Add Codespaces checkout option to PR dropdown and tree context menu

[Copilot]

Implementation Complete ✅

Features Added

1. PR Overview Dropdown

• ✅ "Checkout in Codespaces" option in PR header dropdown menu
• Command: pr.checkoutOnCodespacesFromDescription

2. PR Tree Context Menu

• ✅ "Checkout Pull Request in Codespaces" in right-click context menu
• Command: pr.pickOnCodespaces

Code Quality Improvements

Refactored duplicate code

• Extracted common logic from pr.pickOnVscodeDev and pr.pickOnCodespaces into helper function pickPullRequest
• Added async keyword to command callbacks for clarity
• Reduces code duplication while maintaining same functionality
• Helper function accepts a link generator function and optional head branch requirement flag

Technical Details

Helper Function

const pickPullRequest = async (
  pr: PRNode | RepositoryChangesNode | PullRequestModel, 
  linkGenerator: (pr: PullRequestModel) => string, 
  requiresHead: boolean = false
) => {
  // Validates PR parameter
  // Extracts PullRequestModel from different input types
  // Optionally validates head branch exists
  // Opens external link using provided link generator
}

Usage

• pr.pickOnVscodeDev → async (pr) => pickPullRequest(pr, vscodeDevPrLink)
• pr.pickOnCodespaces → async (pr) => pickPullRequest(pr, codespacesPrLink, true)

Quality Assurance

• ✅ Code compiles successfully
• ✅ Linter passes (no issues)
• ✅ Hygiene check passes
• ✅ Code review passes
• ✅ CodeQL security scan passes (0 vulnerabilities)
• ✅ Reduced code duplication per reviewer feedback
• ✅ Maintains same functionality

Fixes #7424

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add option to checkout PR on Codespaces</issue_title>
<issue_description>Testing #7424

It'd be nice if I had an option to checkout the PR on Codespaces. I was working on a local repo that wasn't set up on my machine, and I wish I had the option from the PR header to checkout on Codespaces so that the repo would be set up for me to test my changes

</issue_description>

Comments on the Issue (you are Copilot in this section)

• Fixes Add option to checkout PR on Codespaces #7450

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[Alex Ross (alexr00)]

Copilot Great, also add it in the right click context menu of PR items in the pull requests tree

[Copilot]

Copilot Great, also add it in the right click context menu of PR items in the pull requests tree

Done in commit a486961. The "Checkout Pull Request in Codespaces" option now appears in the right-click context menu for PR items in the pull requests tree view, positioned right after the "Checkout Pull Request on vscode.dev" option. It opens the PR branch in a new GitHub Codespace using the URL format: https://github.com/codespaces/new/{owner/repo}/tree/{branch}

[Alex Ross (alexr00)]

Copilot Reduce duplicate code between here and pr.pickOnVscodeDev.

[Copilot]

Done in commits 32386b2 and 65f0ca4. Extracted common validation and PR model extraction logic into a pickPullRequest helper function. Both pr.pickOnVscodeDev and pr.pickOnCodespaces now use this shared function with their respective link generators.