A bundle could import only what the toolchain image carried: the compiler and the bundler resolve an import from the module's directory and then the toolchain's node_modules, and nothing ever put anything in the first. So a module needing a database driver (pg, mongodb, mssql) could not be a bundle, and kept a container whose recipe installed it (hq ADR 0198 §4: the backend's own driver inside the bundle).
Now, when a module's package.json depends on anything beyond the SDK, the build installs its production dependencies into the module's directory, in the toolchain image, before the compile: npm ci from the lockfile when there is one, npm install from the ranges otherwise, the mesh's registry for the SDK's scope and the public one for the rest, install scripts off. esbuild then inlines them. A module depending only on the SDK runs exactly the commands it did before.
The SDK stays the toolchain's (hq issue 212): it is taken out of what is installed and any copy something pulls in is removed, so every import of it resolves past the module's node_modules to the one the toolchain carries; a module's own range never shadows it. npm's verified download cache is a named volume; nothing installed is kept between builds. Without a registry, a scoped package is refused rather than resolved on the public registry.
jochen