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/agents/agent-builder.ts

@@ -2,7 +2,7 @@ import type { AgentConfig } from "@opencode-ai/sdk"
 import type { AgentFactory } from "./types"
 import type { CategoriesConfig, CategoryConfig, GitMasterConfig } from "../config/schema"
 import type { BrowserAutomationProvider } from "../config/schema"
-import { DEFAULT_CATEGORIES } from "../tools/delegate-task/constants"
+import { mergeCategories } from "../shared/merge-categories"
 import { resolveMultipleSkills } from "../features/opencode-skill-loader/skill-content"
 
 export type AgentSource = AgentFactory | AgentConfig
@@ -20,9 +20,7 @@ export function buildAgent(
   disabledSkills?: Set<string>
 ): AgentConfig {
   const base = isFactory(source) ? source(model) : { ...source }
-  const categoryConfigs: Record<string, CategoryConfig> = categories
-    ? { ...DEFAULT_CATEGORIES, ...categories }
-    : DEFAULT_CATEGORIES
+  const categoryConfigs: Record<string, CategoryConfig> = mergeCategories(categories)
 
   const agentWithCategory = base as AgentConfig & { category?: string; skills?: string[]; variant?: string }
   if (agentWithCategory.category) {

src/agents/atlas/agent.ts

@@ -15,7 +15,7 @@ import { isGptModel } from "../types"
 import type { AvailableAgent, AvailableSkill, AvailableCategory } from "../dynamic-agent-prompt-builder"
 import { buildCategorySkillsDelegationGuide } from "../dynamic-agent-prompt-builder"
 import type { CategoryConfig } from "../../config/schema"
-import { DEFAULT_CATEGORIES } from "../../tools/delegate-task/constants"
+import { mergeCategories } from "../../shared/merge-categories"
 import { createAgentToolRestrictions } from "../../shared/permission-compat"
 
 import { getDefaultAtlasPrompt } from "./default"
@@ -70,7 +70,7 @@ function buildDynamicOrchestratorPrompt(ctx?: OrchestratorContext): string {
   const userCategories = ctx?.userCategories
   const model = ctx?.model
 
-  const allCategories = { ...DEFAULT_CATEGORIES, ...userCategories }
+  const allCategories = mergeCategories(userCategories)
   const availableCategories: AvailableCategory[] = Object.entries(allCategories).map(([name]) => ({
     name,
     description: getCategoryDescription(name, userCategories),

src/agents/atlas/prompt-section-builder.ts

@@ -7,7 +7,8 @@
 
 import type { CategoryConfig } from "../../config/schema"
 import { formatCustomSkillsBlock, type AvailableAgent, type AvailableSkill } from "../dynamic-agent-prompt-builder"
-import { DEFAULT_CATEGORIES, CATEGORY_DESCRIPTIONS } from "../../tools/delegate-task/constants"
+import { CATEGORY_DESCRIPTIONS } from "../../tools/delegate-task/constants"
+import { mergeCategories } from "../../shared/merge-categories"
 import { truncateDescription } from "../../shared/truncate-description"
 
 export const getCategoryDescription = (name: string, userCategories?: Record<string, CategoryConfig>) =>
@@ -33,7 +34,7 @@ ${rows.join("\n")}`
 }
 
 export function buildCategorySection(userCategories?: Record<string, CategoryConfig>): string {
-  const allCategories = { ...DEFAULT_CATEGORIES, ...userCategories }
+  const allCategories = mergeCategories(userCategories)
   const categoryRows = Object.entries(allCategories).map(([name, config]) => {
     const temp = config.temperature ?? 0.5
     return `| \`${name}\` | ${temp} | ${getCategoryDescription(name, userCategories)} |`
@@ -116,7 +117,7 @@ task(category="[category]", load_skills=["skill-1", "skill-2"], run_in_backgroun
 }
 
 export function buildDecisionMatrix(agents: AvailableAgent[], userCategories?: Record<string, CategoryConfig>): string {
-  const allCategories = { ...DEFAULT_CATEGORIES, ...userCategories }
+  const allCategories = mergeCategories(userCategories)
 
   const categoryRows = Object.entries(allCategories).map(([name]) =>
     `| ${getCategoryDescription(name, userCategories)} | \`category="${name}", load_skills=[...]\` |`

src/agents/builtin-agents.ts

@@ -14,7 +14,8 @@ import { createMomusAgent, momusPromptMetadata } from "./momus"
 import { createHephaestusAgent } from "./hephaestus"
 import type { AvailableCategory } from "./dynamic-agent-prompt-builder"
 import { fetchAvailableModels, readConnectedProvidersCache } from "../shared"
-import { DEFAULT_CATEGORIES, CATEGORY_DESCRIPTIONS } from "../tools/delegate-task/constants"
+import { CATEGORY_DESCRIPTIONS } from "../tools/delegate-task/constants"
+import { mergeCategories } from "../shared/merge-categories"
 import { buildAvailableSkills } from "./builtin-agents/available-skills"
 import { collectPendingBuiltinAgents } from "./builtin-agents/general-agents"
 import { maybeCreateSisyphusConfig } from "./builtin-agents/sisyphus-agent"
@@ -78,9 +79,7 @@ export async function createBuiltinAgents(
 
   const result: Record<string, AgentConfig> = {}
 
-  const mergedCategories = categories
-    ? { ...DEFAULT_CATEGORIES, ...categories }
-    : DEFAULT_CATEGORIES
+  const mergedCategories = mergeCategories(categories)
 
   const availableCategories: AvailableCategory[] = Object.entries(mergedCategories).map(([name]) => ({
     name,