feat(delegate-task): use explicit high variant for unspecified-high category

- Update DEFAULT_CATEGORIES to use 'openai/gpt-5.4-high' directly instead of separate model + variant
- Add helper functions (isExplicitHighModel, getExplicitHighBaseModel) to preserve explicit high models during fuzzy matching
- Update category resolver to avoid collapsing explicit high models to base model + variant pair
- Update tests to verify explicit high model handling in both background and sync modes
- Update documentation examples to reflect new configuration

🤖 Generated with OhMyOpenCode assistance

src/tools/delegate-task/model-selection.ts

@@ -3,6 +3,14 @@ import { normalizeModel } from "../../shared/model-normalization"
 import { fuzzyMatchModel } from "../../shared/model-availability"
 import { transformModelForProvider } from "../../shared/provider-model-id-transform"
 
+function isExplicitHighModel(model: string): boolean {
+  return /(?:^|\/)[^/]+-high$/.test(model)
+}
+
+function getExplicitHighBaseModel(model: string): string | null {
+  return isExplicitHighModel(model) ? model.replace(/-high$/, "") : null
+}
+
 
 export function resolveModelForDelegateTask(input: {
   userModel?: string
@@ -17,6 +25,8 @@ export function resolveModelForDelegateTask(input: {
   }
 
   const categoryDefault = normalizeModel(input.categoryDefaultModel)
+  const explicitHighBaseModel = categoryDefault ? getExplicitHighBaseModel(categoryDefault) : null
+  const explicitHighModel = explicitHighBaseModel ? categoryDefault : undefined
   if (categoryDefault) {
     if (input.availableModels.size === 0) {
       return { model: categoryDefault }
@@ -26,6 +36,10 @@ export function resolveModelForDelegateTask(input: {
     const providerHint = parts.length >= 2 ? [parts[0]] : undefined
     const match = fuzzyMatchModel(categoryDefault, input.availableModels, providerHint)
     if (match) {
+      if (isExplicitHighModel(categoryDefault) && match !== categoryDefault) {
+        return { model: categoryDefault }
+      }
+
       return { model: match }
     }
   }
@@ -45,12 +59,20 @@ export function resolveModelForDelegateTask(input: {
           const fullModel = `${provider}/${entry.model}`
           const match = fuzzyMatchModel(fullModel, input.availableModels, [provider])
           if (match) {
+            if (explicitHighModel && entry.variant === "high" && match === explicitHighBaseModel) {
+              return { model: explicitHighModel }
+            }
+
             return { model: match, variant: entry.variant }
           }
         }
 
         const crossProviderMatch = fuzzyMatchModel(entry.model, input.availableModels)
         if (crossProviderMatch) {
+          if (explicitHighModel && entry.variant === "high" && crossProviderMatch === explicitHighBaseModel) {
+            return { model: explicitHighModel }
+          }
+
           return { model: crossProviderMatch, variant: entry.variant }
         }
       }