{
  "title": "Subagent context",
  "description": "Define which conversation, instructions, files, memory, and tools a child agent receives.",
  "slug": "subagent-context-isolation",
  "locale": "en",
  "seoTitle": "Subagent context compatibility — Can My Agent Use",
  "socialTitle": "Subagent context",
  "socialDescription": "Compare child-agent context, inheritance, isolation, and context-window behavior.",
  "llmSummary": "Subagent context describes what a child receives from its parent. Fresh context, copied history, selected files, shared memory, and task-only context are recorded as distinct qualifiers.",
  "audience": "Engineers evaluating multi-agent correctness, privacy, and token cost.",
  "contentKind": "feature",
  "status": "published",
  "tags": [
    "runtime",
    "subagents",
    "context",
    "isolation",
    "security"
  ],
  "updated": "2026-08-28T00:00:00.000Z",
  "published": "2026-08-28T00:00:00.000Z",
  "category": "runtime",
  "summary": "Define which conversation, instructions, files, memory, and tools a child receives.",
  "specLabel": "Common product term",
  "aliases": [
    "child context",
    "subagent isolation",
    "context inheritance"
  ],
  "capabilityKind": "atomic",
  "parent": "subagents",
  "related": [
    "context-window",
    "subagent-approval-boundaries",
    "secrets-management"
  ],
  "relations": [],
  "highlight": false,
  "notes": [
    {
      "id": 1,
      "text": "Evidence checked 2026-08-28: Claude Code runs each subagent in its own context window with a custom system prompt and tool set; the child receives its task rather than the parent conversation history and returns a summary."
    },
    {
      "id": 2,
      "text": "Evidence checked 2026-08-28: Gemini CLI subagents use an independent context loop, independent history, explicit tool sets, and recursion protection."
    },
    {
      "id": 3,
      "text": "Evidence checked 2026-08-28: Cursor subagents start with clean context, do not receive prior parent history, receive relevant information through the delegation prompt, and may use isolated project copies."
    },
    {
      "id": 4,
      "text": "Evidence checked 2026-08-28: GitHub Copilot CLI describes subagents as separate-context workers, allowing offloaded information to stay outside the main context window."
    },
    {
      "id": 5,
      "text": "Evidence checked 2026-08-28: VS Code documents a separate context window that excludes the parent conversation history and receives the child task, applicable instructions, and current agent configuration."
    }
  ],
  "issues": [],
  "resources": [
    {
      "title": "Methodology",
      "href": "/methodology",
      "kind": "note"
    },
    {
      "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": "How subagents work; manage subagent context"
    },
    {
      "id": "google-gemini-cli-subagents",
      "title": "Google — Gemini CLI subagents",
      "href": "https://geminicli.com/docs/core/subagents/",
      "kind": "docs",
      "publisher": "Google",
      "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-custom-agents",
      "title": "GitHub — Creating custom agents for Copilot CLI",
      "href": "https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/create-custom-agents-for-cli",
      "kind": "docs",
      "publisher": "GitHub",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28"
    },
    {
      "id": "vscode-agent-concepts",
      "title": "Visual Studio Code — Agents concepts",
      "href": "https://code.visualstudio.com/docs/agents/concepts/agents",
      "kind": "docs",
      "publisher": "Microsoft",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28",
      "locator": "Subagents"
    }
  ],
  "support": [
    {
      "harness": "gemini-cli",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            2
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current Gemini CLI documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "a child has independent history and only explicitly granted tools; it cannot invoke another subagent even when granted the all-tools wildcard"
            }
          ],
          "evidence": [
            {
              "resourceId": "google-gemini-cli-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": "clean child context receives a parent-composed task prompt; project files share the checkout by default but can be isolated in a worktree, branch, or cloud VM"
            }
          ],
          "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": "runtime",
              "value": "each subagent receives its own context window; exact inheritance of credentials, instructions, files, and later parent changes remains separately qualified"
            }
          ],
          "evidence": [
            {
              "resourceId": "github-copilot-cli-custom-agents",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    },
    {
      "harness": "claude-cli",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            1
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "current Claude Code subagent documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "the child has a separate model context but normally shares the parent process's project files and environment unless worktree isolation is configured"
            }
          ],
          "evidence": [
            {
              "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 agent-concepts documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "local-default",
          "qualifiers": [
            {
              "type": "runtime",
              "value": "the model context is isolated; project files and tools remain available according to the child agent configuration"
            }
          ],
          "evidence": [
            {
              "resourceId": "vscode-agent-concepts",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ]
        }
      ]
    }
  ],
  "html": "/features/subagent-context-isolation",
  "markdown": "/features/subagent-context-isolation.md",
  "json": "/api/v1/features/subagent-context-isolation.json",
  "body": "This row asks whether the child-agent boundary has documented context semantics. A child may start fresh, receive the full parent transcript, inherit only a task prompt and selected files, share project memory, or receive a compacted summary. Those modes have different correctness, privacy, and token-cost consequences.\n\nEvidence should record inherited system and project instructions, conversation turns, tool schemas, environment variables, files, long-term memory, credentials, approval state, and context budget. It should also say whether later parent changes propagate and whether the operator can inspect the exact handoff."
}