Fix model fallback across main/background/sync agents

src/tools/delegate-task/category-resolver.ts

@@ -1,6 +1,7 @@
 import type { ModelFallbackInfo } from "../../features/task-toast-manager/types"
 import type { DelegateTaskArgs } from "./types"
 import type { ExecutorContext } from "./executor-types"
+import type { FallbackEntry } from "../../shared/model-requirements"
 import { mergeCategories } from "../../shared/merge-categories"
 import { SISYPHUS_JUNIOR_AGENT } from "./sisyphus-junior-agent"
 import { resolveCategoryConfig } from "./categories"
@@ -16,6 +17,7 @@ export interface CategoryResolutionResult {
   modelInfo: ModelFallbackInfo | undefined
   actualModel: string | undefined
   isUnstableAgent: boolean
+  fallbackChain?: FallbackEntry[]  // For runtime retry on model errors
   error?: string
 }
 
@@ -177,5 +179,6 @@ Available categories: ${categoryNames.join(", ")}`,
     modelInfo,
     actualModel,
     isUnstableAgent,
+    fallbackChain: requirement?.fallbackChain,
   }
 }