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VscodeWebviewSchemeHandler

Mountain::Binary::Build::Scheme

Function VscodeWebviewSchemeHandler 

Source 
pub fn VscodeWebviewSchemeHandler<R: Runtime>(
    AppHandle: &AppHandle<R>,
    Request: &Request<Vec<u8>>,
) -> Response<Vec<u8>>
Expand description

Custom URI scheme handler for vscode-webview:// requests.

VS Code’s WebviewElement (used by every extension webview - Roo Code, Claude, GitLens, custom-editor providers) wraps the inner extension HTML in an <iframe> whose src is vscode-webview://<authority>/index.html?.... The <authority> is a per-instance random base32 string. The authority is irrelevant to the bytes served - all that matters is the path component, which always resolves under vs/workbench/contrib/webview/browser/pre/.

In stock Electron VS Code, app.protocol.registerStreamProtocol( 'vscode-webview', ...) serves this directory. Under Tauri 2.x + WKWebView, register_asynchronous_uri_scheme_protocol("vscode-webview", ...) installs an equivalent WKURLSchemeHandler. Without this handler, every extension that uses webviewView / WebviewPanel / CustomEditor lands the inner iframe at a vscode-webview://... URL the WKWebView can’t resolve, the iframe stays blank, and the extension surface is dead.

Three resources live under pre/:

  • index.html - the webview shell that bridges postMessage between workbench host and inner extension HTML
  • service-worker.js - registered by index.html to intercept vscode-webview-resource requests for extension-shipped assets
  • fake.html - sandbox stub used as a placeholder before extension HTML arrives via postMessage

Anything else (querystrings, extra path segments, GUID-like authorities) is silently dropped; the extension’s actual content gets piped in via the swMessage channel after index.html boots, not through this scheme handler.

§Parameters

  • AppHandle: Tauri AppHandle for resolving the embedded asset resolver and the dev-mode Static/Application/ filesystem fallback (same chain as VscodeFileSchemeHandler).
  • Request: The incoming request - typically a GET for one of the three pre-baked files.

§Returns

A Response<Vec<u8>> carrying:

  • 200 OK with the file bytes + correct MIME (text/html / application/javascript) when found, or
  • 404 Not Found when the resolved path falls outside the pre/ directory or the asset isn’t shipped.

CORS headers are permissive (*) to match the workbench host’s vscode-webview-resource: traffic, which round-trips through the service worker registered by index.html.