Concurrency Control

GitHub Agentic Workflows uses dual-level concurrency control to prevent resource exhaustion and ensure predictable execution:

• Per-workflow: Limits based on workflow name and trigger context (issue, PR, branch)
• Per-engine: Limits AI execution across all workflows via engine.concurrency

Per-Workflow Concurrency

Workflow-level concurrency groups include the workflow name plus context-specific identifiers:

Trigger Type	Concurrency Group	Cancel In Progress
Issues	gh-aw-${{ github.workflow }}-${{ issue.number }}	No
Pull Requests	gh-aw-${{ github.workflow }}-${{ pr.number || ref }}	Yes (new commits cancel outdated runs)
Push	gh-aw-${{ github.workflow }}-${{ github.ref }}	No
Schedule/Other	gh-aw-${{ github.workflow }}	No

This ensures workflows on different issues, PRs, or branches run concurrently without interference.

Per-Engine Concurrency

The default per-engine pattern gh-aw-{engine-id} ensures only one agent job runs per engine across all workflows, preventing AI resource exhaustion. The group includes only the engine ID (copilot, claude, codex) and gh-aw- prefix—workflow name, issue/PR numbers, and branches are excluded.

jobs:
  agent:
    concurrency:
      group: "gh-aw-{engine-id}"

Custom Concurrency

Override either level independently:

---
on: push
concurrency:  # Workflow-level
  group: custom-group-${{ github.ref }}
  cancel-in-progress: true
engine:
  id: claude
  concurrency:  # Engine-level
    group: "gh-aw-claude-${{ github.workflow }}"
tools:
  github:
    allowed: [list_issues]
---

Related Documentation

• AI Engines - Engine configuration and capabilities
• Frontmatter - Complete frontmatter reference
• Workflow Structure - Overall workflow organization