Devin adds Claude Haiku 5.5 to its CLI and Fusion sidekick lineup

Devin’s product blog lists Claude Haiku 5.5 as available in Devin in an announcement dated October 7, 2026. The company says the model is now part of the Devin offering and has joined the sidekick choices in Devin Fusion. The detailed post describes a CLI setup with Haiku 5.5 as sidekick and Opus 5.5 as lead. Devin identifies that lead-and-sidekick arrangement as the way to try Haiku 5.5 through the CLI.

On FrontierCode 1.1, Devin reports a 58.4% score for Haiku 5.5. The company describes FrontierCode 1.1 as its proprietary benchmark for grading real-world engineering tasks by quality and mergeability. Devin says the Haiku result is ahead of Sonnet 5, at about one-eighth of the cost per task. That comparison is relative: the announcement does not give a dollar cost per task for either model.

Devin separately reports a FrontierCode score of 66.2 for Fusion when Haiku 5.5 is the sidekick. The company says this setup cuts cost and latency, but does not provide figures for either reduction. The 58.4% result is for Haiku 5.5, while 66.2 refers to the Fusion setup; the figures describe different benchmark subjects. Devin’s post does not give further details quantifying the Fusion result’s cost or latency changes.

For builders evaluating coding models, the announcement offers a model-level benchmark score, a relative cost comparison with Sonnet 5, and a score for a Fusion configuration. The benchmark description provides context for what Devin evaluates, but the reported scores are from Devin’s proprietary FrontierCode 1.1 benchmark. Builders can try the stated Fusion arrangement in the Devin CLI with Opus 5.5 leading. The posts do not provide an absolute Haiku 5.5 task price or numerical cost and latency reductions for the Fusion setup.