feat(categories): add disable field to CategoryConfigSchema

Allow individual categories to be disabled via `disable: true` in
config. Introduce shared `mergeCategories()` utility to centralize
category merging and disabled filtering across all 7 consumption sites.

src/shared/merge-categories.test.ts

@@ -0,0 +1,84 @@
+import { describe, it, expect } from "bun:test"
+import { mergeCategories } from "./merge-categories"
+import { DEFAULT_CATEGORIES } from "../tools/delegate-task/constants"
+
+describe("mergeCategories", () => {
+  it("returns all default categories when no user config provided", () => {
+    //#given
+    const userCategories = undefined
+
+    //#when
+    const result = mergeCategories(userCategories)
+
+    //#then
+    expect(Object.keys(result)).toEqual(Object.keys(DEFAULT_CATEGORIES))
+  })
+
+  it("filters out categories with disable: true", () => {
+    //#given
+    const userCategories = {
+      "quick": { disable: true },
+    }
+
+    //#when
+    const result = mergeCategories(userCategories)
+
+    //#then
+    expect(result["quick"]).toBeUndefined()
+    expect(Object.keys(result).length).toBe(Object.keys(DEFAULT_CATEGORIES).length - 1)
+  })
+
+  it("keeps categories with disable: false", () => {
+    //#given
+    const userCategories = {
+      "quick": { disable: false },
+    }
+
+    //#when
+    const result = mergeCategories(userCategories)
+
+    //#then
+    expect(result["quick"]).toBeDefined()
+  })
+
+  it("allows user to add custom categories", () => {
+    //#given
+    const userCategories = {
+      "my-custom": { model: "openai/gpt-5.2", description: "Custom category" },
+    }
+
+    //#when
+    const result = mergeCategories(userCategories)
+
+    //#then
+    expect(result["my-custom"]).toBeDefined()
+    expect(result["my-custom"].model).toBe("openai/gpt-5.2")
+  })
+
+  it("allows user to disable custom categories", () => {
+    //#given
+    const userCategories = {
+      "my-custom": { model: "openai/gpt-5.2", disable: true },
+    }
+
+    //#when
+    const result = mergeCategories(userCategories)
+
+    //#then
+    expect(result["my-custom"]).toBeUndefined()
+  })
+
+  it("user overrides merge with defaults", () => {
+    //#given
+    const userCategories = {
+      "ultrabrain": { model: "anthropic/claude-opus-4-6" },
+    }
+
+    //#when
+    const result = mergeCategories(userCategories)
+
+    //#then
+    expect(result["ultrabrain"]).toBeDefined()
+    expect(result["ultrabrain"].model).toBe("anthropic/claude-opus-4-6")
+  })
+})

src/shared/merge-categories.ts

@@ -0,0 +1,18 @@
+import type { CategoriesConfig, CategoryConfig } from "../config/schema"
+import { DEFAULT_CATEGORIES } from "../tools/delegate-task/constants"
+
+/**
+ * Merge default and user categories, filtering out disabled ones.
+ * Single source of truth for category merging across the codebase.
+ */
+export function mergeCategories(
+  userCategories?: CategoriesConfig,
+): Record<string, CategoryConfig> {
+  const merged = userCategories
+    ? { ...DEFAULT_CATEGORIES, ...userCategories }
+    : { ...DEFAULT_CATEGORIES }
+
+  return Object.fromEntries(
+    Object.entries(merged).filter(([, config]) => !config.disable),
+  )
+}