CLAUDE_CODE_PLAIN_DELTA_DIRECT_WRITE

Updated November 3, 2026 by Alex Sorokoletov

CLAUDE_CODE_PLAIN_DELTA_DIRECT_WRITE is a Claude Code environment variable: Takes effect only together with CLAUDE_CODE_PLAIN_DELTA_FAST_PATH, under --output-format stream-json with --verbose: a plain-text streaming delta is written out at once while the reader is waiting for output. Removed in v2.1.318, so current releases ignore it. It is not in the official reference.

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_PLAIN_DELTA_DIRECT_WRITE=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_PLAIN_DELTA_DIRECT_WRITE": "<value>"
  }
}

Related variables

• CLAUDE_CODE_PLAIN_DELTA_FAST_PATH: When set, enables a fast path for emitting plain text streaming deltas directly; the fast path is disabled when it is unset.
• CLAUDE_CODE_PLAIN_DELTA_TAKE_AT_SOURCE: When set to true, wraps the model call so plain-text deltas are captured at the source instead of through the normal path.
• CLAUDE_CODE_ARTIFACT_DIRECT_UPLOAD: Forced artifacts to use the direct inline upload path when set; read until v2.1.238.
• CLAUDE_AI_PROJECTS_WRITE_SCOPE
• ANTHROPIC_BETAS: Comma-separated beta feature headers.
• ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
• ANTHROPIC_FEDERATION_RULE_ID
• ANTHROPIC_ORGANIZATION_ID

Frequently asked questions

All variables, searchable: Claude Code environment variables.