New host environment variables and changes to the environment passed to child processes

What

An environment variable is a named setting handed to a program when it starts. This release adds several environment variables used when an app that embeds Claude Code (a host, such as the desktop app or an SDK program) starts it. It also changes which variables reach the programs Claude Code launches itself, called child processes.

• CLAUDE_CODE_DESKTOP_MESSAGE_CARD, CLAUDE_CODE_DESKTOP_MODE_FROM_RECORD, CLAUDE_CODE_DESKTOP_PLUGIN_INSTALL_FRAMES, CLAUDE_CODE_SHOWN_PLUGINS_DIR and CLAUDE_CODE_SDK_MCP_TOOL_IDLE_TIMEOUT are new. Claude Code reads them and then removes them from its environment.
• CLAUDE_CODE_SESSION_CREATED_AT_MS, CLAUDE_CODE_OVERLOADED_RETRY_MAX_WAIT_MS and CLAUDE_CODE_HOST_ARTIFACT_TYPE_COMMANDS are added to the lists of allowed environment variables.
• CLAUDE_CODE_OVERLOADED_RETRY_MAX_WAIT_MS, CLAUDE_CODE_SDK_MCP_TOOL_IDLE_TIMEOUT and CLAUDE_CODE_HOST_ARTIFACT_TYPE_COMMANDS are on the list of host-controlled variables that are scrubbed, meaning removed before a child process starts.
• ANTHROPIC_PROFILE and ANTHROPIC_CONFIG_DIR are now included in the child environment when it is rebuilt.
• The AWS credential chain (the order in which Claude Code looks for Amazon Web Services credentials) and the creation of the AWS STS client now use extra shared configuration and handlers.

Why

Programs started by Claude Code now see a different set of environment variables. ANTHROPIC_PROFILE, the variable that names the Anthropic profile to sign in with, now carries through to them. The host-only variables are kept out. One of the new variables, CLAUDE_CODE_OVERLOADED_RETRY_MAX_WAIT_MS, appears from its name to set a maximum wait when retrying after the service reports it is overloaded. The members do not confirm what it controls.