How a central Git repo with symlinks solved AI agent rule fragmentation

A developer managing multiple AI coding agents — Cursor, Kiro, Codex, and others — found that each tool maintained its own separate rule sets, causing updates to fall out of sync across platforms. To fix this, they created a central Git repository called harness-core to store shared domain rules such as personas, code review skills, and writing guidelines. Symlinks replace local rule folders in trusted agents like Kiro and Cursor, so any single edit instantly propagates across all connected tools. Platform-specific formats, such as Cursor's proprietary .mdc files, are compiled from the central Markdown source via a script rather than edited directly. For skills requiring different technical implementations per platform, isolated per-harness files are kept, preserving a single source of business logic while allowing divergent execution mechanics.