ds4-agent: `-p` one-shot mode fails with "failed to start line editor"

Summary

On macOS (Apple Silicon, ds4 at bd66c40), passing -p "prompt" to ds4-agent fails to start:

failed to start line editor

The equivalent one-shot run through the CLI works fine (ds4 -p "..." with the same model and flags), so this looks specific to the agent's non-interactive prompt path / line-editor init rather than the model runtime.

Expected

ds4-agent -p "..." should run one turn non-interactively (per --help: "Submit an initial prompt after startup").

Workaround

Use ds4 -p directly for one-shot runs.

Happy to provide more details (full command line, terminal type) if needed.