` + `src-tauri/src/commands.rs` | Long-term ECDSA identity key in the OS keyring (`identity:{host}`); peer identity keys pinned in `identity_pins.json`; changed peer key → blocking identity-mismatch modal with safety-number comparison |
| Credentials | `src-tauri/src/credentials.rs` | OS keychain per host; password field `serde(skip)` so it never crosses IPC back to JS |
| Multi-server | `src/lib/profiles.ts` | Server profiles w/ 15s health polling and auto-connect; one active connection, quick-switch replaces WS + tunnels |
| HTTP capability | `src-tauri/capabilities/default.json` | `http:allow-fetch` is the only URL-scoped identifier (the other two `fetch_*` commands take a validated `ResourceId`); allows `https://*` + `http://127.0.0.1:*`, denies https loopback. Wildcard is required by link previews — see [docs/plans/tauri-capability-narrowing.md](../plans/tauri-capability-narrowing.md) |
| Updates | `src/lib/updater.ts` + `update_commands.rs` | Endpoint derived from the connected server URL, https-only, TLS pinned to TOFU fingerprint, minisign-verified |
| Settings | `commands.rs` + `src/lib/preferences.ts` | Split persistence: Rust store (`settings.json`, key-allowlisted) *and* raw `localStorage` for UI prefs/themes |
| Theming | `src/lib/themes.ts` + `styles/tokens.css` | CSS custom properties; 4 built-in themes + custom overrides |
| GIF picker | `src/lib/gifProvider.ts` + `components/GifPicker.ts` | Calls the user's own server (`/api/v1/gif/*`) through `api.ts` — no provider API key in the bundle. Server answers `503 GIF_DISABLED` when unconfigured: the picker shows "GIFs are not enabled on this server" and `onUnavailable` disables the composer's GIF button (with a `title`/`aria-label` reason) instead of failing silently. Returned media URLs are still pinned to the `klipy.com` CDN. |

### Quality tooling

224 test files (~83k LOC — about 2× the source): Vitest unit + integration
(70% coverage gate, blocking in CI), Playwright E2E (web suite in CI —
non-blocking full run plus a blocking `@parity` subset — and a native Tauri
suite that is deliberately not wired to CI), Stryker mutation testing
(manual-only), oxlint + type-checked ESLint, Prettier, Knip (non-blocking),
strict `tsc`. Rust: 84 `cargo test --lib` tests across 10 of the 16 modules,
blocking in CI together with `cargo clippy -D warnings`.

**Source of truth:** `src/main.ts`, `src/lib/dispatcher.ts`, `src/lib/ws.ts`,
`src/lib/api.ts`, `src/lib/store.ts`, `src/stores/*.store.ts`,
`src-tauri/src/lib.rs`, `src-tauri/tauri.conf.json`.
