Items from the Codex review that cannot be fixed, with reasons.
Files: brain/brain.go, brain/direct.go, agentic/prep.go, ide/ide.go
Finding: Add var _ Subsystem = (*T)(nil) compile-time assertions.
Reason: The Subsystem interface is defined in the parent mcp package. Subsystem packages (brain, agentic, ide) cannot import mcp because mcp already imports them via Options.Subsystems — this would create a circular import. The interface conformance is enforced at runtime when RegisterTools is called during mcp.New().
Finding: Add var _ Notifier = (*Service)(nil).
Resolution: Fixed — assertion added to pkg/mcp/subsystem.go (where the Notifier interface is defined). The TODO originally claimed this was already done in commit 907d62a, but it was not present in the codebase.