This Week at YC: AI Harnesses, Founder Sales, and Community Milestones

This Week at YC: AI Harnesses, Founder Sales, and Community Milestones The September 13, 2026 edition of This Week at YC features discussions on AI harness architectures, outbound sales guidance, upcoming enterprise and agent-focused events, and major funding rounds from alumni companies. A YC deep dive explores why model harnesses matter, noting identical model weights jumped from 30% to 95% on ARC-AGI with an improved harness. YC Visiting Partner Christina Gilbert outlined eight tactics for founders to improve outbound sales based on her experience at OneSchema. YC announced upcoming events in San Francisco, including the 'Make Something Agents Want' hackathon and the Fall 2026 Early Access Network kickoff. Community funding highlights include Stoke Space raising $1 billion, Blee securing $27 million, Aqua raising $15 million, and NASA selecting Inversion for aerocapture technology. AI Research and Programming YC highlighted a panel of researchers and founders examining model harnesses, arguing against the view that harnesses are merely prompt engineering scaffolding. Better harnesses enabled the same model weights to improve ARC-AGI scores from 30% to 95%, with YC also drawing on lessons from creating internal agents for its staff. Additionally, YC promoted an upcoming Paper Club session focused on Alternative Compute Paradigms. Events and Founder Resources Visiting Partner Christina Gilbert shared eight recommendations for founder-led outbound sales, addressing recipient targeting, messaging, follow-ups, reply rate troubleshooting, and customer language integration. YC also announced the 'Make Something Agents Want' hackathon in San Francisco scheduled for October 17–18, centering on software designed for AI agents rather than human users. Separately, the invite-only YC Early Access Network opens its Fall 2026 cohort on October 22 to connect enterprise technology leaders with vetted enterprise-AI startups. YC Community Highlights Several YC alumni shared commercial and funding milestones: Stoke Space raised $1 billion to advance fully reusable launch technology, marketing compliance platform Blee raised $27 million, and Aqua raised $15 million to build infrastructure for alternative investments. In other sector news, NASA selected Inversion to develop aerocapture technology for interplanetary missions, Merck KGaA acquired oral fertility molecules from PostEra, and Centralize debuted as a deal-tracking platform for enterprise sales.

YC 周报：框架对模型表现的影响及社区最新动态 Y Combinator 发布的 2026 年 9 月 13 日周报，重点讨论了 AI 框架（Harness）对模型能力的重要性，分享了创始人销售策略、新黑客松活动，并汇总了 Stoke Space 获 10 亿美元融资等多项社区资讯。 YC 深入探讨 AI 框架重要性，指出同一模型在优化框架下 ARC-AGI 得分可从 30% 提升至 95% YC 访问合伙人 Christina Gilbert 分享创始人主导的外拨销售（Outbound Sales）8 项改进方法 YC 将于 10 月举办面向智能体开发的黑客松活动及企业级 AI 早期访问网络活动 YC 社区多家企业公布融资与业务进展，其中 Stoke Space 筹集 10 亿美元以加速完全可回收火箭发射研发 AI 框架与前沿研讨 YC 指出，框架并非仅是简单的脚手架或提示工程，在 ARC-AGI 测试中，采用更好框架可使相同模型权重的得分从 30% 跃升至 95%。YC 汇集研究人员深入探讨框架现状，并基于为每位员工构建智能体的内部实践进行经验总结，后续还将围绕替代计算范式举办 Paper Club 讨论。 创业指导与线下活动 访问合伙人 Christina Gilbert 结合其在 OneSchema 实现数百万元销售的经验，提出了精准定位受众、撰写高质邮件、排查低回复率等 8 种优化外拨销售的方法。此外，YC 将于 10 月 17-18 日在旧金山举办“制造智能体所需之物”黑客松，并于 10 月 22 日开启 2026 年秋季早期访问网络，协助企业级 AI 创始人对接采购高管以推动试点合作。 YC 社区企业动态 多家 YC 校友企业发布重要业务动态：Stoke Space 筹集 1 billion 美元推进完全可重复使用发射项目；Blee 为其营销合规软件融资 2700 万美元；Aqua 筹集 1500 万美元构建另类投资市场基础设施；Inversion 获 NASA 选中推进用于未来行星际任务的空气阻捕技术；Merck KGaA 收购了 PostEra 的口服生育小分子药物；Root Access 推出企业交易工具 Centralize。

| | | | | | | | | | | | | | | This Week at YC **September 13th, 2026** | | | | ✨ **The Latest** | | | | | | | | [Why The Harness Matters More Than The Model](https://youtu.be/n9xKblqyQ28) Harnesses get dismissed as just scaffolding, just prompt engineering, and not real research. But that couldn't be farther from the truth. The same model weights that score 30% on ARC-AGI score 95% with a better harness. So we gathered a group of researchers and founders working at the frontier to do a deep dive into the state of harnesses. We'll cover how we got to this point, the case for making your harness as expressive as possible, and what YC learned building an agent for every employee in the company. Sign up for the next Paper Club, where we'll discuss Alternative Compute Paradigms: [https://events.ycombinator.com/yc-paperclub-Sep23](https://events.ycombinator.com/yc-paperclub-Sep23) | | | | | | | | [How To Get Better At Outbound Sales](https://youtu.be/wr6PMD06hP0) Drawing from her experience generating and closing millions of dollars through founder-led sales at OneSchema, YC Visiting Partner Christina Gilbert shares eight ways founders can improve their outbound, from targeting the right people and writing emails worth reading to following up, debugging low reply rates, and using customer language to sharpen your message. | | | | | | | | [Open Models Change The Economics of AI](https://events.ycombinator.com/yc-early-access-fall-26) The Y Combinator Early Access Network is an invite-only group of senior technology leaders who see YC's enterprise-AI companies before they're on anyone's shortlist. Four times a year, we put a hand-picked group of founders in a room with buyers who actually want to run a pilot. Members get a peer group of technology executives, early looks at curated YC enterprise-AI companies, and the chance to shape roadmaps through pilots. Fall 2026 kicks off October 22 in San Francisco. Membership is by [application](https://events.ycombinator.com/yc-early-access-fall-26?). | | | | | | | | [Join Us For The YC Own Your Intelligence Hackathon](https://events.ycombinator.com/MakeSomethingAgentsWant) We're hosting a "Make Something Agents Want" hackathon October 17-18 at YC in San Francisco. One of the biggest trends we see: agents are replacing humans as users, coders, and decision-makers. But most products are still built primarily for humans. You'll get to learn from the teams at the front lines of building for agents. | | | | | | 🌎 YC Community Highlights/news from YC and YC companies | | | | | | | | [**Stoke Space Raises $1 Billion to Accelerate Fully Reusable Launch**](https://www.stokespace.com/news/stoke-space-series-e) Stoke Space | | | | | | | | [**Centralize is the GPS for Enterprise Deals**](https://www.youtube.com/watch?v=dZLVDPzPITg) Root Access | | | | | | | | [**Aqua Raises $15M To Build Infrastructure for a Growing Alternative Investment Market**](https://www.thisweekinfintech.com/p/exclusive-aqua-raises-15m-to-build-infrastructure-for-a-growing-alternative-investment-market) TWIF | | | | | | | | [**Blee raises $27M for marketing compliance software**](https://www.axios.com/pro/fintech-deals/2026/09/08/blee-27r-million-compliance-software) Axios | | | | | | | | [**Inversion Selected by NASA to Advance Aerocapture Technology for Future Interplanetary Missions**](https://medium.com/@inversion-space/inversion-selected-by-nasa-to-advance-aerocapture-technology-for-future-interplanetary-missions-1567be6fd97c?postPublishedType=initial) Medium | | | | | | | | [**Merck KGaA buys PostEra’s oral fertility molecules**](https://cen.acs.org/pharmaceuticals/drug-development/merck-kgaa-buys-postera-fertility-ivf-small-molecules-ai/104/web/2026/09) c&en | | | | | | [🚀 **The Launchpad**](http://ycombinator.com/launches) [Some of the most recent launches from YC companies](http://ycombinator.com/launches) | | | | | | | | [Find more YC companies and discover new products](https://www.ycombinator.com/launches) | | | | | | [🔥 **Hacker News**](https://news.ycombinator.com) [Top posts from this week](https://news.ycombinator.com) | | | | | | | | [Read more on Hacker News](https://news.ycombinator.com) | | | | | | **More YC resources:** [Apply to YC](https://www.ycombinator.com/apply) \| [YC Library](https://www.ycombinator.com/library) | | | | *Copyright © 2026 Y Combinator, All rights reserved.* Want to change how you receive these emails? You can [update your preferences](https://ycombinator.us7.list-manage.com/profile?u=6507bf4e4c2df3fdbae6ef738&id=547725049b&e=[UNIQID]&c=aa5b3bbc1b) or [unsubscribe from this list](https://ycombinator.us7.list-manage.com/unsubscribe?u=6507bf4e4c2df3fdbae6ef738&id=547725049b&t=b&e=[UNIQID]&c=aa5b3bbc1b). |