Four Primitives, Three Reviews: How a Contributor PR Reshaped a Roadmap

claude-code-slack-channel v0.4.0 shipped a contributor PR that forced a scoping conversation. Four roadmap primitives emerged. Three parallel reviews — architect, sitrep, devils-advocate — converged on a narrower v0.5.0 than the original issues proposed. This is a case study in how collaborative review reshapes plans.