Clicking on .qmd file opens duplicate text tab if already open in Visual mode

Bug description

When a .qmd file is already open and in Visual mode, single-clicking the same file in Explorer opens the file a second time in Source mode instead of focusing the existing Visual editor tab. This happens regardless of the mode in the YAML header (editor: visual or editor: source)

Clicking on a .qmd file that is not already open will correctly open in the mode specified (visual or source).

Steps to reproduce

1. Open a qmd file
   

2. Switch to Visual mode if it is in Source mode
   

3. In Explorer, click on the same file
   

Actual behavior

The .qmd file is opened a second time in a second tab, this time in Source mode.

Expected behavior

1. Explorer click on open file should set focus to existing Visual editor tab.
   

2. No duplicate tab should open.
   

Your environment

This happens on both Positron and VSCode.

Positron Version: 2026.02.0 (user setup) build 139
Code - OSS Version: 1.106.0
Commit: https://github.com/posit-dev/positron/commit/4b472e9bf40ca88f886fe9c7fcfbb9ee702fccd0
Date: 2026-01-29T05:07:35.343Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26200

VSCode Version: 1.109.4 (user setup)
Commit: c3a26841a84f20dfe0850d0a5a9bd01da4f003ea
Date: 2026-02-16T15:35:57.932Z
Electron: 39.3.0
ElectronBuildId: 13313481
Chromium: 142.0.7444.265
Node.js: 22.21.1
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.26200

Reproduce the duplicate-tab behavior by opening a .qmd file in Visual mode, then selecting it again from Explorer, in both Positron and VSCode. Trace the handling of Explorer clicks for already-open .qmd files and compare it with the YAML header mode; done means the existing Visual editor tab receives focus without opening a Source tab.