Implement the work described by the user in the spec or tasks.

1. Establish the boundary

unity-cli and unity-pipeline.
ui-ugui for Runtime/Canvas UI or ui-imgui for Editor IMGUI.
No new external package, Packages/manifest.json change, or editor-resource import such as TMP Essentials.
An opened Editor.

On a failed gate, stop and report with the required user action.

2. Implement and validate

Call the Skill tool with unity-tdd where possible, at pre-agreed seams.
Run typechecking regularly, single test files regularly, and the full test suite once at the end by using unity-pipeline.
Use unity-cli for every non-code edit; never edit Unity YAML directly.
Use ui-ugui for Runtime/Canvas UI and ui-imgui for Editor IMGUI.
Use repository-root .scratch/ for all temporary scripts, files, logs, exports, screenshots, and command output. Remove every artifact created for this work item before reporting.
Report human playtesting, Player Build, as deferred rather than running it.