Pi (pi.dev) is fine. I'm using it with DS v4 right now. It's not close to Claude code but I think that's the point.
By the way OpenRouter version is very slow for some reason. DeepSeek platform is faster (and cheaper with the discount) if you don't mind passing the credit card number / email to this company.
As sibling said, Pi is great, and you can absolutely run it directly (there's even a plugin to use itself as a sub agent), but I mainly run it as a sub agent from other harnesses, for example running a more capable model in copilot, and then delegating simpler chunks to pi (using a cheaper model) as the sub agent. I've tried gas town and some others but never got into that way of working. I'm going to try opencode though as a less vendor specific harness than copilot/claude/gemini.
I've been using OpenCode for a few days now, I like it. It doesn't feel any "less heavy" than Claude Code (they're both massive piles of vibe-coded typescript) but for me it's essentially a 1:1 replacement for Claude Code.
Sidenote, I've been trying deepseek-v4-flash and I'm blown away. It's no Opus, but it's as cheap as tap water and punches far above its weight as a Flash model. I keep throwing tasks at it out of curiosity and it keeps solving them.
By the way OpenRouter version is very slow for some reason. DeepSeek platform is faster (and cheaper with the discount) if you don't mind passing the credit card number / email to this company.