AI Agent Harness Build Night
A Tokyo build night on AI agent harnesses: agent loops, tools, memory, permissions and evals, with optional demos and no judging.
- When
- Tue, November 17, 2026 · 18:00–21:30 JST
- Where
- Tokyo, Japan (venue TBA) · In person
- Organizer
- +81Builders
- Language
- JA/EN
- Source
- Luma
Summary
A build night in Tokyo focused on the harness around an AI agent rather than the model: the loop that runs the model, the tools it can call, how it handles context and memory, what it is allowed to do, and how you check whether it worked. Attendees might write a minimal agent loop from scratch, add tools and sub-agents to an SDK, build an eval set for an agent they already run, or dig into how Claude Code, Codex CLI or an open-source harness works.
The evening opens with a lightning talk on what goes into a harness, followed by about two hours of building and optional 3-minute demos. It is not a hackathon, so there is no judging. Food and drinks are provided, capacity is 100, and attendees bring a laptop and an API key for the model of their choice. English and Japanese speakers are both welcome.
About the community
+81Builders is a Tokyo community for people building the future of Japan's tech, running build nights, talks and demos for developers, designers, founders and students. Members coordinate on Discord for event updates, finding collaborators and sponsor credit support, and events welcome both English and Japanese speakers.
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