Make `agent/runSubagent` opt-in instead of always required

[hayashidayasuhiro]

Background / Problem

Currently, when generating a GitHub Copilot subagent, agent/runSubagent is always added automatically, regardless of user intent.

rulesync/src/features/subagents/copilot-subagent.ts

Line 19 in b480897

const REQUIRED_TOOL = "agent/runSubagent";

rulesync/src/features/subagents/copilot-subagent.ts

Lines 42 to 45 in b480897

	const ensureRequiredTool = (tools: string[]): string[] => {
	const mergedTools = new Set([REQUIRED_TOOL, ...tools]);
	return Array.from(mergedTools);
	};

Even if copilot.tools is empty or not specified, the generated file always contains ["agent/runSubagent"].

Proposal

Make agent/runSubagent opt-in — users should explicitly add it only when needed.

Option A: No default, explicit opt-in

copilot:
  tools:
    - agent/runSubagent  # add explicitly only when needed
    - web/fetch

Option B: Opt-out via flag

copilot:
  runSubagent: false  # default true, set false to disable
  tools:
    - web/fetch

Expected Behavior

• If copilot.tools is not specified or empty → tools field is empty or omitted
• Users explicitly add agent/runSubagent when orchestration between subagents is required

Would you please consider this? Thank you very much.

[dyoshikawa]

@hayashidayasuhiro Thank you for your feedback. In what situations would that be necessary? If agent/runSubagent isn't specified in copilot.tools, I feel it might not be something that should be managed as a subagent for Rulesync.

[hayashidayasuhiro]

@dyoshikawa
Thank you for your response!

My concern is that forcing agent/runSubagent makes it harder to use Rulesync for simple, single-purpose subagents that are invoked directly by the user rather than by another agent.

Not all subagents are part of an orchestration setup, and granting unnecessary permissions feels like a poor practice. Allowing users to opt-in to agent/runSubagent only when needed would make Rulesync more flexible for both simple and complex use cases.

That said, this is just my personal opinion — what do you think?