OpenCode

OpenCode is an open source coding harness that exposes an HTTP API and stays agnostic about which model sits behind it. Three source notes, spread across August and September 2026, use it as a substrate rather than as a finished tool.

At Ramp, the first version of the in-house agent Inspect was a Chrome extension where an engineer designated a region of a page to modify, and it was not adopted. The second version pivoted to a remote environment with an agent on top, built on OpenCode. Adoption rose sharply afterward; Rahul Sengottuvelu, Hamid Dadkhah and Zach Bruggeman report that 75% of merged pull requests now come from Inspect sessions.

Cloudflare took a different direction, building a review orchestration in CI around OpenCode: specialized reviewers, a coordinator, review graded by risk, filtering of noisy files, a human bypass, and carryover of findings from one commit to the next. Over one month, Davis, Gill and Hendrickson count 131,246 reviews covering 48,095 pull requests across 5,169 repositories, averaging 1.2 findings per review.

Alan Blount uses it as a measuring instrument instead, driving OpenCode with promptfoo to compare Claude Fable 5.1 against Gemini 3.8 Flash on his own tasks rather than public leaderboards. On a git branch summary, Flash answers in 1.1 seconds for less than a tenth of a cent while Fable costs 23 times more. The harness itself can be configured with two Vertex providers and sub-agents mapped to distinct models: a worker on Flash, a deep thinker on Fable.