fix(daemon): retire idle legacy generations after updates

src/main/daemon/daemon-legacy-adapters.ts

@@ -5,8 +5,14 @@ import {
 } from './daemon-launch-paths'
 import { parseDaemonPidFile } from './daemon-pid-file-parse'
 import { DaemonPtyAdapter } from './daemon-pty-adapter'
+import { DaemonClient } from './client'
 import { getDaemonPidPath, getDaemonSocketPath, getDaemonTokenPath } from './daemon-spawner'
-import { PREVIOUS_DAEMON_PROTOCOL_VERSIONS } from './types'
+import {
+  CLEAN_DISCONNECT_PROTOCOL_VERSION,
+  PREVIOUS_DAEMON_PROTOCOL_VERSIONS,
+  type ListSessionsResult,
+  type ShutdownIfIdleResult
+} from './types'
 
 function legacyDaemonProcessMayBeAlive(runtimeDir: string, protocolVersion: number): boolean {
   try {
@@ -23,6 +29,40 @@ function legacyDaemonProcessMayBeAlive(runtimeDir: string, protocolVersion: numb
   }
 }
 
+/**
+ * Retire an old daemon that has no live PTYs. Without this, every protocol
+ * generation remains resident after an update even when all of its sessions
+ * have exited (#9138).
+ */
+async function retireIdleLegacyDaemon(
+  socketPath: string,
+  tokenPath: string,
+  protocolVersion: number
+): Promise<boolean> {
+  const client = new DaemonClient({ socketPath, tokenPath, protocolVersion })
+  try {
+    await client.ensureConnectedWithin(1_000)
+    const { sessions } = await client.request<ListSessionsResult>('listSessions', undefined, 1_000)
+    if (sessions.some((session) => session.isAlive)) {
+      return false
+    }
+    if (protocolVersion >= CLEAN_DISCONNECT_PROTOCOL_VERSION) {
+      const result = await client.request<ShutdownIfIdleResult>('shutdownIfIdle', undefined, 1_000)
+      return result.retiring
+    }
+    // Older generations predate shutdownIfIdle; the inventory just proved that
+    // killing this daemon cannot take a live PTY with it.
+    await client.request('shutdown', { killSessions: true }, 1_000)
+    return true
+  } catch {
+    // A failed inventory is not evidence of idleness; preserve the adapter so
+    // its sessions remain adoptable on the next startup.
+    return false
+  } finally {
+    client.disconnect()
+  }
+}
+
 // Why: callers that own an isolated runtime namespace must keep discovery history out of app userData.
 export async function createLegacyDaemonAdapters(
   runtimeDir: string,
@@ -48,6 +88,9 @@ export async function createLegacyDaemonAdapters(
       }
       continue
     }
+    if (await retireIdleLegacyDaemon(socketPath, tokenPath, protocolVersion)) {
+      continue
+    }
     // Keep old-protocol PTYs routed to their original daemon during upgrade; legacy adapters never respawn (new code would recreate stale env semantics).
     // historyPath is still needed for cleanup — without it a later v4 session reusing the same ID could false-restore stale scrollback.bin.
     adapters.push(