fix(athena): address 9 council-audit findings — dead code, bugs, and hardening

Fixes from multi-model council audit (7 members, 19 findings, 9 selected):

- Use parseModelString() for cross-provider Anthropic thinking config (#3)
- Update stale AGENTS.md athena directory listing (#4)
- Replace prompt in appendMissingCouncilPrompt instead of appending (#5)
- Extract duplicated session cleanup logic in agent-switch hook (#6)
- Surface skipped council members when >=2 valid members exist (#9)
- Expand fallback handoff regex with negation guards (#11)
- Remove dead council-member agent from agentSources and tests (#12)
- Make runtime council member duplicate check case-insensitive (#14)
- Fix false-positive schema tests by adding required name field (#18)

src/hooks/agent-switch/fallback-handoff.ts

@@ -51,17 +51,34 @@ export function extractTextPartsFromMessageResponse(response: unknown): string {
     .join("\n")
 }
 
-export function detectFallbackHandoffTarget(messageText: string): "atlas" | "prometheus" | undefined {
+const HANDOFF_TARGETS = ["prometheus", "atlas"] as const
+type HandoffTarget = (typeof HANDOFF_TARGETS)[number]
+
+const HANDOFF_VERBS = [
+  "switching",
+  "handing\\s+off",
+  "delegating",
+  "routing",
+  "transferring",
+  "passing",
+]
+
+function buildHandoffPattern(target: string): RegExp {
+  const verbGroup = HANDOFF_VERBS.join("|")
+  return new RegExp(
+    `(?<!\\bnot\\s+)(?<!\\bdon'?t\\s+)(?<!\\bnever\\s+)(?:${verbGroup})\\s+(?:(?:control|this|it|work)\\s+)?to\\s+\\*{0,2}\\s*${target}\\b`
+  )
+}
+
+export function detectFallbackHandoffTarget(messageText: string): HandoffTarget | undefined {
   if (!messageText) return undefined
 
   const normalized = messageText.toLowerCase()
 
-  if (/switching\s+to\s+\*{0,2}\s*prometheus\b/.test(normalized) || /handing\s+off\s+to\s+\*{0,2}\s*prometheus\b/.test(normalized)) {
-    return "prometheus"
-  }
-
-  if (/switching\s+to\s+\*{0,2}\s*atlas\b/.test(normalized) || /handing\s+off\s+to\s+\*{0,2}\s*atlas\b/.test(normalized)) {
-    return "atlas"
+  for (const target of HANDOFF_TARGETS) {
+    if (buildHandoffPattern(target).test(normalized)) {
+      return target
+    }
   }
 
   return undefined

src/hooks/agent-switch/hook.ts

@@ -14,6 +14,15 @@ import {
 const processedFallbackMessages = new Set<string>()
 const MAX_PROCESSED_FALLBACK_MARKERS = 500
 
+function clearFallbackMarkersForSession(sessionID: string): void {
+  clearPendingSwitchRuntime(sessionID)
+  for (const key of Array.from(processedFallbackMessages)) {
+    if (key.startsWith(`${sessionID}:`)) {
+      processedFallbackMessages.delete(key)
+    }
+  }
+}
+
 function getSessionIDFromStatusEvent(input: { event: { properties?: Record<string, unknown> } }): string | undefined {
   const props = input.event.properties as Record<string, unknown> | undefined
   const fromProps = typeof props?.sessionID === "string" ? props.sessionID : undefined
@@ -46,12 +55,7 @@ export function createAgentSwitchHook(ctx: PluginInput) {
         const info = props?.info as Record<string, unknown> | undefined
         const deletedSessionID = info?.id
         if (typeof deletedSessionID === "string") {
-          clearPendingSwitchRuntime(deletedSessionID)
-          for (const key of Array.from(processedFallbackMessages)) {
-            if (key.startsWith(`${deletedSessionID}:`)) {
-              processedFallbackMessages.delete(key)
-            }
-          }
+          clearFallbackMarkersForSession(deletedSessionID)
         }
         return
       }
@@ -61,12 +65,7 @@ export function createAgentSwitchHook(ctx: PluginInput) {
         const info = props?.info as Record<string, unknown> | undefined
         const erroredSessionID = info?.id ?? props?.sessionID
         if (typeof erroredSessionID === "string") {
-          clearPendingSwitchRuntime(erroredSessionID)
-          for (const key of Array.from(processedFallbackMessages)) {
-            if (key.startsWith(`${erroredSessionID}:`)) {
-              processedFallbackMessages.delete(key)
-            }
-          }
+          clearFallbackMarkersForSession(erroredSessionID)
         }
         return
       }