feat(config): add configurable agent ordering

src/plugin-handlers/agent-priority-order.ts

@@ -1,35 +1,16 @@
-import { getAgentListDisplayName } from "../shared/agent-display-names"
+import { DEFAULT_AGENT_ORDER, resolveAgentOrderDisplayNames } from "../shared/agent-ordering"
 
 /**
- * CRITICAL: This is the ONLY source of truth for core agent ordering.
- * The order is: sisyphus → hephaestus → prometheus → atlas
+ * Default source of truth for core agent ordering.
+ * The default order is: sisyphus → hephaestus → prometheus → atlas.
  *
- * DO NOT CHANGE THIS ORDER. Any PR attempting to modify this order
- * or introduce alternative ordering mechanisms (ZWSP prefixes, sort
- * shims, etc.) will be rejected.
+ * User config may override the runtime order through `agent_order`; missing
+ * core agents still fall back to this default order. Do not reintroduce sort
+ * key prefixes or a second ordering constant.
  *
  * See: src/plugin-handlers/AGENTS.md for architectural context.
  */
-export const CANONICAL_CORE_AGENT_ORDER = [
-  "sisyphus",
-  "hephaestus",
-  "prometheus",
-  "atlas",
-] as const
-
-type CoreAgentName = (typeof CANONICAL_CORE_AGENT_ORDER)[number]
-
-const CORE_AGENT_ORDER: ReadonlyArray<{
-  configKey: CoreAgentName
-  displayName: string
-  order: number
-}> = CANONICAL_CORE_AGENT_ORDER.map((configKey, index) => ({
-  configKey,
-  displayName: getAgentListDisplayName(configKey),
-  order: index + 1,
-}))
-
-const CORE_DISPLAY_NAMES = new Set(CORE_AGENT_ORDER.map((a) => a.displayName))
+export const CANONICAL_CORE_AGENT_ORDER = DEFAULT_AGENT_ORDER
 
 function injectOrderField(agentConfig: unknown, order: number): unknown {
   if (typeof agentConfig === "object" && agentConfig !== null) {
@@ -40,13 +21,15 @@ function injectOrderField(agentConfig: unknown, order: number): unknown {
 
 export function reorderAgentsByPriority(
   agents: Record<string, unknown>,
+  agentOrder?: readonly string[],
 ): Record<string, unknown> {
   const ordered: Record<string, unknown> = {}
   const seen = new Set<string>()
+  const orderedDisplayNames = resolveAgentOrderDisplayNames(agentOrder)
 
-  for (const { displayName, order } of CORE_AGENT_ORDER) {
+  for (const [index, displayName] of orderedDisplayNames.entries()) {
     if (Object.prototype.hasOwnProperty.call(agents, displayName)) {
-      ordered[displayName] = injectOrderField(agents[displayName], order)
+      ordered[displayName] = injectOrderField(agents[displayName], index + 1)
       seen.add(displayName)
     }
   }