refactor(athena): rename session_handoff to switch_agent to avoid confusion with /handoff command

Rename across all layers to eliminate naming ambiguity:
- Tool: session_handoff → switch_agent
- Hook: agent-handoff → agent-switch
- Feature: agent-handoff/ → agent-switch/
- Types: SessionHandoffArgs → SwitchAgentArgs, PendingHandoff → PendingSwitch
- Functions: setPendingHandoff → setPendingSwitch, consumePendingHandoff → consumePendingSwitch

/handoff = inter-session context summary (existing command)
switch_agent = intra-session active agent change (our new tool)

src/plugin/event.ts

@@ -261,7 +261,7 @@ export function createEventHandler(args: {
     await runEventHookSafely("compactionTodoPreserver", hooks.compactionTodoPreserver?.event, input);
     await runEventHookSafely("writeExistingFileGuard", hooks.writeExistingFileGuard?.event, input);
     await runEventHookSafely("atlasHook", hooks.atlasHook?.handler, input);
-    await runEventHookSafely("agentHandoffHook", hooks.agentHandoffHook?.event, input);
+    await runEventHookSafely("agentSwitchHook", hooks.agentSwitchHook?.event, input);
     await runEventHookSafely("autoSlashCommand", hooks.autoSlashCommand?.event, input);
   };
 

src/plugin/hooks/create-continuation-hooks.ts

@@ -9,7 +9,7 @@ import {
   createCompactionContextInjector,
   createCompactionTodoPreserverHook,
   createAtlasHook,
-  createAgentHandoffHook,
+  createAgentSwitchHook,
 } from "../../hooks"
 import { safeCreateHook } from "../../shared/safe-create-hook"
 import { createUnstableAgentBabysitter } from "../unstable-agent-babysitter"
@@ -22,7 +22,7 @@ export type ContinuationHooks = {
   unstableAgentBabysitter: ReturnType<typeof createUnstableAgentBabysitter> | null
   backgroundNotificationHook: ReturnType<typeof createBackgroundNotificationHook> | null
   atlasHook: ReturnType<typeof createAtlasHook> | null
-  agentHandoffHook: ReturnType<typeof createAgentHandoffHook> | null
+  agentSwitchHook: ReturnType<typeof createAgentSwitchHook> | null
 }
 
 type SessionRecovery = {
@@ -118,8 +118,8 @@ export function createContinuationHooks(args: {
         }))
     : null
 
-  const agentHandoffHook = isHookEnabled("agent-handoff")
-    ? safeHook("agent-handoff", () => createAgentHandoffHook(ctx))
+  const agentSwitchHook = isHookEnabled("agent-switch")
+    ? safeHook("agent-switch", () => createAgentSwitchHook(ctx))
     : null
 
   return {
@@ -130,6 +130,6 @@ export function createContinuationHooks(args: {
     unstableAgentBabysitter,
     backgroundNotificationHook,
     atlasHook,
-    agentHandoffHook,
+    agentSwitchHook,
   }
 }

src/plugin/tool-registry.ts

@@ -14,7 +14,7 @@ import {
   createBackgroundTools,
   createCallOmoAgent,
   createAthenaCouncilTool,
-  createSessionHandoffTool,
+  createSwitchAgentTool,
   createLookAt,
   createSkillMcpTool,
   createSkillTool,
@@ -275,7 +275,7 @@ export function createToolRegistry(args: {
     ...backgroundTools,
     call_omo_agent: callOmoAgent,
     athena_council: athenaCouncilTool,
-    session_handoff: createSessionHandoffTool(),
+    switch_agent: createSwitchAgentTool(),
     ...(lookAt ? { look_at: lookAt } : {}),
     task: delegateTask,
     skill_mcp: skillMcpTool,