{
  "title": "Concurrent subagents",
  "description": "Run more than one child-agent task at the same time with documented concurrency and queue limits.",
  "slug": "subagent-concurrency",
  "locale": "en",
  "seoTitle": "Concurrent subagents compatibility — Can My Agent Use",
  "socialTitle": "Concurrent subagents",
  "socialDescription": "Compare parallel child-agent execution, queueing, and concurrency limits.",
  "llmSummary": "Concurrent subagents means multiple child-agent tasks can overlap in time; sequential delegation, tool-call parallelism, and background shell processes are separate behaviors.",
  "audience": "Engineers comparing multi-agent throughput and coordination.",
  "contentKind": "feature",
  "status": "published",
  "tags": [
    "runtime",
    "subagents",
    "concurrency",
    "delegation"
  ],
  "updated": "2026-08-28T00:00:00.000Z",
  "published": "2026-08-28T00:00:00.000Z",
  "category": "runtime",
  "summary": "Run multiple child-agent tasks concurrently with explicit queue and fan-out limits.",
  "specLabel": "Common product term",
  "aliases": [
    "parallel subagents",
    "agent fan-out",
    "concurrent child agents"
  ],
  "capabilityKind": "atomic",
  "parent": "subagents",
  "related": [
    "subagent-delegation",
    "nested-subagents",
    "subagent-context-isolation"
  ],
  "relations": [],
  "highlight": false,
  "notes": [
    {
      "id": 1,
      "text": "Evidence checked 2026-08-28: Claude Code documents multiple foreground or background subagents, describes parallel subagent work, and exposes live subagents in the `/agents` panel and background work in `/tasks`."
    },
    {
      "id": 2,
      "text": "Evidence checked 2026-08-28: ChatGPT Work and local Codex can run specialized agents in parallel; local Codex configuration exposes a maximum concurrent spawned-thread setting."
    },
    {
      "id": 3,
      "text": "Evidence checked 2026-08-28: Cursor can send multiple Task calls in one parent turn so subagents run simultaneously; isolated worktrees or cloud environments are available for parallel writers."
    },
    {
      "id": 4,
      "text": "Evidence checked 2026-08-28: GitHub Copilot CLI documents plan-based concurrent-subagent limits from 2 to 32 and a usage-billing override capped at 32."
    },
    {
      "id": 5,
      "text": "Evidence checked 2026-08-28: VS Code explicitly documents spawning multiple subagents in parallel and provides examples that run several specialized reviewers concurrently."
    }
  ],
  "issues": [],
  "resources": [
    {
      "title": "Methodology",
      "href": "/methodology",
      "kind": "note"
    },
    {
      "id": "anthropic-claude-code-parallel-agents",
      "title": "Anthropic — Run agents in parallel",
      "href": "https://code.claude.com/docs/en/agents",
      "kind": "docs",
      "publisher": "Anthropic",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28",
      "locator": "Choose an approach; check on running work"
    },
    {
      "id": "anthropic-claude-code-subagents",
      "title": "Anthropic — Create custom subagents",
      "href": "https://code.claude.com/docs/en/sub-agents",
      "kind": "docs",
      "publisher": "Anthropic",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28",
      "locator": "Run subagents in foreground or background"
    },
    {
      "id": "openai-subagents",
      "title": "OpenAI — Subagents in ChatGPT and Codex",
      "href": "https://learn.chatgpt.com/docs/agent-configuration/subagents",
      "kind": "docs",
      "publisher": "OpenAI",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28"
    },
    {
      "id": "cursor-subagents",
      "title": "Cursor — Subagents",
      "href": "https://cursor.com/docs/subagents",
      "kind": "docs",
      "publisher": "Cursor",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28"
    },
    {
      "id": "github-copilot-cli-reference",
      "title": "GitHub — Copilot CLI command reference",
      "href": "https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-command-reference",
      "kind": "docs",
      "publisher": "GitHub",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28"
    },
    {
      "id": "vscode-subagents",
      "title": "Visual Studio Code — Subagents in Visual Studio Code",
      "href": "https://code.visualstudio.com/docs/agents/run/subagents",
      "kind": "docs",
      "publisher": "Microsoft",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28",
      "locator": "Parallel code analysis; orchestration patterns"
    }
  ],
  "support": [
    {
      "harness": "chatgpt-web",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            2
          ],
          "target": {
            "kind": "hosted-observation",
            "revision": "2026-08-28 ChatGPT Work web documentation observation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "hosted-default",
          "qualifiers": [
            {
              "type": "plan",
              "value": "available to eligible accounts; the reviewed page establishes parallel execution but does not publish a numeric web fan-out cap"
            }
          ],
          "evidence": [
            {
              "resourceId": "openai-subagents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "chatgpt-desktop",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            2
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current ChatGPT desktop documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "local Codex supports parallel child threads; agents.max_concurrent_threads_per_session caps spawned threads and excludes the primary thread"
            }
          ],
          "evidence": [
            {
              "resourceId": "openai-subagents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "codex-cli",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            2
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current Codex CLI documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "agents.max_concurrent_threads_per_session caps spawned threads and excludes the primary; leaving it unset delegates the default to Codex"
            }
          ],
          "evidence": [
            {
              "resourceId": "openai-subagents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "cursor",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            3
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current Cursor subagent documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "multiple Task calls can start simultaneously; shared-checkout writers can collide unless worktree or cloud isolation is requested"
            }
          ],
          "evidence": [
            {
              "resourceId": "cursor-subagents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "copilot-cli",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            4
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current GitHub Copilot CLI documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "plan",
              "value": "default concurrent limits are 2 Free/Education, 4 Pro/Pro+, 8 Max, 16 Business, and 32 Enterprise; usage-based billing can configure up to 32"
            }
          ],
          "evidence": [
            {
              "resourceId": "github-copilot-cli-reference",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "claude-cli",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            1
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current Claude Code parallel-agent documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "running several subagents at once multiplies token use and shares the account's rate limits"
            }
          ],
          "evidence": [
            {
              "resourceId": "anthropic-claude-code-parallel-agents",
              "type": "documented",
              "observedAt": "2026-08-28"
            },
            {
              "resourceId": "anthropic-claude-code-subagents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "vscode-copilot",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            5
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current VS Code subagent documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "host-role",
              "value": "claim is scoped to GitHub Copilot's local VS Code agent surface; published documentation does not state a fixed maximum parallel-child count"
            }
          ],
          "evidence": [
            {
              "resourceId": "vscode-subagents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    }
  ],
  "html": "/features/subagent-concurrency",
  "markdown": "/features/subagent-concurrency.md",
  "json": "/api/v1/features/subagent-concurrency.json",
  "body": "This row requires two or more child-agent executions whose active intervals overlap. Sequential delegation, concurrent ordinary tool calls, and detached shell commands do not establish concurrent subagents.\n\nEvidence should record maximum active and queued children, nesting effects, per-plan or per-organization quotas, scheduling order, cancellation behavior, rate-limit sharing, and whether concurrent children can safely write to the same workspace. Tests should detect accidental serialization as well as unsafe shared-state races."
}