Tool schemas can validate each language-model-generated call while still allowing quantity identity to disappear during a longer workflow. A model may read 250 milliseconds, checkpoint a bare scalar, and later pass 250 to a destination expecting seconds. We call this loss of executable unit and identity metadata semantic scalarization. We present DIMLOCK, a small runtime that carries quantities as opaque references, resolves exact compatible conversions, and rejects cross-dimensional references before destination execution. We also introduce a frozen stress protocol with logical checkpoint save/load, same- and cross- dimension distractors, and receipt-backed scoring. Across 36 workflows and 540 controlled fault trials, DIMLOCK contains all 108 primary faults while prose and structured scalar handoffs contain none. A same- dimension identity swap defeats every interface, confirming the boundary of dimension-only enforcement. Native MCP pilots cover 216 Codex trajectories and a balanced 36-trajectory Claude Sonnet replication; tested models usually rejected explicit traps, so we make no prevalence claim. The result is a focused runtime invariant and a reproducible test for a failure class that local tool schemas do not express.