[DOCS] Cloud session docs missing `CLAUDE_CODE_FORK_SUBAGENT` enablement for forked subagents

Documentation Type

Missing documentation (feature not documented)

Documentation Location

https://code.claude.com/docs/en/claude-code-on-the-web

Section/Topic

Configure your environment and the cloud-session subagents note under Work with sessions

Current Documentation

The cloud-session docs currently say:

Environments control [network access](#network-access), environment variables, and the [setup script](#setup-scripts) that runs before a session starts. See [Installed tools](#installed-tools) for what's available without any configuration.

Later on the same page they say:

Subagents work the same way they do locally. Claude can spawn them with the Task tool to offload research or parallel work into a separate context window, keeping the main conversation lighter. Subagents defined in your repo's .claude/agents/ are picked up automatically. Agent teams are off by default but can be enabled by adding CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1 to your [environment variables](#configure-your-environment).

The skills docs also document forked subagent context:

Add context: fork to your frontmatter when you want a skill to run in isolation. The skill content becomes the prompt that drives the subagent. It won't have access to your conversation history.

No documentation currently exists for CLAUDE_CODE_FORK_SUBAGENT in the environment variable reference.

What's Wrong or Missing?

Changelog v2.1.117 says: Forked subagents can now be enabled on external builds by setting CLAUDE_CODE_FORK_SUBAGENT=1.

The current docs describe cloud/external sessions, environment variables, and forked subagent contexts, but they never explain that forked subagents on external builds require CLAUDE_CODE_FORK_SUBAGENT=1.

That leaves a gap for users running Claude Code on the web or other external-build workflows: the docs say subagents work in cloud sessions and describe context: fork, but they do not show the required enablement step or where to set it.

Suggested Improvement

Add CLAUDE_CODE_FORK_SUBAGENT to the environment variable reference with a short description such as:

CLAUDE_CODE_FORK_SUBAGENT — Set to 1 to enable forked subagents on external builds/cloud sessions.

Also add a note to the cloud-session docs near the existing subagents section showing where to configure it:

CLAUDE_CODE_FORK_SUBAGENT=1

If context: fork-based skills or similar forked workflows are supported in external builds, add a cross-reference from the relevant skills/subagent docs so users can discover the requirement from those pages too.

Impact

High - Prevents users from using a feature

Additional Context

Affected Pages:

| Page | Context |
|------|---------|
| https://code.claude.com/docs/en/claude-code-on-the-web | Cloud-session environment configuration and the note that subagents work the same way locally |
| https://code.claude.com/docs/en/env-vars | Canonical environment variable reference; CLAUDE_CODE_FORK_SUBAGENT is missing |
| https://code.claude.com/docs/en/skills | Documents context: fork for forked subagent execution but not the external-build enablement requirement |

Total scope: 3 pages affected

Source: Changelog v2.1.117

Exact changelog entry: Forked subagents can now be enabled on external builds by setting CLAUDE_CODE_FORK_SUBAGENT=1