Show HN: Whiteboard (YC W26) – An open-source IDE for thoughtful software design

Whiteboard is an open-source desktop IDE that enables developers and AI agents to co-design software on a shared canvas. It links sequence and ER diagrams directly to code via VSCode LSP support. A Rust-based semantic diff viewer collapses non-essential changes. A decision-log tool traces agent decisions. A WASM-plugin system allows customization. Salesforce and Modal use Whiteboard to review agent-generated prototypes and surface complex changes for human judgment.