Pinned to e5f7607 (v0.12.0), the exact commit already resolved in
Outpost.xcodeproj's Package.resolved — no version change, just gives it
a local, versioned checkout instead of only existing as an Xcode-managed
remote package cache. Brings its own ARCHITECTURE.md along at
Vendor/swift-markdown-engine/ARCHITECTURE.md.
Xcode side still needs a manual follow-up: remove the remote
"swift-markdown-engine" package reference and add
Vendor/swift-markdown-engine as a local package instead (File > Add
Package Dependencies > Add Local...). Not done here — pbxproj package
references aren't safely hand-editable without a build to verify against.