feat: implement explicit context caching for main agent with stable SI hashing

packages/cli/src/config/settingsSchema.ts

@@ -2156,6 +2156,53 @@ const SETTINGS_SCHEMA = {
           },
         },
       },
+      contextCaching: {
+        type: 'object',
+        label: 'Context Caching',
+        category: 'Experimental',
+        requiresRestart: true,
+        default: {},
+        description: 'Explicit context caching for the main agent.',
+        showInDialog: true,
+        properties: {
+          enabled: {
+            type: 'boolean',
+            label: 'Enable Context Caching',
+            category: 'Experimental',
+            requiresRestart: true,
+            default: false,
+            description: 'Enable explicit context caching for the main agent.',
+            showInDialog: true,
+          },
+          thresholdTokens: {
+            type: 'number',
+            label: 'Threshold Tokens',
+            category: 'Experimental',
+            requiresRestart: true,
+            default: 32768,
+            description: 'Minimum tokens required to trigger explicit caching.',
+            showInDialog: true,
+          },
+          ttlMinutes: {
+            type: 'number',
+            label: 'TTL (Minutes)',
+            category: 'Experimental',
+            requiresRestart: true,
+            default: 60,
+            description: 'Time to live for a cache resource in minutes.',
+            showInDialog: true,
+          },
+          autoRenew: {
+            type: 'boolean',
+            label: 'Auto Renew',
+            category: 'Experimental',
+            requiresRestart: true,
+            default: true,
+            description: 'Automatically extend TTL on use.',
+            showInDialog: true,
+          },
+        },
+      },
       adk: {
         type: 'object',
         label: 'ADK',