Substrate-Observation as an Alternative to Envelope Coordination for Concurrent Sessions

This memo articulates a coordination-protocol anti-pattern observed in cross-tool agentic systems and describes a substrate-observation alternative that does not require negotiating a wire format between heterogeneous concurrent sessions of an identity-bound principal. The memo is Informational. No protocol element is being proposed for standardisation; the contribution is the opposite -- a delineation of what should NOT be standardised, and why, with a reference to the substrate-physics primitives that take its place. Companion memos in the morrison-* family describe the identity primitives this memo presumes; specifically, this memo relies on the ~handle namespace established in [IDPRONOUNS] and the per-principal identity substrate referenced in [IDACCORD].