implement-spf-use-case

# Implement an SPF use case Read `references/workflow.md` completely before acting; it contains the detailed composition, prerequisite, implementation, testing, and cascade workflow. Treat the use-case entry as planning input. Read it, its constituent features, current compositions/adapters, tests, and applicable conventions. 1. Verify each required feature is implemented for the requested scope; expose missing prerequisites instead of hiding them in wiring. 2. Reconcile documented assumptions with code and identify material open decisions. 3. Define the smallest observable composition increment and split it into independently testable prerequisite, behavior, composition, adapter, and documentation chunks. 4. Implement each chunk test-first at the correct feature, behavior, composition, or adapter boundary. 5. Run cumulative SPF tests, build, and size checks proportional to impact. 6. Collapse the use-case record to composition decisions, remaining scope, source pointers, and directly affected relationships. Report implemented and deferred scope, evidence, record updates, and remaining risks. Do not claim the use case complete while constituents remain partial. ## Example Input: “Implement the smallest playable low-latency live composition.” Output: A verified minimal composition, exposed prerequisites, cumulative checks, updated use-case evidence, and explicit deferred work.