AI agent frameworks and developer tools #136
Today's Letter
GitHub Copilot, Claude Haiku 5.5 GA
- Claude Haiku 5.5 is now generally available in GitHub Copilot
- The lightweight model targets fast, high-volume work including subagents, quick edits, and terminal tasks
- Early testing found performance comparable to Claude Sonnet 5 on many coding tasks with fewer tokens and steps
- Available to Copilot Pro, Pro+, Max, Business, and Enterprise users
- Supported across major IDEs, Copilot CLI, cloud agent, Copilot app, github.com, and mobile
- Usage is billed at provider list pricing; rollout is gradual and Business and Enterprise administrators can manage access
Source: github.blog
Microsoft, Agent Lightning v1.0 released
- Microsoft Research Asia released Agent Lightning v1.0, an open-source framework for training agents with reinforcement learning
- The framework introduces Harnessed Agentic RL, training agents through the same harness used in deployment
- The codebase is approximately 3,500 lines and supports agents running as native Kubernetes jobs
- An end-to-end Qwen3.5-9B coding-agent pipeline improved SWE-bench Verified Pass@1 from 41.8% to 56.4%
- The result used about 6,000 training samples from an open-source dataset
- An LLM proxy records model calls while leaving existing harness code unchanged
Source: microsoft.com
Jocoletter curates AI, software, and product trends for developers and builders.
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