Lit SSR adapter registration breaks with Vite module resolution

[SisyphusZheng]

Description

Even when installLitAdapter() is called and logs "Lit SSR adapter installed", renderDSD() cannot see the adapter. All Lit components produce the error:

<!-- LessJS ERROR: <about-page> render() returned object, expected string. 
This looks like a Lit TemplateResult — install @lessjs/adapter-lit to handle it. -->

Root Cause

@lessjs/adapter-lit/ssr.ts calls registerAdapter() which writes to a module-scope variable _globalAdapter (from @lessjs/core/render-dsd or @lessjs/core/less-runtime).

When Vite's module resolution resolves @lessjs/adapter-lit and @lessjs/core to different module instances (e.g. via resolveAlias, symlinks, or incomplete ssr.noExternal), registerAdapter() writes to copy A's _globalAdapter, while renderDSD() reads from copy B's _globalAdapter — the adapter is never seen.

Specific Trigger Conditions

• build-metadata.json has resolveAlias pointing @lessjs/adapter-lit and @lessjs/core to local src-tmp/packages/ source files
• ssr.noExternal list is incomplete, causing some packages to be externalized
• Windows + preserveSymlinks: true + JSR node_modules structure creates multiple resolution paths

Suggested Fix

Use globalThis or Symbol.for() as a cross-module-instance bridge for adapter registration, instead of relying on module-scope variable sharing.

Severity

P0 — Projects using resolveAlias (e.g. local development of @lessjs/ui) cannot do SSG rendering at all.