Show HN: Foremerge – Catch Intent Conflicts Between Parallel Coding Agents

Foremerge is an open-source coordination protocol that prevents semantic intent conflicts between parallel coding agents by adding a lightweight shared awareness layer on top of Git. Agents operate in isolated worktrees but publish structured intent declarations (semantic scopes and claims like "change sendEmail") to a small database kept in the project's Git common directory. A deterministic detector compares these declarations and raises advisory collisions before any files change, naming the conflicting agents, explaining why plans clash, and suggesting ways to split work. It deliberately avoids locking files or asking a model to judge conflicts, keeping warnings advisory and decisions reproducible. The canonical example is two agents that respectively replace PaymentService with Stripe and add PayPal support to the old PaymentService - Foremerge flags that the plans conflict even though Git would merge the code without overlap.

The current release is a local-first 0.5.0 MVP that implements a CLI, JSON API, MCP server, SQLite store, deterministic conflict detector, and a verification-gated lifecycle. Installation is via a provided install script or cargo build, and clients like Claude, Codex, and Cursor can be set up with foremerge setup commands. Acceptance is gated by checks Foremerge runs itself (for example cargo test), and unverified work is recorded as such for auditing. The project does not handle cross-machine coordination and public schemas are still evolving, but it supplies the missing shared intent layer while keeping Git as the durable repository.