Use the forwarded address for integrated browser previews

[Yuyang Li (5o1)]

Fixes #817

Problem

When Live Preview runs in a Dev Container, the server may listen on remote port 3000 while VS Code forwards it to a different local port. If local port 3000 is unavailable, VS Code may forward the server to localhost:3001, but the integrated preview previously continued to open localhost:3000 and failed to connect.

Changes

• Resolve the HTTP URI through vscode.env.asExternalUri before opening the integrated browser.
• Preserve paths and query parameters from the forwarded URI.
• Add regression coverage to verify that the integrated browser receives the resolved address.

Expected behavior

The integrated browser now follows the Forwarded Address selected by VS Code. For example, when remote port 3000 is forwarded to local port 3001, the preview opens through localhost:3001 while retaining the Live Preview browser reuse marker.

Validation

• npm run compile
• npm run lint
• Full extension test suite: 53 passing
• Fork GitHub Actions: Compile and Test passed

[Yuyang Li (5o1)]

Yuyang Li (Yuyang Li (@5o1)) please read the following Contributor License Agreement(CLA). If you agree with the CLA, please reply with the following information.

@microsoft-github-policy-service agree [company="{your company}"]

Options:

• (default - no company specified) I have sole ownership of intellectual property rights to my Submissions and I am not making Submissions in the course of work for my employer.

@microsoft-github-policy-service agree

• (when company given) I am making Submissions in the course of work for my employer (or my employer has intellectual property rights in my Submissions by contract or applicable law). I have permission from my employer to make Submissions and enter into this Agreement on behalf of my employer. By signing below, the defined term “You” includes me and my employer.

@microsoft-github-policy-service agree company="Microsoft"

Contributor License Agreement

@microsoft-github-policy-service agree

[Copilot]

Pull request overview

This PR fixes Dev Container / port-forwarding scenarios where the integrated (workbench) browser preview previously opened the non-forwarded http://{connection.host}:{connection.httpPort} address, causing failures when VS Code forwards the remote port to a different local port.

Changes:

• Resolve the preview base URI via connection.resolveExternalHTTPUri() (backed by vscode.env.asExternalUri) before opening the integrated browser.
• Rebuild the integrated-browser URL by joining the forwarded base URI with the requested path and ensuring the Live Preview reuse marker is present in the query string.
• Add a regression test asserting the integrated browser receives the forwarded address (including preserved base path/query).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/editorPreview/previewManager.ts	Uses resolveExternalHTTPUri() and vscode.Uri.joinPath to open the integrated browser with the forwarded address while retaining/augmenting query params.
src/test/suite/preview.test.ts	Adds a regression test verifying the integrated browser command is invoked with the resolved forwarded URL.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.