# Web preview webview

The chat screen can open a split-screen [[src/renderer/src/screens/Chat/WebPreviewPanel.tsx#WebPreviewPanel]] — an embedded Electron `<webview>` with a browser toolbar and an inspect-element mode — so the agent's links and locally served apps render in-app instead of an external browser.

It auto-opens when an in-app link is clicked or a web tool reports a URL, via the `web-preview:navigate` `CustomEvent` that [[src/renderer/src/screens/Chat/Chat.tsx]] listens for. Inspect mode injects a hover/click overlay into the page and feeds the picked element's pretty-printed HTML back into the chat input.

The panel's width is free-resizable: a drag handle on its left edge sets a `width` clamped between `MIN_PANEL_WIDTH` and `window.innerWidth - 360`, persisted to `localStorage` under `hermes:webPreviewWidth`. During a drag the webview's `pointer-events` are disabled so it doesn't swallow the move stream.

## Webview identification and HTTPS policy

The preview is the only webview allowed to load remote HTTPS; all others stay restricted to loopback HTTP. It is identified by its `partition="web-preview"` attribute, which Electron forwards to both security gates (unlike `name`).

[[src/main/security.ts#isAllowedWebviewUrl]] gains an `allowHttps` flag: HTTPS and `about:blank` are permitted only when the caller passes it. Two gates set that flag for the preview, each identifying it by a signal Electron actually exposes at that point:

- **Attach gate** — [[src/main/app/start.ts#startMainProcess]]'s `will-attach-webview` handler reads `params.partition === "web-preview"` (attributes are forwarded as a `Record<string, string>`) and, when true, calls `isAllowedWebviewUrl(src, true)`.
- **Navigation gate** — in `web-contents-created`, [[src/main/app/start.ts#startMainProcess]] calls [[src/main/security.ts#hardenAttachedWebContents]], which applies the `allowHttps` flag to web-preview navigations.

The session comparison is deliberate: `getLastWebPreferences()` is not a public Electron API (returns `undefined`), so reading attributes back from the attached webContents is unreliable — the partition session is the only signal available in `web-contents-created`. Without it, redirects (e.g. `google.com` → `www.google.com`) and subsequent navigations are wrongly blocked even though the initial attach succeeded.

Remote pages still run fully sandboxed: `hardenWebviewPreferences` forces `nodeIntegration:false`, `contextIsolation:true`, `sandbox:true`, `webSecurity:true` and deletes any preload, so loading arbitrary HTTPS grants the page no host or Node access.