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Environment variables
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| `ANTHROPIC_API_KEY` | API key sent as `X-Api-Key` header. When set, this key is used instead of your Claude Pro, Max, Team, or Enterprise subscription even if you are logged in. In non-interactive mode (`-p`), the key is always used when present. In interactive mode, you are prompted to approve the key once before it overrides your subscription. To use your subscription instead, run `unset ANTHROPIC_API_KEY` | | `ANTHROPIC_AUTH_TOKEN` | Custom value for the `Authorization` header (the value you set here will be prefixed with `Bearer `) | | `ANTHROPIC_AWS_API_KEY` | Workspace API key for [Claude Platform on AWS](/docs/en/claude-platform-on-aws), generated in the AWS Console. Sent as `x-api-key` and takes precedence over AWS SigV4 | -| `ANTHROPIC_AWS_BASE_URL` | Override the [Claude Platform on AWS](/docs/en/claude-platform-on-aws) endpoint URL. Use for custom regions or when routing through an [LLM gateway](/docs/en/llm-gateway). Defaults to `https://aws-external-anthropic.{AWS_REGION}.api.aws` | +| `ANTHROPIC_AWS_BASE_URL` | Override the [Claude Platform on AWS](/docs/en/claude-platform-on-aws) endpoint URL. Use for custom regions or when routing through an [LLM gateway](/docs/en/llm-gateway). Defaults to `https://aws-external-anthropic.{region}.api.aws`. Claude Code resolves the region with the [same precedence as on Amazon Bedrock](/docs/en/amazon-bedrock#3-configure-claude-code) | | `ANTHROPIC_AWS_WORKSPACE_ID` | Required for [Claude Platform on AWS](/docs/en/claude-platform-on-aws). Sent on every request as the `anthropic-workspace-id` header | | `ANTHROPIC_BASE_URL` | Override the API endpoint to route requests through a proxy or gateway. When set to a non-first-party host, [MCP tool search](/docs/en/mcp#scale-with-mcp-tool-search) is disabled by default. Set `ENABLE_TOOL_SEARCH=true` if your proxy forwards `tool_reference` blocks. As of v2.1.196, [Remote Control](/docs/en/remote-control#requirements) is disabled when this points at a host other than `api.anthropic.com`, matching its behavior on Amazon Bedrock, Google Cloud's Agent Platform, and Microsoft Foundry | | `ANTHROPIC_BEDROCK_BASE_URL` | Override the Amazon Bedrock endpoint URL. Use for custom Amazon Bedrock endpoints or when routing through an [LLM gateway](/docs/en/llm-gateway). See [Amazon Bedrock](/docs/en/amazon-bedrock) |
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| `CLAUDE_CODE_SKIP_FAST_MODE_NETWORK_ERRORS` | Set to `1` to treat a failed [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) availability check as available, for networks that block the check's direct request to `api.anthropic.com`. Claude Code still honors a "disabled by your organization" response | | `CLAUDE_CODE_SKIP_FAST_MODE_ORG_CHECK` | Set to `1` to skip the client-side [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) availability check, for proxies that intercept the check's request rather than refuse it. The API still rejects fast mode requests when your organization has fast mode disabled | | `CLAUDE_CODE_SKIP_FOUNDRY_AUTH` | Skip Azure authentication for Microsoft Foundry, for a proxy or gateway that injects its own `Authorization` header. Claude Code sends requests without an Azure credential and preserves the `Authorization` header you supply, for example through `ANTHROPIC_CUSTOM_HEADERS`. Ignored when `ANTHROPIC_FOUNDRY_API_KEY` or `ANTHROPIC_FOUNDRY_AUTH_TOKEN` is set. Before v2.1.203, this variable left the Microsoft Foundry client unable to send requests unless an API key was also set | -| `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway) +| `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway)
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| `CLAUDE_CODE_FORCE_SESSION_PERSISTENCE` | Set to `1` to force transcript persistence, prompt history, and `claude agents` registration even when this `claude` was launched from inside another Claude Code session. Use when an inherited `CLAUDE_CODE_CHILD_SESSION` value, for example from a `screen` session or a background launcher first started by Claude Code's Bash tool, causes a genuine top-level session to be misclassified as nested. As of v2.1.178, Claude Code detects the tmux case automatically and ignores the inherited marker, so tmux no longer needs this variable. Also honored on v2.1.169 and earlier; has no effect on v2.1.170 and v2.1.171, where the nested-session detection it overrides was removed | | `CLAUDE_CODE_FORCE_STRIKETHROUGH` | Set to `1` to force strikethrough rendering for `~~text~~` in Claude's responses when your terminal supports it but is not auto-detected, such as over SSH without `TERM_PROGRAM` forwarded. Without this, undetected terminals show the literal `~~` markers instead of rendering the text as strikethrough. Requires Claude Code v2.1.186 or later | | `CLAUDE_CODE_FORCE_SYNC_OUTPUT` | Set to `1` to force-enable DEC private mode 2026 [synchronized output](https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036) when your terminal supports it but is not auto-detected. Useful for emulators such as Emacs `eat` that implement BSU/ESU but do not reply to the capability probe. Has no effect under tmux. Unlike `CLAUDE_CODE_NO_FLICKER`, which switches to [fullscreen rendering](/docs/en/fullscreen), this doesn't change the renderer | -| `CLAUDE_CODE_FORK_SUBAGENT` | Controls [fork mode](/docs/en/sub-agents#turn-fork-mode-on-or-off), which lets Claude spawn [forked subagents](/docs/en/sub-agents#fork-the-current-conversation) itself and is on by default in interactive sessions only. Set to `1` to turn it on in `claude -p` and the Agent SDK as well, or `0` to turn it off in every kind of session. The `/subtask` command works whether or not fork mode is on. The interactive default requires Claude Code v2.1.232 or later | +| `CLAUDE_CODE_FORK_SUBAGENT` | Controls [fork mode](/docs/en/sub-agents#turn-fork-mode-on-or-off), which lets Claude spawn [forked subagents](/docs/en/sub-agents#fork-the-current-conversation) itself and is on by default in interactive sessions only. Set to `1` to turn it on in `claude -p` and the Agent SDK as well, or `0` to turn it off in every kind of session. You can run `/subtask` whether or not fork mode is on. The interactive default requires Claude Code v2.1.232 or later; on earlier versions, set the variable to `1` to turn fork mode on | | `CLAUDE_CODE_FORWARD_SUBAGENT_TEXT` | Set to `1` to emit [subagent](/docs/en/sub-agents) text and thinking blocks in `claude -p --output-format stream-json` output, the same behavior as the [`--forward-subagent-text`](/docs/en/cli-reference#cli-flags) flag. Use the variable when a harness invokes `claude` and can't pass the flag itself. Unlike the flag, which exits with an error outside non-interactive mode with stream-json output, the variable is ignored there so that nested invocations keep working when it's set process-wide. Requires Claude Code v2.1.211 or later | | `CLAUDE_CODE_GIT_BASH_PATH` | Windows only: path to the Git Bash executable (`bash.exe`). Use when Git Bash is installed but not in your PATH. If the path doesn't exist or the file isn't named `bash.exe`, `sh.exe`, `bash`, or `sh`, Claude Code ignores the variable and auto-detects Git Bash as if it were unset, logging a warning visible with `--debug`. Before v2.1.219, Claude Code exited at startup when the path didn't exist, and used any existing file as the shell without checking that it was bash or sh. See [Windows setup](/docs/en/setup#set-up-on-windows) | | `CLAUDE_CODE_GLOB_HIDDEN` | Set to `false` to exclude dotfiles from results when Claude invokes the [Glob tool](/docs/en/tools-reference#glob-tool-behavior). Included by default. Does not affect `@` file autocomplete, `ls`, Grep, or Read |
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| `CLAUDE_CODE_DISABLE_NONSTREAMING_FALLBACK` | Set to `1` to disable the non-streaming fallback when a streaming request fails mid-stream. Streaming errors propagate to the retry layer instead. Useful when a proxy or gateway causes the fallback to produce duplicate tool execution | | `CLAUDE_CODE_DISABLE_NOTIFICATION_PRESENCE_CHECK` | Set to `1` to send the `PushNotification` tool's desktop notification even while you are typing in or focused on the terminal. By default the tool skips both the desktop notification and the [mobile push](/docs/en/remote-control#mobile-push-notifications) when it detects recent keyboard activity or terminal focus. This variable disables only that local check, so the server can still suppress the mobile push when it detects that you are active. Requires Claude Code v2.1.193 or later | | `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` | Set to `1` to disable automatic registration of the official plugin marketplace. Claude Code reads the variable when it is about to register the marketplace, usually during a machine's first interactive launch. If the variable is set at that point, Claude Code skips the registration permanently. Unsetting the variable later doesn't undo the skip. Run `claude plugin marketplace add anthropics/claude-plugins-official` to register the marketplace at any time | +| `CLAUDE_CODE_DISABLE_PERMISSION_PROMPT_NOTIFY_HOOKS` | Set to `1` to stop Claude Code from running your [`Notification` hooks for unanswered permission requests](/docs/en/hooks#notification) in sessions where Claude Code sends them to the Agent SDK's `canUseTool` callback, which is how Claude Desktop and the VS Code extension host Claude Code. Has no effect in terminal sessions. Requires Claude Code v2.1.233 or later | | `CLAUDE_CODE_DISABLE_POLICY_SKILLS` | Set to `1` to skip loading skills from the system-wide managed skills directory. Useful for container or CI sessions that should not load operator-provisioned skills | | `CLAUDE_CODE_DISABLE_TERMINAL_TITLE` | Set to `1` to disable automatic terminal title updates based on conversation context. In Agent SDK and `claude -p` sessions, this also skips the background small/fast-model request that generates the session title | | `CLAUDE_CODE_DISABLE_THINKING` | Set to `1` to omit the `thinking` parameter from API requests entirely. This is a compatibility option for proxies and gateways that reject the parameter. The variable's behavior is unchanged from earlier versions; on models that think by default, omitting the parameter means the model may still think. To explicitly disable [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) on the Anthropic API, use `MAX_THINKING_TOKENS=0` instead, which is also ineffective on Fable 5 since it cannot have thinking turned off. On [third-party providers](/docs/en/third-party-integrations), `0` likewise omits the parameter, so the two variables behave the same there |
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| `CLAUDE_CODE_SKIP_FAST_MODE_NETWORK_ERRORS` | Set to `1` to treat a failed [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) availability check as available, for networks that block the check's direct request to `api.anthropic.com`. Claude Code still honors a "disabled by your organization" response | | `CLAUDE_CODE_SKIP_FAST_MODE_ORG_CHECK` | Set to `1` to skip the client-side [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) availability check, for proxies that intercept the check's request rather than refuse it. The API still rejects fast mode requests when your organization has fast mode disabled | | `CLAUDE_CODE_SKIP_FOUNDRY_AUTH` | Skip Azure authentication for Microsoft Foundry, for a proxy or gateway that injects its own `Authorization` header. Claude Code sends requests without an Azure credential and preserves the `Authorization` header you supply, for example through `ANTHROPIC_CUSTOM_HEADERS`. Ignored when `ANTHROPIC_FOUNDRY_API_KEY` or `ANTHROPIC_FOUNDRY_AUTH_TOKEN` is set. Before v2.1.203, this variable left the Microsoft Foundry client unable to send requests unless an API key was also set | -| `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway) | -| `CLAUDE_CODE_SKIP_PROMPT_HISTORY` | Set to `1` to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in `--resume`, `--continue`, or up-arrow history. Useful for ephemeral scripted sessions +| `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway)
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| `CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY` | Set to `1` to populate the `/model` picker from your gateway's `/v1/models` endpoint when `ANTHROPIC_BASE_URL` points at an Anthropic-compatible gateway such as LiteLLM, Kong, or an internal proxy. Off by default because gateways backed by a shared API key would otherwise show every user every model the key can access. Discovered models are still filtered by an [`availableModels`](/docs/en/settings#available-settings) allowlist the session receives; deliver the list through [MDM or a managed settings file](/docs/en/settings#settings-files), since [server-managed delivery is not available on gateway configurations](/docs/en/server-managed-settings#platform-availability) | | `CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE` | Removed in v2.1.142, when the [fast mode](/docs/en/fast-mode) default moved from Opus 4.6 to Opus 4.7 | | `CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION` | Set to `false` to disable prompt suggestions (the "Prompt suggestions" toggle in `/config`). These are the grayed-out predictions that appear in your prompt input. Takes precedence over the [`promptSuggestionEnabled`](/docs/en/settings#available-settings) setting. See [Prompt suggestions](/docs/en/interactive-mode#prompt-suggestions) | -| `CLAUDE_CODE_ENABLE_TASKS` | Controls whether sessions use the structured Task tools (`TaskCreate`, `TaskUpdate`, `TaskGet`, `TaskList`) or the legacy `TodoWrite` tool. Task tools are the default in all modes. Set to `0` to use `TodoWrite`. See [Task list](/docs/en/interactive-mode#task-list) and [Migrate to Task tools](/docs/en/agent-sdk/todo-tracking#migrate-to-task-tools) | +| `CLAUDE_CODE_ENABLE_TASKS` | Selects which task-tracking tools Claude Code provides in [sessions that have them](/docs/en/tools-reference#task-tool-availability). By default, Claude Code provides the Task tools `TaskCreate`, `TaskUpdate`, `TaskGet`, and `TaskList`. Set to `0` to get the legacy `TodoWrite` tool instead. See [Task list](/docs/en/interactive-mode#task-list) and [Migrate to Task tools](/docs/en/agent-sdk/todo-tracking#migrate-to-task-tools) | | `CLAUDE_CODE_ENABLE_TELEMETRY` | Set to `1` to enable OpenTelemetry data collection for metrics and logging. Required before configuring OTel exporters. See [Monitoring](/docs/en/monitoring-usage) | +| `CLAUDE_CODE_ENABLE_TODO_TOOLS` | Set to `1` to get the task-tracking tools on the models listed under [Task tool availability](/docs/en/tools-reference#task-tool-availability), where Claude Code otherwise leaves them out. `CLAUDE_CODE_ENABLE_TASKS` still selects the Task tools or `TodoWrite`. Requires Claude Code v2.1.233 or later | | `CLAUDE_CODE_EXIT_AFTER_STOP_DELAY` | Time in milliseconds to wait after the query loop becomes idle before automatically exiting. Useful for automated workflows and scripts using SDK mode | | `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS` | Set to `1` to enable [agent teams](/docs/en/agent-teams). Agent teams are experimental and disabled by default | | `CLAUDE_CODE_EXTRA_BODY` | JSON object to merge into the top level of every API request body. Useful for passing provider-specific parameters that Claude Code doesn't expose directly. A value exported in your shell also applies to the [background sessions](/docs/en/agent-view) you dispatch with `claude agents` or `--bg`. Before v2.1.206, background sessions ignored a shell-exported value and used whatever copy the background supervisor process inherited |
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| `CLAUDE_CODE_SKIP_FAST_MODE_ORG_CHECK` | Set to `1` to skip the client-side [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) availability check, for proxies that intercept the check's request rather than refuse it. The API still rejects fast mode requests when your organization has fast mode disabled | | `CLAUDE_CODE_SKIP_FOUNDRY_AUTH` | Skip Azure authentication for Microsoft Foundry, for a proxy or gateway that injects its own `Authorization` header. Claude Code sends requests without an Azure credential and preserves the `Authorization` header you supply, for example through `ANTHROPIC_CUSTOM_HEADERS`. Ignored when `ANTHROPIC_FOUNDRY_API_KEY` or `ANTHROPIC_FOUNDRY_AUTH_TOKEN` is set. Before v2.1.203, this variable left the Microsoft Foundry client unable to send requests unless an API key was also set | | `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway) | -| `CLAUDE_CODE_SKIP_PROMPT_HISTORY` | Set to `1` to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in `--resume`, `--continue`, or up-arrow history. Useful for ephemeral scripted sessions | -| `CLAUDE_CODE_SKIP_VERTEX_AUTH` | Skip Google authentication for Google Cloud's Agent Platform (for example, when using an LLM gateway) +| `CLAUDE_CODE_SKIP_PROMPT_HISTORY` | Set to `1` to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in `--resume`, `--continue`, or up-arrow history. Useful for ephemeral scripted sessions
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| `CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP` | Set to `1` to prevent automatic remapping of Opus 4.0 and 4.1 to the current Opus version on the Anthropic API. Use when you intentionally want to pin an older model. The remap does not run on Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry | | `CLAUDE_CODE_DISABLE_MOUSE` | Set to `1` to disable mouse tracking in [fullscreen rendering](/docs/en/fullscreen). Keyboard scrolling with `PgUp` and `PgDn` still works. Use this to keep your terminal's native copy-on-select behavior | | `CLAUDE_CODE_DISABLE_MOUSE_CLICKS` | Set to `1` to disable click, drag, and hover handling in [fullscreen rendering](/docs/en/fullscreen) while keeping mouse-wheel scrolling. Use this when you want wheel scroll to work inside Claude Code but don't want clicks to position the cursor, expand tool output, or open links. `CLAUDE_CODE_DISABLE_MOUSE` takes precedence when both are set. Requires Claude Code v2.1.195 or later | +| `CLAUDE_CODE_DISABLE_MTLS_RELOAD_ON_STALE_CONNECTION` | Set to `1` to stop Claude Code from re-reading the [mTLS client certificate and key](/docs/en/network-config#mtls-authentication) when an API request fails with a connection-level error, such as a connection reset or a TLS handshake error. With the reload disabled, Claude Code loads rotated files only when it next applies settings or at the next startup. Requires Claude Code v2.1.232 or later | | `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC` | Set to any non-empty value, such as `1`, to disable nonessential network traffic: auto-updates, telemetry, error reporting, the `/feedback` command, release notes, [gateway model discovery](/docs/en/llm-gateway-connect#add-gateway-models-to-the-model-picker) refreshes, and availability checks such as the [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) check. It also stops the [background runs of plugin `command` sources](/docs/en/plugin-marketplaces#when-claude-code-re-runs-the-command), which are local commands rather than network traffic, because they can trigger dependency installs. **Setting it to `0` or `false` still disables this traffic**, unlike most on/off variables; unset the variable to allow it again. Also disables feature-flag fetching, which makes [Remote Control](/docs/en/remote-control#requirements) and the other [features that need feature-flag fetching](#features-that-need-feature-flag-fetching) unavailable. Official plugin marketplace auto-install isn't covered; disable it with `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` | | `CLAUDE_CODE_DISABLE_NONSTREAMING_FALLBACK` | Set to `1` to disable the non-streaming fallback when a streaming request fails mid-stream. Streaming errors propagate to the retry layer instead. Useful when a proxy or gateway causes the fallback to produce duplicate tool execution | | `CLAUDE_CODE_DISABLE_NOTIFICATION_PRESENCE_CHECK` | Set to `1` to send the `PushNotification` tool's desktop notification even while you are typing in or focused on the terminal. By default the tool skips both the desktop notification and the [mobile push](/docs/en/remote-control#mobile-push-notifications) when it detects recent keyboard activity or terminal focus. This variable disables only that local check, so the server can still suppress the mobile push when it detects that you are active. Requires Claude Code v2.1.193 or later |
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| `CLAUDE_CODE_SKIP_FOUNDRY_AUTH` | Skip Azure authentication for Microsoft Foundry, for a proxy or gateway that injects its own `Authorization` header. Claude Code sends requests without an Azure credential and preserves the `Authorization` header you supply, for example through `ANTHROPIC_CUSTOM_HEADERS`. Ignored when `ANTHROPIC_FOUNDRY_API_KEY` or `ANTHROPIC_FOUNDRY_AUTH_TOKEN` is set. Before v2.1.203, this variable left the Microsoft Foundry client unable to send requests unless an API key was also set | | `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway) | | `CLAUDE_CODE_SKIP_PROMPT_HISTORY` | Set to `1` to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in `--resume`, `--continue`, or up-arrow history. Useful for ephemeral scripted sessions | -| `CLAUDE_CODE_SKIP_VERTEX_AUTH` | Skip Google authentication for Google Cloud's Agent Platform (for example, when using an LLM gateway) | -| `CLAUDE_CODE_STOP_HOOK_BLOCK_CAP` | Maximum number of consecutive times a [Stop](/docs/en/hooks#stop) or [SubagentStop](/docs/en/hooks#subagentstop) hook may block the turn from ending before Claude Code overrides it and ends the turn anyway (default: 8). Set to `0` to disable the cap. Raise this if your hook legitimately needs more iterations to resolve +| `CLAUDE_CODE_SKIP_VERTEX_AUTH` | Skip Google authentication for Google Cloud's Agent Platform (for example, when using an LLM gateway)
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| `CLAUDE_CODE_DISABLE_VIRTUAL_SCROLL` | Set to `1` to disable virtual scrolling in [fullscreen rendering](/docs/en/fullscreen) and render every message in the transcript. Use this if scrolling in fullscreen mode shows blank regions where messages should appear | | `CLAUDE_CODE_DISABLE_WORKFLOWS` | Set to `1` to disable [workflows](/docs/en/workflows#turn-workflows-off). Equivalent to the [`disableWorkflows`](/docs/en/settings#available-settings) setting | | `CLAUDE_CODE_EFFORT_LEVEL` | Set the effort level for supported models. Values: `low`, `medium`, `high`, `xhigh`, `max`, or `auto` to use the model default. Available levels depend on the model. Takes precedence over `/effort` and the `effortLevel` setting. See [Adjust effort level](/docs/en/model-config#adjust-effort-level) | -| `CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT` | Set to `1` to enable appending extra text to the end of every [subagent](/docs/en/sub-agents)'s system prompt. The [`--append-subagent-system-prompt`](/docs/en/cli-reference#cli-flags) flag supplies the appended text and sets this variable automatically, so you don't need to set it yourself. Requires Claude Code v2.1.205 or later | +| `CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT` | Set to `1` to enable appending extra text to the end of the system prompt of every [subagent](/docs/en/sub-agents) other than a [forked subagent](/docs/en/sub-agents#fork-the-current-conversation). The [`--append-subagent-system-prompt`](/docs/en/cli-reference#cli-flags) flag supplies the appended text and sets this variable automatically, so you don't need to set it yourself. Requires Claude Code v2.1.205 or later | | `CLAUDE_CODE_ENABLE_AUTO_MODE` | Accepted for compatibility with older releases and has no effect. Auto mode is available by default on every provider, including Amazon Bedrock, Google Cloud's Agent Platform, Microsoft Foundry, and signed-in [Claude apps gateway](/docs/en/claude-apps-gateway) sessions. In v2.1.158 through v2.1.206, setting this to `1` was required to make [auto mode](/docs/en/permission-modes#eliminate-prompts-with-auto-mode) available on those providers | | `CLAUDE_CODE_ENABLE_AWAY_SUMMARY` | Override [session recap](/docs/en/interactive-mode#session-recap) availability. Set to `0` to force recaps off regardless of the `/config` toggle. Set to `1` to force recaps on when [`awaySummaryEnabled`](/docs/en/settings#available-settings) is `false`. Takes precedence over the setting and `/config` toggle | | `CLAUDE_CODE_ENABLE_BACKGROUND_PLUGIN_REFRESH` | Set to `1` to refresh plugin state at turn boundaries in [non-interactive mode](/docs/en/headless) after a background install completes. Off by default because the refresh changes the system prompt mid-session, which invalidates [prompt caching](/docs/en/prompt-caching) for that turn |
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| `CLAUDE_CODE_SKIP_MANTLE_AUTH` | Skip AWS authentication for Amazon Bedrock Mantle (for example, when using an LLM gateway) | | `CLAUDE_CODE_SKIP_PROMPT_HISTORY` | Set to `1` to skip writing prompt history and session transcripts to disk. Sessions started with this variable set do not appear in `--resume`, `--continue`, or up-arrow history. Useful for ephemeral scripted sessions | | `CLAUDE_CODE_SKIP_VERTEX_AUTH` | Skip Google authentication for Google Cloud's Agent Platform (for example, when using an LLM gateway) | -| `CLAUDE_CODE_STOP_HOOK_BLOCK_CAP` | Maximum number of consecutive times a [Stop](/docs/en/hooks#stop) or [SubagentStop](/docs/en/hooks#subagentstop) hook may block the turn from ending before Claude Code overrides it and ends the turn anyway (default: 8). Set to `0` to disable the cap. Raise this if your hook legitimately needs more iterations to resolve +| `CLAUDE_CODE_STOP_HOOK_BLOCK_CAP` | Maximum number of consecutive times a [Stop](/docs/en/hooks#stop) or [SubagentStop](/docs/en/hooks#subagentstop) hook may block the turn from ending before Claude Code overrides it and ends the turn anyway (default: 8). Set to `0` to disable the cap. Raise this if your hook legitimately needs more iterations to resolve
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| `CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY` | Set to `1` to populate the `/model` picker from your gateway's `/v1/models` endpoint when `ANTHROPIC_BASE_URL` points at an Anthropic-compatible gateway such as LiteLLM, Kong, or an internal proxy. Off by default because gateways backed by a shared API key would otherwise show every user every model the key can access. Discovered models are still filtered by an [`availableModels`](/docs/en/settings#available-settings) allowlist the session receives; deliver the list through [MDM or a managed settings file](/docs/en/settings#settings-files), since [server-managed delivery is not available on gateway configurations](/docs/en/server-managed-settings#platform-availability) | | `CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE` | Removed in v2.1.142, when the [fast mode](/docs/en/fast-mode) default moved from Opus 4.6 to Opus 4.7 | | `CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION` | Set to `false` to disable prompt suggestions (the "Prompt suggestions" toggle in `/config`). These are the grayed-out predictions that appear in your prompt input. Takes precedence over the [`promptSuggestionEnabled`](/docs/en/settings#available-settings) setting. See [Prompt suggestions](/docs/en/interactive-mode#prompt-suggestions) | -| `CLAUDE_CODE_ENABLE_TASKS` | Controls whether sessions use the structured Task tools (`TaskCreate`, `TaskUpdate`, `TaskGet`, `TaskList`) or the legacy `TodoWrite` tool. As of Claude Code v2.1.142, Task tools are the default in all modes. Set to `0` to revert to `TodoWrite`. See [Task list](/docs/en/interactive-mode#task-list) and [Migrate to Task tools](/docs/en/agent-sdk/todo-tracking#migrate-to-task-tools) | +| `CLAUDE_CODE_ENABLE_TASKS` | Controls whether sessions use the structured Task tools (`TaskCreate`, `TaskUpdate`, `TaskGet`, `TaskList`) or the legacy `TodoWrite` tool. Task tools are the default in all modes. Set to `0` to use `TodoWrite`. See [Task list](/docs/en/interactive-mode#task-list) and [Migrate to Task tools](/docs/en/agent-sdk/todo-tracking#migrate-to-task-tools) | | `CLAUDE_CODE_ENABLE_TELEMETRY` | Set to `1` to enable OpenTelemetry data collection for metrics and logging. Required before configuring OTel exporters. See [Monitoring](/docs/en/monitoring-usage) | | `CLAUDE_CODE_EXIT_AFTER_STOP_DELAY` | Time in milliseconds to wait after the query loop becomes idle before automatically exiting. Useful for automated workflows and scripts using SDK mode | | `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS` | Set to `1` to enable [agent teams](/docs/en/agent-teams). Agent teams are experimental and disabled by default |
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# Environment variables ## Set environment variables ### In your shell ### In settings files ## Precedence ## Variables ## Features that need feature-flag fetching ### First session after an install or upgrade ## See also
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# Environment variables
> Reference for environment variables that control Claude Code behavior.
Environment variables can control Claude Code behavior such as model selection, authentication, request routing, and feature toggles. Many of the same behaviors can also be configured through a [settings file](/docs/en/settings) field, a [CLI flag](/docs/en/cli-reference), or an in-session command like `/model`.
This page covers how to:
* [Set environment variables](#set-environment-variables) in your shell or in a settings file
* [Check which value applies](#precedence) when a behavior can be set more than one way
* [Look up the variables Claude Code reads](#variables)
* [See which features stop working](#features-that-need-feature-flag-fetching) when a variable turns feature-flag fetching off
## Set environment variables
A variable you set in your shell lasts for that terminal session, while a variable in a settings file applies every time `claude` runs.
### In your shell
Set the variable before launching `claude`:
<Tabs>
<Tab title="macOS, Linux, WSL">
```bash theme={null}
export API_TIMEOUT_MS="1200000"
claude
```
To set it for every session, add the `export` line to `~/.bashrc`, `~/.zshrc`, or your shell's profile file.
</Tab>
<Tab title="Windows PowerShell">
```powershell theme={null}
$env:API_TIMEOUT_MS = "1200000"
claude
```
To set it for every session, run `[Environment]::SetEnvironmentVariable("API_TIMEOUT_MS", "1200000", "User")` and open a new terminal.
</Tab>
<Tab title="Windows CMD">
```batch theme={null}
set API_TIMEOUT_MS=1200000
claude
```
To set it for every session, run `setx API_TIMEOUT_MS "1200000"` and open a new terminal.
</Tab>
</Tabs>
The assignment line prints nothing on success, so confirm the variable is set by printing it in the same shell before you run `claude`:
<Tabs>
<Tab title="macOS, Linux, WSL">
```bash theme={null}
echo $API_TIMEOUT_MS
```
</Tab>
<Tab title="Windows PowerShell">
```powershell theme={null}
echo $env:API_TIMEOUT_MS
```
</Tab>
<Tab title="Windows CMD">
```batch theme={null}
echo %API_TIMEOUT_MS%
```
</Tab>
</Tabs>
### In settings files
Add variables under the `env` key in a `settings.json` file, creating the file if it doesn't exist. Claude Code reads them directly from the file, so they take effect no matter how `claude` was launched. A running session applies new and changed values to its environment when you save the file, but a feature that reads its variables once at startup, such as [OpenTelemetry monitoring](/docs/en/monitoring-usage), keeps its startup values until you relaunch. Removing a variable from the file doesn't unset it in a running session; the removal takes effect the next time you launch `claude`.
```json ~/.claude/settings.json theme={null}
{
"env": {
"API_TIMEOUT_MS": "1200000",
"BASH_DEFAULT_TIMEOUT_MS": "300000"
}
}
```
The file you choose controls who the variables apply to:
| File | Applies to |
| :---------------------------- | :------------------------------------------------------------------------------------------------------------------------------ |
| `~/.claude/settings.json` | You, in every project |
| `.claude/settings.json` | Everyone working in the project, checked into source control |
| `.claude/settings.local.json` | You, in this project only, gitignored when Claude Code saves a setting to it; add it to your gitignore if you create it by hand |
| Managed settings | Everyone in your organization, deployed by an admin |
See [Settings files](/docs/en/settings#settings-files) for where each file lives and [Settings precedence](/docs/en/settings#settings-precedence) for how they combine when more than one sets the same variable.
## Precedence
Some behaviors have both an environment variable and a dedicated settings key. If you set both, the environment variable takes precedence. For example, `ANTHROPIC_MODEL` overrides the `model` setting, and `CLAUDE_CODE_AUTO_CONNECT_IDE` overrides `autoConnectIde`. Claude Code uses the settings key only when the environment variable is unset.
When the same variable is set in both your shell and a settings file `env` block, the settings file value applies. Claude Code writes each `env` entry into the process environment at startup and again when the file changes, replacing the value inherited from the shell. A few variables are special-cased; the [`env` setting](/docs/en/settings#available-settings) lists the exceptions.
In a settings file you can set a variable but you can't remove one. To override a variable you can't unset, such as a stale `CLAUDE_CODE_USE_VERTEX` exported by a shell profile you don't control, set it to an empty string in the `env` block: `"CLAUDE_CODE_USE_VERTEX": ""`. Claude Code treats the empty value as unset for provider selection. Subprocesses still inherit the empty value.
Between settings files, `env` values follow [settings precedence](/docs/en/settings#settings-precedence), so a managed settings entry overrides the same variable in user or project settings.
How an environment variable interacts with CLI flags and in-session commands varies per feature: `--model` and `/model` override `ANTHROPIC_MODEL`, while `CLAUDE_CODE_EFFORT_LEVEL` overrides `/effort`. When a variable interacts with another configuration source, its row in the [Variables](#variables) list states the precedence or links to the page that documents it.
Claude Code reads shell environment variables at startup, so changes to them take effect the next time you launch `claude`. Variables set under the `env` key in settings files are reapplied to a running session when the file changes, with the startup-only exception described in [In settings files](#in-settings-files).
## Variables
Numeric variables such as timeouts, token budgets, and retry counts accept scientific notation and digit-separator spellings in addition to plain digits, except where a variable's row notes it takes plain digits only. For example, Claude Code reads `2e3` as 2000 and `64_000` as 64000. Before v2.1.211, these spellings could silently set a much smaller value, such as `1e6` setting a timeout to 1.
<Note>
For variables that turn a behavior on or off, set `1` or `true` to turn it on and `0` or `false` to turn it off, in any casing.
Some variables read only whether you set them at all, so any non-empty value including `0` turns the behavior on, and you turn the behavior off by unsetting the variable or setting it to an empty value. These variables work that way:
* `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC`
* `DISABLE_TELEMETRY`
* `DISABLE_ERROR_REPORTING`
* `CLAUDE_CODE_TMUX_TRUECOLOR`
* `FALLBACK_FOR_ALL_PRIMARY_MODELS`
* `IS_DEMO`
One other variable has its own rule: `FORCE_HYPERLINK` reads a number, so only `0` turns it off. Each variable's row also states its own rule.
</Note>
| Variable | Purpose |
| :------------------------------------------------------ | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `ANTHROPIC_API_KEY` | API key sent as `X-Api-Key` header. When set, this key is used instead of your Claude Pro, Max, Team, or Enterprise subscription even if you are logged in. In non-interactive mode (`-p`), the key is always used when present. In interactive mode, you are prompted to approve the key once before it overrides your subscription. To use your subscription instead, run `unset ANTHROPIC_API_KEY` |
| `ANTHROPIC_AUTH_TOKEN` | Custom value for the `Authorization` header (the value you set here will be prefixed with `Bearer `) |
| `ANTHROPIC_AWS_API_KEY` | Workspace API key for [Claude Platform on AWS](/docs/en/claude-platform-on-aws), generated in the AWS Console. Sent as `x-api-key` and takes precedence over AWS SigV4 |
| `ANTHROPIC_AWS_BASE_URL` | Override the [Claude Platform on AWS](/docs/en/claude-platform-on-aws) endpoint URL. Use for custom regions or when routing through an [LLM gateway](/docs/en/llm-gateway). Defaults to `https://aws-external-anthropic.{AWS_REGION}.api.aws` |
| `ANTHROPIC_AWS_WORKSPACE_ID` | Required for [Claude Platform on AWS](/docs/en/claude-platform-on-aws). Sent on every request as the `anthropic-workspace-id` header |
| `ANTHROPIC_BASE_URL` | Override the API endpoint to route requests through a proxy or gateway. When set to a non-first-party host, [MCP tool search](/docs/en/mcp#scale-with-mcp-tool-search) is disabled by default. Set `ENABLE_TOOL_SEARCH=true` if your proxy forwards `tool_reference` blocks. As of v2.1.196, [Remote Control](/docs/en/remote-control#requirements) is disabled when this points at a host other than `api.anthropic.com`, matching its behavior on Amazon Bedrock, Google Cloud's Agent Platform, and Microsoft Foundry |
| `ANTHROPIC_BEDROCK_BASE_URL` | Override the Amazon Bedrock endpoint URL. Use for custom Amazon Bedrock endpoints or when routing through an [LLM gateway](/docs/en/llm-gateway). See [Amazon Bedrock](/docs/en/amazon-bedrock) |
| `ANTHROPIC_BEDROCK_MANTLE_BASE_URL` | Override the Amazon Bedrock Mantle endpoint URL. See [Mantle endpoint](/docs/en/amazon-bedrock#use-the-mantle-endpoint) |
| `ANTHROPIC_BEDROCK_REGION_PREFIX` | Cross-region inference profile prefix (`us`, `eu`, `apac`, `jp`, `au`, or `global`) Claude Code tries first instead of the one derived from the AWS region. Ignored in AWS GovCloud regions. Requires Claude Code v2.1.224 or later. See [Amazon Bedrock](/docs/en/amazon-bedrock#cross-region-inference-profile-prefixes) |
| `ANTHROPIC_BEDROCK_SERVICE_TIER` | Amazon Bedrock [service tier](https://docs.aws.amazon.com/bedrock/latest/userguide/service-tiers-inference.html) (`default`, `flex`, or `priority`). Sent as the `X-Amzn-Bedrock-Service-Tier` header. See [Amazon Bedrock](/docs/en/amazon-bedrock#service-tiers) |
| `ANTHROPIC_BETAS` | Comma-separated list of additional `anthropic-beta` header values to include in API requests. Claude Code already sends the beta headers it needs; use this to opt into an [Anthropic API beta](https://platform.claude.com/docs/en/api/beta-headers) before Claude Code adds native support. Unlike the [`--betas` flag](/docs/en/cli-reference#cli-flags), which requires API key authentication, this variable works with all auth methods including Claude.ai subscription |
| `ANTHROPIC_CUSTOM_HEADERS` | Custom headers to add to requests (`Name: Value` format, newline-separated for multiple headers). If a name or value contains a character an HTTP header can't carry, such as a curly quote or a zero-width space, Claude Code fails the request with an error that identifies the pair by position. Requires Claude Code v2.1.227 or later. [Invalid request header value](/docs/en/errors#invalid-request-header-value) lists the exact character set and where the check runs |
| `ANTHROPIC_CUSTOM_MODEL_OPTION` | Model ID to add as a custom entry in the `/model` picker. Use this to make a non-standard or gateway-specific model selectable without replacing built-in aliases. See [Model configuration](/docs/en/model-config#add-a-custom-model-option) |
| `ANTHROPIC_CUSTOM_MODEL_OPTION_DESCRIPTION` | Display description for the custom model entry in the `/model` picker. Defaults to `Custom model (<model-id>)` when not set |
| `ANTHROPIC_CUSTOM_MODEL_OPTION_NAME` | Display name for the custom model entry in the `/model` picker. Defaults to the model ID when not set |
| `ANTHROPIC_CUSTOM_MODEL_OPTION_SUPPORTED_CAPABILITIES` | Comma-separated list of [capabilities](/docs/en/model-config#customize-pinned-model-display-and-capabilities) the custom model supports, for example `effort,thinking`. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL` | Model ID that the `fable` alias resolves to, and the ID Claude Code recognizes as Fable 5 for [automatic model fallback](/docs/en/model-config#automatic-model-fallback) on third-party providers. See [Model configuration](/docs/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL_DESCRIPTION` | Display description for the pinned Fable model in the `/model` picker. Defaults to `Custom Fable model` when not set. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL_NAME` | Display name for the pinned Fable model in the `/model` picker. Defaults to the model ID when not set. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_FABLE_MODEL_SUPPORTED_CAPABILITIES` | Comma-separated list of [capabilities](/docs/en/model-config#customize-pinned-model-display-and-capabilities) the pinned Fable model supports, for example `effort,thinking`. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL` | Model ID that the `haiku` alias resolves to, also used for [background functionality](/docs/en/costs#background-token-usage). See [Model configuration](/docs/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL_DESCRIPTION` | Display description for the pinned Haiku model in the `/model` picker. Defaults to `Custom Haiku model` when not set. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME` | Display name for the pinned Haiku model in the `/model` picker. Defaults to the model ID when not set. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_HAIKU_MODEL_SUPPORTED_CAPABILITIES` | Comma-separated list of [capabilities](/docs/en/model-config#customize-pinned-model-display-and-capabilities) the pinned Haiku model supports, for example `effort,thinking`. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL` | Model ID that the `opus` alias resolves to, and that `opusplan` uses while Plan Mode is active. See [Model configuration](/docs/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL_DESCRIPTION` | Display description for the pinned Opus model in the `/model` picker. When not set, defaults to `Custom Opus model`, or `Custom Opus model (1M context)` if the pinned model ID has the `[1m]` suffix and `CLAUDE_CODE_DISABLE_1M_CONTEXT` isn't turned on. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL_NAME` | Display name for the pinned Opus model in the `/model` picker. Defaults to the model ID when not set. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_OPUS_MODEL_SUPPORTED_CAPABILITIES` | Comma-separated list of [capabilities](/docs/en/model-config#customize-pinned-model-display-and-capabilities) the pinned Opus model supports, for example `effort,thinking`. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL` | Model ID that the `sonnet` alias resolves to, and that `opusplan` uses when Plan Mode is not active. See [Model configuration](/docs/en/model-config#environment-variables) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL_DESCRIPTION` | Display description for the pinned Sonnet model in the `/model` picker. When not set, defaults to `Custom Sonnet model`, or `Custom Sonnet model (1M context)` if the pinned model ID has the `[1m]` suffix and `CLAUDE_CODE_DISABLE_1M_CONTEXT` isn't turned on. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL_NAME` | Display name for the pinned Sonnet model in the `/model` picker. Defaults to the model ID when not set. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_DEFAULT_SONNET_MODEL_SUPPORTED_CAPABILITIES` | Comma-separated list of [capabilities](/docs/en/model-config#customize-pinned-model-display-and-capabilities) the pinned Sonnet model supports, for example `effort,thinking`. See [Model configuration](/docs/en/model-config#customize-pinned-model-display-and-capabilities) |
| `ANTHROPIC_FEDERATION_RULE_ID` | Federation rule ID for [Workload Identity Federation](https://platform.claude.com/docs/en/manage-claude/workload-identity-federation). When you set it together with `ANTHROPIC_ORGANIZATION_ID`, Claude Code selects federation credentials, which rank above your `/login` credential. See [authentication precedence](/docs/en/authentication#authentication-precedence) |
| `ANTHROPIC_FOUNDRY_API_KEY` | API key for Microsoft Foundry authentication (see [Microsoft Foundry](/docs/en/microsoft-foundry)) |
| `ANTHROPIC_FOUNDRY_AUTH_TOKEN` | Bearer token for Microsoft Foundry authentication, such as a Microsoft Entra access token. Claude Code sends it as the `Authorization: Bearer` header. Takes precedence over `ANTHROPIC_FOUNDRY_API_KEY` and over the Azure default credential chain. See [Microsoft Foundry](/docs/en/microsoft-foundry). Requires Claude Code v2.1.203 or later |
| `ANTHROPIC_FOUNDRY_BASE_URL` | Full base URL for the Microsoft Foundry resource (for example, `https://my-resource.services.ai.azure.com/anthropic`). Alternative to `ANTHROPIC_FOUNDRY_RESOURCE` (see [Microsoft Foundry](/docs/en/microsoft-foundry)) |
| `ANTHROPIC_FOUNDRY_RESOURCE` | Microsoft Foundry resource name (for example, `my-resource`). Required if `ANTHROPIC_FOUNDRY_BASE_URL` is not set (see [Microsoft Foundry](/docs/en/microsoft-foundry)) |
| `ANTHROPIC_MODEL` | Name of the model setting to use (see [Model Configuration](/docs/en/model-config#environment-variables)) |
| `ANTHROPIC_ORGANIZATION_ID` | Organization ID for [Workload Identity Federation](https://platform.claude.com/docs/en/manage-claude/workload-identity-federation). Set it together with `ANTHROPIC_FEDERATION_RULE_ID`. See [authentication precedence](/docs/en/authentication#authentication-precedence) |
| `ANTHROPIC_PROFILE` | Name of the Anthropic profile to authenticate with, such as one created by [`ant auth login`](https://platform.claude.com/docs/en/cli-sdks-libraries/cli/authentication). The named profile ranks above your `/login` credential. See [authentication precedence](/docs/en/authentication#authentication-precedence) |
| `ANTHROPIC_SMALL_FAST_MODEL` | \[DEPRECATED] Name of [Haiku-class model for background tasks](/docs/en/costs) |
| `ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION` | Override AWS region for the Haiku-class model when using Amazon Bedrock or Amazon Bedrock Mantle. On Amazon Bedrock, this only takes effect when `ANTHROPIC_DEFAULT_HAIKU_MODEL` or the deprecated `ANTHROPIC_SMALL_FAST_MODEL` is also set, since Amazon Bedrock otherwise runs background tasks on the [default Sonnet model or the primary model](/docs/en/amazon-bedrock#4-pin-model-versions) in the session region |
| `ANTHROPIC_VERTEX_BASE_URL` | Override Google Cloud's Agent Platform endpoint URL. Use for custom Google Cloud's Agent Platform endpoints or when routing through an [LLM gateway](/docs/en/llm-gateway). See [Google Cloud's Agent Platform](/docs/en/google-vertex-ai) |
| `ANTHROPIC_VERTEX_PROJECT_ID` | GCP project ID for Google Cloud's Agent Platform requests. Overridden by `GCLOUD_PROJECT`, `GOOGLE_CLOUD_PROJECT`, or the project in your `GOOGLE_APPLICATION_CREDENTIALS` credential file. See [Google Cloud's Agent Platform](/docs/en/google-vertex-ai) |
| `ANTHROPIC_WORKSPACE_ID` | Workspace ID for [workload identity federation](https://platform.claude.com/docs/en/manage-claude/workload-identity-federation). Set this when your federation rule is scoped to more than one workspace so the token exchange knows which workspace to target |
| `API_FORCE_IDLE_TIMEOUT` | Override the 5-minute body idle timeout that aborts a streaming model response when no bytes arrive. Set to `0` to turn the timeout off, for example when a slow [gateway](/docs/en/llm-gateway) or local model pauses longer than 5 minutes between chunks, or `1` to keep it on for every provider. When unset, the timeout is active on providers other than the direct Anthropic API and [Claude Platform on AWS](/docs/en/claude-platform-on-aws). The [stream watchdogs](/docs/en/network-config#streaming-idle-watchdogs) run independently of it and abort a long silent pause even when you set `0` here. Requires Claude Code v2.1.169 or later |
| `API_TIMEOUT_MS` | Timeout for API requests in milliseconds (default: 600000, or 10 minutes; maximum: 2147483647). Increase this when requests time out on slow networks or when routing through a proxy. Values above the maximum overflow the underlying timer and cause requests to fail immediately |
| `AWS_BEARER_TOKEN_BEDROCK` | Amazon Bedrock API key for authentication (see [Amazon Bedrock API keys](https://aws.amazon.com/blogs/machine-learning/accelerate-ai-development-with-amazon-bedrock-api-keys/)) |
| `BASH_DEFAULT_TIMEOUT_MS` | Default timeout for long-running bash commands (default: 120000, or 2 minutes) |
| `BASH_MAX_OUTPUT_LENGTH` | Maximum number of characters of bash output that Claude Code reads back into a command's result (default: 30000; maximum: 150000). See [Output limits](/docs/en/tools-reference#output-limits) |
| `BASH_MAX_TIMEOUT_MS` | Maximum timeout the model can set for long-running bash commands (default: 600000, or 10 minutes). The effective ceiling is the larger of this and `BASH_DEFAULT_TIMEOUT_MS` |
| `CCR_FORCE_BUNDLE` | Set to `1` to force [`claude --cloud`](/docs/en/claude-code-on-the-web#send-local-repositories-without-github) to bundle and upload your local repository even when GitHub access is available |
| `CLAUDECODE` | Set to `1` in subprocesses Claude Code spawns (Bash and PowerShell tools, tmux sessions, [hook](/docs/en/hooks) commands, [status line](/docs/en/statusline) commands, stdio [MCP server](/docs/en/mcp) subprocesses). IDE extensions also set this in their integrated terminals. Use to detect when a script is running inside a subprocess spawned by Claude Code. To check whether the current process was spawned directly by a tool call or hook, rather than inside a stdio MCP server that Claude Code started, use `CLAUDE_CODE_CHILD_SESSION` instead |
| `CLAUDE_AFK_COUNTDOWN_MS` | How many milliseconds before auto-continue the on-screen countdown appears on an unanswered [`AskUserQuestion`](/docs/en/tools-reference) dialog. Default `20000` (20 seconds), capped at the auto-continue timeout. Has no effect unless auto-continue is on; see the [`askUserQuestionTimeout`](/docs/en/settings#available-settings) setting and `CLAUDE_AFK_TIMEOUT_MS`. Requires Claude Code v2.1.198 or later |
| `CLAUDE_AFK_TIMEOUT_MS` | How many milliseconds of idle time before an unanswered [`AskUserQuestion`](/docs/en/tools-reference) dialog auto-continues without you. Auto-continue is off by default; opt in with the [`askUserQuestionTimeout`](/docs/en/settings#available-settings) setting. This variable is an override for demos and automated tests: when set, it takes precedence over that setting and turns auto-continue on even when the setting is unset or `never`. Setting `0` doesn't turn the timeout off; it closes the dialog immediately. In v2.1.198 and v2.1.199, auto-continue was on by default with a `60000` (60 seconds) timeout. Requires Claude Code v2.1.198 or later |
| `CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS` | Set to `1` to disable all built-in [subagent](/docs/en/sub-agents) types such as Explore and Plan. Only applies in non-interactive mode (the `-p` flag). Useful for SDK users who want a blank slate |
| `CLAUDE_AGENT_SDK_MCP_NO_PREFIX` | Set to `1` to skip the `mcp__<server>__` prefix on tool names from SDK-created MCP servers. Tools use their original names. SDK usage only |
| `CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS` | Stall timeout in milliseconds for background subagents. Default `600000` (10 minutes). The timer resets on each streaming progress event; if no progress arrives within the window, the subagent is aborted and the task is marked failed, surfacing any partial result to the parent |
| `CLAUDE_AUTOCOMPACT_PCT_OVERRIDE` | Set the percentage (1-100) of the auto-compact window at which auto-compaction triggers. Use lower values like `50` to compact earlier; the variable can't raise the threshold, so values above the default percentage are ignored. It applies only in sessions that [compact before the model's context limit](/docs/en/model-config#context-window-and-auto-compaction). Applies to both main conversations and subagents |
| `CLAUDE_AUTO_BACKGROUND_TASKS` | Set to `1` to force-enable automatic backgrounding of long-running agent tasks. When enabled, subagents are moved to the background after running for approximately two minutes. Also enables [automatic backgrounding of long MCP tool calls](/docs/en/mcp#automatic-backgrounding-of-long-tool-calls) in non-interactive mode on Claude Code v2.1.212 or later |
| `CLAUDE_AX_SCREEN_READER` | Set to `1` to render screen-reader friendly output: flat text without decorative borders or animations. Set to `0` to force screen-reader mode off even when [`axScreenReader`](/docs/en/settings#available-settings) is `true`. The [`--ax-screen-reader`](/docs/en/cli-reference#cli-flags) flag takes precedence. Requires Claude Code v2.1.181 or later |
| `CLAUDE_AX_STARTUP_QUIET_MS` | In [screen reader mode](/docs/en/accessibility), how many milliseconds Claude Code holds the first interface render after the startup confirmation line, so your screen reader can speak the line in full before new output interrupts it. Default `3000`. Set `0` to render immediately. Claude Code caps the hold at `600000` (10 minutes). Your first keystroke ends the hold early. Requires Claude Code v2.1.217 or later |
| `CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR` | Return to the original working directory after each Bash or PowerShell command in the main session |
| `CLAUDE_BYTE_STREAM_IDLE_TIMEOUT_MS` | Timeout in milliseconds for the byte-level streaming idle watchdog only; when set, it takes precedence over `CLAUDE_STREAM_IDLE_TIMEOUT_MS` for that watchdog and leaves the event-level watchdog unchanged. Claude Code clamps this variable to between 10 seconds and 30 minutes. Requires Claude Code v2.1.210 or later |
| `CLAUDE_CLIENT_PRESENCE_FILE` | Path to a file that an external tool, such as a screen-lock listener, creates when you unlock your screen and deletes when you lock it. While the file exists, Claude Code skips [Remote Control mobile push notifications](/docs/en/remote-control#mobile-push-notifications), so you stop getting pushes while you are actively using the computer. When the file is absent or unreadable, notifications are sent as normal. Claude Code checks the file once per push-triggering event rather than polling it. Requires Claude Code v2.1.181 or later |
| `CLAUDE_CODE_ACCESSIBILITY` | Set to `1` to keep the native terminal cursor visible and disable the inverted-text cursor indicator. Allows screen magnifiers like macOS Zoom to track cursor position |
| `CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD` | Set to `1` to load memory files from directories specified with `--add-dir`. Loads `CLAUDE.md`, `.claude/CLAUDE.md`, `.claude/rules/*.md`, and `CLAUDE.local.md`. By default, additional directories do not load memory files |
| `CLAUDE_CODE_ALT_SCREEN_FULL_REPAINT` | Set to `1` to repaint the entire screen on every frame in [fullscreen rendering](/docs/en/fullscreen) instead of sending incremental updates. Use this if fullscreen mode shows stale or misplaced text fragments. Claude Code enables this automatically for background sessions and [agent view](/docs/en/agent-view) on Windows |
| `CLAUDE_CODE_ALWAYS_ENABLE_EFFORT` | Set to `1` to send the [effort](/docs/en/model-config#adjust-effort-level) parameter with every request, even when Claude Code does not recognize the model ID as effort-capable. Use this when routing through an [LLM gateway](/docs/en/llm-gateway) or third-party provider that serves models under custom identifiers. Models that reject the effort parameter at the API, including Claude 3 models, Sonnet 4.0 and 4.5, Opus 4.0 and 4.1, and Haiku 4.5, are still excluded so requests do not fail |
| `CLAUDE_CODE_API_KEY_HELPER_TTL_MS` | Interval in milliseconds at which credentials should be refreshed (when using [`apiKeyHelper`](/docs/en/settings#available-settings)) |
| `CLAUDE_CODE_ARTIFACT_AUTO_OPEN` | Set to `0` to stop Claude Code from opening the browser automatically when a new [artifact](/docs/en/artifacts) is published. Republishing an existing artifact does not open the browser regardless of this setting |
| `CLAUDE_CODE_ATTRIBUTION_HEADER` | Set to `0` to omit the [attribution block](/docs/en/llm-gateway-protocol#system-prompt-attribution-block), which carries the client version and a prompt fingerprint, from the start of the system prompt. Caching on a direct connection to the Anthropic API is unaffected either way. In some direct-connection setups, Claude Code keeps the block on [auto mode](/docs/en/permission-modes#eliminate-prompts-with-auto-mode) classifier requests even when you set `0`. In [System prompt attribution block](/docs/en/llm-gateway-protocol#system-prompt-attribution-block), check which connections and credentials this covers. Before v2.1.181 the block included a per-request token on custom base URLs and Microsoft Foundry connections, so on those versions set it to `0` when your LLM gateway caches on the request body or forwards requests to a third-party provider, or when you connect to Microsoft Foundry directly |
| `CLAUDE_CODE_AUTO_COMPACT_WINDOW` | Set the [auto-compact window](/docs/en/model-config#set-the-auto-compact-window) in tokens, from `100000` to `1000000`. Accepts a plain integer such as `500000` only: a value like `500k` reads as `500` and clamps to the 100K minimum. Takes precedence over the `/autocompact` command, the `--autocompact` flag, and the `autoCompactWindow` setting. The status line's `used_percentage` always measures against the model's full context window, so once this variable is set, that percentage no longer indicates when compaction will run |
| `CLAUDE_CODE_AUTO_CONNECT_IDE` | Override automatic [IDE connection](/docs/en/vs-code). By default, Claude Code connects automatically when launched inside a supported IDE's integrated terminal. Set to `false` to prevent this. Set to `true` to force a connection attempt when auto-detection fails, such as when tmux obscures the parent terminal. Takes precedence over the [`autoConnectIde`](/docs/en/settings#global-config-settings) global config setting |
| `CLAUDE_CODE_AWS_CHAIN_RESOLVE_TIMEOUT_MS` | Time in milliseconds Claude Code waits for the AWS default credential provider chain to produce credentials before the request fails with [`AWS default-chain credential resolve timed out`](/docs/en/errors#aws-default-chain-credential-resolve-timed-out) (default: `60000`). Raise it when a step in your chain legitimately needs longer, such as a browser-based SSO sign-in with MFA through a wrapper like `aws-vault`. Applies wherever Claude Code signs with the default chain: [Amazon Bedrock](/docs/en/amazon-bedrock#credential-caching-and-resolution-timeout), [Claude Platform on AWS](/docs/en/claude-platform-on-aws), and the [Mantle endpoint](/docs/en/amazon-bedrock#use-the-mantle-endpoint). Requires Claude Code v2.1.207 or later |
| `CLAUDE_CODE_BRIDGE_SESSION_ID` | Set automatically in Bash tool and [hook command](/docs/en/hooks) subprocesses while the session has an active [Remote Control](/docs/en/remote-control) connection, and removed when the connection ends. The value is the session's ID in `session_` form, the same identifier that appears in the session's `claude.ai/code` URL, so a script can link back to the session that ran it. Requires Claude Code v2.1.199 or later. In [cloud sessions](/docs/en/claude-code-on-the-web), read `CLAUDE_CODE_REMOTE_SESSION_ID` instead |
| `CLAUDE_CODE_CERT_STORE` | Comma-separated list of CA certificate sources for TLS connections. `bundled` is the Mozilla CA set shipped with Claude Code. `system` is the operating system trust store, read only on runtimes with `tls.getCACertificates`: the native binary, or Node 22.15 or later for npm installs. See [CA certificate store](/docs/en/network-config#ca-certificate-store). Default is `bundled,system` |
| `CLAUDE_CODE_CHILD_SESSION` | Set to `1` in subprocesses Claude Code spawns via the Bash, PowerShell, and Monitor tools, [hook](/docs/en/hooks) commands, and [status line](/docs/en/statusline) commands. Not set for stdio [MCP server](/docs/en/mcp) subprocesses, which are long-lived and outlive the session that spawned them. Unlike `CLAUDECODE`, this is only set by Claude Code itself when it launches a subprocess and not by IDE extensions, so it reliably distinguishes a nested session from a top-level `claude` launched in an IDE-integrated terminal. A nested interactive `claude` TUI started this way is automatically excluded from `--resume`, `--continue`, up-arrow history, and the `claude agents` list. Non-interactive `claude -p` sessions still persist. Set `CLAUDE_CODE_FORCE_SESSION_PERSISTENCE=1` to override this exclusion. Requires Claude Code v2.1.172 or later |
| `CLAUDE_CODE_CLIENT_CERT` | Path to client certificate file for mTLS authentication |
| `CLAUDE_CODE_CLIENT_KEY` | Path to client private key file for mTLS authentication |
| `CLAUDE_CODE_CLIENT_KEY_PASSPHRASE` | Passphrase for encrypted CLAUDE\_CODE\_CLIENT\_KEY (optional) |
| `CLAUDE_CODE_CONNECT_TIMEOUT_MS` | Removed in v2.1.186 and now a no-op. Previously set a separate timeout for the connect, TLS, and response-header phase of a streaming API request. Use `API_TIMEOUT_MS` for the per-request timeout |
| `CLAUDE_CODE_DEBUG_LOGS_DIR` | Override the debug log file path. Despite the name, this is a file path, not a directory. Requires debug mode to be enabled separately via `--debug`, `/debug`, or the `DEBUG` environment variable: setting this variable alone does not enable logging. The [`--debug-file`](/docs/en/cli-reference#cli-flags) flag does both at once. Defaults to `~/.claude/debug/<session-id>.txt` |
| `CLAUDE_CODE_DEBUG_LOG_LEVEL` | Minimum log level written to the debug log file. Values: `verbose`, `debug` (default), `info`, `warn`, `error`. Set to `verbose` to include high-volume diagnostics like full status line command output, or raise to `error` to reduce noise |
| `CLAUDE_CODE_DISABLE_1M_CONTEXT` | Set to `1` to disable [1M context window](/docs/en/model-config#extended-context) support. When set, 1M model variants are unavailable in the model picker, and Claude Code holds sessions on models with a native 1M window, such as [Sonnet 5](/docs/en/model-config#sonnet-5-context-window) and Fable 5, to a 200K window; see [Extended context](/docs/en/model-config#extended-context) for how the hold is enforced. Useful for enterprise environments with compliance requirements. For its role in correcting the window for an unrecognized `[1m]` model ID, see [Correct the window for a gateway or custom model ID](/docs/en/model-config#correct-the-window-for-a-gateway-or-custom-model-id) |
| `CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING` | Set to `1` to disable [adaptive reasoning](/docs/en/model-config#adjust-effort-level) on Opus 4.6 and Sonnet 4.6 and fall back to the fixed thinking budget controlled by `MAX_THINKING_TOKENS`. Has no effect on Fable 5, Sonnet 5, or Opus 4.7 and later, which always use adaptive reasoning |
| `CLAUDE_CODE_DISABLE_ADMIN_ENV_UNION` | Set to `1` to stop Claude Code from merging [managed settings](/docs/en/settings#precedence-within-the-managed-tier) `env` blocks per key across admin sources, so only the highest-priority source's whole `env` block applies, as before v2.1.223. Set it in the environment that launches Claude Code, since Claude Code ignores a copy delivered through a settings `env` block. Requires Claude Code v2.1.223 or later |
| `CLAUDE_CODE_DISABLE_ADVISOR_TOOL` | Set to `1` to disable the [advisor tool](/docs/en/advisor). The `/advisor` command becomes unavailable, any configured `advisorModel` is ignored, and the `--advisor` flag is accepted but has no effect, so existing scripts that pass it continue to work without errors |
| `CLAUDE_CODE_DISABLE_AGENT_VIEW` | Set to `1` to turn off [background agents and agent view](/docs/en/agent-view): `claude agents`, `--bg`, `/background`, and the on-demand supervisor. Equivalent to the [`disableAgentView`](/docs/en/settings#available-settings) setting |
| `CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN` | Set to `1` to disable [fullscreen rendering](/docs/en/fullscreen) and use the classic main-screen renderer. The conversation stays in your terminal's native scrollback so `Cmd+f` and tmux copy mode work as usual. Takes precedence over `CLAUDE_CODE_NO_FLICKER` and the [`tui`](/docs/en/settings#available-settings) setting. You can also switch with `/tui default`. Does not apply to background sessions opened from [agent view](/docs/en/agent-view), which always use fullscreen rendering |
| `CLAUDE_CODE_DISABLE_ARTIFACT` | Set to `1` to disable the [Artifact](/docs/en/artifacts) tool, which publishes session output as a private web page on claude.ai. Equivalent to the [`disableArtifact`](/docs/en/settings#available-settings) setting |
| `CLAUDE_CODE_DISABLE_ATTACHMENTS` | Set to `1` to disable attachment processing. File mentions with `@` syntax are sent as plain text instead of being expanded into file content |
| `CLAUDE_CODE_DISABLE_AUTO_MEMORY` | Set to `1` to disable [auto memory](/docs/en/memory#auto-memory). Set to `0` to force auto memory on even when `--bare` mode or [`autoMemoryEnabled: false`](/docs/en/settings#available-settings) would otherwise disable it. When disabled, Claude does not create or load auto memory files |
| `CLAUDE_CODE_DISABLE_BACKGROUND_TASKS` | Set to `1` to disable all background task functionality, including the `run_in_background` parameter on Bash and subagent tools, auto-backgrounding, and the Ctrl+B shortcut |
| `CLAUDE_CODE_DISABLE_BEDROCK_CONTENT_TYPE_GUARD` | Set to `1` to skip the check that an [Amazon Bedrock](/docs/en/amazon-bedrock) streaming response carries the `application/vnd.amazon.eventstream` content-type. Without this variable, a response with a different content-type fails with an error naming that content-type, which means a [gateway or proxy is transforming the response](/docs/en/amazon-bedrock#streaming-errors-behind-a-gateway-or-proxy). Set it only when the gateway rewrites the `Content-Type` header but passes the binary event-stream body through unmodified; if the body itself was transformed, requests fail with `Truncated event message received` instead. Requires Claude Code v2.1.208 or later |
| `CLAUDE_CODE_DISABLE_BG_EXIT_HANDOFF` | Set to `1` to stop a [background session's](/docs/en/agent-view) running background shell commands, dynamic workflows, and, as of v2.1.198, background subagents when the [supervisor](/docs/en/agent-view#the-supervisor-process) stops, restarts, or updates that session's process, instead of handing them to the session's next process. Affects only that handoff: backgrounding a session with `←` or [`/background`](/docs/en/agent-view#from-inside-a-session) still carries in-flight work over, and `CLAUDE_DISABLE_ADOPT` turns off both. Requires Claude Code v2.1.196 or later |
| `CLAUDE_CODE_DISABLE_BG_SHELL_PRESSURE_REAP` | Set to `1` to stop Claude Code from terminating [background shell commands](/docs/en/interactive-mode#background-bash-commands) when the operating system reports memory pressure. By default, on macOS and Linux, Claude Code terminates a background shell started in the main session on a memory-pressure signal once the session has been idle for 30 minutes and no turn or subagent is running. Windows has no memory-pressure signal, so this variable has no effect there. Requires Claude Code v2.1.193 or later |
| `CLAUDE_CODE_DISABLE_BUNDLED_SKILLS` | Set to `1` to disable the [skills](/docs/en/skills) and workflows included with Claude Code: bundled skills and workflows are removed entirely, while built-in commands like `/init` stay typable but are hidden from the model. `/doctor` stays typable like the built-in commands; hide it with `DISABLE_DOCTOR_COMMAND` instead. Skills from plugins, `.claude/skills/`, and `.claude/commands/` are unaffected. Equivalent to the [`disableBundledSkills`](/docs/en/settings#available-settings) setting |
| `CLAUDE_CODE_DISABLE_CLAUDE_MDS` | Set to `1` to prevent loading any CLAUDE.md memory files into context, including user, project, and auto memory files |
| `CLAUDE_CODE_DISABLE_CRON` | Set to `1` to disable [scheduled tasks](/docs/en/scheduled-tasks). The `/loop` skill and cron tools become unavailable and any already-scheduled tasks stop firing, including tasks that are already running mid-session |
| `CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS` | Set to `1` to strip Anthropic-specific `anthropic-beta` request headers and beta tool-schema fields (such as `defer_loading` and `eager_input_streaming`) from API requests. Use this when a proxy gateway rejects requests with errors like "Unexpected value(s) for the `anthropic-beta` header" or "Extra inputs are not permitted". Standard fields (`name`, `description`, `input_schema`, `cache_control`) are preserved. [MCP tool search](/docs/en/mcp#scale-with-mcp-tool-search) is disabled and all MCP tools load upfront, even when you set `ENABLE_TOOL_SEARCH`. On Claude Code v2.1.227 or later, [managed settings](/docs/en/settings#settings-files) can keep tool search on. [Disable pre-release capabilities](/docs/en/llm-gateway-protocol#disable-pre-release-capabilities) covers where the override applies |
| `CLAUDE_CODE_DISABLE_EXPLORE_PLAN_AGENTS` | Set to `1` to disable the built-in [Explore and Plan subagents](/docs/en/sub-agents#built-in-subagents). Claude explores with its search tools or the general-purpose subagent instead, and [plan mode](/docs/en/permission-modes#analyze-before-you-edit-with-plan-mode) reads files directly rather than launching Explore and Plan agents. Custom subagents named `Explore` or `Plan` are unaffected. To remove every built-in subagent type in the Agent SDK or non-interactive mode, use `CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS` instead. Requires Claude Code v2.1.198 or later |
| `CLAUDE_CODE_DISABLE_FAST_MODE` | Set to `1` to disable [fast mode](/docs/en/fast-mode) |
| `CLAUDE_CODE_DISABLE_FEEDBACK_SURVEY` | Set to `1` to disable the "How is Claude doing?" session quality surveys. Surveys are also disabled when `DISABLE_TELEMETRY`, `DO_NOT_TRACK`, or `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC` is set, unless `CLAUDE_CODE_ENABLE_FEEDBACK_SURVEY_FOR_OTEL` opts back in. To set a sample rate instead of disabling outright, use the [`feedbackSurveyRate`](/docs/en/settings#available-settings) setting. See [Session quality surveys](/docs/en/data-usage#session-quality-surveys) |
| `CLAUDE_CODE_DISABLE_FILE_CHECKPOINTING` | Set to `1` to disable file [checkpointing](/docs/en/checkpointing). The `/rewind` command will not be able to restore code changes. Overrides the [`fileCheckpointingEnabled`](/docs/en/settings#available-settings) setting |
| `CLAUDE_CODE_DISABLE_GIT_INSTRUCTIONS` | Set to `1` to remove built-in commit and PR workflow instructions and the git status snapshot from Claude's system prompt. Useful when using your own git workflow skills. Takes precedence over the [`includeGitInstructions`](/docs/en/settings#available-settings) setting when set |
| `CLAUDE_CODE_DISABLE_LEGACY_MODEL_REMAP` | Set to `1` to prevent automatic remapping of Opus 4.0 and 4.1 to the current Opus version on the Anthropic API. Use when you intentionally want to pin an older model. The remap does not run on Amazon Bedrock, Google Cloud's Agent Platform, or Microsoft Foundry |
| `CLAUDE_CODE_DISABLE_MOUSE` | Set to `1` to disable mouse tracking in [fullscreen rendering](/docs/en/fullscreen). Keyboard scrolling with `PgUp` and `PgDn` still works. Use this to keep your terminal's native copy-on-select behavior |
| `CLAUDE_CODE_DISABLE_MOUSE_CLICKS` | Set to `1` to disable click, drag, and hover handling in [fullscreen rendering](/docs/en/fullscreen) while keeping mouse-wheel scrolling. Use this when you want wheel scroll to work inside Claude Code but don't want clicks to position the cursor, expand tool output, or open links. `CLAUDE_CODE_DISABLE_MOUSE` takes precedence when both are set. Requires Claude Code v2.1.195 or later |
| `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC` | Set to any non-empty value, such as `1`, to disable nonessential network traffic: auto-updates, telemetry, error reporting, the `/feedback` command, release notes, [gateway model discovery](/docs/en/llm-gateway-connect#add-gateway-models-to-the-model-picker) refreshes, and availability checks such as the [fast mode](/docs/en/fast-mode#use-fast-mode-behind-proxies-and-llm-gateways) check. It also stops the [background runs of plugin `command` sources](/docs/en/plugin-marketplaces#when-claude-code-re-runs-the-command), which are local commands rather than network traffic, because they can trigger dependency installs. **Setting it to `0` or `false` still disables this traffic**, unlike most on/off variables; unset the variable to allow it again. Also disables feature-flag fetching, which makes [Remote Control](/docs/en/remote-control#requirements) and the other [features that need feature-flag fetching](#features-that-need-feature-flag-fetching) unavailable. Official plugin marketplace auto-install isn't covered; disable it with `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` |
| `CLAUDE_CODE_DISABLE_NONSTREAMING_FALLBACK` | Set to `1` to disable the non-streaming fallback when a streaming request fails mid-stream. Streaming errors propagate to the retry layer instead. Useful when a proxy or gateway causes the fallback to produce duplicate tool execution |
| `CLAUDE_CODE_DISABLE_NOTIFICATION_PRESENCE_CHECK` | Set to `1` to send the `PushNotification` tool's desktop notification even while you are typing in or focused on the terminal. By default the tool skips both the desktop notification and the [mobile push](/docs/en/remote-control#mobile-push-notifications) when it detects recent keyboard activity or terminal focus. This variable disables only that local check, so the server can still suppress the mobile push when it detects that you are active. Requires Claude Code v2.1.193 or later |
| `CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL` | Set to `1` to disable automatic registration of the official plugin marketplace. Claude Code reads the variable when it is about to register the marketplace, usually during a machine's first interactive launch. If the variable is set at that point, Claude Code skips the registration permanently. Unsetting the variable later doesn't undo the skip. Run `claude plugin marketplace add anthropics/claude-plugins-official` to register the marketplace at any time |
| `CLAUDE_CODE_DISABLE_POLICY_SKILLS` | Set to `1` to skip loading skills from the system-wide managed skills directory. Useful for container or CI sessions that should not load operator-provisioned skills |
| `CLAUDE_CODE_DISABLE_TERMINAL_TITLE` | Set to `1` to disable automatic terminal title updates based on conversation context. In Agent SDK and `claude -p` sessions, this also skips the background small/fast-model request that generates the session title |
| `CLAUDE_CODE_DISABLE_THINKING` | Set to `1` to omit the `thinking` parameter from API requests entirely. This is a compatibility option for proxies and gateways that reject the parameter. The variable's behavior is unchanged from earlier versions; on models that think by default, omitting the parameter means the model may still think. To explicitly disable [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) on the Anthropic API, use `MAX_THINKING_TOKENS=0` instead, which is also ineffective on Fable 5 since it cannot have thinking turned off. On [third-party providers](/docs/en/third-party-integrations), `0` likewise omits the parameter, so the two variables behave the same there |
| `CLAUDE_CODE_DISABLE_UNKNOWN_MODEL_WINDOW_ENFORCEMENT` | Set to `1` to skip proactive [auto-compaction](/docs/en/costs#reduce-token-usage) when Claude Code doesn't recognize the model ID, such as an [LLM gateway](/docs/en/llm-gateway) alias. Without this variable, Claude Code compacts at the context window it assumes for the ID. `CLAUDE_CODE_MAX_CONTEXT_TOKENS` can correct the assumed window instead; see [Correct the window for a gateway or custom model ID](/docs/en/model-config#correct-the-window-for-a-gateway-or-custom-model-id) for when each variable applies. Requires Claude Code v2.1.223 or later |
| `CLAUDE_CODE_DISABLE_VIRTUAL_SCROLL` | Set to `1` to disable virtual scrolling in [fullscreen rendering](/docs/en/fullscreen) and render every message in the transcript. Use this if scrolling in fullscreen mode shows blank regions where messages should appear |
| `CLAUDE_CODE_DISABLE_WORKFLOWS` | Set to `1` to disable [workflows](/docs/en/workflows#turn-workflows-off). Equivalent to the [`disableWorkflows`](/docs/en/settings#available-settings) setting |
| `CLAUDE_CODE_EFFORT_LEVEL` | Set the effort level for supported models. Values: `low`, `medium`, `high`, `xhigh`, `max`, or `auto` to use the model default. Available levels depend on the model. Takes precedence over `/effort` and the `effortLevel` setting. See [Adjust effort level](/docs/en/model-config#adjust-effort-level) |
| `CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT` | Set to `1` to enable appending extra text to the end of every [subagent](/docs/en/sub-agents)'s system prompt. The [`--append-subagent-system-prompt`](/docs/en/cli-reference#cli-flags) flag supplies the appended text and sets this variable automatically, so you don't need to set it yourself. Requires Claude Code v2.1.205 or later |
| `CLAUDE_CODE_ENABLE_AUTO_MODE` | Accepted for compatibility with older releases and has no effect. Auto mode is available by default on every provider, including Amazon Bedrock, Google Cloud's Agent Platform, Microsoft Foundry, and signed-in [Claude apps gateway](/docs/en/claude-apps-gateway) sessions. In v2.1.158 through v2.1.206, setting this to `1` was required to make [auto mode](/docs/en/permission-modes#eliminate-prompts-with-auto-mode) available on those providers |
| `CLAUDE_CODE_ENABLE_AWAY_SUMMARY` | Override [session recap](/docs/en/interactive-mode#session-recap) availability. Set to `0` to force recaps off regardless of the `/config` toggle. Set to `1` to force recaps on when [`awaySummaryEnabled`](/docs/en/settings#available-settings) is `false`. Takes precedence over the setting and `/config` toggle |
| `CLAUDE_CODE_ENABLE_BACKGROUND_PLUGIN_REFRESH` | Set to `1` to refresh plugin state at turn boundaries in [non-interactive mode](/docs/en/headless) after a background install completes. Off by default because the refresh changes the system prompt mid-session, which invalidates [prompt caching](/docs/en/prompt-caching) for that turn |
| `CLAUDE_CODE_ENABLE_FEEDBACK_SURVEY_FOR_OTEL` | Set to `1` to route the "How is Claude doing?" session quality survey to your own [OpenTelemetry collector](/docs/en/monitoring-usage) when Anthropic-bound nonessential traffic is blocked. Survey ratings are emitted only as OTEL events to your configured collector. No survey data is sent to Anthropic in this mode. Applies when `CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC`, `DISABLE_TELEMETRY`, or `DO_NOT_TRACK` is set, and has no effect otherwise. `CLAUDE_CODE_DISABLE_FEEDBACK_SURVEY` and the organization product feedback policy take precedence |
| `CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING` | Controls whether tool call inputs stream from the API as Claude generates them. With this off, a large tool input such as a long file write arrives only after Claude finishes generating it, which can look like it's hanging. Enabled by default on the Anthropic API. On Amazon Bedrock and Google Cloud's Agent Platform, enabled per model where the deployed container supports it. Set to `0` to opt out. Set to `1` to force on when routing through a proxy via `ANTHROPIC_BASE_URL`, `ANTHROPIC_VERTEX_BASE_URL`, or `ANTHROPIC_BEDROCK_BASE_URL`. Off by default on Microsoft Foundry and [gateway](/docs/en/llm-gateway) connections |
| `CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY` | Set to `1` to populate the `/model` picker from your gateway's `/v1/models` endpoint when `ANTHROPIC_BASE_URL` points at an Anthropic-compatible gateway such as LiteLLM, Kong, or an internal proxy. Off by default because gateways backed by a shared API key would otherwise show every user every model the key can access. Discovered models are still filtered by an [`availableModels`](/docs/en/settings#available-settings) allowlist the session receives; deliver the list through [MDM or a managed settings file](/docs/en/settings#settings-files), since [server-managed delivery is not available on gateway configurations](/docs/en/server-managed-settings#platform-availability) |
| `CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE` | Removed in v2.1.142, when the [fast mode](/docs/en/fast-mode) default moved from Opus 4.6 to Opus 4.7 |
| `CLAUDE_CODE_ENABLE_PROMPT_SUGGESTION` | Set to `false` to disable prompt suggestions (the "Prompt suggestions" toggle in `/config`). These are the grayed-out predictions that appear in your prompt input. Takes precedence over the [`promptSuggestionEnabled`](/docs/en/settings#available-settings) setting. See [Prompt suggestions](/docs/en/interactive-mode#prompt-suggestions) |
| `CLAUDE_CODE_ENABLE_TASKS` | Controls whether sessions use the structured Task tools (`TaskCreate`, `TaskUpdate`, `TaskGet`, `TaskList`) or the legacy `TodoWrite` tool. As of Claude Code v2.1.142, Task tools are the default in all modes. Set to `0` to revert to `TodoWrite`. See [Task list](/docs/en/interactive-mode#task-list) and [Migrate to Task tools](/docs/en/agent-sdk/todo-tracking#migrate-to-task-tools) |
| `CLAUDE_CODE_ENABLE_TELEMETRY` | Set to `1` to enable OpenTelemetry data collection for metrics and logging. Required before configuring OTel exporters. See [Monitoring](/docs/en/monitoring-usage) |
| `CLAUDE_CODE_EXIT_AFTER_STOP_DELAY` | Time in milliseconds to wait after the query loop becomes idle before automatically exiting. Useful for automated workflows and scripts using SDK mode |
| `CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS` | Set to `1` to enable [agent teams](/docs/en/agent-teams). Agent teams are experimental and disabled by default |
| `CLAUDE_CODE_EXTRA_BODY` | JSON object to merge into the top level of every API request body. Useful for passing provider-specific parameters that Claude Code doesn't expose directly. A value exported in your shell also applies to the [background sessions](/docs/en/agent-view) you dispatch with `claude agents` or `--bg`. Before v2.1.206, background sessions ignored a shell-exported value and used whatever copy the background supervisor process inherited |
| `CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS` | Override the default token limit for file reads. Useful when you need to read larger files in full |
| `CLAUDE_CODE_FORCE_SESSION_PERSISTENCE` | Set to `1` to force transcript persistence, prompt history, and `claude agents` registration even when this `claude` was launched from inside another Claude Code session. Use when an inherited `CLAUDE_CODE_CHILD_SESSION` value, for example from a `screen` session or a background launcher first started by Claude Code's Bash tool, causes a genuine top-level session to be misclassified as nested. As of v2.1.178, Claude Code detects the tmux case automatically and ignores the inherited marker, so tmux no longer needs this variable. Also honored on v2.1.169 and earlier; has no effect on v2.1.170 and v2.1.171, where the nested-session detection it overrides was removed |
| `CLAUDE_CODE_FORCE_STRIKETHROUGH` | Set to `1` to force strikethrough rendering for `~~text~~` in Claude's responses when your terminal supports it but is not auto-detected, such as over SSH without `TERM_PROGRAM` forwarded. Without this, undetected terminals show the literal `~~` markers instead of rendering the text as strikethrough. Requires Claude Code v2.1.186 or later |
| `CLAUDE_CODE_FORCE_SYNC_OUTPUT` | Set to `1` to force-enable DEC private mode 2026 [synchronized output](https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036) when your terminal supports it but is not auto-detected. Useful for emulators such as Emacs `eat` that implement BSU/ESU but do not reply to the capability probe. Has no effect under tmux. Unlike `CLAUDE_CODE_NO_FLICKER`, which switches to [fullscreen rendering](/docs/en/fullscreen), this doesn't change the renderer |
| `CLAUDE_CODE_FORK_SUBAGENT` | Controls [fork mode](/docs/en/sub-agents#turn-fork-mode-on-or-off), which lets Claude spawn [forked subagents](/docs/en/sub-agents#fork-the-current-conversation) itself and is on by default in interactive sessions only. Set to `1` to turn it on in `claude -p` and the Agent SDK as well, or `0` to turn it off in every kind of session. The `/subtask` command works whether or not fork mode is on. The interactive default requires Claude Code v2.1.232 or later |
| `CLAUDE_CODE_FORWARD_SUBAGENT_TEXT` | Set to `1` to emit [subagent](/docs/en/sub-agents) text and thinking blocks in `claude -p --output-format stream-json` output, the same behavior as the [`--forward-subagent-text`](/docs/en/cli-reference#cli-flags) flag. Use the variable when a harness invokes `claude` and can't pass the flag itself. Unlike the flag, which exits with an error outside non-interactive mode with stream-json output, the variable is ignored there so that nested invocations keep working when it's set process-wide. Requires Claude Code v2.1.211 or later |
| `CLAUDE_CODE_GIT_BASH_PATH` | Windows only: path to the Git Bash executable (`bash.exe`). Use when Git Bash is installed but not in your PATH. If the path doesn't exist or the file isn't named `bash.exe`, `sh.exe`, `bash`, or `sh`, Claude Code ignores the variable and auto-detects Git Bash as if it were unset, logging a warning visible with `--debug`. Before v2.1.219, Claude Code exited at startup when the path didn't exist, and used any existing file as the shell without checking that it was bash or sh. See [Windows setup](/docs/en/setup#set-up-on-windows) |
| `CLAUDE_CODE_GLOB_HIDDEN` | Set to `false` to exclude dotfiles from results when Claude invokes the [Glob tool](/docs/en/tools-reference#glob-tool-behavior). Included by default. Does not affect `@` file autocomplete, `ls`, Grep, or Read |
| `CLAUDE_CODE_GLOB_NO_IGNORE` | Set to `false` to make the [Glob tool](/docs/en/tools-reference#glob-tool-behavior) respect `.gitignore` patterns. By default, Glob returns all matching files including gitignored ones. Does not affect `@` file autocomplete, which has its own [`respectGitignore` setting](/docs/en/settings#available-settings) |
| `CLAUDE_CODE_GLOB_TIMEOUT_SECONDS` | Timeout in seconds for Glob tool file discovery. Defaults to 20 seconds on most platforms and 60 seconds on WSL |
| `CLAUDE_CODE_HIDE_CWD` | Set to `1` to hide the working directory in the startup logo. Useful for screenshares or recordings where the path exposes your OS username |
| `CLAUDE_CODE_IDE_HOST_OVERRIDE` | Override the host address used to connect to the IDE extension. By default Claude Code auto-detects the correct address, including WSL-to-Windows routing |
| `CLAUDE_CODE_IDE_SKIP_AUTO_INSTALL` | Set to `1` to skip auto-installation of IDE extensions. Equivalent to setting [`autoInstallIdeExtension`](/docs/en/settings#global-config-settings) to `false` |
| `CLAUDE_CODE_IDE_SKIP_VALID_CHECK` | Set to `1` to skip validation of IDE lockfile entries during connection. Use when auto-connect fails to find your IDE despite it running |
| `CLAUDE_CODE_MAX_CONCURRENT_SUBAGENTS` | How many [subagents](/docs/en/sub-agents#concurrent-subagent-limit) can be running in one session before the Agent tool refuses to spawn another (default: 20). Accepts a positive whole number in plain digits; anything else is ignored, so the variable can adjust the cap but can't disable it. Requires Claude Code v2.1.217 or later |
| `CLAUDE_CODE_MAX_CONTEXT_TOKENS` | Override the context window size Claude Code assumes for the active model. As of v2.1.193, how it applies depends on how Claude Code resolves the model ID; see [Correct the window for a gateway or custom model ID](/docs/en/model-config#correct-the-window-for-a-gateway-or-custom-model-id). Use this when routing to a model through `ANTHROPIC_BASE_URL` whose context window does not match the built-in size for its name |
| `CLAUDE_CODE_MAX_OUTPUT_TOKENS` | Set the maximum number of output tokens for most requests. Defaults and caps vary by model; see [max output tokens](https://platform.claude.com/docs/en/about-claude/models/overview#latest-models-comparison). Claude Code defaults to 32000 for model IDs it doesn't recognize, such as gateway-specific names, and lowers values above a model's cap to the cap. Increasing this value reduces the effective context window available before [auto-compaction](/docs/en/costs#reduce-token-usage) triggers |
| `CLAUDE_CODE_MAX_RETRIES` | Override the number of times to retry failed API requests (default: 10). Capped at 15 as of v2.1.186; as of v2.1.199, `CLAUDE_CODE_RETRY_WATCHDOG` raises the default and removes the cap. For unattended sessions that need to wait through longer outages, set `CLAUDE_CODE_RETRY_WATCHDOG` instead |
| `CLAUDE_CODE_MAX_SUBAGENTS_PER_SESSION` | Removed in v2.1.224 and now a no-op. Previously capped the total number of [subagents](/docs/en/sub-agents) Claude could spawn with the Agent tool in one session (default: 200); spawning past the cap failed with `Subagent spawn limit reached`. The [concurrent subagent limit](/docs/en/sub-agents#concurrent-subagent-limit) and the [depth limit](/docs/en/sub-agents#let-subagents-spawn-their-own-subagents) still apply |
| `CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH` | Number of [subagent layers](/docs/en/sub-agents#let-subagents-spawn-their-own-subagents) allowed below the main conversation (default: 3). At the default, subagents can spawn their own subagents, and a subagent at the third layer can't spawn further; set `1` to turn nesting off. In v2.1.217 through v2.1.218, the default was 1, so a subagent couldn't spawn its own unless you raised the limit; v2.1.219 raised the default to 3. Accepts a positive whole number in plain digits; anything else is ignored, so the limit can be adjusted but not removed. Requires Claude Code v2.1.217 or later |
| `CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY` | Maximum number of read-only tools and subagents that can execute in parallel (default: 10). Higher values increase parallelism but consume more resources |
| `CLAUDE_CODE_MAX_TURNS` | Cap the number of agentic turns when no explicit limit is passed. Equivalent to passing [`--max-turns`](/docs/en/cli-reference#cli-flags), which takes precedence when both are set. A value that is not a positive integer is rejected at startup with an error rather than treated as no cap |
| `CLAUDE_CODE_MAX_WEB_SEARCHES_PER_SESSION` | Cap on the total number of [WebSearch](/docs/en/tools-reference#websearch-tool-behavior) calls one session can make (default: 200). When Claude reaches the cap, further WebSearch calls return a notice telling it to continue with the information it already gathered. Accepts a positive whole number with no upper bound. Anything else is ignored and the default applies, so the cap can be raised but not turned off. Requires Claude Code v2.1.212 or later |
| `CLAUDE_CODE_MCP_ALLOWLIST_ENV` | Set to `1` to spawn stdio MCP servers with only a safe baseline environment plus the server's configured `env`, instead of inheriting your shell environment |
| `CLAUDE_CODE_MCP_AUTO_BACKGROUND_MS` | Elapsed time in milliseconds before a still-running MCP tool call [moves to a background task](/docs/en/mcp#automatic-backgrounding-of-long-tool-calls) (default: 120000, or 2 minutes). Set to `0` to turn automatic backgrounding off. Requires Claude Code v2.1.212 or later |
| `CLAUDE_CODE_MCP_TOOL_IDLE_TIMEOUT` | Idle timeout in milliseconds for MCP tool calls. When a stdio, HTTP, SSE, WebSocket, or [claude.ai connector](/docs/en/mcp#use-mcp-servers-from-claude-ai) MCP server sends no response and no progress notification for this long, the tool call aborts with an error instead of waiting for the overall `MCP_TOOL_TIMEOUT`. Overrides the per-transport defaults of 300000 (5 minutes) for network servers and 1800000 (30 minutes) for stdio servers. Set to `0` to disable the idle check. Values below 1000 are raised to one second, and the value is capped at the effective `MCP_TOOL_TIMEOUT`. A per-server `timeout` in `.mcp.json` of at least 1000 raises that server's idle window to at least the `timeout` value. Doesn't apply to IDE servers or SDK in-process servers. Requires Claude Code v2.1.187 or later. Before v2.1.203, stdio servers were exempt from the idle timeout |
| `CLAUDE_CODE_MESSAGING_SOCKET` | Set by Claude Code, not by you: in sessions that bind an [inbox socket](/docs/en/cross-session-messaging#the-sessions-inbox-socket), Claude Code exports that socket's path to hooks and Bash commands when it binds the socket. In a session that starts with messaging on, Claude Code binds the socket before any hook runs. Other sessions on the machine deliver messages to this path. Each session exports its own socket rather than one inherited from a parent, and messages arriving on it go through the session's [inbound controls](/docs/en/cross-session-messaging#control-inbound-messages). Settings `env` blocks can't set it. Requires Claude Code v2.1.224 or later |
| `CLAUDE_CODE_MESSAGING_TOKEN` | Set by Claude Code, not by you: in sessions that bind an [inbox socket](/docs/en/cross-session-messaging#the-sessions-inbox-socket), Claude Code exports this per-session token to hooks and Bash commands alongside `CLAUDE_CODE_MESSAGING_SOCKET`. A script posting to the socket can send `{"type":"auth","token":"<token>"}` as its first line to prove it belongs to the session. The [own-child rules](/docs/en/cross-session-messaging#the-sessions-inbox-socket) say when Claude Code consults it. Each session exports its own token, never one inherited from a parent session. Settings `env` blocks can't set it. Requires Claude Code v2.1.228 or later |
| `CLAUDE_CODE_NATIVE_CURSOR` | Set to `1` to show the terminal's own cursor at the input caret instead of a drawn block. The cursor respects the terminal's blink, shape, and focus settings |
| `CLAUDE_CODE_NEW_INIT` | Set to `1` to make `/init` run an interactive setup flow. The flow asks which files to generate, including CLAUDE.md, skills, and hooks, before exploring the codebase and writing them. Without this variable, `/init` generates a CLAUDE.md automatically without prompting |
| `CLAUDE_CODE_NO_FLICKER` | Set to `1` to enable [fullscreen rendering](/docs/en/fullscreen), a research preview that reduces flicker and keeps memory flat in long conversations. Equivalent to the [`tui`](/docs/en/settings#available-settings) setting; you can also switch with `/tui fullscreen` |
| `CLAUDE_CODE_OAUTH_REFRESH_TOKEN` | OAuth refresh token for Claude.ai authentication. When set, `claude auth login` exchanges this token directly instead of opening a browser. Requires `CLAUDE_CODE_OAUTH_SCOPES`. Useful for provisioning authentication in automated environments |
| `CLAUDE_CODE_OAUTH_SCOPES` | Space-separated OAuth scopes the refresh token was issued with, such as `"user:profile user:inference user:sessions:claude_code"`. Required when `CLAUDE_CODE_OAUTH_REFRESH_TOKEN` is set |
| `CLAUDE_CODE_OAUTH_TOKEN` | OAuth access token for claude.ai authentication. Alternative to `/login` for SDK and automated environments. Takes precedence over keychain-stored credentials. Generate one with [`claude setup-token`](/docs/en/authentication#generate-a-long-lived-token). Unless you run [`/login`](/docs/en/authentication#authentication-precedence), Claude Code uses the token you set for the whole session. To replace an expired token, generate a new one and restart |
| `CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE` | Removed in v2.1.160 and now a no-op. Previously pinned [fast mode](/docs/en/fast-mode) to Claude Opus 4.6 instead of the current default. Opus 4.6 no longer supports fast mode |
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