Support file content change part for cloud agent

src/extension/chatSessions/vscode-node/chatSessions.ts

@@ -26,6 +26,7 @@ import { ClaudeChatSessionParticipant } from './claudeChatSessionParticipant';
 import { CopilotCLIChatSessionContentProvider, CopilotCLIChatSessionItemProvider, CopilotCLIChatSessionParticipant, registerCLIChatCommands } from './copilotCLIChatSessionsContribution';
 import { CopilotCLITerminalIntegration, ICopilotCLITerminalIntegration } from './copilotCLITerminalIntegration';
 import { CopilotChatSessionsProvider } from './copilotCloudSessionsProvider';
+import { PRContentProvider } from './prContentProvider';
 import { IPullRequestFileChangesService, PullRequestFileChangesService } from './pullRequestFileChangesService';
 import { CopilotCLIPromptResolver } from '../../agents/copilotcli/node/copilotcliPromptResolver';
 
@@ -135,6 +136,11 @@ export class ChatSessionsContrib extends Disposable implements IExtensionContrib
 		if (enabled && !this.copilotCloudRegistrations) {
 			// Register the Copilot Cloud chat participant
 			this.copilotCloudRegistrations = new DisposableStore();
+
+			this.copilotCloudRegistrations.add(
+				this.copilotAgentInstaService.createInstance(PRContentProvider)
+			);
+
 			const copilotSessionsProvider = this.copilotCloudRegistrations.add(
 				this.copilotAgentInstaService.createInstance(CopilotChatSessionsProvider)
 			);

src/extension/chatSessions/vscode-node/prContentProvider.ts

@@ -0,0 +1,110 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import { IOctoKitService } from '../../../platform/github/common/githubService';
+import { ILogService } from '../../../platform/log/common/logService';
+import { Disposable } from '../../../util/vs/base/common/lifecycle';
+
+/**
+ * URI scheme for PR content
+ */
+export const PR_SCHEME = 'copilot-pr';
+
+/**
+ * Parameters encoded in PR content URIs
+ */
+export interface PRContentUriParams {
+	owner: string;
+	repo: string;
+	prNumber: number;
+	fileName: string;
+	commitSha: string;
+	isBase: boolean; // true for left side, false for right side
+	previousFileName?: string; // for renames
+}
+
+/**
+ * Create a URI for PR file content
+ */
+export function toPRContentUri(
+	fileName: string,
+	params: Omit<PRContentUriParams, 'fileName'>
+): vscode.Uri {
+	return vscode.Uri.from({
+		scheme: PR_SCHEME,
+		path: `/${fileName}`,
+		query: JSON.stringify({ ...params, fileName })
+	});
+}
+
+/**
+ * Parse parameters from a PR content URI
+ */
+export function fromPRContentUri(uri: vscode.Uri): PRContentUriParams | undefined {
+	if (uri.scheme !== PR_SCHEME) {
+		return undefined;
+	}
+	try {
+		return JSON.parse(uri.query) as PRContentUriParams;
+	} catch (e) {
+		return undefined;
+	}
+}
+
+/**
+ * TextDocumentContentProvider for PR content that fetches file content from GitHub
+ */
+export class PRContentProvider extends Disposable implements vscode.TextDocumentContentProvider {
+	private static readonly ID = 'PRContentProvider';
+	private _onDidChange = this._register(new vscode.EventEmitter<vscode.Uri>());
+	readonly onDidChange = this._onDidChange.event;
+
+	constructor(
+		@IOctoKitService private readonly _octoKitService: IOctoKitService,
+		@ILogService private readonly logService: ILogService,
+	) {
+		super();
+
+		// Register text document content provider for PR scheme
+		this._register(
+			vscode.workspace.registerTextDocumentContentProvider(
+				PR_SCHEME,
+				this
+			)
+		);
+	}
+
+	async provideTextDocumentContent(uri: vscode.Uri): Promise<string> {
+		const params = fromPRContentUri(uri);
+		if (!params) {
+			this.logService.error(`[${PRContentProvider.ID}] Invalid PR content URI: ${uri.toString()}`);
+			return '';
+		}
+
+		try {
+			this.logService.trace(
+				`[${PRContentProvider.ID}] Fetching ${params.isBase ? 'base' : 'head'} content for ${params.fileName} ` +
+				`from ${params.owner}/${params.repo}#${params.prNumber} at ${params.commitSha}`
+			);
+
+			// Fetch file content from GitHub
+			const content = await this._octoKitService.getFileContent(
+				params.owner,
+				params.repo,
+				params.commitSha,
+				params.fileName
+			);
+
+			return content;
+		} catch (error) {
+			this.logService.error(
+				`[${PRContentProvider.ID}] Failed to fetch PR file content: ${error instanceof Error ? error.message : String(error)}`
+			);
+			// Return empty content instead of throwing to avoid breaking the diff view
+			return '';
+		}
+	}
+}

src/extension/chatSessions/vscode-node/pullRequestFileChangesService.ts

@@ -4,13 +4,13 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as vscode from 'vscode';
-import { IGitExtensionService } from '../../../platform/git/common/gitExtensionService';
 import { IGitService } from '../../../platform/git/common/gitService';
 import { PullRequestSearchItem } from '../../../platform/github/common/githubAPI';
 import { IOctoKitService } from '../../../platform/github/common/githubService';
 import { ILogService } from '../../../platform/log/common/logService';
 import { createServiceIdentifier } from '../../../util/common/services';
 import { getRepoId } from '../vscode/copilotCodingAgentUtils';
+import { toPRContentUri } from './prContentProvider';
 
 export const IPullRequestFileChangesService = createServiceIdentifier<IPullRequestFileChangesService>('IPullRequestFileChangesService');
 
@@ -25,7 +25,6 @@ export class PullRequestFileChangesService implements IPullRequestFileChangesSer
 	constructor(
 		@IGitService private readonly _gitService: IGitService,
 		@IOctoKitService private readonly _octoKitService: IOctoKitService,
-		@IGitExtensionService private readonly _gitExtensionService: IGitExtensionService,
 		@ILogService private readonly logService: ILogService,
 	) { }
 
@@ -47,34 +46,54 @@ export class PullRequestFileChangesService implements IPullRequestFileChangesSer
 				return undefined;
 			}
 
-			const diffEntries: vscode.ChatResponseDiffEntry[] = [];
-			const git = this._gitExtensionService.getExtensionApi();
-			const repo = git?.repositories[0];
-			const workspaceRoot = repo?.rootUri;
-
-			if (!workspaceRoot) {
-				this.logService.warn('No workspace root found for file URIs');
+			// Check if we have base and head commit SHAs
+			if (!pullRequest.baseRefOid || !pullRequest.headRefOid) {
+				this.logService.warn('PR missing base or head commit SHA, cannot create diff URIs');
 				return undefined;
 			}
 
+			const diffEntries: vscode.ChatResponseDiffEntry[] = [];
+
 			for (const file of files) {
-				const fileUri = vscode.Uri.joinPath(workspaceRoot, file.filename);
-				const originalUri = file.previous_filename
-					? vscode.Uri.joinPath(workspaceRoot, file.previous_filename)
-					: fileUri;
+				// Always use remote URIs to ensure we show the exact PR content
+				// Local files may be on different branches or have different changes
+				this.logService.trace(`Creating remote URIs for ${file.filename}`);
+
+				const originalUri = toPRContentUri(
+					file.previous_filename || file.filename,
+					{
+						owner: repoId.org,
+						repo: repoId.repo,
+						prNumber: pullRequest.number,
+						commitSha: pullRequest.baseRefOid,
+						isBase: true,
+						previousFileName: file.previous_filename
+					}
+				);
+
+				const modifiedUri = toPRContentUri(
+					file.filename,
+					{
+						owner: repoId.org,
+						repo: repoId.repo,
+						prNumber: pullRequest.number,
+						commitSha: pullRequest.headRefOid,
+						isBase: false
+					}
+				);
 
-				this.logService.trace(`DiffEntry -> original='${originalUri.fsPath}' modified='${fileUri.fsPath}' (+${file.additions} -${file.deletions})`);
+				this.logService.trace(`DiffEntry -> original='${originalUri.toString()}' modified='${modifiedUri.toString()}' (+${file.additions} -${file.deletions})`);
 				diffEntries.push({
 					originalUri,
-					modifiedUri: fileUri,
-					goToFileUri: fileUri,
+					modifiedUri,
+					goToFileUri: modifiedUri,
 					added: file.additions,
 					removed: file.deletions,
 				});
 			}
 
 			const title = `Changes in Pull Request #${pullRequest.number}`;
-			return new vscode.ChatResponseMultiDiffPart(diffEntries, title, true /* readOnly */);
+			return new vscode.ChatResponseMultiDiffPart(diffEntries, title, false);
 		} catch (error) {
 			this.logService.error(`Failed to get file changes multi diff part: ${error}`);
 			return undefined;

src/platform/github/common/githubAPI.ts

@@ -27,7 +27,8 @@ export interface PullRequestSearchItem {
 	additions: number;
 	deletions: number;
 	fullDatabaseId: number;
-	headRefOid: number;
+	headRefOid: string;
+	baseRefOid?: string;
 	body: string;
 }
 
@@ -184,6 +185,7 @@ export async function makeSearchGraphQLRequest(
 						id
 						fullDatabaseId
 						headRefOid
+						baseRefOid
 						title
 						state
 						url
@@ -240,6 +242,7 @@ export async function getPullRequestFromGlobalId(
 					id
 					fullDatabaseId
 					headRefOid
+					baseRefOid
 					title
 					state
 					url

src/platform/github/common/githubService.ts

@@ -5,6 +5,7 @@
 
 import type { Endpoints } from "@octokit/types";
 import { createServiceIdentifier } from '../../../util/common/services';
+import { decodeBase64 } from '../../../util/vs/base/common/buffer';
 import { ICAPIClientService } from '../../endpoint/common/capiClient';
 import { ILogService } from '../../log/common/logService';
 import { IFetcherService } from '../../networking/common/fetcherService';
@@ -261,6 +262,16 @@ export interface IOctoKitService {
 	 * @returns A promise that resolves to true if the PR was successfully closed
 	 */
 	closePullRequest(owner: string, repo: string, pullNumber: number): Promise<boolean>;
+
+	/**
+	 * Get file content from a specific commit.
+	 * @param owner The repository owner
+	 * @param repo The repository name
+	 * @param ref The commit SHA, branch name, or tag
+	 * @param path The file path within the repository
+	 * @returns The file content as a string
+	 */
+	getFileContent(owner: string, repo: string, ref: string, path: string): Promise<string>;
 }
 
 /**
@@ -348,4 +359,14 @@ export class BaseOctoKitService {
 	protected async closePullRequestWithToken(owner: string, repo: string, pullNumber: number, token: string): Promise<boolean> {
 		return closePullRequest(this._fetcherService, this._logService, this._telemetryService, this._capiClientService.dotcomAPIURL, token, owner, repo, pullNumber);
 	}
+
+	protected async getFileContentWithToken(owner: string, repo: string, ref: string, path: string, token: string): Promise<string> {
+		const response = await makeGitHubAPIRequest(this._fetcherService, this._logService, this._telemetryService, this._capiClientService.dotcomAPIURL, `repos/${owner}/${repo}/contents/${path}?ref=${encodeURIComponent(ref)}`, 'GET', token, undefined);
+
+		if (response?.content && response.encoding === 'base64') {
+			return decodeBase64(response.content.replace(/\n/g, '')).toString();
+		} else {
+			return '';
+		}
+	}
 }

src/platform/github/common/octoKitServiceImpl.ts

@@ -178,4 +178,12 @@ export class OctoKitService extends BaseOctoKitService implements IOctoKitServic
 		}
 		return this.closePullRequestWithToken(owner, repo, pullNumber, authToken);
 	}
+
+	async getFileContent(owner: string, repo: string, ref: string, path: string): Promise<string> {
+		const authToken = (await this._authService.getAnyGitHubSession())?.accessToken;
+		if (!authToken) {
+			throw new Error('No GitHub authentication available');
+		}
+		return this.getFileContentWithToken(owner, repo, ref, path, authToken);
+	}
 }