GitLab 18.5: Intelligence that moves software development forward

What this post added

Introduces a modernized UI with a panel-based layout for persistent GitLab Duo Chat and improved navigation. Enhances the GitLab Duo Agent Platform with the Security Analyst Agent for automated vulnerability triage and the GitLab Duo Planner for backlog management (read-only). Integrates popular external AI tools (Claude, OpenAI Codex, Gemini CLI, Amazon Q Developer, OpenCode) into the AI Catalog as native GitLab agents, with Duo Enterprise subscriptions including Claude and Codex. Moves the Self-hosted GitLab Duo Agent Platform to beta for on-premises AI execution. Adds Static Reachability Analysis for Java to identify exploitable vulnerabilities, complementing existing support for Python, JS, and TS. Introduces Secret Validity Checks to distinguish active from expired secrets in the Vulnerability Report. Enables Custom Rules for Advanced SAST using TOML files for tailored detection logic. Adds Advanced SAST support for C and C++ languages, requiring compilation database generation.