How do package access and @_spi differ from public and internal, and what do they look like in a .swiftinterface?

Predict first

What do the interfaces and the clients say?

// === Lib.swift ===
public struct Api {
    public init() {}
    public func open() -> Int { 1 }
    package func shared() -> Int { 2 }
    @_spi(Internal) public func secret() -> Int { 3 }
}
// === A.swift ===
import Lib
print(Api().open(), Api().shared())
// === B.swift ===
@_spi(Internal) import Lib
print(Api().secret())
// === C.swift ===
import Lib
print(Api().secret())
// === run.sh ===
swiftc -swift-version 6 -parse-as-library -package-name Core -emit-module -module-name Lib -emit-module-interface-path Lib.swiftinterface -enable-library-evolution -emit-private-module-interface-path Lib.private.swiftinterface -o Lib.swiftmodule Lib.swift
echo "public interface lists: $(grep -E 'func ' Lib.swiftinterface | sed 's/.*func \([a-z]*\).*/\1/' | tr '\n' ' ')"
echo "private interface lists: $(grep -E 'func ' Lib.private.swiftinterface | sed 's/.*func \([a-z]*\).*/\1/' | tr '\n' ' ')"
for f in A B C; do
  echo "$f same package: $(swiftc -swift-version 6 -typecheck -I . -package-name Core $f.swift 2>&1 | grep -q 'error:' && echo error || echo ok)"
  echo "$f other package: $(swiftc -swift-version 6 -typecheck -I . -package-name App $f.swift 2>&1 | grep -q 'error:' && echo error || echo ok)"
done

• public lists open; private lists open and secret; A: ok same package, 1 other package; B: 0 and 0; C: 1 and 1
• both list all three functions
• package members appear in the public interface
• SPI members compile without the import