--append-system-prompt
A Claude Code CLI flag, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
Append custom text to the end of the default system prompt
Anthropic's own wording. Read off CLI reference, captured 2026-09-26.
In the changelogs
9Releases whose published page names --append-system-prompt.
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v2.1.284
Cloud sessions can keep a verified start of the appended prompt in the cached part
In cloud sessions,
CLAUDE_CODE_APPEND_PROMPT_HEADcan move a verified opening of--append-system-prompttext into the cacheable system promptfound in this entry's text
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v2.1.283
--system-promptand--system-prompt-filecan now be used togetherPassing both
--system-promptand--system-prompt-fileno longer stops Claude Code from starting; the two are combinedfound in this entry's text
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v2.1.265
--system-prompt-snapshot now defaults on universally, not just for the built-in prompt
--system-prompt-snapshot's documented default is now described as always-on, not just for the built-in prompt
found in this entry's text
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v2.1.257
New
--system-prompt-snapshotCLI/agent optionA new --system-prompt-snapshot option makes a session record its system prompt once and reuse it on resume.
found in this entry's text
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v2.1.242
Command-line system prompts kept separate from resolved ones
Your typed --system-prompt values are kept apart from the resolved ones for cloud and remote setup.
named in this entry, found in this entry's text
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v2.1.234
Early flag scan no longer mistakes tool lists and directories for flags
Tool lists and directories passed to flags are no longer misread as flags themselves at startup.
named in this entry, found in this entry's text
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v2.1.234
Spawned processes get
--flag=valuewhen the value looks like a flagPrompts and model names starting with a dash are no longer swallowed as options by subagents and background tasks.
found in this entry's text
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v2.1.232
Cloud gateway sign-in explains its restart, and refuses when it cannot
Cloud gateway sign-in explains its restart, and ends the session when a restart can't carry state.
found in this entry's text
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v0.2.117
Enhanced Print Mode (
--print) 📄found in this entry's text
First cited
3The earliest release whose published evidence quoted --append-system-prompt was v2.1.234, 17 Aug 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the CLI flag does. All CLI flags.