~anthropic/claude-sonnet-latest → B (60:40)

Side B is a coherent, testable identity refactor (splitting canonical_path/identity, making delegate optional, removing sigil-mangling in the reducer, plus new integration tests asserting rejection of '@') that fixes a real correctness/security concern in wire identity handling. Side A is a large mechanical rename (CanonicalItemUrl -> ItemId) that mostly shuffles code between files/modules without adding new capability, and even leaves an unfinished plan.md-driven refactor with fallback 'opaque' hacks that weaken the type safety it claims to add.