UI Linter

Halo Studios · Halo: Campaign Evolved · Internal Unreal plugin · 2025

UI Linter Message Log output showing dozens of rule findings across widget tree and event graph rules, with clickable Fix suggestions.

A three-pillar static analyzer for Unreal Widget Blueprints, 22 deterministic rules mined from real Jira patterns, surfacing findings inline in the Editor and via CLI.

Widget Blueprint editor toolbar with Lint This Widget and Add New Rule buttons.
Message Log window showing UI Linter category with dozens of tree and event-graph findings, severity icons, and clickable Fix links.

Technical deep-dive. How the tool was built, why the three pillars (Knowledge Base, Checklist Generator, Deterministic Linter), and what changed in team practice after adoption: UI Linter, Widget Blueprint Static Analysis →

Role
Designer, engineer, owner (solo build, AI-assisted)
Team
Halo Studios · UI
Technical Stack
Unreal Engine · C++ plugin · Python · pytest · Copilot CLI
Released
2025 · Internal Halo Studios tool
What it does
  • Runs a deterministic pass over any Widget Blueprint, 14 widget-tree rules (L001–L014) and 8 event-graph rules (L020–L027).
  • Surfaces findings inline in the Editor's Message Log with clickable navigation to the offending widget or Blueprint node.
  • Offers one-click Fix actions for common issues (uncategorized variables, unused declarations, dead handlers).
  • Ships an identical CLI for pre-merge validation and Copilot-driven review.
  • "Add New Rule" launches Copilot CLI with the active widget as context to draft a new rule from a real example.
Impact
  • ~34 layout bugs prevented in the first two months post-adoption.
  • Adopted team-wide as the pre-merge validation gate; pull requests started including linter output as an evidence artifact.
  • Rules are grounded in a Jira mining pass over 100+ real bugs, distilled into 17 pattern DNAs across 6 categories.
  • Continuously extended over months, contribution barrier kept low because rules ship as JSON, not builds.