prompt-file

spex new --prompt-file <path> (or - for stdin) reads the task prompt from a file — fail-loud exclusive with the inline prompt, so long multi-paragraph prompts never fight shell quoting.

raw source

A real launch prompt is often long and multi-paragraph, and argv is a hostile carrier for it: shell quoting turns backticks and $() into evaluation hazards, so callers end up writing the prompt to a file anyway and threading it through "$(cat file)" (field report: gugu-promo multi-agent coordination, ~15 workers in one night). The tool should accept the file directly.

expanded spec

spex session new accepts --prompt-file <path>: the task prompt is the file's contents, read verbatim by the CLI before the create POST — the backend and everything downstream (launch artifact, spex session show) see exactly the same prompt text an inline caller would have sent; nothing else about launch changes. --prompt-file - reads the prompt from stdin, so spex session new --prompt-file - <<'EOF' … works without a temp file.

Fail-loud, never guess:

• Exclusive with the inline prompt. Given together with a positional prompt or --prompt, the command refuses with a one-line usage error (exit 2) — it never silently picks one source.
• An unreadable path or an empty/whitespace-only file refuses the launch with a one-line error naming the path (exit 2) — an empty prompt via an explicit file is a caller mistake, not a request for a promptless session.

spex help new advertises the flag alongside the positional form.