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+# RFC 004: Budget allocate and enforce
+
+## Problem
+
+- Spec `BudgetPolicy` used for both request and response with client-supplied `budgetId`.
+- Platform allocate: server-generated `budgetId`, `ttlSeconds`, `maxCostUsd`, usage counters on response.
+- Spec `enforceBudget` uses tier `ModelRoutingPolicy`; platform uses `budgetId` + `fallbackModel`.
+
+## Proposal
+
+Split allocate request/response schemas; document enforce operation for budget-bound routing.