fix(delegate-task): make plan agent categories/skills dynamic

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

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

src/tools/delegate-task/prompt-builder.ts

@@ -1,14 +1,22 @@
-import { PLAN_AGENT_SYSTEM_PREPEND, isPlanAgent } from "./constants"
 import type { BuildSystemContentInput } from "./types"
+import { buildPlanAgentSystemPrepend, isPlanAgent } from "./constants"
 
 /**
  * Build the system content to inject into the agent prompt.
  * Combines skill content, category prompt append, and plan agent system prepend.
  */
 export function buildSystemContent(input: BuildSystemContentInput): string | undefined {
-  const { skillContent, categoryPromptAppend, agentName } = input
+  const {
+    skillContent,
+    categoryPromptAppend,
+    agentName,
+    availableCategories,
+    availableSkills,
+  } = input
 
-  const planAgentPrepend = isPlanAgent(agentName) ? PLAN_AGENT_SYSTEM_PREPEND : ""
+  const planAgentPrepend = isPlanAgent(agentName)
+    ? buildPlanAgentSystemPrepend(availableCategories, availableSkills)
+    : ""
 
   if (!skillContent && !categoryPromptAppend && !planAgentPrepend) {
     return undefined