[Feature]: Open HTML files in the integrated browser or the system browser from the Files panel

[jasperlg]

Before submitting

• I searched existing issues and discussions and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/web (Files panel) and apps/desktop (integrated browser / system browser)

Problem or use case

When an agent writes an HTML file (a status report, a small prototype, a local preview), I can open it as source in the file viewer, but I cannot open the rendered page from the Files panel.

Right-clicking an .html file only shows Copy mention and Add to chat. There is no Open in Integrated Browser or Open in System Browser.

I want both:

• Open in Integrated Browser: preview the file in T3 Code's built-in browser, without leaving the app
• Open in System Browser: open the same file in the OS default browser (Safari, Chrome, …)

Proposed solution

On Files panel rows for .html / .htm files, add two context menu items:

• Open in Integrated Browser
• Open in System Browser

Suggested menu for an HTML file:

• Copy mention
• Add to chat
• Open in Integrated Browser
• Open in System Browser

Behavior:

• Integrated browser: reuse the existing desktop preview / integrated browser path for workspace HTML files
• System browser: open the local file:// URL (or the equivalent signed workspace asset URL if file:// is not available) in the default OS browser

Leave non-HTML files unchanged.

Why this matters

Agents often produce self-contained HTML artifacts. Reading the source is not the same as seeing the rendered page. Opening the file from Finder or reconstructing the path in a terminal is extra work, and the integrated browser already exists on desktop.

Smallest useful scope

• .html and .htm rows in the Files panel context menu
• Two open actions, no extra preview modes, no asset rewriting for relative CSS/JS in a first pass
• Desktop first, where the integrated browser already exists

Related

Adjacent, but not the same request:

• [Feature]: Render HTML files in the web file preview #6846 (Source / Rendered toggle inside the web file preview)
• Allow browser preview for absolute file links outside project root #7027 (opening absolute file links that sit outside the project root)

This request is specifically about Files panel context menu actions for HTML files.

Environment

• T3 Code Nightly 0.0.34-nightly.20260811.1064
• macOS, desktop app