Fix: Detect PR files in #openPullRequest when single file is open (#7892)

* Initial plan

* Initial analysis complete

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

* Fix: Detect PR files in #openPullRequest when single file is open

The OpenPullRequestTool now also detects PR-associated files when a single file with PR scheme is open, not just when a diff is open. This allows users to ask about #openPullRequest when they have newly added files open in a PR.

Added support for:
- TabInputText with Schemes.Pr (PR files from GitHub)
- TabInputText with Schemes.Review (checked out PR files)

This fixes the issue where PRs with only newly created files were not detected.

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

* Revert proposed changes

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/github/copilotRemoteAgentUtils.ts

@@ -50,7 +50,7 @@ export function extractTitle(prompt: string, context: string | undefined): strin
 			return prompt;
 		}
 		return prompt.substring(0, 20) + '...';
-	}
+	};
 	const titleMatch = context?.match(/TITLE: \s*(.*)/i);
 	if (titleMatch && titleMatch[1]) {
 		return titleMatch[1].trim();

src/lm/tools/openPullRequestTool.ts

@@ -43,6 +43,22 @@ export class OpenPullRequestTool extends PullRequestTool {
 					}
 				}
 			}
+		} else if (activeTab?.input instanceof vscode.TabInputText) {
+			// Check if a single file with PR scheme is open (e.g., newly added files)
+			const textInput = activeTab.input;
+			if (textInput.uri.scheme === Schemes.Pr) {
+				const prParams = fromPRUri(textInput.uri);
+				if (prParams) {
+					return this._findPullRequestByNumber(prParams.prNumber, prParams.remoteName);
+				}
+			} else if (textInput.uri.scheme === Schemes.Review) {
+				const reviewParams = fromReviewUri(textInput.uri.query);
+				if (reviewParams) {
+					const rootUri = vscode.Uri.file(reviewParams.rootPath);
+					const folderManager = this.folderManagers.getManagerForFile(rootUri);
+					return folderManager?.activePullRequest;
+				}
+			}
 		}
 
 		return undefined;