feat(config): add custom_agents overrides and strict agent validation

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

@@ -15,7 +15,9 @@ export async function resolveSubagentExecution(
   args: DelegateTaskArgs,
   executorCtx: ExecutorContext,
   parentAgent: string | undefined,
-  categoryExamples: string
+  categoryExamples: string,
+  inheritedModel?: string,
+  systemDefaultModel?: string,
 ): Promise<{ agentToUse: string; categoryModel: { providerID: string; modelID: string; variant?: string } | undefined; fallbackChain?: FallbackEntry[]; error?: string }> {
   const { client, agentOverrides } = executorCtx
 
@@ -123,6 +125,16 @@ Create the work plan directly - that's your job as the planning agent.`,
     if (!categoryModel && matchedAgent.model) {
       categoryModel = matchedAgent.model
     }
+
+    if (!categoryModel) {
+      const fallbackModel = inheritedModel ?? systemDefaultModel
+      if (fallbackModel) {
+        const parsedFallback = parseModelString(fallbackModel)
+        if (parsedFallback) {
+          categoryModel = parsedFallback
+        }
+      }
+    }
   } catch (error) {
     const errorMessage = error instanceof Error ? error.message : String(error)
     log("[delegate-task] Failed to resolve subagent execution", {