Fix: Enter review mode for explicitly switched PRs regardless of state

[Copilot]

When opening a closed/merged PR via URI link (e.g., vscode-insiders://github.vscode-pull-request-github/checkout-pull-request?...), the extension fetches the branch but fails to enter review mode because the PR state doesn't match the useReviewMode setting.

Changes

Track explicitly switched PRs

• Added _switchedToPullRequest property to store the PR the user explicitly switched to via the switch() method
• Set this property when switch() is called
• Clear it when exiting review mode

Bypass state checks for explicit switches

• In validateState(), check if current PR matches _switchedToPullRequest
• If matched, enter review mode regardless of PR state (closed/merged) or settings

// Before: Would clear review mode for closed PRs based on setting
if (pr.isClosed && !useReviewConfiguration.closed) {
    await this.clear(true);
    return;
}

// After: Bypass check if user explicitly switched to this PR
const isSwitchedToPullRequest = this._switchedToPullRequest?.number === pr.number;
if (pr.isClosed && !useReviewConfiguration.closed && !isSwitchedToPullRequest) {
    await this.clear(true);
    return;
}

This ensures explicit user actions (clicking links, using checkout commands) always show the PR, while respecting settings for automatic branch-based activation.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Trying to open a closed PR results in NOP</issue_title>
<issue_description>Testing microsoft/vscode#274805

Repro Steps

1. Load vscode repo in Insiders
2. Open this link in browser: vscode-insiders://github.vscode-pull-request-github/checkout-pull-request?%7B%22owner%22%3A%22microsoft%22%2C%22repo%22%3A%22vscode%22%2C%22pullRequestNumber%22%3A273860%7D
3. It will show progress (good), it will ask you to fetch the PR (good), it will create a branch (good)

Actual Result
After a while, nothing happens.

Expected Result
To see the PR.

Git Log

2025-11-05 14:45:52.770 [info] > git rev-parse refs/remotes/origin/dev/dmitriv/glob-2 [64ms]
2025-11-05 14:45:52.936 [info] > git status -z -uall [161ms]
2025-11-05 14:45:53.031 [info] > git for-each-ref --sort -committerdate --format %(refname)%00%(objectname)%00%(*objectname) [252ms]
2025-11-05 14:46:26.715 [info] > git config --get commit.template [62ms]
2025-11-05 14:46:26.774 [info] > git for-each-ref --format=%(refname)%00%(upstream:short)%00%(objectname)%00%(upstream:track)%00%(upstream:remotename)%00%(upstream:remoteref) --ignore-case refs/heads/dev/dmitriv/glob-2 refs/remotes/dev/dmitriv/glob-2 [115ms]
2025-11-05 14:46:26.779 [warning] [Git][revParse] Unable to read file: ENOENT: no such file or directory, open 'c:\Users\dmitriv\repos\vscode\.git\refs\remotes\origin\dev\dmitriv\glob-2'
2025-11-05 14:46:26.838 [info] > git rev-parse refs/remotes/origin/dev/dmitriv/glob-2 [60ms]
2025-11-05 14:46:27.000 [info] > git status -z -uall [158ms]
2025-11-05 14:46:27.091 [info] > git for-each-ref --sort -committerdate --format %(refname)%00%(objectname)%00%(*objectname) [244ms]

GitHug Pull Request Log

2025-11-05 14:45:22.214 [info] [Review+0] Switch to Pull Request microsoft/vscode#273860 - start
2025-11-05 14:45:22.283 [info] [PullRequestGitHelper] Fetch tracked branch refs/remotes/origin/dev/dmitriv/glob-2
2025-11-05 14:45:23.697 [info] [PullRequestGitHelper] Branch dev/dmitriv/glob-2 doesn't exist on local disk yet. Creating from remote.
2025-11-05 14:45:26.623 [info] [PullRequestGitHelper] associate dev/dmitriv/glob-2 with Pull Request microsoft/vscode#273860
2025-11-05 14:45:27.484 [info] [Review+0] Switch to Pull Request microsoft/vscode#273860 - done
2025-11-05 14:45:27.484 [info] [Review+0] Validate state in progress
2025-11-05 14:45:27.484 [info] [Review+0] Validating state...
2025-11-05 14:45:27.501 [info] [FolderRepositoryManager+0] Found GitHub remote for folder c:\Users\dmitriv\repos\vscode
2025-11-05 14:45:27.502 [info] [FolderRepositoryManager+0] Using in-memory cached assignable users.
2025-11-05 14:45:27.597 [info] [Review+0] Found matching pull request metadata for current branch dev/dmitriv/glob-2. Repo: microsoft/vscode PR: 273860
2025-11-05 14:45:27.597 [info] [Review+0] current branch dev/dmitriv/glob-2 is associated with pull request microsoft/vscode#273860
2025-11-05 14:45:27.597 [info] [Review+0] Resolving pull request
2025-11-05 14:45:29.003 [info] [GitHubRepository+0] Fetch branch main - enter
2025-11-05 14:45:29.346 [info] [GitHubRepository+0] Fetch branch main - done: true
2025-11-05 14:45:29.346 [info] [Review+0] Resolved PR microsoft/vscode#273860, state is CLOSED
2025-11-05 14:45:30.030 [info] [Review+0] Found matching pull request metadata on GitHub for current branch dev/dmitriv/glob-2. Repo: microsoft/vscode PR: 273860
2025-11-05 14:45:30.030 [info] [PullRequestGitHelper] associate dev/dmitriv/glob-2 with Pull Request microsoft/vscode#273860
2025-11-05 14:45:30.665 [info] [Review+0] This PR is closed
```</issue_description>

<agent_instructions>In revieweManager.ts, add the concept of a `_switchedToPullRequest`, which is the last PR that the user `switch`ed to. If the current branch in `validateState` is the `_switchedToPullRequest`, regardless of opened/closed/merged state, use review mode.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@alexr00</author><body>
So, by default we don't enter review mode for closed PRs. This is controlled by the setting `githubPullRequests.useReviewMode`.  It does seem confusing though that we wouldn't enter review mode for a PR that was opened via a link like this.</body></comment_new>
<comment_new><author>@dmitrivMS</author><body>
Agreed, I think it should open PR regardless of the setting in this scenario.</body></comment_new>
</comments>

• Fixes Trying to open a closed PR results in NOP #8129

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