feat(bedrock): enable prompt caching toggle for custom ARN and default to ON

Author: roomote

webview-ui/src/components/settings/providers/Bedrock.tsx

@@ -198,7 +198,7 @@ export const Bedrock = ({ apiConfiguration, setApiConfigurationField, selectedMo
 			{selectedModelInfo?.supportsPromptCache && (
 				<>
 					<Checkbox
-						checked={apiConfiguration?.awsUsePromptCache || false}
+						checked={apiConfiguration?.awsUsePromptCache ?? true}
 						onChange={handleInputChange("awsUsePromptCache", noTransform)}>
 						<div className="flex items-center gap-1">
 							<span>{t("settings:providers.enablePromptCaching")}</span>

webview-ui/src/components/ui/hooks/useSelectedModel.ts

@@ -212,10 +212,13 @@ function getSelectedModel({
 			const baseInfo = bedrockModels[id as keyof typeof bedrockModels]
 
 			// Special case for custom ARN.
+			// Custom ARN is treated as an advanced option where users know what they are doing.
+			// Since custom ARNs often point to newer Claude models that support prompt caching,
+			// we enable the prompt cache toggle to let users decide.
 			if (id === "custom-arn") {
 				return {
 					id,
-					info: { maxTokens: 5000, contextWindow: 128_000, supportsPromptCache: false, supportsImages: true },
+					info: { maxTokens: 5000, contextWindow: 128_000, supportsPromptCache: true, supportsImages: true },
 				}
 			}