feat: complete pre-ai local completion v3

central/app/ai/provider.py

@@ -18,6 +18,14 @@ class SemanticOutputError(ValueError):
     """Raised when a provider answer violates the strict structured-output schema."""
 
 
+class ProviderTransportError(RuntimeError):
+    """A retryable failure while contacting a semantic provider."""
+
+
+class ProviderContractError(ValueError):
+    """A non-retryable provider response or protocol violation."""
+
+
 @dataclass
 class StructuredResult:
     task_type: str
@@ -137,3 +145,11 @@ class BudgetGuard:
         if plan.get("estimated_cost") is None:
             return allow_unknown_cost
         return plan["estimated_cost"] <= self.max_run_cost_usd
+
+    def authorize_usage(self, input_tokens: int, output_tokens: int, *, prior_cost_usd: float = 0.0,
+                        allow_unknown_cost: bool = False) -> bool:
+        """Apply the same guard to actual usage before accepting a provider result."""
+        plan = self.estimate(input_tokens, output_tokens)
+        if plan.get("estimated_cost") is None:
+            return allow_unknown_cost
+        return float(prior_cost_usd) + plan["estimated_cost"] <= self.max_run_cost_usd