[FEATURE] Use CLAUDE_CODE_TMPDIR for Session Scratchpad

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When CLAUDE_CODE_TMPDIR environment variable is set, Claude Code should use this directory for the session-specific scratchpad instead of generating a path under /tmp/claude/....

Current Behavior

• CLAUDE_CODE_TMPDIR can be set to a custom temp directory (e.g., /var/tmp/claude-username)
• However, the session scratchpad directory is auto-generated based on the current working directory:

``
/tmp/claude/-home-www-vhosts-other-project/session-uuid/scratchpad
``

• Background task outputs are stored in:

``
/tmp/claude/-home-www-vhosts-other-project/tasks/
``

Use Case

On shared servers or systems with specific temp directory policies, administrators may want all temporary files to be stored in a consistent location (e.g., /var/tmp/ instead of /tmp/). The CLAUDE_CODE_TMPDIR variable already exists for this purpose, but the session scratchpad doesn't respect it.

Environment

• Claude Code version: (current)
• OS: Linux (Debian)
• CLAUDE_CODE_TMPDIR=/var/tmp/claude-username is set in shell environment

Proposed Solution

When CLAUDE_CODE_TMPDIR is set, the scratchpad and task output directories should be created under this path:

/var/tmp/claude-username/session-uuid/scratchpad
/var/tmp/claude-username/tasks/

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_