GitHub Copilot subagents generated by rulesync lack the required .agent.md extension

[flanny7]

Hello,
I always appreciate rulesync.

I found an issue where the subagent files generated for GitHub Copilot are not being loaded in VSCode Copilot Chat, and I'd like to share it.

Problem

When rulesync generate creates subagents for GitHub Copilot, the generated file names do not match the format supported by VSCode Copilot Chat. Specifically, they lack the .agent.md extension.

Example: For a source file .rulesync/subagents/planner.md

• Incorrect: .github/agents/planner.md
• Correct: .github/agents/planner.agent.md

Because of this, the custom agents generated by rulesync cannot be utilized in GitHub Copilot.

Evidence

According to the source code of vscode-copilot-chat, the .agent.md extension is explicitly expected for agent files.

https://github.com/microsoft/vscode-copilot-chat/blob/main/src/platform/customInstructions/common/promptTypes.ts#L39

export const AGENT_FILE_EXTENSION = '.agent.md';

https://github.com/microsoft/vscode-copilot-chat/blob/main/src/extension/chatSessions/copilotcli/node/copilotCli.ts#L337

export function getAgentFileNameFromFilePath(filePath: URI): string {
	const nameFromFile = basename(filePath);
	const indexOfAgentMd = nameFromFile.toLowerCase().indexOf('.agent.md');
	const agentName = indexOfAgentMd > 0 ? nameFromFile.substring(0, indexOfAgentMd) : nameFromFile;
	return agentName;
}

• If .agent.md is found -> The string before it becomes the agent name.
• If not found -> The entire file name is used as the agent name. While it doesn't cause an error, the glob pattern does not match, so the file is never loaded.

I am planning to create a PR for this myself when I have some free time.

Your confirmation would be appreciated.