{"name":"CLAUDE_CODE_DISABLE_ATTACHMENTS","slug":"claude-code-disable-attachments","family":"env","title":"Environment variables","noun":"environment variable","description":"Set to `1` to disable attachment processing. File mentions with `@` syntax are sent as plain text instead of being expanded into file content","description_source":"docs","described_by":{"doc":"claude-code\/env-vars","title":"Environment variables"},"presence":{"first_seen":"2.1.138","removed_in":null,"in_current_build":true,"newest_mined":"2.1.309","builds":150,"mined_builds":150,"first_cited":{"version":"2.1.280","released_at":"2026-09-22 15:44:39","spans":1}},"aliases":[],"entries":[{"version":"2.1.290","anchor":"new-proactivity-startup-level-gated-by-tengu-proactivity","heading":"New --proactivity flag sets how much Claude does on its own at startup","line":"A `--proactivity` flag picks the proactivity level when Claude Code starts, and `CLAUDE_CODE_DISABLE_PROACTIVITY` turns the selector off","released_at":"2026-10-05 18:12:44","reason":"found in this entry's text"},{"version":"2.1.290","anchor":"new-relaunchproactivity-env-vars-added-to-a-scrub-list-no","heading":"New variables to turn off proactivity and carry it across a relaunch","line":"Claude Code adds `CLAUDE_CODE_DISABLE_PROACTIVITY` and variables that pass proactivity state to a relaunched Claude Code","released_at":"2026-10-05 18:12:44","reason":"found in this entry's text"},{"version":"2.1.290","anchor":"proactivity-opt-in-restored-across-worker-epochs","heading":"Proactive mode choice now survives worker restarts","line":"In headless sessions, Claude Code now keeps your proactivity opt-in when the worker restarts","released_at":"2026-10-05 18:12:44","reason":"found in this entry's text, named in this entry"},{"version":"2.1.283","anchor":"context-shows-mcp-server-instructions-as-a-separate-categor","heading":"\/context lists MCP server instructions as their own category","line":"The `\/context` breakdown now shows how much of the context MCP server instructions take up, next to MCP tools","released_at":"2026-09-25 18:46:11","reason":"found in this entry's text"},{"version":"2.1.280","anchor":"builtin-hooks-module-capability-manifests-expanded","heading":"Builtin hooks-module capability manifests expanded","line":"Builtin plugin hook modules were granted access to more host calls, including two new environment variables","released_at":"2026-09-22 15:44:39","reason":"found in this entry's text"},{"version":"2.1.248","anchor":"retaining-tool-definitions-across-context-loss-and-credentia","heading":"Retaining tool definitions across context loss and credential changes, off by default","line":"Tool definitions could survive context loss and credential changes, but both halves are off.","released_at":"2026-08-27 20:35:36","reason":"found in this entry's text"},{"version":"2.1.233","anchor":"remaining-token-countdown-is-now-on-by-default","heading":"Remaining-token countdown is now on by default","line":"Claude now gets a running count of tokens left by default, re-anchored on each of your prompts.","released_at":"2026-08-14 18:50:44","reason":"found in this entry's text"}],"entries_total":7,"docs":[{"source":"claude-code","path":"env-vars","title":"Environment variables","documented":true},{"source":"claude-code","path":"agent-sdk\/modifying-system-prompts","title":"Modifying system prompts","documented":false},{"source":"claude-code","path":"changelog","title":"Claude Code changelog","documented":false},{"source":"claude-code","path":"settings-reference","title":"All settings","documented":false}],"docs_total":4,"gates":[],"related":[{"name":"CLAUDE_CODE_DISABLE_1M_CONTEXT","slug":"claude-code-disable-1m-context","description":"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 5.5](\/docs\/en\/model-config#sonnet-5-5-and-sonnet-5-context-window) and the Fable models, 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)"},{"name":"CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING","slug":"claude-code-disable-adaptive-thinking","description":"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 models](\/docs\/en\/model-config#extended-thinking), Sonnet 5 and later, or Opus 4.7 and later, which always use adaptive reasoning"},{"name":"CLAUDE_CODE_DISABLE_ADMIN_ENV_UNION","slug":"claude-code-disable-admin-env-union","description":"Set to `1` to stop Claude Code from merging [managed settings](\/docs\/en\/managed-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"},{"name":"CLAUDE_CODE_DISABLE_ADVISOR_TOOL","slug":"claude-code-disable-advisor-tool","description":"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"},{"name":"CLAUDE_CODE_DISABLE_AGENT_VIEW","slug":"claude-code-disable-agent-view","description":"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-reference#disableagentview) setting"},{"name":"CLAUDE_CODE_DISABLE_AGENTS_FLEET","slug":"claude-code-disable-agents-fleet","description":"A true value (`1`, `true`, `yes`, `on`) turns off the background-agents fleet, the same as the `disableBackgroundAgents` setting: the fleet gate that otherwise follows `tengu_slate_meadow` returns false, so `claude daemon` subcommands that need the gate stop with `'daemon' is not enabled.`, the built-in Claude agent is left out of the built-in agent list, and `claude daemon run` exits with `claude daemon: background agents disabled (ZDR\/3P\/opt-out)`."},{"name":"CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN","slug":"claude-code-disable-alternate-screen","description":"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-reference#tui) 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"},{"name":"CLAUDE_CODE_DISABLE_ARTIFACT","slug":"claude-code-disable-artifact","description":"Set to `1` to turn off the [Artifact](\/docs\/en\/artifacts) tool, which publishes session output as a private web page on claude.ai. Once you set it, no settings file turns the tool back on. To turn the tool off from a settings file instead, set [`enableArtifact`](\/docs\/en\/settings-reference#enableartifact) to `false`; the deprecated [`disableArtifact`](\/docs\/en\/settings-reference#disableartifact) key also turns it off"},{"name":"CLAUDE_CODE_DISABLE_ATTRIBUTION_BASELINE_REUSE","slug":"claude-code-disable-attribution-baseline-reuse","description":null},{"name":"CLAUDE_CODE_DISABLE_ATTRIBUTION_CROSS_REPO","slug":"claude-code-disable-attribution-cross-repo","description":"Two new environment variables are now recognized: CLAUDE_CODE_DISABLE_ATTRIBUTION_CROSS_REPO and CLAUDE_CODE_SDK_HAS_OAUTH_REFRESH"}],"url":"https:\/\/changelogs.core-directive.com\/reference\/env\/claude-code-disable-attachments","family_url":"https:\/\/changelogs.core-directive.com\/reference\/env.json"}