Make request execution overrides presence-aware

internal/usecase/runner.go

@@ -187,7 +187,10 @@ func (r *Runner) Prepare(ctx context.Context, req domain.RunRequest) (*domain.Pr
 		return nil, fmt.Errorf("%w: %w", ErrProfileLoad, err)
 	}
 
-	effectiveModel := resolveExecutionTarget(execProfile, req.Execution)
+	effectiveModel, err := resolveExecutionTarget(execProfile, req.Execution)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %w", ErrInvalidRequest, err)
+	}
 	if strings.TrimSpace(effectiveModel.Endpoint) == "" {
 		return nil, fmt.Errorf("%w: execution endpoint is required", ErrInvalidRequest)
 	}
@@ -355,22 +358,69 @@ func mergeExecutionTarget(base domain.ExecutionTarget, override domain.Execution
 		out.APIKeyEnv = override.APIKeyEnv
 	}
 	if len(override.ExtraParams) > 0 {
-		cp := make(map[string]string, len(override.ExtraParams))
-		for k, v := range override.ExtraParams {
-			cp[k] = v
-		}
-		out.ExtraParams = cp
+		out.ExtraParams = copyExtraParams(override.ExtraParams)
 	}
 	return out
 }
 
-func resolveExecutionTarget(profileValue *domain.ExecutionProfile, override *domain.ExecutionTarget) domain.ExecutionTarget {
+func mergeExecutionTargetOverride(base domain.ExecutionTarget, override domain.ExecutionTargetOverride) (domain.ExecutionTarget, error) {
+	out := base
+	if override.Endpoint != "" {
+		out.Endpoint = override.Endpoint
+	}
+	if override.Model != "" {
+		out.Model = override.Model
+	}
+	if override.Temperature != nil {
+		if *override.Temperature < 0 || *override.Temperature > 2 {
+			return domain.ExecutionTarget{}, errors.New("temperature must be between 0 and 2")
+		}
+		out.Temperature = *override.Temperature
+	}
+	if override.MaxTokens != nil {
+		if *override.MaxTokens < 0 {
+			return domain.ExecutionTarget{}, errors.New("max_tokens must be greater than or equal to 0")
+		}
+		out.MaxTokens = *override.MaxTokens
+	}
+	if override.TopP != nil {
+		if *override.TopP < 0 || *override.TopP > 1 {
+			return domain.ExecutionTarget{}, errors.New("top_p must be between 0 and 1")
+		}
+		out.TopP = *override.TopP
+	}
+	if override.TimeoutSeconds != nil {
+		if *override.TimeoutSeconds < 0 {
+			return domain.ExecutionTarget{}, errors.New("timeout_seconds must be greater than or equal to 0")
+		}
+		out.TimeoutSeconds = *override.TimeoutSeconds
+	}
+	if strings.TrimSpace(override.ServiceTier) != "" {
+		out.ServiceTier = override.ServiceTier
+	}
+	if strings.TrimSpace(override.ReasoningEffort) != "" {
+		out.ReasoningEffort = override.ReasoningEffort
+	}
+	if strings.TrimSpace(override.APIKeyEnv) != "" {
+		out.APIKeyEnv = override.APIKeyEnv
+	}
+	if len(override.ExtraParams) > 0 {
+		out.ExtraParams = copyExtraParams(override.ExtraParams)
+	}
+	return out, nil
+}
+
+func resolveExecutionTarget(profileValue *domain.ExecutionProfile, override *domain.ExecutionTargetOverride) (domain.ExecutionTarget, error) {
 	out := defaults.ExecutionTargetDefault()
 	out = mergeExecutionTarget(out, executionProfileToTarget(profileValue))
 	if override != nil {
-		out = mergeExecutionTarget(out, *override)
+		var err error
+		out, err = mergeExecutionTargetOverride(out, *override)
+		if err != nil {
+			return domain.ExecutionTarget{}, err
+		}
 	}
-	return out
+	return out, nil
 }
 
 func validateAPIKeyEnv(apiKeyEnv string) error {
@@ -388,13 +438,6 @@ func executionProfileToTarget(p *domain.ExecutionProfile) domain.ExecutionTarget
 	if p == nil {
 		return domain.ExecutionTarget{}
 	}
-	cp := map[string]string(nil)
-	if len(p.ExtraParams) > 0 {
-		cp = make(map[string]string, len(p.ExtraParams))
-		for k, v := range p.ExtraParams {
-			cp[k] = v
-		}
-	}
 	return domain.ExecutionTarget{
 		Endpoint:        p.Endpoint,
 		Model:           p.Model,
@@ -405,10 +448,21 @@ func executionProfileToTarget(p *domain.ExecutionProfile) domain.ExecutionTarget
 		ServiceTier:     p.ServiceTier,
 		ReasoningEffort: p.ReasoningEffort,
 		APIKeyEnv:       p.APIKeyEnv,
-		ExtraParams:     cp,
+		ExtraParams:     copyExtraParams(p.ExtraParams),
 	}
 }
 
+func copyExtraParams(src map[string]any) map[string]any {
+	if len(src) == 0 {
+		return nil
+	}
+	cp := make(map[string]any, len(src))
+	for k, v := range src {
+		cp[k] = v
+	}
+	return cp
+}
+
 func resolveOutputContract(def *domain.PromptDefinition, override *domain.OutputContract) domain.OutputContract {
 	contract := def.Validation
 	if contract.Format == "" {