~anthropic/claude-sonnet-latest → A (3:1)

Side A fixes a genuine correctness issue (removing an unwrap_or that silently masked a missing-post-id bug with an expect that surfaces invariant violations), aligns the index scheme consistently across template, types docs, and adds regression tests verifying the 0-based indexing behavior. Side B merely deletes a dead/unused test function (missing #[test] attribute) that was never actually run, which is a trivial cleanup with no functional impact.