Modifying system prompts changedagent-sdk/modifying-system-prompts
Nearest release: v2.1.300, published 2 hours before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Upstream edited this page at 14 Oct 2026 16:48 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 14 Oct 2026 17:07 UTC.
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430430Claude Code's built-in commit and pull request instructions aren't a reminder. They are part of the Bash tool's description, so they also reach Claude when you pass a custom `systemPrompt`.
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432If you set `CLAUDE_CODE_DISABLE_ATTACHMENTS`, Claude Code also sends `@` file mentions as plain text instead of expanding them into file content. The list of available subagents and background task notifications still arrive.
432If you set `CLAUDE_CODE_DISABLE_ATTACHMENTS`, Claude Code also sends `@` file mentions as plain text instead of expanding them into file content. The list of available subagents and background task notifications still arrive. To stop only `@` file mentions from expanding, set [`CLAUDE_CODE_DISABLE_FILE_MENTIONS=1`](/docs/en/env-vars#variables) instead, on Claude Code v2.1.299 or later. Claude then gets the mentioned paths plus a note to read them with its file tools.
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434434The following example is for an agent that carries its own commit rules in `append`. It sets both `attribution` keys to empty strings to remove the trailer and footer, and turns off `includeGitInstructions` so Claude Code's own commit workflow instructions don't compete with yours:
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