Pi Agent Harness (formerly badlogic/pi-mono; 108k+ stars, MIT/TypeScript). Not one CLI but layered packages usable on their own: pi-coding-agent (interactive coding agent), pi-agent-core (runtime with tool calling and state), pi-ai (unified multi-provider LLM API), plus chord composition runtime, pi-telemetry contracts, pi-durable persistence and pi-tui differential terminal rendering. The README states plainly that there is no built-in permission system and offers micro-VM / Docker / sandbox paths instead. Not benchmarked by us; graded needs-reproduction.
ByteDance's open-source super agent harness (82k+ stars). 2.0 is a ground-up rewrite sharing no code with 1.x: sub-agents, extensible skills, sandbox and file system, long-term memory, session goals, plus Manual Context Compaction that hands context management back to the operator. Positioning lifted from a deep-research framework to a runtime for any task. Not benchmarked by us; graded needs-reproduction.