Add issue status changes as MCP Events for agent subscriptions #3692

Describe the feature or problem you’d like to solve

Agents need to react automatically when an issue’s status changes (opened, closed, reopened, labeled, assigned, etc.). Today the server only offers on-demand tools (issue_read, issue_write, list_issues) and polling via the notifications toolset. There is no way to subscribe to issue status changes as events so an agent can be woken up and take action.

Proposed solution

Expose issue status changes (and ideally other key issue/PR lifecycle events) as MCP Events (following the experimental Events extension / SEP). Support at least:

• Subscription by repository + optional filters (labels, assignees, specific issue number, action types)
• Delivery via webhook and/or push stream
• Payload containing the issue number, action, new state, actor, and relevant fields

This would enable autonomous agent workflows (triage, notifications, status updates, follow-up actions) without constant polling.

Example prompts or workflows

1. “Watch this repository and automatically comment on any new bug labeled ‘priority:high’.”
2. “When issue Issue: Fix incorrect VS Code installation URL (both buttons point to Insiders) #123 is closed, open a follow-up issue summarizing the resolution and assign it to the original reporter.”
3. “Subscribe to all issues assigned to me and summarize status changes every morning.”
4. “When a PR is merged, close related issues and post a release note draft.”

Additional context

• MCP Events extension: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/seps/0000-events-extension.md
• Related: notifications toolset already exists for polling; this request is for push/event-driven behavior.
• GitHub webhooks already emit issues events with actions (opened, closed, labeled, etc.) — the main work is exposing them cleanly through the MCP Events surface.