fix: plugin skill files not accessible when connected to remote

When connected to an SSH/WSL/dev container remote, local file:// URIs
for agent plugin skill files were being passed as native filesystem
paths to the remote extension host, which can't read them.

Fix getFilePath() to emit vscode-local:// URIs for local file:// paths
when isRemote is true — the remote extension host can resolve these via
the built-in local file bridge.

Also fix _listExtensionPromptFiles to include plugin-storage files so
they pass the trust check without triggering a confirmation dialog on
every read.

Fixes #305168

Author: cavalloJustinEmery

src/vs/workbench/contrib/chat/common/promptSyntax/chatPromptFilesContribution.ts

@@ -175,11 +175,16 @@ CommandsRegistry.registerCommand('_listExtensionPromptFiles', async (accessor):
 		promptsService.listPromptFiles(PromptsType.hook, CancellationToken.None),
 	]);
 
-	// Combine all files and collect extension-contributed ones
+	// Combine all files and collect extension- and plugin-contributed ones.
+	// Plugin files are included so the copilot extension can trust them and
+	// serve them to the LLM without a confirmation dialog when connected to a
+	// remote (where they are emitted as vscode-local:// URIs).
 	const result: IExtensionPromptFileResult[] = [];
 	for (const file of [...agents, ...instructions, ...prompts, ...skills, ...hooks]) {
 		if (file.storage === PromptsStorage.extension) {
 			result.push({ uri: file.uri.toJSON(), type: file.type, extensionId: file.extension.identifier.value });
+		} else if (file.storage === PromptsStorage.plugin) {
+			result.push({ uri: file.uri.toJSON(), type: file.type, extensionId: file.pluginUri.toString() });
 		}
 	}
 

src/vs/workbench/contrib/chat/common/promptSyntax/computeAutomaticInstructions.ts

@@ -345,7 +345,8 @@ export class ComputeAutomaticInstructions {
 
 		const remoteEnv = await this._remoteAgentService.getEnvironment();
 		const remoteOS = remoteEnv?.os;
-		const filePath = (uri: URI) => getFilePath(uri, remoteOS);
+		const isRemote = this._remoteAgentService.getConnection() !== null;
+		const filePath = (uri: URI) => getFilePath(uri, remoteOS, isRemote);
 
 		const entries: string[] = [];
 		if (readTool) {
@@ -579,7 +580,14 @@ export class ComputeAutomaticInstructions {
 }
 
 
-export function getFilePath(uri: URI, remoteOS: OperatingSystem | undefined): string {
+export function getFilePath(uri: URI, remoteOS: OperatingSystem | undefined, isRemote = false): string {
+	// When connected to a remote, local file:// URIs must be represented as
+	// vscode-local:// so the remote extension host can read them via the local
+	// file bridge. This works for WSL, SSH, and dev containers without any
+	// cache migration.
+	if (isRemote && uri.scheme === Schemas.file) {
+		return uri.with({ scheme: 'vscode-local' }).toString();
+	}
 	if (uri.scheme === Schemas.file || uri.scheme === Schemas.vscodeRemote) {
 		const fsPath = uri.fsPath;
 		// uri.fsPath uses the local OS's path separators, but the path

src/vs/workbench/contrib/chat/test/common/promptSyntax/computeAutomaticInstructions.test.ts

@@ -185,6 +185,7 @@ suite('ComputeAutomaticInstructions', () => {
 
 		instaService.stub(IRemoteAgentService, {
 			getEnvironment: () => Promise.resolve(null),
+			getConnection: () => null,
 		});
 
 		instaService.stub(IContextKeyService, new MockContextKeyService());
@@ -2700,4 +2701,28 @@ suite('getFilePath', () => {
 		const result = getFilePath(uri, undefined);
 		assert.strictEqual(result, uri.fsPath);
 	});
+
+	test('should return vscode-local:// URI string for file:// URIs when connected to a remote', () => {
+		const uri = URI.file('/C:/Users/user/AppData/Roaming/agent-plugins/my-skill/SKILL.md');
+		const result = getFilePath(uri, OperatingSystem.Linux, /* isRemote */ true);
+		assert.strictEqual(result, uri.with({ scheme: 'vscode-local' }).toString());
+	});
+
+	test('should return vscode-local:// URI string for file:// URIs when connected to a Windows remote', () => {
+		const uri = URI.file('/C:/Users/user/AppData/Roaming/agent-plugins/my-skill/SKILL.md');
+		const result = getFilePath(uri, OperatingSystem.Windows, /* isRemote */ true);
+		assert.strictEqual(result, uri.with({ scheme: 'vscode-local' }).toString());
+	});
+
+	test('should not convert file:// URIs to vscode-local:// when not connected to a remote', () => {
+		const uri = URI.file('/home/user/.copilot/agent-plugins/my-skill/SKILL.md');
+		const result = getFilePath(uri, undefined, /* isRemote */ false);
+		assert.strictEqual(result, uri.fsPath);
+	});
+
+	test('should not convert vscode-remote:// URIs when connected to a remote', () => {
+		const uri = URI.from({ scheme: Schemas.vscodeRemote, authority: 'wsl+ubuntu', path: '/home/user/project/file.ts' });
+		const result = getFilePath(uri, OperatingSystem.Linux, /* isRemote */ true);
+		assert.strictEqual(result, uri.fsPath);
+	});
 });