“I hit Install, and within minutes cubic was flagging an AWS foot‑gun that even tests missed.”

— Alex Chantavy, cofounder and maintainer of Cartography

Cartography is a Cloud Native Computing Foundation (CNCF) project under the Linux Foundation. It maps cloud and on-prem resources into a detailed security knowledge graph.

Maintainers at Subimage, founded by Alex Chantavy and Kunaal Sikka (YC W25), struggled to provide timely feedback on community contributions. They were often overwhelmed, leaving contributors waiting weeks for initial responses.

After adopting cubic, Cartography cut average PR merge times to just 10 hours 34 minutes: a 76% improvement.

cubic now automatically catches production-level bugs, engages contributors, and frees maintainers for high-level feedback.

The Challenge

“One of the biggest struggles in open source is giving fast feedback while keeping a quality bar.” — Alex Chantavy

Maintainers faced a backlog of PRs. Contributors waited weeks for an initial response. Minor style issues either consumed reviewer time or were ignored altogether.

“We went from apologizing for two‑week silences to giving feedback before contributors go for coffee.” — Alex Chantavy

The “Aha” Moment: AI Awareness & Rule Inference

Shortly after installing cubic, Alex noticed it suggesting rules based on existing coding patterns. One particular rule stood out: a decorator frequently applied to certain functions.

Although Alex had never documented it formally, cubic recognized its consistent use.

With Alex’s approval, cubic quickly turned this informal convention into a documented, enforceable rule, ensuring consistency across the entire repository.

“It saw the convention, created a rule, and applied it repo‑wide. That was the aha moment for me.” — Alex Chantavy

Immediate Impact

1 — Live in Minutes

cubic integrated quickly with GitHub, learned project-specific rules, and immediately began reviewing new pull requests.

2 — Real‑World Bug Catching

cubic flagged that a batch request to AWS’s Resource Groups Tagging API exceeded the documented 20‑item limit: an error no unit test covered. This was the exact comment: Link.

3 — Faster, Friendlier Community Reviews

With routine checks automated, maintainers could focus on architecture and functionality. Contributors received clear feedback immediately, keeping them engaged.

“Now I review whether the feature actually solves a problem, not variable names.” — Alex Chantavy

Results

• 76% faster PR merges (down to 10h 34m)

• Feedback in minutes, not weeks

• More maintainer time for high-level design and security

• Engaged, motivated contributors

cubic vs GitHub Copilot

Comparing cubic head-to-head with GitHub Copilot, Alex shared:

“The comments I got from cubic were definitely more useful than the ones from Copilot. cubic found issues Copilot missed and gave clearer suggestions.” — Alex Chantavy

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