A rebuilt WPF project only resolves its own pack URIs when every entry of
"<AssemblyName>.g.resources" comes back under the resource ID it had before.
The file on disk cannot carry that ID: it is sanitized for the file system,
and the ID itself is escaped. Verified against a WPF assembly built for this:
the WPF build tasks re-escape whatever LogicalName they are given, so the item
has to hand them the decoded name, and an entry left as EmbeddedResource
rebuilds into a manifest resource of its own instead of into ".g.resources".
The adjustment is made where the items are collected, so it covers the base
class and both hosts that plug their own BAML handling into it without
widening the WriteResourceToFile or IResourceFileHandler contracts.
The Resource build action this gives them is also what #2253 asks for.
Assisted-by: Claude:claude-opus-5[1m]:Claude Code
Siegfried Pammer