Rubber Duck is a new experimental mode in GitHub Copilot CLI that uses a second model from a different AI family to review plans, implementations, and tests before the agent moves forward. It is designed to catch architectural mistakes, edge cases, and cross-file issues earlier.
It triggers a second model (can be a different family) that reviews the main agent’s plan and output at key moments — after planning, after big implementations, before tests. Think of it as an independent rubber duck that actually talks back.
Early numbers are solid: Claude Sonnet + Rubber Duck closes 74.7% of the gap to Opus on SWE-Bench Pro, especially on complex multi-file work.
If you’re already living in Copilot CLI, just turn on /experimental and you’ll probably stay afloat🛟
The good ol' Rubber Duck. Every developer knows how useful that can be (I use colleagues as rubber duckies sometimes tho, they don't always appreciate).
About Rubber Duck on Product Hunt
“Cross-model reviews in GitHub Copilot CLI”
Rubber Duck launched on Product Hunt on April 9th, 2026 and earned 87 upvotes and 2 comments, placing #43 on the daily leaderboard. Rubber Duck is a new experimental mode in GitHub Copilot CLI that uses a second model from a different AI family to review plans, implementations, and tests before the agent moves forward. It is designed to catch architectural mistakes, edge cases, and cross-file issues earlier.
Rubber Duck was featured in Artificial Intelligence (466.4k followers), GitHub (41.2k followers) and Development (5.8k followers) on Product Hunt. Together, these topics include over 109.7k products, making this a competitive space to launch in.
Who hunted Rubber Duck?
Rubber Duck was hunted by Zac Zuo. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
Want to see how Rubber Duck stacked up against nearby launches in real time? Check out the live launch dashboard for upvote speed charts, proximity comparisons, and more analytics.
Zac Zuo
Hi everyone!
@Github Copilot CLI added Rubber Duck in experimental mode.
It triggers a second model (can be a different family) that reviews the main agent’s plan and output at key moments — after planning, after big implementations, before tests. Think of it as an independent rubber duck that actually talks back.
Early numbers are solid: Claude Sonnet + Rubber Duck closes 74.7% of the gap to Opus on SWE-Bench Pro, especially on complex multi-file work.
If you’re already living in Copilot CLI, just turn on /experimental and you’ll probably stay afloat🛟