com.unity.pipeline: CS0234 on 6000.3.0a1-a4 — UNITY_6000_3_OR_NEWER guards a using that needs UNITY_6000_5_OR_NEWER

Reported by Illia Komendantov (Core Pipeline / Automated PR Testing / Explorer team).
Slack thread: https://unity.slack.com/archives/C0AUDHS49UJ/p1788513906115499
Full report attached to that thread: "Unity CLI: Explorer's Remaining Gaps".

Summary

com.unity.pipeline's hard Editor-version dependency breaks the whole package's assembly on Unity 6000.3.0a1 through 6000.3.0a4 with CS0234. Every published version from 0.2.0-exp.2 to 0.5.0-exp.1 carries this.

CommandRegistry.cs:7-8 and PipelineUtils.cs:5-6 guard using UnityEngine.Assemblies; with #if UNITY_6000_3_OR_NEWER, but every use of that namespace is guarded #if UNITY_6000_5_OR_NEWER — and UnityEngine.Assemblies doesn't exist until 6000.3.0a5. On 6000.3.0a1-a4 the UNITY_6000_3_OR_NEWER define is on, the namespace doesn't exist yet, and the using fails CS0234, taking the whole assembly (and every pipeline command) down with it.

Reporter's own Yamato job hit this: 74492342. The reporting team (Explorer / Automated PR Testing) reverted their hard dependency on com.unity.pipeline on 2026-09-01 specifically over this bug — it's the cheapest fix in the whole report and is blocking them today.

Fix (looks like a ~2-line change)

• CommandRegistry.cs:8's using UnityEngine.Assemblies; is dead — its only contact with the namespace is PipelineUtils.GetLoadedAssemblies() at :129 — delete the using outright.
• In PipelineUtils.cs, either move the :5 guard from UNITY_6000_3_OR_NEWER to UNITY_6000_5_OR_NEWER (matching every actual use), or fully-qualify CurrentAssemblies at :130 the way :112 already does.

Repro

Build com.unity.pipeline against a 6000.3.0a1-a4 Editor. CommandRegistry/PipelineUtils fail CS0234 and the whole package assembly fails to compile.

Related

[Internal link] (Versioned dependency on the pipeline package) covers the general dependency-versioning contract; this is a specific compile-breaking bug in the package's own versionDefine guards, independent of how the CLI declares its dependency. Link added.