Add ModelChain support to ModelConfigService and make ModelDialog dynamic (#22914)

packages/cli/src/config/settingsSchema.ts

@@ -1081,6 +1081,20 @@ const SETTINGS_SCHEMA = {
           ref: 'ModelResolution',
         },
       },
+      modelChains: {
+        type: 'object',
+        label: 'Model Chains',
+        category: 'Model',
+        requiresRestart: true,
+        default: DEFAULT_MODEL_CONFIGS.modelChains,
+        description:
+          'Availability policy chains defining fallback behavior for models.',
+        showInDialog: false,
+        additionalProperties: {
+          type: 'array',
+          ref: 'ModelPolicy',
+        },
+      },
     },
   },
 
@@ -2877,6 +2891,34 @@ export const SETTINGS_SCHEMA_DEFINITIONS: Record<
       },
     },
   },
+  ModelPolicy: {
+    type: 'object',
+    description:
+      'Defines the policy for a single model in the availability chain.',
+    properties: {
+      model: { type: 'string' },
+      isLastResort: { type: 'boolean' },
+      actions: {
+        type: 'object',
+        properties: {
+          terminal: { type: 'string', enum: ['silent', 'prompt'] },
+          transient: { type: 'string', enum: ['silent', 'prompt'] },
+          not_found: { type: 'string', enum: ['silent', 'prompt'] },
+          unknown: { type: 'string', enum: ['silent', 'prompt'] },
+        },
+      },
+      stateTransitions: {
+        type: 'object',
+        properties: {
+          terminal: { type: 'string', enum: ['terminal', 'sticky_retry'] },
+          transient: { type: 'string', enum: ['terminal', 'sticky_retry'] },
+          not_found: { type: 'string', enum: ['terminal', 'sticky_retry'] },
+          unknown: { type: 'string', enum: ['terminal', 'sticky_retry'] },
+        },
+      },
+    },
+    required: ['model'],
+  },
 };
 
 export function getSettingsSchema(): SettingsSchemaType {