Sema adds a content-addressed vocabulary of 452 cognitive patterns to Claude. Each pattern has a handle like StateLock#5602 — a SHA-256 hash of its definition — so two agents using the same handle are provably talking about the same thing. Any divergence in meaning produces a different hash, making silent misalignment impossible. Key features: - sema_search — semantic + keyword search across the pattern library • sema_resolve — full definition, mechanism, invariants, and dependency graph for any handle • sema_handshake — verify two agents share the exact same definition; halt on mismatch • sema_tree — browse the taxonomy (Physics / Mind / Society / Infrastructure) • sema_root — one-hash fingerprint of the whole vocabulary, for fast drift checks • sema_mint — add project-local patterns (survives pip upgrades) • sema pull — sync a project DB with upstream, auto-redirecting renamed handles