The Harness Ecosystem Battle Among Model Vendors

It feels like everyone now realizes the harness is the must-win battleground in the model vendors’ ecosystem. Kimi K2.6 has made huge progress, but Kimi’s model occasionally falls into tool-call infinite loops inside Claude Code’s harness — something that doesn’t happen in Kimi’s own Code CLI. One view: a big part of why Claude is so strong at coding today is that the model has been specifically trained against the Claude Code harness, so its coding performance is exceptional together with that harness. Kimi’s situation is the same in principle. Other model vendors are now also pushing their own CLIs and their own models. The combination of CLI + harness + model — producing an ecosystem — is the key to competition.