refactor(migration): split model and category helpers (#1561)

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/migration/agent-category.ts

@@ -0,0 +1,60 @@
+/**
+ * @deprecated LEGACY MIGRATION ONLY
+ *
+ * This map exists solely for migrating old configs that used hardcoded model strings.
+ * It maps legacy model strings to semantic category names, allowing users to migrate
+ * from explicit model configs to category-based configs.
+ *
+ * DO NOT add new entries here. New agents should use:
+ * - Category-based config (preferred): { category: "unspecified-high" }
+ * - Or inherit from OpenCode's config.model
+ *
+ * This map will be removed in a future major version once migration period ends.
+ */
+export const MODEL_TO_CATEGORY_MAP: Record<string, string> = {
+  "google/gemini-3-pro": "visual-engineering",
+  "google/gemini-3-flash": "writing",
+  "openai/gpt-5.2": "ultrabrain",
+  "anthropic/claude-haiku-4-5": "quick",
+  "anthropic/claude-opus-4-6": "unspecified-high",
+  "anthropic/claude-sonnet-4-5": "unspecified-low",
+}
+
+export function migrateAgentConfigToCategory(config: Record<string, unknown>): {
+  migrated: Record<string, unknown>
+  changed: boolean
+} {
+  const { model, ...rest } = config
+  if (typeof model !== "string") {
+    return { migrated: config, changed: false }
+  }
+
+  const category = MODEL_TO_CATEGORY_MAP[model]
+  if (!category) {
+    return { migrated: config, changed: false }
+  }
+
+  return {
+    migrated: { category, ...rest },
+    changed: true,
+  }
+}
+
+export function shouldDeleteAgentConfig(
+  config: Record<string, unknown>,
+  category: string
+): boolean {
+  const { DEFAULT_CATEGORIES } = require("../../tools/delegate-task/constants")
+  const defaults = DEFAULT_CATEGORIES[category]
+  if (!defaults) return false
+
+  const keys = Object.keys(config).filter((k) => k !== "category")
+  if (keys.length === 0) return true
+
+  for (const key of keys) {
+    if (config[key] !== (defaults as Record<string, unknown>)[key]) {
+      return false
+    }
+  }
+  return true
+}