Context and Compaction

These variables change how Claude Code manages the conversation size. They set when compaction starts, how big the context window is, how memory files load, and how the prompt cache behaves. Use them for long sessions or when a gateway needs different cache behavior.

This page lists 49 variables. Set a new value and start a new session. Many rows are on or off switches.

Example

~/.claude/settings.json

{
  "env": {
    "CLAUDE_AUTOCOMPACT_PCT_OVERRIDE": "70"
  }
}

Compaction starts earlier than the default.

Variables

The table is sorted by name. See Environment Variables for what each column and badge means.

Variable	Status	What it does	Values and default	Notes
CLAUDE_AUTOCOMPACT_PCT_OVERRIDE	Documented	Lowers the percentage of the window at which auto-compaction starts.	Text. Also used for the fork compaction check	Main sessions and subagents. Project env can set it before trust
CLAUDE_BG_MEMORY_TOGGLED_OFF	Undocumented	Tells a background session that memory was turned off. The session then calls its memory-off handler.	Text. Acts only when the value is 1 and CLAUDE_CODE_SESSION_KIND is bg. The dispatcher sets it	Background sessions. Not set from project env before trust
CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD	Documented	Loads memory files from --add-dir directories.	On or off. The remote add_directory request also needs it set in the container	All sessions. Not set from project env before trust
CLAUDE_CODE_AUTO_COMPACT_WINDOW	Documented	Sets the auto-compact window in tokens. It is capped at the model context window.	Text. Accepts k and M suffixes, such as 200k, like --autocompact (since 2.1.304). Claude Code warns when a value is out of range or ignored. Project env may set it before trust	All sessions, allowed in. Project env can set it before trust
CLAUDE_CODE_BLOCKING_LIMIT_OVERRIDE	Undocumented	Overrides the context blocking limit for tests. Claude Code passes it as testBlockingOverride.	A number	All sessions
CLAUDE_CODE_DISABLE_1M_CONTEXT	Documented	Turns off 1M context. Removes [1m] model variants and keeps 1M models at 200K.	On or off. Warns about a missing auto compact window when set	All sessions
CLAUDE_CODE_DISABLE_ATTACHMENTS	Documented	Turns off attachment processing, so @ mentions stay plain text. Also turns off kept deferred tools.	On or off. Docs: ignored in project and local settings	All sessions
CLAUDE_CODE_DISABLE_AUTO_MEMORY	Documented	Turns auto memory off. A value of 0 forces it on, even in bare mode or with autoMemoryEnabled: false.	On or off	All sessions
CLAUDE_CODE_DISABLE_CLAUDE_MDS	Documented	Stops all CLAUDE.md memory files from loading.	On or off. The loaders return an empty list when set	All sessions
CLAUDE_CODE_DISABLE_FILE_MENTIONS	Documented	Stops @ mention expansion. Claude gets the paths with a note to read them.	On or off. Docs: ignored in project and local settings. Claude Code also passes it to auto mode classifier children	All sessions
CLAUDE_CODE_DISABLE_GIT_INSTRUCTIONS	Documented	Removes built-in commit and PR instructions and the git status snapshot. Beats includeGitInstructions.	On, off, or unset, on by default. When set to any parsed value, the result is its negation. Else the setting, default on	All sessions
CLAUDE_CODE_DISABLE_MEMORY_BULK_INFLATE	Undocumented	Skips the bulk pull of all memory files from a memory store backend.	On or off. A feature flag also gates it	Memory store sync
CLAUDE_CODE_DISABLE_MEMORY_MASS_DELETE_HOLD	Undocumented	Sets the memory mass delete threshold to infinity. The threshold is otherwise the larger of 50 and 10 percent of the files.	On or off, off by default	Memory store sync
CLAUDE_CODE_DISABLE_MEMORY_PERIODIC_RESYNC	Undocumented	Sets the memory store resync interval to 0, which turns the periodic resync off.	On or off, 60 by default. Otherwise the interval is a feature flag, default 60	Memory store sync
CLAUDE_CODE_DISABLE_MEMORY_RO_UNSAVED_NOTICE	Undocumented	Skips the scan that warns about unsaved writes in a read-only memory store mount.	On or off, off by default	Memory store sync. Project env can set it before trust
CLAUDE_CODE_DISABLE_MEMORY_STREAM_LIST	Undocumented	Skips the streamed metadata listing in memory store sync.	On or off. A feature flag also gates it	Memory store sync
CLAUDE_CODE_DISABLE_ORG_MEMORY	Undocumented Gated	Makes the org memory gate return false. That gate also needs a feature flag.	On or off, off by default	Org memory
CLAUDE_CODE_DISABLE_UNKNOWN_MODEL_WINDOW_ENFORCEMENT	Documented	Skips proactive auto-compaction at an assumed window for a model id that Claude Code does not know.	On or off. Messages say it restores the earlier wait-for-the-API behavior	All sessions. Project env can set it before trust
CLAUDE_CODE_ENABLE_TOKEN_USAGE_ATTACHMENT	Undocumented	Adds a token_usage attachment with used, total, and remaining tokens to the turn.	On or off, off by default	All sessions
CLAUDE_CODE_IDLE_COMPACT_MIN_TOKENS	Documented	Sets the context size in tokens where idle compaction applies. It also feeds the sleep compaction timer.	A number. Whole number min 1, whole value. Unset uses a built-in default	All sessions. Project env can set it before trust
CLAUDE_CODE_JUNIPER_SUNDIAL	Undocumented Gated	Sets the number of turns between maintenance runs, default 10. No visible effect in a print-mode probe (Probes).	A number. Whole number min 1, digits only. Order is env, then client data a feature flag, then the flag of that name, then 10	All sessions
CLAUDE_CODE_MAX_CONTEXT_TOKENS	Documented	Overrides the context window that Claude Code assumes for the model, when the model id allows it.	A number. A value above 0 counts. Also used with DISABLE_COMPACT	All sessions. Project env can set it before trust
CLAUDE_CODE_MEMORY_PUSH_DELETE_MODE	Undocumented Gated	Sets the delete mode for memory push. Values are corroborate, immediate, and never.	corroborate by default. enum. Unset reads a feature flag, default corroborate	Memory sync
CLAUDE_CODE_POST_TURN_MEMORY	Undocumented	Turns on the hosted post-turn memory extraction pass. It needs a valid CLAUDE_CODE_POST_TURN_MEMORY_CONFIG.	On or off. With a missing or bad config the code logs a warning and the pass stays off	Cloud and hosted sessions
CLAUDE_CODE_POST_TURN_MEMORY_CONFIG	Undocumented	Gives the JSON config of the post-turn memory pass.	JSON text	Cloud and hosted sessions
CLAUDE_CODE_POST_TURN_MEMORY_SYNC	Undocumented	Makes the post-turn memory pass run after every turn with no idle flush delay.	On or off. Sets every_n_turns to 1 and the idle flush to 0	Cloud and hosted sessions
CLAUDE_CODE_REMOTE_MEMORY_DIR	Undocumented	Sets the memory base dir in a cloud session. It also keeps auto memory on there.	Text	Cloud sessions
CLAUDE_CODE_RIPPLING_TULIP	Undocumented Gated	Overrides a feature flag value for the total-tokens reminder. A positive whole number sets the reminder size.	A number. Must be a positive safe integer. It does nothing when the reminder is off or attachments are disabled	Total-tokens reminder. Also blocked by CLAUDE_CODE_DISABLE_ATTACHMENTS and CLAUDE_CODE_SIMPLE
CLAUDE_CODE_SLEEP_COMPACT	Undocumented	Turns on sleep compaction. A timer queues /compact while the session idles and before the prompt cache expires.	On or off. Active only on a host that qualifies. The timer fires at 0.9 of the cache time window	Idle sessions on supported hosts
CLAUDE_CODE_SLEEP_COMPACT_AFTER_MS	Undocumented	Sets how long after a turn ends the sleep compaction may fire.	A number of milliseconds. Integer 1 or more. The code clamps it between 60000 and 210000 ms	Idle sessions with sleep compaction
CLAUDE_CODE_TOASTY_THIMBLE	Undocumented Gated	Overrides the batching reminder, a prompt note that tells the model to request all independent tool calls in one response.	Text. The accepted values are not shown here	Models served with the reminder
CLAUDE_CODE_TOTAL_TOKENS_REMINDER	Undocumented	Sets the mode of the total_tokens reminder that shows the tokens left. off turns it off.	Text. Known modes include off, padded-countdown, infinite, and fixed. Env wins over settings and flag	All sessions
CLAUDE_CODE_TOTAL_TOKENS_REMINDER_AFTER_USER_TURN	Undocumented	Chooses if the total_tokens reminder shows after each user prompt and re-anchors the budget on each user turn.	On, off, or unset, on by default. Env wins over settings and a feature flag	All sessions
CLAUDE_CODE_TOTAL_TOKENS_REMINDER_BUDGET	Undocumented	Sets the starting token budget for the padded-countdown reminder mode.	A number, 15000000 by default. Integer above 0. Env wins over settings and flag	All sessions
CLAUDE_COWORK_MEMORY_EXTRA_GUIDELINES	Undocumented	Adds extra guideline text to the auto memory and agent memory prompts.	Text. Ignored when empty	Cowork hosts
CLAUDE_COWORK_MEMORY_GUIDELINES	Undocumented	Replaces the auto memory prompt with # auto memory plus this text. It also forces file-based memory.	Text. Needs auto memory on	Cowork hosts
CLAUDE_COWORK_MEMORY_INDEX_CONTENT	Undocumented	Supplies the memory index text and not the file. An empty string turns the injection off.	Text	Cowork hosts
CLAUDE_COWORK_MEMORY_PATH_OVERRIDE	Undocumented	Sets the auto memory directory. It also keeps auto memory on in remote mode.	Text. Must be a valid absolute path, else it is ignored	Cowork hosts
CLAUDE_MEMORY_STORES	Undocumented	Mounts extra memory stores from a JSON list. While set, it also turns the org memory feature off.	-	-
CLAUDE_PROJECT_UUID	Undocumented Gated	Names a Claude project. Claude Code fetches the project context block and the project memory index for it.	-	-
DISABLE_AUTO_COMPACT	Documented	Turns off automatic compaction.	On or off	-
DISABLE_COMPACT	Documented	Turns off all compaction.	On or off	-
DISABLE_PROMPT_CACHING	Documented	Turns off prompt caching for all models.	On or off	-
DISABLE_PROMPT_CACHING_FABLE	Documented	Turns off prompt caching for Fable models.	On or off	-
DISABLE_PROMPT_CACHING_HAIKU	Documented	Turns off prompt caching for the default Haiku model.	On or off	-
DISABLE_PROMPT_CACHING_MYTHOS	Undocumented	Turns off prompt caching for models that the Mythos check matches.	On or off	-
MAX_MCP_OUTPUT_TOKENS	Documented	Sets the token limit for one MCP tool result.	A number	-
SLASH_COMMAND_TOOL_CHAR_BUDGET	Documented	Overrides the character budget for the skill listing shown to the model.	A number, 1 by default. Integer, min 1. If set, it wins over the dynamic budget (context window times 4 times a fraction, default 1%)	All sessions
USE_API_CONTEXT_MANAGEMENT	Undocumented Gated	Would turn on the API context-management beta. It is inert in 2.1.304.	On or off. The code ANDs it with a constant false, so it has no effect	Inert, first-party models

How It Works

Claude Code counts the tokens in the conversation. When the count passes a limit, it compacts: it asks the model to summarize older turns and keeps the summary. The variables here move that limit, turn compaction off, or change what stays in the prompt cache. See Context and Compaction for the full flow.

Related Pages

• Environment Variables: how Claude Code reads variables and which value wins.
• Sessions and Storage
• Models and Effort
• Undocumented Items: every item that only the program shows.

Source: the program (variable names found in the 2.1.304 binary) and the Environment Variables page of the official docs.