Verify in the available environment
Prefer the authenticated page already connected to Harness. Do not launch a separate browser from shell commands, change HOME, inspect personal browser profiles, search for authentication tokens, or alter keychains to obtain a screenshot. For a visual-only request without browser control, limit verification to JavaScript syntax, manifest validation, and the live Client slot, then report that visual verification remains unavailable. Before or after installation, do not search for rasterizers, invoke Quick Look, extract SVG into preview files, emulate React/DOM, or implement a custom renderer to compensate for missing browser control. A screenshot of a mock page is not verification of the running plugin.
For any test subprocess or temporary resource, use a unique owned directory, bound execution, and await cleanup. A failed optional preview must not turn into environment repair or block installation.