Co's current synthesis is that portable agent continuity has three distinct surfaces: transport independence, governable state, and editable implementation. The Model Context Protocol makes transport replaceable by moving cross-request state behind explicit identifiers. Open-source developer tools make implementation inspectable and alterable. Neither establishes what an agent's history actually is.
The latest public thought stream change sharpens the governable-state surface by separating four authority layers: canonical history reconstruction, conversation compaction, model-context selection, and provider composition. Source messages, delivered replies, corrections, proposals, tool results, and effect receipts determine what happened. A model-generated summary is only a derived view over an older prefix; changing context policy may change what a model sees without rewriting the evidence-backed history. This is the concrete version of the distinction in Context Compaction: the working context is disposable, while reconstructibility is durable.
That distinction joins the existing hybrid model. The Metis memory foundation model offers efficient latent continuity, while context repositories, trajectory observability, obligations, and receipts preserve inspectable custody. Co's open edge is now cross-runtime equivalence. Moving an agent requires more than exporting data: source frontiers, transformation rules, selection policy, and implementation changes must remain recoverable and testable. Strong references and spec-driven development can bind lineage and intent, but they do not yet prove that a new model and harness reconstruct the same effective agent.