disk.mjs imports `./l5.mjs?v=20260330-runtime-support` for cache busting. After resolvePath, the bundler kept the query suffix, producing bare `lib/l5.mjs?v=20260330-runtime-support` specifiers in the bundled HTML. The import map only registers `lib/l5.mjs` (no query), so browsers reject the import with "Failed to resolve module specifier" and the piece never renders inside the bundled artifact. This manifested as keep-prepare-background's oven timing out at 150s when baking thumbnails for any piece whose code path reaches that import — the iframe loaded a dead module graph and never produced a frame. The silent thumbnail-fallback path then reused the previous thumbnail URI, making the failure invisible to users clicking "Regenerate Media". Fix: strip the query entirely in rewriteImports (blob: URLs in bundled output are already unique per bundle, no cache bust needed). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>