Claude Code shell does not inherit AWS_REGION from user's terminal session

Description

When Claude Code runs Bash tool calls, the shell does not inherit environment variables set in the user's terminal session — specifically AWS_REGION (and AWS_DEFAULT_REGION). This causes all aws CLI and pulumi commands that depend on region configuration to silently fall back to us-east-1, even when the user has AWS_REGION=us-west-2 set in their own shell.

Steps to Reproduce

1. In your terminal, run export AWS_REGION=us-west-2
2. Open Claude Code in that terminal (or in a project where it's launched from that session)
3. Ask Claude to run any AWS CLI command, e.g. aws ecs list-clusters
4. The command executes against us-east-1 instead of us-west-2

Expected Behavior

Claude Code's Bash tool should inherit environment variables from the shell session it was launched from, or at minimum respect AWS_REGION / AWS_DEFAULT_REGION if set in the user's environment.

Actual Behavior

The Bash tool uses a fresh shell that does not inherit the user's exported environment variables. Region-dependent AWS and Pulumi commands silently use the wrong region.

Workaround

Prefix every aws/pulumi Bash call with the region inline:

AWS_REGION=us-west-2 aws ecs list-clusters
AWS_REGION=us-west-2 pulumi up --stack stage

This is workable but requires the region to be hardcoded in project instructions (CLAUDE.md).

Environment

• Platform: macOS (darwin)
• Shell: zsh
• Claude Code version: current