Cursor CLI: launch-time instruction injection (--append-system-prompt flag or env var)

Ideas Feature Requests
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Feature request for product/service

Cursor CLI

Describe the request

Hi Cursor team! Thanks for bringing the agent to the CLI — it’s been great to build with. A feature request:

Request: a way for the Cursor CLI (agent / cursor-agent) to append instructions at launch, scoped to that invocation only:

agent --append-system-prompt "extra instructions..."
agent --append-system-prompt-file /path/to/instructions.md

and/or an env-var equivalent (e.g. CURSOR_APPEND_RULES=/path), which wrappers that construct the child environment could set without touching argv.

Use case: terminal wrappers and session managers (SSH session tools, terminal mirrors/multiplexers, CI harnesses) want any agent launched inside them to know about environment-specific capabilities — “this session is remote/mirrored, these extra commands are available”. The wrapper controls the argv and environment of the child process, so a launch-time flag or env var is the natural integration point: nothing written into the user’s repo or home directory, and the context disappears when the session ends.

As far as I can tell, there’s currently no path for this in the CLI:

  • No flag on agent carries instruction text (checked the parameters reference).
  • The only documented env vars are auth-related (CURSOR_API_KEY).
  • .cursor/rules and AGENTS.md are project files — a wrapper shouldn’t write into someone’s repo, and the content would persist outside the wrapped session.
  • User-level/global rules for the CLI are themselves still an open request (Global rules with Cursor CLI) — though that’s a slightly different ask: persistent user rules there, ephemeral per-launch injection here.

Prior art — several comparable agent CLIs already ship this surface: Claude Code (--append-system-prompt, --append-system-prompt-file), Factory droid (same flags), Grok Build (--rules, alias --append-system-prompt), pi (--append-system-prompt), Codex (-c developer_instructions="..."), Goose (goose run --system). I’ve filed the same request with the other tools that don’t have it yet — on GitHub: google-gemini/gemini-cli issue 29112, QwenLM/qwen-code issue 10332, charmbracelet/crush issue 3659, aaif-goose/goose issue 11644 (can’t include more links as a new forum user, sorry!).

Append semantics are the important part: the stock system prompt and normal rules loading would stay intact — the flag only adds to it.

Thanks for considering! Happy to share more detail on the wrapper use case if helpful.