From 1d0e262d9ca8043e83fc63ee061af009d347b613 Mon Sep 17 00:00:00 2001
From: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>
Date: Thu, 27 Aug 2026 09:35:49 -0700
Subject: [PATCH] fix(daemon): recover concurrent spawns after disconnect

---
 src/main/daemon/daemon-endpoint-errors.ts     |  4 +
 ...on-pty-adapter-concurrent-recovery.test.ts | 78 +++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 src/main/daemon/daemon-pty-adapter-concurrent-recovery.test.ts

diff --git a/src/main/daemon/daemon-endpoint-errors.ts b/src/main/daemon/daemon-endpoint-errors.ts
index 663b11ff3fa..b792f0e7044 100644
--- a/src/main/daemon/daemon-endpoint-errors.ts
+++ b/src/main/daemon/daemon-endpoint-errors.ts
@@ -1,4 +1,5 @@
 import { DAEMON_ENDPOINT_LOST_MESSAGE } from './daemon-endpoint-ownership'
+import { DaemonConnectionLostError } from './daemon-errors'
 import { DAEMON_UNAVAILABLE_RECONNECT_MESSAGE } from './types'
 
 /**
@@ -17,6 +18,9 @@ export function isDaemonGoneError(err: unknown): boolean {
   if (!(err instanceof Error)) {
     return false
   }
+  if (err instanceof DaemonConnectionLostError) {
+    return true
+  }
   const errno = err as NodeJS.ErrnoException
   if ((errno.code === 'ENOENT' || errno.code === 'ECONNREFUSED') && errno.syscall === 'connect') {
     return true
diff --git a/src/main/daemon/daemon-pty-adapter-concurrent-recovery.test.ts b/src/main/daemon/daemon-pty-adapter-concurrent-recovery.test.ts
new file mode 100644
index 00000000000..12805c0b3ee
--- /dev/null
+++ b/src/main/daemon/daemon-pty-adapter-concurrent-recovery.test.ts
@@ -0,0 +1,78 @@
+import { expect, it, vi } from 'vitest'
+import { mkdtempSync, rmSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { DaemonPtyAdapter } from './daemon-pty-adapter'
+import { DaemonServer } from './daemon-server'
+import { createMockSubprocess } from './daemon-pty-adapter-test-harness'
+import { getDaemonSocketPath } from './daemon-spawner'
+
+it('recovers concurrent spawns rejected by an adapter-initiated disconnect', async () => {
+  const concurrentSpawnCount = 70
+  const dir = mkdtempSync(join(tmpdir(), 'daemon-concurrent-recovery-test-'))
+  const socketPath = getDaemonSocketPath(dir)
+  const tokenPath = join(dir, 'test.token')
+  const allPreparationsEntered = Promise.withResolvers<void>()
+  const releaseHeldPreparations = Promise.withResolvers<void>()
+  const spawnedSessionIds: string[] = []
+  let preparationCount = 0
+
+  const spawnSubprocess: ConstructorParameters<typeof DaemonServer>[0]['spawnSubprocess'] = (
+    options
+  ) => {
+    spawnedSessionIds.push(options.sessionId)
+    return createMockSubprocess()
+  }
+  let server = new DaemonServer({
+    socketPath,
+    tokenPath,
+    spawnSubprocess,
+    // Hold siblings until one retriable reply makes the adapter disconnect their shared socket.
+    preparePtySpawn: async () => {
+      const preparationNumber = ++preparationCount
+      if (preparationCount === concurrentSpawnCount) {
+        allPreparationsEntered.resolve()
+      }
+      await allPreparationsEntered.promise
+      if (preparationNumber === 1) {
+        throw new Error('Connection lost')
+      }
+      await releaseHeldPreparations.promise
+    }
+  })
+  await server.start()
+
+  const respawn = vi.fn(async () => {
+    await server.shutdown()
+    releaseHeldPreparations.resolve()
+    server = new DaemonServer({ socketPath, tokenPath, spawnSubprocess })
+    await server.start()
+  })
+  const adapter = new DaemonPtyAdapter({ socketPath, tokenPath, respawn })
+
+  try {
+    const sessionIds = Array.from(
+      { length: concurrentSpawnCount },
+      (_, index) => `high-volume-${index}`
+    )
+    const results = await Promise.all(
+      sessionIds.map((sessionId) => adapter.spawn({ sessionId, cols: 80, rows: 24 }))
+    )
+
+    expect(preparationCount).toBe(concurrentSpawnCount)
+    expect(respawn).toHaveBeenCalledTimes(1)
+    expect(respawn).toHaveBeenCalledWith('daemon_died')
+    expect(new Set(results.map(({ id }) => id))).toEqual(new Set(sessionIds))
+    expect(new Set(spawnedSessionIds)).toEqual(new Set(sessionIds))
+
+    const later = await adapter.spawn({ sessionId: 'after-recovery', cols: 80, rows: 24 })
+    expect(later.id).toBe('after-recovery')
+    expect(respawn).toHaveBeenCalledTimes(1)
+    expect(spawnedSessionIds).toHaveLength(concurrentSpawnCount + 1)
+  } finally {
+    adapter.dispose()
+    releaseHeldPreparations.resolve()
+    await server.shutdown()
+    rmSync(dir, { recursive: true, force: true })
+  }
+})